Pharmacology · Antiparkinson anticholinergics

Biperiden !

A central anticholinergic on the WHO essential list, given by mouth or injection for parkinsonism and acute dystonia from antipsychotics.

Updated 2026-11-01

Class: Antiparkinson anticholinergics
Receptor: Muscarinic acetylcholine receptors (M1 shown)
ATC code: N04AA02
WHO Model List of Essential Medicines

Muscarinic acetylcholine receptors (M1 shown)Biperiden

The figure shows tiotropium, another muscarinic antagonist, in the human M1 receptor; biperiden blocks the same acetylcholine binding site.

Target in 3D: Muscarinic acetylcholine receptors (M1 shown). PDB structure 5CXV (RCSB PDB, public domain). View the structure at RCSB PDB

Mechanism of action

Biperiden is a tertiary-amine antimuscarinic that enters the brain and blocks muscarinic receptors in the striatum, restoring part of the dopamine-acetylcholine balance. Its injectable form acts quickly in acute dystonic reactions.

A dopamine blocker or Parkinson leaves acetylcholine unopposed
Biperiden blocks muscarinic receptors in the striatum
Dystonic spasms, tremor and rigidity ease

Pharmacokinetics

Absorption: Given by mouth, or intravenously or intramuscularly for acute dystonia
Distribution: Lipid-soluble; enters the brain

Indications

Parkinson disease (WHO essential medicine) Parkinson disease →
Acute dystonia and parkinsonism caused by antipsychotics Antipsychotic-induced movement disorders (dystonia, akathisia, parkinsonism, tardive dyskinesia) →

Adverse effects

Common

Dry mouth, blurred vision, constipation
Urinary hesitancy
Drowsiness and dizziness

Contraindications

Angle-closure glaucoma
Caution: prostate enlargement, bowel obstruction, older adults, dementia
Not used for tardive dyskinesia (may worsen it)

Key interactions

Other anticholinergics (tricyclics, antihistamines, some antipsychotics): Additive anticholinergic burden
Alcohol and sedatives: More sedation

What is monitored

Response of the dystonia after an injection
Mental state and cognition
Urination and bowel habit

Administration and safety

For acute dystonia it is given by intravenous or intramuscular injection
Oral treatment is withdrawn gradually

Nursing care

After injection, check blood pressure, pulse and sedation
Watch older patients for confusion and urinary retention
Explain that dystonia from antipsychotics is frightening but treatable

Pregnancy and breastfeeding

Human data are limited; it is used only if clearly needed.

Test yourself

Think of the answer, then tap the question to see it.

Which acute antipsychotic reaction is treated with parenteral biperiden?

Acute dystonia (for example torticollis or oculogyric crisis).

Which anticholinergic antiparkinson drug is on the WHO essential list?

Biperiden (tablets and injection).

Which eye condition contraindicates biperiden?

Angle-closure glaucoma.

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: eEML - Electronic Essential Medicines List (World Health Organization, 2025); Farmacología básica y clínica (Katzung), 16.ª ed., cap. 28 (McGraw Hill, 2025); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 21 (McGraw Hill, 2023); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.