Pacitane (Trihexyphenidyl) for Extrapyramidal Symptoms
Pacitane (trihexyphenidyl) 2 mg is primarily used for the treatment of drug-induced extrapyramidal symptoms and Parkinson's disease.
Mechanism of Action
Trihexyphenidyl is an anticholinergic medication that works by blocking the action of acetylcholine in the central nervous system. It helps to:
- Block muscarinic receptors in the brain
- Reduce excessive cholinergic activity in the basal ganglia
- Restore balance between cholinergic and dopaminergic systems
Primary Indications
1. Drug-Induced Extrapyramidal Symptoms (EPS)
- Particularly effective for acute dystonic reactions
- Helps manage drug-induced parkinsonism from antipsychotics
- Reduces rigidity, tremor, and bradykinesia associated with neuroleptic medications
2. Parkinson's Disease
- Adjunctive therapy to levodopa
- Particularly helpful for controlling tremor and rigidity
- May provide symptomatic relief in early stages of the disease
Dosing Recommendations
- Starting dose: 1-2 mg daily
- Gradual titration: Increase by 2 mg every 3-5 days as needed
- Maintenance dose: Usually 6-10 mg daily in divided doses
- Maximum dose: 12-15 mg daily in divided doses
- Elderly patients: Start with lower doses (1 mg) and titrate more slowly
Side Effects and Monitoring
Common Side Effects
- Dry mouth
- Blurred vision
- Constipation
- Urinary retention
- Confusion (especially in elderly)
- Dizziness
Contraindications
- Narrow-angle glaucoma
- Gastrointestinal obstruction
- Myasthenia gravis
- Prostatic hypertrophy with urinary retention
Clinical Pearls
- Most effective for tremor compared to other parkinsonian symptoms
- Should be taken with meals to reduce GI side effects
- Anticholinergic side effects are dose-dependent
- Abrupt discontinuation should be avoided to prevent withdrawal symptoms
- Elderly patients are more susceptible to cognitive side effects and should be monitored closely
Monitoring Parameters
- Assess for improvement in extrapyramidal symptoms
- Monitor for anticholinergic side effects
- Evaluate cognitive function, especially in elderly patients
- Check for urinary retention or constipation
- Monitor intraocular pressure in patients at risk for glaucoma
While Pacitane is effective for managing extrapyramidal symptoms, it should be used at the lowest effective dose and for the shortest duration necessary to minimize adverse effects, particularly in elderly patients where anticholinergic burden can significantly impact cognition and quality of life.