TRIHEXYPHENIDYL oral

Therapeutic action

• Anticholinergic antiparkinson drug

Indications

• Second-line treatment of extrapyramidal reactions induced by antipsychotics

Forms and strengths

• 2 mg tablet

Dosage

• Adult: 2 mg once daily, then increase if necessary up to 2 mg 2 or 3 times daily (max. 12 mg daily)
• Administer the lowest effective dose in elderly patients and do not exceed 10 mg daily.

Duration

• As long as antipsychotic treatment lasts.

Contra-indications, adverse effects, precautions

• Do not administer to patients with closed-angle glaucoma, prostate disorders, gastrointestinal obstruction or atony.
• Administer with caution and carefully monitor use in elderly patients (risk of mental confusion, hallucinations).
• May cause: anticholinergic effects (dry mouth, constipation, blurred vision, tachycardia, disorders of micturition), confusion, hallucinations, memory loss.
• Avoid or monitor combination with other anticholinergic drugs (atropine, amitriptyline, chlorpromazine, promethazine, etc.).
• Pregnancy: re-evaluate whether the antipsychotic treatment is still necessary; if treatment is continued, administer trihexyphenidyl at the lowest effective dose; observe the neonate if the mother was under treatment in the 3^rd trimester (risk of anticholinergic effects, e.g. tremors, abdominal distension).
• Breast-feeding: if treatment is necessary, administer at the lowest effective dose and observe the child (risk of anticholinergic effects, e.g. tachycardia, constipation, thickening of bronchial secretions).

Remarks

• Take with meals.
• Also comes in 2 mg extended-release capsule, administered once daily.
• Trihexyphenidyl is also used in treatment of Parkinson’s disease.

Storage