Reduction of clozapine-induced hypersalivation by pirenzepine is safe.

Introduction Hypersalivation is known as a frequent, disturbing, and socially stigmatizing side effect of therapy with the atypical antipsychotic clozapine. It has been shown that the addition of the anticholinergic pirenzepine is able to reduce clozapine-induced hypersalivation, probably by blocking M4-receptors. Nevertheless, a pharmacokinetic interaction between both compounds cannot be excluded. Methods In this pilot study, 29 schizophrenic patients (ICD-10; 51.7 % female; age: 36.7 +/- 8.7 years [mean +/- SD]) were included. Serum concentrations of clozapine and its pharmacologically active metabolite N-desmethylclozapine were determined under steady-state conditions by automated HPLC …