What is trihexyphenidyl’s mechanism of action (MoA)?
Trihexyphenidyl is an anticholinergic medicine. It blocks muscarinic acetylcholine receptors in the central nervous system and peripheral tissues, which reduces cholinergic signaling involved in movement disorders. This is the basis for its effectiveness in treating Parkinsonian tremor and other drug-induced or neurologic movement problems. [1]
How does blocking muscarinic receptors help with Parkinson’s symptoms?
Parkinson’s disease involves an imbalance between dopamine and acetylcholine activity in the basal ganglia. By inhibiting muscarinic receptors (reducing acetylcholine effects), trihexyphenidyl helps rebalance signaling and can lessen symptoms such as tremor, rigidity, and slowed movement. [1]
What conditions does this MoA target?
Because it reduces muscarinic (cholinergic) activity, trihexyphenidyl is used for:
- Parkinson’s disease symptoms
- Drug-induced extrapyramidal symptoms (from medications that increase dopamine blockade in the brain)
- Other movement disorders where cholinergic overactivity contributes to abnormal movements [1]
Is trihexyphenidyl a dopamine drug?
No. Its therapeutic effect comes from antimuscarinic (anticholinergic) activity, not from direct dopamine receptor stimulation or dopamine release. [1]
What side effects make sense given its anticholinergic MoA?
Blocking muscarinic receptors can cause classic anticholinergic effects, including dry mouth, constipation, blurred vision, urinary retention, and cognitive confusion in some patients. These risks align with its mechanism of action. [1]
Source
- Trihexyphenidyl – Wikipedia