Trihexyphenidyl oral

Therapeutic action

Anticholinergic antiparkinson drug.

Indications

Second-line treatment of extrapyramidal reactions induced by antipsychotics.

Forms and strengths

• 2 mg tablet.

Dose

• Adult: 2 mg once daily, then increase if necessary up to 2 mg 2 or 3 times daily, maximum 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 because of the risk of mental confusion and hallucinations.
• May cause anticholinergic effects, confusion, hallucinations, and memory loss.
• Avoid or monitor combination with other anticholinergic drugs such as atropine, amitriptyline, chlorpromazine, and promethazine.
• Pregnancy: re-evaluate whether the antipsychotic treatment is still necessary. If treatment is continued, administer trihexyphenidyl at the lowest effective dose and observe the neonate if exposure occurred in the third trimester.
• Breast-feeding: if treatment is necessary, administer at the lowest effective dose and observe the child for anticholinergic effects.
• Take with meals.