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Pharmacology · Antiparkinson anticholinergics

Benzatropine !

A central anticholinergic used for drug-induced dystonia and parkinsonism and for Parkinson tremor. Older adults tolerate it poorly.

Updated 2026-11-01

Also called: Benztropine, Benztropina

The figure shows tiotropium, another muscarinic antagonist, in the human M1 receptor; benzatropine 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

Benzatropine blocks muscarinic acetylcholine receptors in the striatum, where cholinergic interneurons become overactive when dopamine is low. It also has antihistamine activity, but only the anticholinergic effect matters for parkinsonism.

  1. Low dopamine leaves striatal acetylcholine unopposed
  2. Benzatropine blocks muscarinic receptors in the brain
  3. The dopamine-acetylcholine balance is partly restored
  4. Tremor, rigidity and acute dystonia ease

Pharmacokinetics

Absorption
Given by mouth; injectable forms are used for acute dystonia
Distribution
Lipid-soluble tertiary amine that enters the brain

Indications

Adverse effects

Common

  • Dry mouth, blurred vision, constipation
  • Difficulty urinating
  • Reduced sweating (anhidrosis)
  • Sedation, confusion and excitement, more in older people

Contraindications

  • Children under three years of age
  • Angle-closure glaucoma (avoided)
  • Tardive dyskinesia (not recommended; may worsen it)
  • Hypersensitivity to benzatropine

Key interactions

Phenothiazines, haloperidol, tricyclic antidepressants
Additive anticholinergic effects: paralytic ileus, hyperthermia, heat stroke
Other anticholinergics (antihistamines, bladder antimuscarinics)
Higher anticholinergic burden: confusion, retention, constipation
Alcohol and other sedatives
More drowsiness

What is monitored

  • Mental state and cognition, especially in older adults
  • Bowel movements, urination and temperature in hot weather
  • Vision changes or eye pain (glaucoma)

Administration and safety

  • Oral tablets; an injectable form is used in hospital for acute dystonic reactions
  • Withdrawn gradually to avoid rebound parkinsonism

Nursing care

  • Screen older adults for confusion, constipation and urinary retention
  • Teach to avoid overheating and to drink fluids in hot weather or heavy work
  • Warn about drowsiness before driving
  • Report eye pain, fever or abdominal distension promptly

Pregnancy and breastfeeding

Safe use in pregnancy has not been established.

Test yourself

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

Why is benzatropine usually avoided in people over 65?

It is less safe than alternatives: confusion, delirium, urinary retention, constipation and falls.

Which antipsychotic movement disorder does benzatropine treat, and which does it not?

It treats acute dystonia and drug-induced parkinsonism; it does not treat tardive dyskinesia.

Which dangerous effect can occur in hot weather with benzatropine plus an antipsychotic?

Heat stroke and hyperthermia, because sweating is reduced.

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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: DailyMed - BENZTROPINE MESYLATE tablet (DailyMed (U.S. National Library of Medicine), 2026); Benztropine: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2018); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 21 (McGraw Hill, 2023); Farmacología básica y clínica (Katzung), 16.ª ed., cap. 28 (McGraw Hill, 2025).

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Representative model, for educational purposes only.