trihexyphenidyl ARTANE

Class: Anticholinergic/​Parasympatholytic
FDA Indications: Parkinson's Disease, Drug-induced Extrapyramidal Reactions
Off-Label Use: Psychotic Depression , Idiopathic Generalized Dystonia
Forms: 2, 5mg tablet; 2mg/5mL injectable
Dose Range: 5-15 mg/day
Starting: EPS: 5-15 mg/day; assess effect and increase dose empirically as tolerated
Parkinsonism: start at 1 mg qd; after 3 days can increase in 2 mg increments q 3-5 days as tolerated until clinical effect is reached; total daily dose should be given t.i.d. a.c.
Stopping: Do not abruptly discontinue. has been reported in association with dose reduction or discontinuation of trexyphenidyl

NAMI drug fact sheet

Contraindications: Narrow angle glaucoma
Side Effects: anticholinergic side effects
1° MOA: Centrally-acting antimuscarinic agent; reinstates balance of dopaminergic to cholinergic activity in the nigrostriatal pathway (as dopaminergic activity ↓ d/t D2-blockade, the anti-ACh aims to likewise ↓ cholineric activity and restore the DA/ACh ratio)
Target: M1
t½: 3.7 (3.3-4.1)° TMAX:
Substrate of: Hydroxylation
Inhibits: ∅ ; Induces:
Active Metabolites:
  • - caution with co-prescribed CNS depressants which can ↑ sedative effects
  • - can enhance anticholinergic actions of other anticholinergic agents
  • - may be more abusable than other anticholinergic medications, presumably due to its dopamine-enhancing actions
  • - sedation limits use, especially in older patients
  • - useful adjunct in younger Parkinson's patients with tremor
  • - can cause cognitive side effects with chronic use, so periodic trials of discontinuation may be useful to justify continuous use, especially in institutional settings as adjunct to antipsychotics
Special Populations

Category C—The limited human pregnancy experience and the absence of animal reproduction data prevents a better assessment of the embryo-fetal risk. However, in general, anticholinergics are considered low risk in pregnancy.

Limited Human Data—Probably Compatible

Use with caution; elderly patients may be more susceptible to side effects

2019 BEE℞S Recommendation: Avoid. Not recommended for prevention or treatment of extrapyramidal symptoms with antipsychotics; more effective agents available for treatment of Parkinson disease.

No known effects, but use with caution

No known effects, but use with caution


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Last updated February 29 2024 20:54:18. Disclaimer: This website does not provide medical advice, nor is it a substitute for clinical judgment.