API

Benzhexol hydrochloride

Drug classification

Dosage form

Tablet

API strength per dosage

5MG

Dose

Adults: Initially 1 mg daily, increased by 2 mg at intervals of 3–5 days to 5–15 mg daily in divided doses. Elderly: Use lower initial doses. Pediatrics: Not recommended. Adjust dose in hepatic or renal impairment; use with caution.

Mechanism of action

Selectively antagonizes central muscarinic acetylcholine receptors (primarily M1 subtype), inhibiting acetylcholine binding, thereby reducing cholinergic neurotransmission in the basal ganglia. This decreases excessive cholinergic activity relative to dopaminergic tone, alleviating extrapyramidal motor symptoms such as tremor and rigidity.

Indications

Parkinsonism, drug-induced extrapyramidal symptoms, dystonia, adjunct in Parkinson’s disease therapy.

Side effects

Dry mouth, blurred vision, constipation, urinary retention, confusion, agitation, hallucinations, tachycardia, nausea, dizziness, impaired memory, increased intraocular pressure, heat intolerance.

Pregnancy category

Category C

Precautions

Elderly patients, prostatic hypertrophy, urinary retention, glaucoma, cardiovascular disease, hepatic impairment, renal impairment, history of psychosis, risk of heat stroke, pregnancy, breastfeeding, abrupt withdrawal, concurrent use with other anticholinergics, caution in children, monitor for cognitive or psychiatric effects.

Contraindications

Hypersensitivity to benzhexol, angle-closure glaucoma, urinary retention, prostatic hypertrophy, obstructive diseases of the gastrointestinal tract, myasthenia gravis, untreated toxic megacolon.