What does Benztropine do?

Benztropine: Mechanism and Clinical Applications

Benztropine is an anticholinergic medication primarily used to treat extrapyramidal symptoms caused by antipsychotic medications, with a secondary role in managing Parkinson's disease symptoms. 1

Pharmacological Mechanism

Benztropine works through two primary mechanisms:

• Anticholinergic activity: Blocks muscarinic acetylcholine receptors with potency approximately half that of atropine when administered orally. This is the therapeutically significant mechanism for managing parkinsonism and drug-induced extrapyramidal symptoms. 1

• Antihistaminic effects: Possesses antihistaminic properties similar to pyrilamine maleate, though this action is less clinically significant for its primary indications. 1

Primary Clinical Applications

1. Management of Antipsychotic-Induced Extrapyramidal Symptoms (EPS)

Benztropine is commonly used to treat:

• Drug-induced parkinsonism
• Acute dystonic reactions
• Akathisia

However, it should be used with caution as guidelines recommend:

• Avoiding benztropine when possible due to significant anticholinergic side effects 2
• Using it only for problematic extrapyramidal symptoms that cannot be managed by other means 2

2. Adjunctive Treatment in Parkinson's Disease

Benztropine can help manage:

• Tremor
• Rigidity
• Bradykinesia

Important Clinical Considerations

Medication Combinations

Benztropine is often used in combination therapy:

• As part of a medication combination to address side effects of an effective agent (specifically for extrapyramidal symptoms secondary to antipsychotics) 2

Contraindications and Cautions

1. Avoid in elderly patients with dementia: Can worsen cognitive function and cause delirium 3

2. Risk of anticholinergic toxicity: Can cause serious adverse effects including:

   • Delirium and psychosis 3
   • Stereotyped movements 3
   • Potentially fatal toxicity in overdose 4

3. Withdrawal concerns: Abrupt discontinuation may lead to withdrawal-emergent dyskinesia 5

Adverse Effects

Common adverse effects include:

• Dry mouth
• Blurred vision
• Constipation
• Urinary retention
• Cognitive impairment
• Confusion
• Hallucinations

Severe cases can present with:

• Delirium 3
• Stereotyped movements 3
• Mania or hypomania (dose-related) 6

Clinical Pearls

1. Dosing considerations: Start with low doses and titrate carefully, especially in elderly patients

2. Monitoring: Watch for signs of anticholinergic toxicity including confusion, hallucinations, and urinary retention

3. Discontinuation: Taper gradually rather than stopping abruptly to avoid withdrawal-emergent dyskinesia 5

4. Alternative options: Consider atypical antipsychotics with lower EPS risk when possible, rather than adding benztropine to high-risk antipsychotics 2

5. Mood effects: At very low doses (0.25 mg daily), benztropine may have mood-elevating effects in some patients with Parkinson's disease and depression 6

Comparison with Other Anticholinergics

Some evidence suggests that benztropine may have more central nervous system side effects compared to other anticholinergics:

• Patients treated with benztropine showed more anxiety and depression compared to those treated with ethopropazine 7
• Benztropine treatment was associated with increased tardive dyskinesia compared to procyclidine 7