Dosing & Uses
Dosage Forms & Strengths
capsule/tablet, extended release
- 0.375mg
elixir
- 0.125mg/5mL
injection solution
- 0.5mg/mL
oral drops
- 0.125mg/mL
tablet
- 0.125mg
Gastrointestinal Disorders
Immediate release: 0.125-0.25 mg PO/SL q4hr PRN; no more than 1.5 mg/day
Extended release: 0.375-0.75 mg PO q12hr; no more than 1.5 mg/day
IM/SC/IV: 0.25-0.5 mg q4hr PRN; no more than 4 times per day
Hypermotility of Lower Urinary Tract
Adjunctive treatment
Immediate release: 0.15-0.3 mg PO/SL q6hr
Extended release: 0.375 mg PO q12hr
Peptic Ulcer Disease
Adjunctive treatment
0.125-0.25 mg PO/SL q4hr PRN; no more than 1.5 mg/day
Irritable Bowel Syndrome
Adjunctive treatment
0.125-0.25 mg PO/SL q4hr PRN; no more than 1.5 mg/day
Dosage Forms & Strengths
capsule/tablet, extended release
- 0.375mg
elixir
- 0.125mg/5mL
injection solution
- 0.5mg/mL
oral drops
- 0.125mg/mL
tablet
- 0.125mg
Gastrointestinal Disorders
<2 years (oral drops)
- 2.3-3.3 kg: 3 drops PO q4hr PRN; no more than 18 drops/day
- 3.4-4 kg: 4 drops PO q4hr PRN; no more than 24 drops/day
- 5-6 kg: 5 drops PO q4hr PRN; no more than 30 drops/day
- 7-9 kg: 6 drops PO q4hr PRN; no more than 36 drops/day
- 10-14 kg: 8 drops PO q4hr PRN; no more than 48 drops/day
- ≥15 kg: 11 drops PO q4hr PRN; no more than 66 drops/day
2-12 years (tablet)
- Immediate release/SL: 0.0625-0.125 mg PO q4hr PRN; no more than 0.75mg/day
- Extended release: 0.375 PO q12hr; no more than 0.75 mg/day
2-12 years (elixir)
- 10-19 kg: 1/4 tsp (1.25 mL) PO q4hr PRN
- 20-39 kg: 1/2 tsp (2.5 mL) PO q4hr PRN
- 40-49 kg: 3/4 tsp (3.75 mL) PO q4hr PRN
- ≥50 kg: 1 tsp (5 mL) PO q4hr PRN
IV/IM/SQ
- >12 years: 0.025-0.5 mg q4hr PRN; no more than 4 times daily
Hypermotility of lower urinary tract
Immediate release: 0.125-0.25 mg PO/SL q6hr
Extended release: 0.375 mg PO q12hr
Dosing considerations
Avoid except in short-term situations to decrease secretions; high incidence of anticholinergic effects (Beers criteria)
Interactions
Interaction Checker
No Results

Contraindicated
Serious - Use Alternative
Significant - Monitor Closely
Minor

Contraindicated (0)
Serious - Use Alternative (7)
- glucagon
glucagon increases toxicity of hyoscyamine by Other (see comment). Avoid or Use Alternate Drug. Comment: Coadministration of anticholinergic drugs and glucagon increase the risk of gastrointestinal adverse reactions due to additive effects on inhibition of gastrointestinal motility. .
- glucagon intranasal
glucagon intranasal increases toxicity of hyoscyamine by Other (see comment). Avoid or Use Alternate Drug. Comment: Coadministration of anticholinergic drugs and glucagon increase the risk of gastrointestinal adverse reactions due to additive effects on inhibition of gastrointestinal motility. .
- glycopyrronium tosylate topical
glycopyrronium tosylate topical, hyoscyamine. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Coadministration of glycopyrronium tosylate topical with other anticholinergic medications may result in additive anticholinergic adverse effects.
- pramlintide
pramlintide, hyoscyamine. Either increases effects of the other by pharmacodynamic synergism. Contraindicated. Synergistic inhibition of GI motility.
- revefenacin
revefenacin and hyoscyamine both decrease cholinergic effects/transmission. Avoid or Use Alternate Drug. Coadministration may cause additive anticholinergic effects.
- secretin
hyoscyamine decreases effects of secretin by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Concomitant use of anticholinergic drugs may cause a hyporesponse to stimulation testing with secretin. Discontinue anticholinergic drugs at least 5 half-lives before administering secretin.
- umeclidinium bromide/vilanterol inhaled
hyoscyamine, umeclidinium bromide/vilanterol inhaled. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Concomitant use with other anticholinergic-containing drugs may lead to additive anticholinergic adverse effects.
Monitor Closely (98)
- abobotulinumtoxinA
abobotulinumtoxinA increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Use of anticholinergic drugs after administration of botulinum toxin-containing products may potentiate systemic anticholinergic effects. .
- aclidinium
hyoscyamine and aclidinium both decrease cholinergic effects/transmission. Use Caution/Monitor.
- amantadine
hyoscyamine, amantadine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Potential for increased anticholinergic adverse effects.
- amitriptyline
hyoscyamine and amitriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.
- amoxapine
hyoscyamine and amoxapine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- anticholinergic/sedative combos
anticholinergic/sedative combos and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- aripiprazole
hyoscyamine decreases levels of aripiprazole by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of aripiprazole by pharmacodynamic antagonism. Use Caution/Monitor.
aripiprazole increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - atracurium
atracurium and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- atropine
atropine and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- atropine IV/IM
atropine IV/IM and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- belladonna alkaloids
belladonna alkaloids and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- belladonna and opium
hyoscyamine and belladonna and opium both decrease cholinergic effects/transmission. Use Caution/Monitor.
- benperidol
hyoscyamine decreases levels of benperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of benperidol by pharmacodynamic antagonism. Use Caution/Monitor.
benperidol increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - benztropine
benztropine and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor. Additive anticholinergic adverse effects may be seen with concurrent use.
- bethanechol
bethanechol increases and hyoscyamine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- buprenorphine, long-acting injection
buprenorphine, long-acting injection increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Coadministration of buprenorphine with anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
- carbachol
carbachol increases and hyoscyamine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- cevimeline
cevimeline increases and hyoscyamine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- chlorpromazine
hyoscyamine decreases levels of chlorpromazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of chlorpromazine by pharmacodynamic antagonism. Use Caution/Monitor.
chlorpromazine increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - cisatracurium
cisatracurium and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- clomipramine
hyoscyamine and clomipramine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- clozapine
hyoscyamine decreases levels of clozapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of clozapine by pharmacodynamic antagonism. Use Caution/Monitor.
clozapine increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - cyclizine
cyclizine and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- cyclobenzaprine
cyclobenzaprine and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- darifenacin
darifenacin and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- desipramine
hyoscyamine and desipramine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- dicyclomine
dicyclomine and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- diphenhydramine
diphenhydramine and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- donepezil
donepezil increases and hyoscyamine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- donepezil transdermal
donepezil transdermal, hyoscyamine. Either decreases effects of the other by pharmacodynamic antagonism. Use Caution/Monitor.
- dosulepin
hyoscyamine and dosulepin both decrease cholinergic effects/transmission. Use Caution/Monitor.
- doxepin
hyoscyamine and doxepin both decrease cholinergic effects/transmission. Use Caution/Monitor.
- droperidol
hyoscyamine decreases levels of droperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of droperidol by pharmacodynamic antagonism. Use Caution/Monitor.
droperidol increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - echothiophate iodide
echothiophate iodide increases and hyoscyamine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- fesoterodine
fesoterodine and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- flavoxate
flavoxate and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- fluphenazine
hyoscyamine decreases levels of fluphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of fluphenazine by pharmacodynamic antagonism. Use Caution/Monitor.
fluphenazine increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - galantamine
galantamine increases and hyoscyamine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- glycopyrrolate
glycopyrrolate and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- glycopyrrolate inhaled
glycopyrrolate inhaled and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- haloperidol
hyoscyamine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
haloperidol increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - henbane
henbane and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- homatropine
homatropine and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- huperzine A
huperzine A increases and hyoscyamine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- hydroxyzine
hydroxyzine and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- iloperidone
hyoscyamine decreases levels of iloperidone by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of iloperidone by pharmacodynamic antagonism. Use Caution/Monitor.
iloperidone increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - imipramine
hyoscyamine and imipramine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- ipratropium
hyoscyamine and ipratropium both decrease cholinergic effects/transmission. Use Caution/Monitor. Due to the poor systemic absorption of ipratropium, interaction unlikely at regularly recommended dosages.
- levodopa
hyoscyamine, levodopa. Other (see comment). Use Caution/Monitor. Comment: Anticholinergic agents may enhance the therapeutic effects of levodopa; however, anticholinergic agents can exacerbate tardive dyskinesia. In high dosage, anticholinergics may decrease the effects of levodopa by delaying its GI absorption. .
- lofepramine
hyoscyamine and lofepramine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- loxapine
hyoscyamine decreases levels of loxapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of loxapine by pharmacodynamic antagonism. Use Caution/Monitor.
loxapine increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - loxapine inhaled
loxapine inhaled increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.
hyoscyamine decreases levels of loxapine inhaled by pharmacodynamic antagonism. Use Caution/Monitor. - maprotiline
hyoscyamine and maprotiline both decrease cholinergic effects/transmission. Use Caution/Monitor.
- meclizine
hyoscyamine and meclizine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- methscopolamine
hyoscyamine and methscopolamine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- metoclopramide intranasal
hyoscyamine will decrease the level or effect of metoclopramide intranasal by Other (see comment). Use Caution/Monitor. Coadministration of metoclopramide intranasal with drugs that impair GI motility may decrease systemic absorption of metoclopramide. Monitor for reduced therapeutic effect.
- neostigmine
neostigmine increases and hyoscyamine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- nortriptyline
hyoscyamine and nortriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.
- olanzapine
hyoscyamine decreases levels of olanzapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of olanzapine by pharmacodynamic antagonism. Use Caution/Monitor.
olanzapine increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - oliceridine
hyoscyamine increases toxicity of oliceridine by Other (see comment). Use Caution/Monitor. Comment: Anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Monitor for signs of urinary retention or reduced gastric motility if oliceridine is coadministered with anticholinergics.
- onabotulinumtoxinA
onabotulinumtoxinA and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- orphenadrine
hyoscyamine and orphenadrine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- oxybutynin
hyoscyamine and oxybutynin both decrease cholinergic effects/transmission. Use Caution/Monitor.
- oxybutynin topical
hyoscyamine and oxybutynin topical both decrease cholinergic effects/transmission. Use Caution/Monitor.
- oxybutynin transdermal
hyoscyamine and oxybutynin transdermal both decrease cholinergic effects/transmission. Use Caution/Monitor.
- paliperidone
hyoscyamine decreases levels of paliperidone by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of paliperidone by pharmacodynamic antagonism. Use Caution/Monitor.
paliperidone increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - pancuronium
hyoscyamine and pancuronium both decrease cholinergic effects/transmission. Use Caution/Monitor.
- perphenazine
hyoscyamine decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.
perphenazine increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - physostigmine
physostigmine increases and hyoscyamine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- pilocarpine
pilocarpine increases and hyoscyamine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- pimozide
hyoscyamine decreases levels of pimozide by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of pimozide by pharmacodynamic antagonism. Use Caution/Monitor.
pimozide increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - prabotulinumtoxinA
hyoscyamine, prabotulinumtoxinA. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Use of anticholinergic drugs after administration of botulinum toxin-containing products may potentiate systemic anticholinergic effects.
- pralidoxime
hyoscyamine and pralidoxime both decrease cholinergic effects/transmission. Use Caution/Monitor.
- prochlorperazine
hyoscyamine decreases levels of prochlorperazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of prochlorperazine by pharmacodynamic antagonism. Use Caution/Monitor.
prochlorperazine increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - promethazine
hyoscyamine decreases levels of promethazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of promethazine by pharmacodynamic antagonism. Use Caution/Monitor.
promethazine increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - propantheline
hyoscyamine and propantheline both decrease cholinergic effects/transmission. Use Caution/Monitor.
- protriptyline
hyoscyamine and protriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.
- pyridostigmine
pyridostigmine increases and hyoscyamine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- quetiapine
hyoscyamine decreases levels of quetiapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of quetiapine by pharmacodynamic antagonism. Use Caution/Monitor.
quetiapine increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - rapacuronium
hyoscyamine and rapacuronium both decrease cholinergic effects/transmission. Use Caution/Monitor.
- risperidone
hyoscyamine decreases levels of risperidone by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of risperidone by pharmacodynamic antagonism. Use Caution/Monitor.
risperidone increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - rocuronium
hyoscyamine and rocuronium both decrease cholinergic effects/transmission. Use Caution/Monitor.
- scopolamine
hyoscyamine and scopolamine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- solifenacin
hyoscyamine and solifenacin both decrease cholinergic effects/transmission. Use Caution/Monitor.
- succinylcholine
succinylcholine increases and hyoscyamine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- thioridazine
hyoscyamine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - thiothixene
hyoscyamine decreases levels of thiothixene by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of thiothixene by pharmacodynamic antagonism. Use Caution/Monitor.
thiothixene increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - tiotropium
hyoscyamine and tiotropium both decrease cholinergic effects/transmission. Use Caution/Monitor.
- tolterodine
hyoscyamine and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- trazodone
hyoscyamine and trazodone both decrease cholinergic effects/transmission. Use Caution/Monitor.
- trifluoperazine
hyoscyamine decreases levels of trifluoperazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of trifluoperazine by pharmacodynamic antagonism. Use Caution/Monitor.
trifluoperazine increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - trihexyphenidyl
hyoscyamine and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.
- trimipramine
hyoscyamine and trimipramine both decrease cholinergic effects/transmission. Use Caution/Monitor.
- trospium chloride
hyoscyamine and trospium chloride both decrease cholinergic effects/transmission. Use Caution/Monitor.
- umeclidinium bromide
umeclidinium bromide and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor. If possible, avoid coadministration of additional anticholinergic agents
- vecuronium
hyoscyamine and vecuronium both decrease cholinergic effects/transmission. Use Caution/Monitor.
- ziprasidone
hyoscyamine decreases levels of ziprasidone by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of ziprasidone by pharmacodynamic antagonism. Use Caution/Monitor.
ziprasidone increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - zotepine
hyoscyamine decreases levels of zotepine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of zotepine by pharmacodynamic antagonism. Use Caution/Monitor.
Minor (3)
- dimenhydrinate
dimenhydrinate increases toxicity of hyoscyamine by pharmacodynamic synergism. Minor/Significance Unknown. Additive anticholinergic effects.
- donepezil
donepezil decreases effects of hyoscyamine by pharmacodynamic antagonism. Minor/Significance Unknown.
- galantamine
galantamine decreases effects of hyoscyamine by pharmacodynamic antagonism. Minor/Significance Unknown.
Adverse Effects
>10%
Dry skin
1-10%
Blurred vision
Constipation
Dysphagia
Photosensitivity
<1%
Headache
Orthostatic hypotension
Tachycardia
Frequency Not Defined
Xerostomia
Urinary hesitancy/retention
HTN
Dysphagia
Respiratory depression
CNS stimulation
Fever
Ataxia
Excitation
Lethargy
Palpitations
Mydriasis
Cycloplegia
Increased IOP
Weakness
Bloated feeling
Suppression of lactation
Impotence
Anhidrosis
Warnings
Contraindications
Hypersensitivity to hyoscyamine or related compounds
Closed-angle glaucoma
Myasthenia gravis
Hemorrhage with cardiovascular instability
Paralytic ileus
Intestinal atony of elderly/debilitated patient
Obstructive uropathy
Toxic megacolon
GI obstruction
Tachycardia secondary to cardiac insufficiency or thyrotoxicosis
Breastfeeding
Cautions
Discontinue treatment if diarrhea occurs; it may be a sign of incomplete intestinal obstruction, especially in colostomy or ileostomy
May cause drowsiness; caution patients about performing a hazardous task, like driving heavy machinery, that requires mental alertness
Use caution in hot weather or exercise; heat prostration reported in the presence of increased environmental temperature
Psychosis reported in patients susceptible to anticholinergic effects; usually resolved within 12-48 hr after therapy discontinuation
Use caution in patients with hyperthyroidism, prostatic hyperplasia, renal impairment, hiatal hernia, or cardiovascular disease, including heart failure, tachyarrhythmias, hypertension, or coronary artery disease; evaluate tachycardia prior to initiating therapy
Pregnancy & Lactation
Pregnancy category: C
Lactation: Enters breast milk; use not recommended
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
Parasympatholytic, atropine-like effects, especially peripherally; blocks the action of acetylcholine at parasympathetic sites in smooth muscle, secretory glands, and CNS
Absorption
Bioavailability: Tab (100%), SR (81%)
Onset: IV/IM/SC (2-3 min), SL (5-20 min), tab/SR (20-30 min)
Duration: IV/IM/SC/tab/SL (up to 4 hr), SR (12 hr)
Peak plasma time: Tab/SR (2.5 hr)
Distribution
Protein bound: 50%
Vd: 1.2-1.9 L/kg (adults); 1.1-3.7 L/kg (children aged 4-16 years)
Metabolism
Hepatic
Metabolites: Tropic acid, tropine, hyoscyamine glucuronide
Elimination
Half-life: Tab (3.5 hr), SR (5-9 hr)
Dialyzable: Yes; removed by hemodialysis and peritoneal dialysis
Excretion: Majority excreted in urine as unchanged drug
Images
Formulary
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