Benztropine 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). Benztropine 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.
Benztropine is an anticholinergic used in the symptomatic treatment of all etiologic groups of parkinsonism and drug-induced extrapyramidal reactions (except tardive dyskinesia). Benztropine possesses both anticholinergic and antihistaminic effects, although only the former has been established as therapeutically significant in the management of parkinsonism. Benztropine's anticholinergic activity is about equal to that of atropine. Benztropine also inhibits dopamine reuptake via the dopamine transporter at nerve terminals.
Signs of overdose include confusion, nervousness, listlessness, hallucinations, dizziness; muscle weakness, ataxia, dry mouth, mydriasis, blurred vision, palpitations, tachycardia, elevated blood pressure, nausea, vomiting, dysuria, numbness of fingers, headache, delirium, coma, shock, convulsions, respiratory arrest, anhidrosis, hyperthermia, glaucoma, and constipation.