A placebo-controlled trial of trihexyphenidyl in unmedicated patients with schizophrenia

Seventeen patients with schizophrenia who had been free of medication for at least 2 months entered a placebo-controlled, random-order crossover trial of 5 mg of trihexyphenidyl twice daily for 4 weeks. Ten patients completed trials of both drug and placebo. Ratings of anticholinergic symptoms and of feeling the effects of the drug, controlled for order effects, were significantly higher at week 4 of the trihexyphenidyl trial than at week 4 of the placebo trial. Measures of psychosis, negative symptoms, depression, and liking the drug did not differ between trihexyphenidyl and placebo trials.