| Indication | Indicated for the treatment of parkinson's disease and extrapyramidal reactions caused by drugs. |
| Pharmacodynamics | Trihexyphenidyl is an anticholinergic used in the symptomatic treatment of all etiologic groups of parkinsonism and drug induced extrapyramidal reactions (except tardive dyskinesia). Trihexyphenidyl possesses both anticholinergic and antihistaminic effects, although only the former has been established as therapeutically significant in the management of parkinsonism. |
| Mechanism of action | Trihexyphenidyl is a selective M1 muscarinic acetylcholine receptor antagonist. It is able to discriminate between the M1 (cortical or neuronal) and the peripheral muscarinic subtypes (cardiac and glandular). Trihexyphenidyl partially blocks cholinergic activity in the CNS, which is responsible for the symptoms of Parkinson's disease. It is also thought to increase the availability of dopamine, a brain chemical that is critical in the initiation and smooth control of voluntary muscle movement. |
| Absorption | Trihexyphenidyl is rapidly absorbed from the gastrointestinal tract. |
| Volume of distribution | Not Available |
| Protein binding | Not Available |
| Metabolism | Not Available |
| Route of elimination | Not Available |
| Half life | 3.3-4.1 hours |
| Clearance | Not Available |
| Toxicity | Symptoms of overdose include mydriasis, dryness of mucous membranes, red face, atonic states of bowels and bladder, and hyperthermia in high doses. Central consequences are agitation, confusion, and hallucinations. An untreated overdose may be fatal, particular in children. Premortal signs are respiratory depression and cardiac arrest. |