Second-line treatment of extra pyramidal 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 3rd 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.