Dosing & Uses
Dosage Forms & Strengths
isometheptene/dichloralphenazone/acetaminophen
capsule: Schedule IV
- 65mg/100mg/325mg
Migraine Headache
2 capsules PO at onset of headache, then 1 capsule PO q1hr until headache relieved up to a cumulative dose of 5 capsules/12 hr
Tension Headache
1-2 capsules PO q4hr; not to exceed 8 capsules/24 hr
Safety and efficacy not established
Interactions
Interaction Checker
No Results
Contraindicated
Serious - Use Alternative
Significant - Monitor Closely
Minor
Contraindicated (5)
- isocarboxazid
isocarboxazid, isometheptene. Either increases effects of the other by pharmacodynamic synergism. Contraindicated. Hypertension, V tach.
- linezolid
linezolid, isometheptene. Either increases effects of the other by pharmacodynamic synergism. Contraindicated. Hypertension, V tach.
- phenelzine
phenelzine, isometheptene. Either increases effects of the other by pharmacodynamic synergism. Contraindicated. Hypertension, V tach.
- selegiline transdermal
selegiline transdermal, isometheptene. Either increases effects of the other by pharmacodynamic synergism. Contraindicated. Hypertension, V tach.
- tranylcypromine
tranylcypromine, isometheptene. Either increases effects of the other by pharmacodynamic synergism. Contraindicated. Hypertension, V tach.
Serious - Use Alternative (5)
- lonafarnib
acetaminophen will increase the level or effect of lonafarnib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of lonafarnib (a sensitive CYP3A substrate) with weak CYP3A inhibitors is unavoidable, reduce to, or continue lonafarnib at starting dose. Closely monitor for arrhythmias and events (eg, syncope, heart palpitations) since lonafarnib effect on QT interval is unknown.
- metoclopramide intranasal
dichloralphenazone, 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.
- pexidartinib
acetaminophen and pexidartinib both increase Other (see comment). Avoid or Use Alternate Drug. Pexidartinib can cause hepatotoxicity. Avoid coadministration of pexidartinib with other products know to cause hepatoxicity.
- pretomanid
acetaminophen, pretomanid. Either increases toxicity of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Pretomanid regimen associated with hepatotoxicity. Avoid alcohol and hepatotoxic agents, including herbal supplements and drugs other than bedaquiline and linezolid.
- ropeginterferon alfa 2b
ropeginterferon alfa 2b and dichloralphenazone 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.
Monitor Closely (13)
- apalutamide
apalutamide will decrease the level or effect of acetaminophen by increasing elimination. Use Caution/Monitor. Apalutamide induces UGT and may decrease systemic exposure of drugs that are UGT substrates.
- atogepant
acetaminophen will increase the level or effect of atogepant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- avapritinib
acetaminophen will increase the level or effect of avapritinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- axitinib
acetaminophen increases levels of axitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
- bupivacaine implant
acetaminophen, bupivacaine implant. Either increases toxicity of the other by Other (see comment). Use Caution/Monitor. Comment: Local anesthetics may increase the risk of developing methemoglobinemia when concurrently exposed to drugs that also cause methemoglobinemia.
- busulfan
acetaminophen increases levels of busulfan by decreasing metabolism. Use Caution/Monitor. Use of acetaminophen prior to (< 72 hours) or concurrently with busulfan may result in decreased clearance of busulfan due to acetaminophen-induced decreases in glutathione levels.
- cenobamate
cenobamate, dichloralphenazone. Either increases effects of the other by sedation. Use Caution/Monitor.
- dapsone topical
acetaminophen increases toxicity of dapsone topical by altering metabolism. Modify Therapy/Monitor Closely. May induce methemoglobinemia .
- daridorexant
dichloralphenazone 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.
- difelikefalin
difelikefalin and dichloralphenazone both increase sedation. Use Caution/Monitor.
- droxidopa
isometheptene and droxidopa both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. May increase risk for supine hypertension
- eltrombopag
eltrombopag increases levels of acetaminophen by decreasing metabolism. Use Caution/Monitor. UGT inhibition; significance of interaction unclear.
- midazolam intranasal
midazolam intranasal, dichloralphenazone. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Concomitant use of barbiturates, alcohol, or other CNS depressants may increase risk of hypoventilation, airway obstruction, desaturation, or apnea and may contribute to profound and/or prolonged drug effect.
Minor (51)
- acetazolamide
acetazolamide decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- albiglutide
albiglutide decreases levels of acetaminophen by unspecified interaction mechanism. Minor/Significance Unknown.
- antithrombin alfa
acetaminophen increases effects of antithrombin alfa by unknown mechanism. Minor/Significance Unknown.
- antithrombin III
acetaminophen increases effects of antithrombin III by unknown mechanism. Minor/Significance Unknown.
- argatroban
acetaminophen increases effects of argatroban by unknown mechanism. Minor/Significance Unknown.
- bemiparin
acetaminophen increases effects of bemiparin by unknown mechanism. Minor/Significance Unknown.
- bivalirudin
acetaminophen increases effects of bivalirudin by unknown mechanism. Minor/Significance Unknown.
- carbamazepine
carbamazepine decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- cholestyramine
cholestyramine decreases levels of acetaminophen by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.
- clonazepam
clonazepam decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- colestipol
colestipol decreases levels of acetaminophen by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.
- dalteparin
acetaminophen increases effects of dalteparin by unknown mechanism. Minor/Significance Unknown.
- diazepam
diazepam decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- disulfiram
disulfiram will increase the level or effect of acetaminophen by affecting hepatic enzyme CYP2E1 metabolism. Minor/Significance Unknown.
- enoxaparin
acetaminophen increases effects of enoxaparin by unknown mechanism. Minor/Significance Unknown.
- ethanol
ethanol will decrease the level or effect of acetaminophen by affecting hepatic enzyme CYP2E1 metabolism. Minor/Significance Unknown.
ethanol increases toxicity of acetaminophen by decreasing metabolism. Minor/Significance Unknown. - ethosuximide
ethosuximide decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- felbamate
felbamate decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- fondaparinux
acetaminophen increases effects of fondaparinux by unknown mechanism. Minor/Significance Unknown.
- fosphenytoin
fosphenytoin decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- gabapentin
gabapentin decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- gabapentin enacarbil
gabapentin enacarbil decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- green tea
green tea increases effects of acetaminophen by pharmacodynamic synergism. Minor/Significance Unknown. (Theoretical, due to caffeine content).
- heparin
acetaminophen increases effects of heparin by unknown mechanism. Minor/Significance Unknown.
- isoniazid
isoniazid increases toxicity of acetaminophen by unknown mechanism. Minor/Significance Unknown.
- lacosamide
lacosamide decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- lamotrigine
lamotrigine decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- levetiracetam
levetiracetam decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- liraglutide
liraglutide decreases levels of acetaminophen by unspecified interaction mechanism. Minor/Significance Unknown.
- lorazepam
lorazepam decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- methsuximide
methsuximide decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- metoclopramide
metoclopramide increases levels of acetaminophen by enhancing GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.
- metronidazole
metronidazole will increase the level or effect of acetaminophen by affecting hepatic enzyme CYP2E1 metabolism. Minor/Significance Unknown.
- oxcarbazepine
oxcarbazepine decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- oxybutynin
oxybutynin decreases levels of acetaminophen by unspecified interaction mechanism. Minor/Significance Unknown.
- oxybutynin topical
oxybutynin topical decreases levels of acetaminophen by unspecified interaction mechanism. Minor/Significance Unknown.
- oxybutynin transdermal
oxybutynin transdermal decreases levels of acetaminophen by unspecified interaction mechanism. Minor/Significance Unknown.
- phenindione
acetaminophen increases effects of phenindione by unknown mechanism. Minor/Significance Unknown.
- phenobarbital
phenobarbital decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- phenytoin
phenytoin decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- primidone
primidone decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- protamine
acetaminophen increases effects of protamine by unknown mechanism. Minor/Significance Unknown.
- rifabutin
rifabutin decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- rifampin
rifampin decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- rufinamide
rufinamide decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- ruxolitinib
acetaminophen will increase the level or effect of ruxolitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
- ruxolitinib topical
acetaminophen will increase the level or effect of ruxolitinib topical by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
- tiagabine
tiagabine decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- topiramate
topiramate decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- valproic acid
valproic acid decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism incr levels of hepatotoxic metabolites.
- zonisamide
zonisamide decreases levels of acetaminophen by increasing metabolism. Minor/Significance Unknown. Enhanced metabolism increase levels of hepatotoxic metabolites.
Adverse Effects
Frequency Not Defined
Rash
Transient dizziness
Warnings
Contraindications
Hypersensitivity
Hepatitis or hepatic disease
Glaucoma
Severe renal impairment
Hypertension
Peripheral vascular disease
Cardiovascular insufficiency, including recent MI or stroke
Organic heart disease
Within 14 days of taking MAO inhibitors
Cautions
Acetaminophen use is associated with rare, but serious skin reactions that can be fatal; these reactions include Stevens-Johnson Syndrome (SJS), toxic epidermal necrolysis (TEN), and acute generalized exanthematous pustulosis (AGEP); symptoms may include skin redness, blisters and rash
May increase respiratory depressant effects; caution with head injury, COPD, or other conditions with decreased respiratory drive
Controlled substance (dichloralphenazone); may cause tolerance/dependence
If therapy seems to become less effective over time, it may be a sign that the patient is becoming dependent on the medication; dose should not be increased to improve relief
If new headache occurs within 1 day after taking the medication, a headache begins to occur every day or continues for several days in a row, it may be a sign of becoming dependent on the medication; continuing therapy when this occurs may cause even more headaches over time; ask healthcare professional how to relieve the headaches
May cause sedation, dizziness, and the patient may become less alert; these effects may increase if additional CNS depressants coadministered with this medication; medications that may increase CNS effects may include barbiturates, narcotics, antiseizure medications, muscle relaxants, antihistamines, and anesthetics; if not able to lie down after taking medication, make sure to know how the medication affects alertness before driving or using heavy machinery
Consuming alcoholic beverages while receiving therapy may increase risk of liver damage caused by acetaminophen, especially if consuming large amounts of alcohol; alcoholic beverages may also make headaches worse or cause new headaches to occur; alcohol consumption should be avoided by those who experience frequent headaches
Use caution in patients with known G6PD deficiency; hemolysis reported rarely with acetaminophen use
Pregnancy & Lactation
Pregnancy
Refer to individual monographs
Lactation
Refer to individual monographs
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
Isometheptene: Elicits sympathomimetic effect; constricts dilated cerebral/cranial arterioles
Dichloralphenazone: Elicits mild sedative effect; reduces emotional response to painful stimulus
Acetaminophen: Inhibitis prostaglandin sythesis in CNS and may block peripheral pain impulse generation; acts on hypothalamus to antipyresis
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