Dosing & Uses
Dosage Forms & Strengths
tablet (Tenex)
- 1mg
- 2mg
Hypertension
Tenex: 1 mg PO qHS; may increase to 2 mg after 3-4 weeks
Usual range 0.5-2 mg/day
Do not exceed 3 mg qDay due to increased risk of adverse effects
Heroin Withdrawal (Off-label)
0.03-1.75 mg/day PO for 5-15 days
Migraine Prophylaxis (Off-label)
Initial: 1 mg/day; do not exceed 3 mg/day
Fragile X Syndrome (Orphan)
Orphan sponsor
- Watson Laboratories, Inc; 311 Bonnie Circle, PO Box 1900; Corona, CA 91718-1900
Dosage Modifications
Strong or moderate CYP3A4 inhibitors
- Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations
- FDA-labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the reommended dose; specific recommendations for immediate-release (IR) guanfacine are not available
- Starting therapy while currently taking CYP3A4 inhibitor: Decrease dose to half the recommended level
- Continuing therapy while adding CYP3A4 inhibitor: Decrease dose to half the recommended level
- Continuing therapy while stopping CYP3A4 inhibitor: Increase dose to recommended level
Strong or moderate CYP3A4 inducers
- CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life
- If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response
- For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered
- Starting therapy while currently taking CYP3A4 inducer: Increase dose up to double the recommended level
- Continuing therapy while adding CYP3A4 inducer: Increase dose up to double the recommended level over 1-2 weeks
- Continuing therapy while stopping CYP3A4 inducer: Increase dose to recommended level
Discontinuation of therapy
- To minimize risk of rebound hypertension upon discontinuation, taper total daily dose in decrements of no more than 1 mg every 3 to 7 days; blood pressure and heart rate should be monitored when reducing dose or discontinuing therapy; follow patients closely for rebound hypertension if abrupt discontinuation occurs (especially with concomitant stimulant use)
Dosage Forms & Strengths
tablet (Tenex)
- 1mg
- 2mg
tablet, extended-release (Intuniv)
- 1mg
- 2mg
- 3mg
- 4mg
Hypertension
<12 years
- Safety and efficacy not established
≥12 years
- Tenex: 1 mg PO qHS; may increase to 2-3 mg after 3-4 weeks
- Usual range: 0.5-2 mg/day
Attention Deficit Hyperactivity Disorder
Intuniv only
Monotherapy for ADHD or adjunct to stimulants
<6 years: Safety and efficacy not established
6-18 years
- Intuniv: 1 mg/day PO initially; may adjust dose using increasing increments (not exceeding 1 mg/wk)
- To balance the exposure-related potential benefits and risks, recommended target dose range depending on clinical response and tolerability is 0.05-0.12 mg/kg/day PO initially
- Aged 6-12 years: Doses >4 mg/day not evaluated
- Aged 13-17 years: Doses >7 mg/day not evaluated
- Adjunctive trials with psychostimulants: Doses >4 mg/day not evaluated
Target dose range by weight
- 25-33.9 kg: 2-3 mg/day
- 34-41.4 kg: 2-4 mg/day
- 41.5-49.4 kg: 3-5 mg/day
- 49.5-58.4 kg: 3-6 mg/day
- 58.5-91 kg: 4-7 mg/day
- >91 kg: 5-7 mg/day
Dosage Modifications
Extended-release tablets
- Renal impairment: Dose reduction may be necessary in patients with significant impairment of renal function
- Hepatic impairment: Dose reduction may be necessary in patients with significant impairment of hepatic function
Strong or moderate CYP3A4 inhibitors
- Strong or moderate CYP3A4 inhibitors (eg, ketoconazole) significantly increase guanfacine plasma concentrations
- Starting therapy while currently taking CYP3A4 inhibitor: Decrease dose to half the recommended level
- Continuing therapy while adding CYP3A4 inhibitor: Decrease dose to half the recommended level
- Continuing therapy while stopping CYP3A4 inhibitor: Increase dose to recommended level
Strong or moderate CYP3A4 inducers
- CYP3A4 inducers (eg, carbamazepine) significantly reduce guanfacine plasma concentrations and elimination half-life
- If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response
Extended-release tablets
- Starting therapy while currently taking CYP3A4 inducer: Increase dose up to double the recommended level
- Continuing therapy while adding CYP3A4 inducer: Increase dose up to double the recommended level over 1-2 weeks
- Continuing therapy while stopping CYP3A4 inducer: Decrease dose to recommended level over 1-2 weeks
Dosing Considerations
Immediate-release and extended-release formulations are not interchangeable due to differences in bioavailability
If switching from immediate-release guanfacine, discontinue treatment; titrate with extended-release tablets following recommended schedule
Discontinuation of extended-release guanfacine
- Following discontinuation of extended-release tablets, patients may experience increases in blood pressure and heart rate
- Monitor blood pressure and pulse when reducing dose or discontinuing treatment
- Taper daily dose in decrements of ≤1 mg q3-7d to minimize the risk of rebound hypertension
Tourette Syndrome (Orphan)
Orphan designation for combination of guanfacine and amphetamine to treatment Tourette syndrome
Sponsor
- Genco Sciences, LLC; 1011 Greenwood Avenue; Willmette, Illinois 60091
Interactions
Interaction Checker
No Results

Contraindicated
Serious - Use Alternative
Significant - Monitor Closely
Minor

Contraindicated (0)
Serious - Use Alternative (29)
- amitriptyline
amitriptyline decreases effects of guanfacine by Other (see comment). Avoid or Use Alternate Drug. Comment: Inhibition of uptake by adrenergic neurons.
- amoxapine
amoxapine decreases effects of guanfacine by Other (see comment). Avoid or Use Alternate Drug. Comment: Inhibition of uptake by adrenergic neurons.
- apalutamide
apalutamide will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of apalutamide, a strong CYP3A4 inducer, with drugs that are CYP3A4 substrates can result in lower exposure to these medications. Avoid or substitute another drug for these medications when possible. Evaluate for loss of therapeutic effect if medication must be coadministered. Adjust dose according to prescribing information if needed.
- ceritinib
ceritinib will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- chloramphenicol
chloramphenicol will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
- clomipramine
clomipramine decreases effects of guanfacine by Other (see comment). Avoid or Use Alternate Drug. Comment: Inhibition of uptake by adrenergic neurons.
- cobicistat
cobicistat will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
- desipramine
desipramine decreases effects of guanfacine by Other (see comment). Avoid or Use Alternate Drug. Comment: Inhibition of uptake by adrenergic neurons.
- doxepin
doxepin decreases effects of guanfacine by Other (see comment). Avoid or Use Alternate Drug. Comment: Inhibition of uptake by adrenergic neurons.
- fexinidazole
fexinidazole will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Fexinidazole inhibits CYP3A4. Coadministration may increase risk for adverse effects of CYP3A4 substrates.
- imipramine
imipramine decreases effects of guanfacine by Other (see comment). Avoid or Use Alternate Drug. Comment: Inhibition of uptake by adrenergic neurons.
- iobenguane I 131
guanfacine will decrease the level or effect of iobenguane I 131 by Other (see comment). Avoid or Use Alternate Drug. Based on the mechanism of action of iobenguane, drugs that reduce catecholamine uptake or that deplete catecholamine stores may interfere with iobenguane uptake into cells, and thus, reduce iobenguane efficacy. Discontinue interfering drugs for at least 5 half-lives before administration of either the dosimetry or an iobenguane dose. Do not administer these drugs until at least 7 days after each iobenguane dose.
- ivosidenib
ivosidenib will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP3A4 substrates with ivosidenib or replace with alternate therapies. If coadministration is unavoidable, monitor patients for loss of therapeutic effect of these drugs.
- lofepramine
lofepramine decreases effects of guanfacine by Other (see comment). Avoid or Use Alternate Drug. Comment: Inhibition of uptake by adrenergic neurons.
- lofexidine
lofexidine, guanfacine. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid coadministration with other drugs that decrease pulse or blood pressure to mitigate risk of excessive bradycardia and hypotension.
- lorlatinib
lorlatinib will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
- maprotiline
maprotiline decreases effects of guanfacine by Other (see comment). Avoid or Use Alternate Drug. Comment: Inhibition of uptake by adrenergic neurons.
- metoclopramide intranasal
guanfacine, metoclopramide intranasal. Either increases effects of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid use of metoclopramide intranasal or interacting drug, depending on importance of drug to patient.
- mifepristone
mifepristone will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
- mirtazapine
mirtazapine decreases effects of guanfacine by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of hypertensive urgency.
- nortriptyline
nortriptyline decreases effects of guanfacine by Other (see comment). Avoid or Use Alternate Drug. Comment: Inhibition of uptake by adrenergic neurons.
- olopatadine intranasal
guanfacine and olopatadine intranasal both increase sedation. Avoid or Use Alternate Drug. Coadministration increases risk of CNS depression, which can lead to additive impairment of psychomotor performance and cause daytime impairment.
- ponesimod
ponesimod, guanfacine. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Consult cardiologist if considering treatment. Coadministration of ponesimod with drugs that decrease HR may have additive effects on decreasing HR and should generally not be initiated in these patients.
- protriptyline
protriptyline decreases effects of guanfacine by Other (see comment). Avoid or Use Alternate Drug. Comment: Inhibition of uptake by adrenergic neurons.
- ropeginterferon alfa 2b
ropeginterferon alfa 2b and guanfacine both increase Other (see comment). Avoid or Use Alternate Drug. Narcotics, hypnotics or sedatives can produce additive neuropsychiatric side effects. Avoid use and monitor patients receiving the combination for effects of excessive CNS toxicity.
- trazodone
trazodone decreases effects of guanfacine by Other (see comment). Avoid or Use Alternate Drug. Comment: Inhibition of uptake by adrenergic neurons.
- trimipramine
trimipramine decreases effects of guanfacine by Other (see comment). Avoid or Use Alternate Drug. Comment: Inhibition of uptake by adrenergic neurons.
- tucatinib
tucatinib will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid concomitant use of tucatinib with CYP3A substrates, where minimal concentration changes may lead to serious or life-threatening toxicities. If unavoidable, reduce CYP3A substrate dose according to product labeling.
- voxelotor
voxelotor will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Voxelotor increases systemic exposure of sensitive CYP3A4 substrates. Avoid coadministration with sensitive CYP3A4 substrates with a narrow therapeutic index. Consider dose reduction of the sensitive CYP3A4 substrate(s) if unable to avoid.
Monitor Closely (155)
- acrivastine
acrivastine and guanfacine both increase sedation. Use Caution/Monitor.
- aldesleukin
aldesleukin increases effects of guanfacine by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.
- amifostine
amifostine, guanfacine. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration with blood pressure lowering agents may increase the risk and severity of hypotension associated with amifostine. When amifostine is used at chemotherapeutic doses, withhold blood pressure lowering medications for 24 hr prior to amifostine; if blood pressure lowering medication cannot be withheld, do not administer amifostine.
- amiodarone
amiodarone will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- amisulpride
amisulpride and guanfacine both increase sedation. Use Caution/Monitor.
- amobarbital
amobarbital will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- aprepitant
aprepitant will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- aripiprazole
guanfacine, aripiprazole. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
- armodafinil
armodafinil will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- artemether/lumefantrine
artemether/lumefantrine will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- asenapine
asenapine and guanfacine both increase sedation. Use Caution/Monitor.
- asenapine transdermal
asenapine transdermal and guanfacine both increase sedation. Use Caution/Monitor.
- atazanavir
atazanavir will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- avanafil
avanafil increases effects of guanfacine by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.
- avapritinib
avapritinib and guanfacine both increase sedation. Use Caution/Monitor.
- belzutifan
belzutifan will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If unable to avoid coadministration of belzutifan with sensitive CYP3A4 substrates, consider increasing the sensitive CYP3A4 substrate dose in accordance with its prescribing information.
- benperidol
guanfacine, benperidol. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
- benzhydrocodone/acetaminophen
benzhydrocodone/acetaminophen and guanfacine both increase sedation. Use Caution/Monitor.
- bicalutamide
bicalutamide will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- bosentan
bosentan will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- brexanolone
brexanolone, guanfacine. Either increases toxicity of the other by sedation. Use Caution/Monitor.
- brexpiprazole
brexpiprazole and guanfacine both increase sedation. Use Caution/Monitor.
- brimonidine
brimonidine and guanfacine both increase sedation. Use Caution/Monitor.
- brivaracetam
brivaracetam and guanfacine both increase sedation. Use Caution/Monitor.
- buprenorphine subdermal implant
buprenorphine subdermal implant and guanfacine both increase sedation. Use Caution/Monitor.
- buprenorphine transdermal
buprenorphine transdermal and guanfacine both increase sedation. Use Caution/Monitor.
- buprenorphine, long-acting injection
buprenorphine, long-acting injection and guanfacine both increase sedation. Use Caution/Monitor.
- butabarbital
butabarbital will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- butalbital
butalbital will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- carbamazepine
carbamazepine will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- carbidopa
carbidopa increases effects of guanfacine by pharmacodynamic synergism. Use Caution/Monitor. Therapy with carbidopa, given with or without levodopa or carbidopa-levodopa combination products, is started, dosage adjustment of the antihypertensive drug may be required.
- cenobamate
cenobamate will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Increase dose of CYP3A4 substrate, as needed, when coadministered with cenobamate.
- chlorpromazine
guanfacine, chlorpromazine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
- clarithromycin
clarithromycin will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- clobazam
guanfacine, clobazam. Other (see comment). Use Caution/Monitor. Comment: Concomitant administration can increase the potential for CNS effects (e.g., increased sedation or respiratory depression).
clobazam will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered. - clonidine
clonidine, guanfacine. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Sympatholytic action may worsen sinus node dysfunction and atrioventricular (AV) block.
- clozapine
guanfacine, clozapine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
- conivaptan
conivaptan will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- crizotinib
crizotinib will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- cyclosporine
cyclosporine will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- dabrafenib
dabrafenib will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- daridorexant
guanfacine and daridorexant both increase sedation. Modify Therapy/Monitor Closely. Coadministration increases risk of CNS depression, which can lead to additive impairment of psychomotor performance and cause daytime impairment.
- darunavir
darunavir will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- dexamethasone
dexamethasone will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- DHEA, herbal
DHEA, herbal will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- difelikefalin
difelikefalin and guanfacine both increase sedation. Use Caution/Monitor.
- diltiazem
diltiazem will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce guanfacine ER dose by 50% when initiating concomitant therapy with a moderate CYP3A4 inhibitor. When discontinuing moderate CYP3A4 inhibitor, increase guanfacine dose to recommended dose range. Monitor for excessive guanfacine response (eg, hypotension, bradycardia, CNS depression).
- doxycycline
doxycycline will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- dronedarone
dronedarone will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- droperidol
guanfacine, droperidol. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
- duvelisib
duvelisib will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with duvelisib increases AUC of a sensitive CYP3A4 substrate which may increase the risk of toxicities of these drugs. Consider reducing the dose of the sensitive CYP3A4 substrate and monitor for signs of toxicities of the coadministered sensitive CYP3A substrate.
- efavirenz
efavirenz will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- elagolix
elagolix decreases levels of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak-to-moderate CYP3A4 inducer. Monitor CYP3A substrates if coadministered. Consider increasing CYP3A substrate dose if needed.
- elvitegravir/cobicistat/emtricitabine/tenofovir DF
elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available. .
- encorafenib
encorafenib, guanfacine. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Encorafenib both inhibits and induces CYP3A4 at clinically relevant plasma concentrations. Coadministration of encorafenib with sensitive CYP3A4 substrates may result in increased toxicity or decreased efficacy of these agents.
- enzalutamide
enzalutamide will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- epinephrine inhaled
guanfacine, epinephrine inhaled. Either increases effects of the other by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
- erythromycin base
erythromycin base will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- erythromycin ethylsuccinate
erythromycin ethylsuccinate will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- erythromycin lactobionate
erythromycin lactobionate will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- erythromycin stearate
erythromycin stearate will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- esketamine intranasal
esketamine intranasal, guanfacine. Either increases toxicity of the other by sedation. Use Caution/Monitor.
esketamine intranasal, guanfacine. Either increases toxicity of the other by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. Closely monitor blood pressure with concomitant use of esketamine nasal with stimulants. . - eslicarbazepine acetate
eslicarbazepine acetate will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- etravirine
etravirine will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- fedratinib
fedratinib will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP3A4 substrates as necessary.
- fentanyl
fentanyl and guanfacine both increase sedation. Use Caution/Monitor.
- fentanyl intranasal
fentanyl intranasal and guanfacine both increase sedation. Use Caution/Monitor.
- fentanyl iontophoretic transdermal system
fentanyl iontophoretic transdermal system and guanfacine both increase sedation. Use Caution/Monitor.
- fentanyl transdermal
fentanyl transdermal and guanfacine both increase sedation. Use Caution/Monitor.
- fluconazole
fluconazole will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- fluphenazine
guanfacine, fluphenazine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
- fluvoxamine
fluvoxamine will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If coadministered with extended release, reduce guanfacine dosage in half of recommended dose; specific recommendation for immediate release form not available
- fosamprenavir
fosamprenavir will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- fosaprepitant
fosaprepitant will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- fosphenytoin
fosphenytoin will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- ganaxolone
guanfacine and ganaxolone both increase sedation. Use Caution/Monitor.
- grapefruit
grapefruit will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- haloperidol
guanfacine, haloperidol. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
haloperidol will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available. - hydrocortisone
hydrocortisone will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- idelalisib
idelalisib will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- iloperidone
guanfacine, iloperidone. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
iloperidone increases levels of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available. . - imatinib
imatinib will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- indinavir
indinavir will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- isoniazid
isoniazid will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- istradefylline
istradefylline will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of CYP3A4 substrates in clinical trials. This effect was not observed with istradefylline 20 mg/day. Consider dose reduction of sensitive CYP3A4 substrates.
- itraconazole
itraconazole will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. For extended-release (ER) guanfacine, if coadministered, decrease the guanfacine dosage to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- ketoconazole
ketoconazole will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- lapatinib
lapatinib will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- lasmiditan
lasmiditan, guanfacine. Either increases effects of the other by sedation. Use Caution/Monitor. Coadministration of lasmiditan and other CNS depressant drugs, including alcohol have not been evaluated in clinical studies. Lasmiditan may cause sedation, as well as other cognitive and/or neuropsychiatric adverse reactions.
- lemborexant
lemborexant, guanfacine. Either increases effects of the other by sedation. Modify Therapy/Monitor Closely. Dosage adjustment may be necessary if lemborexant is coadministered with other CNS depressants because of potentially additive effects.
- lenacapavir
lenacapavir will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lencapavir may increase CYP3A4 substrates initiated within 9 months after last SC dose of lenacapavir, which may increase potential risk of adverse reactions of CYP3A4 substrates.
- levodopa
levodopa increases effects of guanfacine by pharmacodynamic synergism. Use Caution/Monitor. Consider decreasing dosage of antihypertensive agent.
- levoketoconazole
levoketoconazole will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- lopinavir
lopinavir will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- loxapine
guanfacine, loxapine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
- loxapine inhaled
guanfacine, loxapine inhaled. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
- lumacaftor/ivacaftor
lumacaftor/ivacaftor will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- lurasidone
lurasidone increases effects of guanfacine by Other (see comment). Use Caution/Monitor. Comment: Potential for increased risk of hypotension with concurrent use. Monitor blood pressure and adjust dose of antihypertensive agent as needed.
lurasidone, guanfacine. Either increases toxicity of the other by sedation. Use Caution/Monitor. Potential for increased CNS depressant effects when used concurrently; monitor for increased adverse effects and toxicity. - metronidazole
metronidazole will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- midazolam intranasal
midazolam intranasal, guanfacine. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Concomitant use of barbiturates, alcohol, or other CNS depressants may increase the risk of hypoventilation, airway obstruction, desaturation, or apnea and may contribute to profound and/or prolonged drug effect.
- mitotane
mitotane decreases levels of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- nadolol
nadolol, guanfacine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Non selective beta blocker administration during withdrawal from centrally acting alpha agonists may result in rebound hypertension.
- nafcillin
nafcillin will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- nefazodone
nefazodone will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- nelfinavir
nelfinavir will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- netupitant/palonosetron
netupitant/palonosetron will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- nevirapine
nevirapine will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- nicardipine
nicardipine will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- nilotinib
nilotinib will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- nitroglycerin rectal
nitroglycerin rectal, guanfacine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Observe for possible additive hypotensive effects during concomitant use. .
- nitroprusside sodium
nitroprusside sodium, guanfacine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.
- olanzapine
guanfacine, olanzapine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
- oxcarbazepine
oxcarbazepine will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- paliperidone
guanfacine, paliperidone. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
- pentobarbital
pentobarbital will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- perphenazine
guanfacine, perphenazine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
- phenobarbital
phenobarbital will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- phenytoin
phenytoin will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- pimozide
guanfacine, pimozide. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
- pindolol
pindolol, guanfacine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Non selective beta blocker administration during withdrawal from centrally acting alpha agonists may result in rebound hypertension.
- posaconazole
posaconazole will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- primidone
primidone will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- prochlorperazine
guanfacine, prochlorperazine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
- promethazine
guanfacine, promethazine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
- propranolol
propranolol, guanfacine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Non selective beta blocker administration during withdrawal from centrally acting alpha agonists may result in rebound hypertension.
- quetiapine
guanfacine, quetiapine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
- quinupristin/dalfopristin
quinupristin/dalfopristin will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- ribociclib
ribociclib will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.
- rifabutin
rifabutin will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- rifampin
rifampin will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- rifapentine
rifapentine will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- risperidone
guanfacine, risperidone. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
- ritonavir
ritonavir will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- rucaparib
rucaparib will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust dosage of CYP3A4 substrates, if clinically indicated.
- saquinavir
saquinavir will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- schisandra
schisandra will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- secobarbital
secobarbital will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- sertraline
sertraline will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- sofosbuvir/velpatasvir
sofosbuvir/velpatasvir will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- St John's Wort
St John's Wort will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inducers significantly reduce guanfacine plasma concentrations and elimination half-life. If coadministered, more frequent dosing of the IR product may be required to achieve or maintain the desired hypotensive response. For patients with ADHD, FDA-approved labeling for ER guanfacine recommends that, if coadministered, doubling the recommended dose of guanfacine should be considered.
- stiripentol
stiripentol, guanfacine. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Stiripentol is a CYP3A4 inhibitor and inducer. Monitor CYP3A4 substrates coadministered with stiripentol for increased or decreased effects. CYP3A4 substrates may require dosage adjustment.
stiripentol, guanfacine. Either increases effects of the other by sedation. Use Caution/Monitor. Concomitant use stiripentol with other CNS depressants, including alcohol, may increase the risk of sedation and somnolence. - tadalafil
tadalafil increases effects of guanfacine by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.
- tazemetostat
tazemetostat will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- tecovirimat
tecovirimat will decrease the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Tecovirimat is a weak CYP3A4 inducer. Monitor sensitive CYP3A4 substrates for effectiveness if coadministered.
- thioridazine
guanfacine, thioridazine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
- thiothixene
guanfacine, thiothixene. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
- timolol
timolol, guanfacine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Non selective beta blocker administration during withdrawal from centrally acting alpha agonists may result in rebound hypertension.
- tipranavir
tipranavir will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- trifluoperazine
guanfacine, trifluoperazine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
- valproic acid
guanfacine increases levels of valproic acid by unknown mechanism. Use Caution/Monitor. Both 3-hydroxy guanfacine (metabolite) and valproic acid are metabolized by glucuronidation, possibly resulting in competitive inhibition.
- verapamil
verapamil will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- voriconazole
voriconazole will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.
- xipamide
xipamide increases effects of guanfacine by pharmacodynamic synergism. Use Caution/Monitor.
- ziprasidone
guanfacine, ziprasidone. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
- zotepine
guanfacine, zotepine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
Minor (47)
- acarbose
guanfacine decreases effects of acarbose by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia.
guanfacine, acarbose. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production. - acebutolol
acebutolol, guanfacine. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Selective beta blocker administration during withdrawal from centrally acting alpha agonists may result in rebound hypertension.
- acetazolamide
acetazolamide will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
- agrimony
agrimony increases effects of guanfacine by pharmacodynamic synergism. Minor/Significance Unknown.
- anastrozole
anastrozole will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
- atenolol
atenolol, guanfacine. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Selective beta blocker administration during withdrawal from centrally acting alpha agonists may result in rebound hypertension.
- betaxolol
betaxolol, guanfacine. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Selective beta blocker administration during withdrawal from centrally acting alpha agonists may result in rebound hypertension.
- bisoprolol
bisoprolol, guanfacine. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Selective beta blocker administration during withdrawal from centrally acting alpha agonists may result in rebound hypertension.
- brimonidine
brimonidine increases effects of guanfacine by pharmacodynamic synergism. Minor/Significance Unknown.
- celiprolol
celiprolol, guanfacine. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Selective beta blocker administration during withdrawal from centrally acting alpha agonists may result in rebound hypertension.
- chlorpropamide
guanfacine decreases effects of chlorpropamide by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia.
guanfacine, chlorpropamide. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production. - cornsilk
cornsilk increases effects of guanfacine by pharmacodynamic synergism. Minor/Significance Unknown.
- cyclophosphamide
cyclophosphamide will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
- esmolol
esmolol, guanfacine. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Selective beta blocker administration during withdrawal from centrally acting alpha agonists may result in rebound hypertension.
- forskolin
forskolin increases effects of guanfacine by pharmacodynamic synergism. Minor/Significance Unknown.
- glimepiride
guanfacine decreases effects of glimepiride by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia.
guanfacine, glimepiride. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production. - glipizide
guanfacine decreases effects of glipizide by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia.
guanfacine, glipizide. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production. - glyburide
guanfacine decreases effects of glyburide by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia.
guanfacine, glyburide. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production. - insulin aspart
guanfacine decreases effects of insulin aspart by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia.
guanfacine, insulin aspart. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production. - insulin detemir
guanfacine, insulin detemir. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production.
guanfacine decreases effects of insulin detemir by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia. - insulin glargine
guanfacine, insulin glargine. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production.
guanfacine decreases effects of insulin glargine by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia. - insulin glulisine
guanfacine, insulin glulisine. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production.
guanfacine decreases effects of insulin glulisine by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia. - insulin lispro
guanfacine decreases effects of insulin lispro by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia.
guanfacine, insulin lispro. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production. - insulin NPH
guanfacine, insulin NPH. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production.
guanfacine decreases effects of insulin NPH by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia. - insulin regular human
guanfacine decreases effects of insulin regular human by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia.
guanfacine, insulin regular human. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production. - larotrectinib
larotrectinib will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
- maitake
maitake increases effects of guanfacine by pharmacodynamic synergism. Minor/Significance Unknown.
- metformin
guanfacine decreases effects of metformin by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia.
guanfacine, metformin. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production. - metoprolol
metoprolol, guanfacine. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Selective beta blocker administration during withdrawal from centrally acting alpha agonists may result in rebound hypertension.
- miglitol
guanfacine decreases effects of miglitol by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia.
guanfacine, miglitol. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production. - nateglinide
guanfacine decreases effects of nateglinide by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia.
guanfacine, nateglinide. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production. - nebivolol
nebivolol, guanfacine. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Selective beta blocker administration during withdrawal from centrally acting alpha agonists may result in rebound hypertension.
- octacosanol
octacosanol increases effects of guanfacine by pharmacodynamic synergism. Minor/Significance Unknown.
- penbutolol
penbutolol, guanfacine. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Selective beta blocker administration during withdrawal from centrally acting alpha agonists may result in rebound hypertension.
- pioglitazone
guanfacine decreases effects of pioglitazone by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia.
guanfacine, pioglitazone. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production. - reishi
reishi increases effects of guanfacine by pharmacodynamic synergism. Minor/Significance Unknown.
- repaglinide
guanfacine decreases effects of repaglinide by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia.
guanfacine, repaglinide. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production. - rosiglitazone
guanfacine decreases effects of rosiglitazone by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia.
guanfacine, rosiglitazone. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production. - saxagliptin
guanfacine decreases effects of saxagliptin by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia.
guanfacine, saxagliptin. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production. - shepherd's purse
shepherd's purse, guanfacine. Other (see comment). Minor/Significance Unknown. Comment: Theoretically, shepherd's purse may interfere with BP control.
- sitagliptin
guanfacine decreases effects of sitagliptin by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia.
guanfacine, sitagliptin. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production. - sotalol
sotalol, guanfacine. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Selective beta blocker administration during withdrawal from centrally acting alpha agonists may result in rebound hypertension.
- tizanidine
tizanidine increases effects of guanfacine by pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypotension.
- tolazamide
guanfacine decreases effects of tolazamide by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia.
guanfacine, tolazamide. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production. - tolbutamide
guanfacine decreases effects of tolbutamide by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia.
guanfacine, tolbutamide. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production. - treprostinil
treprostinil increases effects of guanfacine by pharmacodynamic synergism. Minor/Significance Unknown.
- vildagliptin
guanfacine decreases effects of vildagliptin by pharmacodynamic antagonism. Minor/Significance Unknown. Diminished symptoms of hypoglycemia.
guanfacine, vildagliptin. Other (see comment). Minor/Significance Unknown. Comment: Decreased symptoms of hypoglycemia. Mechanism: decreased hypoglycemia induced catecholamine production.
Adverse Effects
>10%
Xerostomia (10-60%)
Somnolence (5-39%)
Headache (0.2-26%)
Dizziness (2-15%)
Constipation (2-16%)
Fatigue (2-15%)
Abdominal pain (11%)
Extended-release tablets
- Somnolence (6-38%)
- Headache (23%)
- Dizziness (6-16%)
- Decreased appetite (6-15%)
- Fatigue (2-14%)
- Abdominal pain (11%)
1-10%
Hypotension (7%)
Asthenia (2-7%)
Impotence (0-7%)
Lethargy (6%)
Dizziness (6%)
Irritability (6%)
Nausea (3-6%)
Decreased appetite (5%)
Weakness (1-5%)
Insomnia (3-4%)
Bradycardia (3%)
Palpitations (3%)
Confusion (3%)
Depression (3%)
Dyspnea (3%)
Alopecia (3%)
Dermatitis (3%)
Diaphoresis (3%)
Pruritus (3%)
Dyspepsia (3%)
Dysphagia (3%)
Hypokinesia (3%)
Leg cramps (3%)
Extended-release tablets
- Hypotension (7%)
- Insomnia (7%)
- Irritability (6%)
- Lethargy (6%)
- Nausea (6%)
- Postural dizziness (5%)
- Bradycardia (5%)
- Diarrhea (5%)
- Anxiety (5%)
- Dry mouth (3-4%)
- Constipation (3%)
- Increased weight (3%)
- Rash (3%)
- Nightmare (2%)
- Enuresis (2%)
Frequency Not Defined
Orthostatic hypotension
Exfoliation
Rash
Arthralgia
Myalgia
Extended-release tablets
- Atrioventricular block
- Asthenia
- Chest pain
- Hypersensitivity
- Increased alanine aminotransferase
- Convulsion Increased urinary frequency
- Hypertension
- Pallor
Postmarketing Reports
Cardiovascular: Bradycardia, palpitations, syncope, tachycardia, rebound hypertension, hypertensive encephalopathy
CNS: Paresthesias, vertigo
GI: Abdominal pain, constipation, diarrhea, dyspepsia
Liver/biliary: Abnormal LFTs
Musculoskeletal: Arthralgia, leg cramps, leg pain, myalgia
Psychiatric: Agitation, anxiety, confusion, depression, hallucinations, insomnia, nervousness
Reproductive: Impotence
Respiratory: Dyspnea
Skin: Alopecia, dermatitis, exfoliative dermatitis, pruritus, rash
Sensory: Blurred vision, alterations in taste
Urinary: Nocturia, urinary frequency
Other: Asthenia, chest pain, edema, malaise, tremor
Extended-release tablets
- General: Edema, malaise, tremor
- Cardiovascular: Palpitations, tachycardia, rebound hypertension, hypertensive encephalopathy
- Central nervous system: Paresthesias, vertigo
- Eye disorders: blurred vision
- Musculoskeletal System: Arthralgia, leg cramps, leg pain, myalgia
- Psychiatric: Confusion, hallucinations
- Reproductive system, male: Erectile dysfunction
- Respiratory System: Dyspnea
- Skin and appendages: Alopecia, dermatitis, exfoliative dermatitis, pruritus, rash
- Special senses: Alterations in taste
Warnings
Contraindications
Hypersensitivity
Cautions
Avoid abrupt withdrawal (can result in anxiety, nervousness, and rebound hypertension)
May cause hypotension, orthostasis, bradycardia, and syncope, use with caution in history of cerebrovascular disease, recent MI, severe coronary insufficiency, or syncope
Chronic renal/hepatic failure
May cause sedation, especially at start; avoid operating heavy machinery
Skin rash with exfoliation reported
Avoid concomitant use with other CNS depressants (eg, alcohol) as they may potentiate CNS effects
Risk of cardiovascular effects may increase when administered concurrently with antihypertensive medications or drugs that affect heart rate
In post marketing experience, abrupt discontinuation of the extended-release tablets has resulted in clinically significant and persistent rebound hypertension above baseline levels and increases in heart rate; hypertensive encephalopathy reported in association with rebound hypertension with guanfacine
ADHD
- Hypotension is dose-limiting
- Do not substitute extended-release tablet for immediate-release guanfacine on a mg/mg basis, because of differing pharmacokinetic profiles
- May cause dose-dependent hypotension, bradycardia, and syncope
- Hallucinations reported in children with ADHD treated with guanfacine
Geriatric patients
- May cause adverse CNS effects
- May cause bradycardia and orthostatic hypotension
- Not recommended as routine treatment for hypertension (Beers criteria)
Pregnancy & Lactation
Pregnancy
There is pregnancy exposure registry that monitors pregnancy outcomes in women exposed to ADHD medications, during pregnancy; healthcare providers are encouraged to register patients by calling National Pregnancy Registry for ADHD Medications at 1-866-961-2388.
Available data with guanfacine over decades of use in pregnant women have not identified a drug-associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes; however, use of guanfacine in pregnant women over this time has been infrequent;
Animal data
- In animal reproduction studies, rabbits and rats exposed to 3 and 4 times the maximum recommended human dose (MRHD), respectively, showed no adverse outcomes. However, higher doses were associated with reduced fetal survival and maternal toxicity
Lactation
There are no data on presence of guanfacine in human milk or effects on breastfed infant; effects on milk production are also unknown; drug is present in milk of lactating rats; if drug is present in animal milk, it is likely that drug will be present in human milk; if an infant is exposed to drug through breastmilk, monitor for symptoms of hypotension and bradycardia such as sedation, lethargy and poor feeding; the developmental and health benefits of breastfeeding should be considered along with mother’s clinical need for drug and any potential adverse effects on breastfed child from therapy or from underlying maternal condition.
Monitor breastfeeding infants exposed to guanfacine through breastmilk for sedation, lethargy, and poor feeding
Pregnancy Categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk. C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done. D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk. X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist. NA: Information not available.Pharmacology
Mechanism of Action
Selective alpha2-adrenergic receptor agonist causing decreased sympathetic outflow and subsequent decrease in vasomotor tone and heart rate; may preferentially bind postsynaptic alpha2A adrenoreceptors in the prefrontal cortex, which may improve delay-related firing of prefrontal cortex neurons (as a result, behavioral inhibition may be affected); mechanism of action in ADHD is not known
Absorption
AUC: 56 ng·hr/mL (immediate release tablets); 32 ng·hr/mL (extended release tablets)
Peak plasma concentration: 2.5 ng/mL (Immediate release tablets); 1 ng/mL (extended release tablets)
Peak plasma time: 3 hr (immediate release tablets); 6 hr (extended release tablets)
Bioavailability: 80-100% (immediate release tablets); 58% (extended release tablets)
Onset: Initial effect (2 hr); maximum effect (6 hr)
Duration: 24 hr
Distribution
Protein bound: 70%
Vd: 6.3 L/kg
Metabolism
Via CYP3A4 (hepatic)
Metabolites: Glucuronide and sulfate of 3-hydroxy guanfacine, oxidized mercapturic acid derivatives (inactive)
Elimination
Half-life: 16 hr (immediate release tablets); 18 hr (extended release tablets)
Dialyzable: HD (No)
Excretion: Urine 80% (unchanged)
Administration
Oral Administration
Administer orally once a day
Extended-release tablets
- Do not administer with high-fat meals due to potential for increased serum levels
- Swallow tablets whole; do not crush, chew, or break tablets because this will increase the rate of guanfacine release
- Missed dose: Repeat dosage titration based on patient tolerability
Storage
Immediate-release tablets: at 20-25°C (68-77°F); dispense in a tight, light-resistant container
Extended-release tablets: Store at 20-25°C (68-77°F); excursions permitted to 15-30°C (59-86°F)
Images
BRAND | FORM. | UNIT PRICE | PILL IMAGE |
---|---|---|---|
guanfacine oral - | 4 mg tablet | ![]() | |
guanfacine oral - | 3 mg tablet | ![]() | |
guanfacine oral - | 1 mg tablet | ![]() | |
guanfacine oral - | 4 mg tablet | ![]() | |
guanfacine oral - | 3 mg tablet | ![]() | |
guanfacine oral - | 1 mg tablet | ![]() | |
guanfacine oral - | 2 mg tablet | ![]() | |
guanfacine oral - | 1 mg tablet | ![]() | |
guanfacine oral - | 3 mg tablet | ![]() | |
guanfacine oral - | 2 mg tablet | ![]() | |
guanfacine oral - | 1 mg tablet | ![]() | |
guanfacine oral - | 2 mg tablet | ![]() | |
guanfacine oral - | 1 mg tablet | ![]() | |
guanfacine oral - | 1 mg tablet | ![]() | |
guanfacine oral - | 2 mg tablet | ![]() | |
guanfacine oral - | 1 mg tablet | ![]() | |
guanfacine oral - | 2 mg tablet | ![]() | |
guanfacine oral - | 2 mg tablet | ![]() | |
guanfacine oral - | 2 mg tablet | ![]() | |
guanfacine oral - | 4 mg tablet | ![]() | |
guanfacine oral - | 3 mg tablet | ![]() | |
guanfacine oral - | 2 mg tablet | ![]() | |
guanfacine oral - | 4 mg tablet | ![]() | |
guanfacine oral - | 1 mg tablet | ![]() | |
guanfacine oral - | 1 mg tablet | ![]() | |
guanfacine oral - | 3 mg tablet | ![]() | |
guanfacine oral - | 2 mg tablet | ![]() | |
guanfacine oral - | 1 mg tablet | ![]() | |
guanfacine oral - | 1 mg tablet | ![]() | |
guanfacine oral - | 2 mg tablet | ![]() | |
guanfacine oral - | 2 mg tablet | ![]() | |
guanfacine oral - | 1 mg tablet | ![]() | |
guanfacine oral - | 2 mg tablet | ![]() | |
guanfacine oral - | 1 mg tablet | ![]() | |
guanfacine oral - | 2 mg tablet | ![]() | |
guanfacine oral - | 2 mg tablet | ![]() | |
guanfacine oral - | 1 mg tablet | ![]() | |
Intuniv ER oral - | 4 mg tablet | ![]() | |
Intuniv ER oral - | 3 mg tablet | ![]() | |
Intuniv ER oral - | 2 mg tablet | ![]() | |
Intuniv ER oral - | 1 mg tablet | ![]() |
Copyright © 2010 First DataBank, Inc.
Patient Handout
guanfacine oral
GUANFACINE - ORAL
(GWAN-fuh-seen)
COMMON BRAND NAME(S): Tenex
USES: This medication is used alone or with other medications to treat high blood pressure (hypertension). Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems. Guanfacine acts in the brain. It decreases certain nerve signals from the brain to the blood vessels and the heart. This causes the blood vessels to relax so that blood can flow more easily and also slows the heart rate. These effects help to lower blood pressure.
HOW TO USE: Take this medication by mouth with or without food as directed by your doctor, usually once daily at bedtime.The dosage is based on your medical condition, response to treatment, and other medications you may be taking. Be sure to tell your doctor and pharmacist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).Use this medication regularly to get the most benefit from it. To help you remember, take it at the same time each day.It may take several weeks before you get the full benefit of this medication. Keep taking this medication even if you feel well. Most people with high blood pressure do not feel sick.Do not stop taking this medication without consulting your doctor. Some conditions may become worse when this drug is suddenly stopped. Also, you may experience symptoms such as headache, nervousness, agitation, tremor, fast heartbeat, and high blood pressure. To prevent these symptoms while you are stopping treatment with this drug, your doctor may reduce your dose gradually. Ask your doctor or pharmacist for more details. Report any new or worsening symptoms right away.Tell your doctor if your condition does not improve or if it worsens (for example, your routine blood pressure readings remain high or increase).
SIDE EFFECTS: Dry mouth, drowsiness, dizziness, constipation, tiredness, and weakness may occur. Decreased sexual ability has been reported rarely. If any of these effects last or get worse, tell your doctor or pharmacist promptly.To relieve dry mouth, suck on (sugarless) hard candy or ice chips, chew (sugarless) gum, drink water, or use a saliva substitute.To reduce the risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position.Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.Tell your doctor right away if you have any serious side effects, including: fast/slow heartbeat, fainting, mental/mood changes (such as depression, hallucinations, confusion, thoughts of suicide).A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
PRECAUTIONS: Before taking guanfacine, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.Before using this medication, tell your doctor or pharmacist your medical history, especially of: kidney disease, liver disease, personal/family history of mental/mood disorders (such as bipolar disorder, depression, suicidal thoughts).This drug may make you dizzy or drowsy. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).Children may be more sensitive to the side effects of this drug, especially hallucinations and mental/mood changes.Older adults may be more sensitive to the side effects of this drug, especially dizziness (more likely when standing up), drowsiness, slow heartbeat, or depression. Dizziness and drowsiness can increase the risk of falling.During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.It is unknown if this medication passes into breast milk. Consult your doctor before breast-feeding.
DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.Tell your doctor or pharmacist if you are taking other products that cause drowsiness including alcohol, marijuana (cannabis), antihistamines (such as cetirizine, diphenhydramine), drugs for sleep or anxiety (such as alprazolam, diazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), and opioid pain relievers (such as codeine, hydrocodone).Check the labels on all your medicines (such as cough-and-cold products, diet aids, nonsteroidal anti-inflammatory drugs-NSAIDs such as ibuprofen for pain/fever reduction) because they may contain ingredients that cause drowsiness or could increase your blood pressure or heart rate. Ask your pharmacist about using those products safely.
OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: severe drowsiness, severe dizziness, severe tiredness, very slow heartbeat.
NOTES: Do not share this medication with others.Talk with your doctor about making changes to your lifestyle that may help this medication work better (such as stress reduction programs, exercise, and dietary changes).Have your blood pressure and heart rate checked regularly while taking this medication. Learn how to check your own blood pressure and heart rate at home, and share the results with your doctor.
MISSED DOSE: If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.
STORAGE: Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.
Information last revised November 2023. Copyright(c) 2023 First Databank, Inc.
IMPORTANT: HOW TO USE THIS INFORMATION: This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of your health care professional. Always ask your health care professional for complete information about this product and your specific health needs.
Formulary
Adding plans allows you to compare formulary status to other drugs in the same class.
To view formulary information first create a list of plans. Your list will be saved and can be edited at any time.
Adding plans allows you to:
- View the formulary and any restrictions for each plan.
- Manage and view all your plans together – even plans in different states.
- Compare formulary status to other drugs in the same class.
- Access your plan list on any device – mobile or desktop.