The Effect of Glycopyrrolate on Nocturnal Sialorrhea in Patients Using Clozapine: A Randomized, Crossover, Double-Blind, Placebo-Controlled Trial

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Nocturnal sialorrhea is one of the most frequent adverse events in clozapine treatment. Symptomatic management of sialorrhea usually consists of off-label treatment with anticholinergic agents. The aim of the current study is to evaluate the efficacy and safety of glycopyrrolate in patients using clozapine that experience sialorrhea.


In a double-blind randomized crossover trial, patients with nocturnal sialorrhea (n = 32) were randomized to treatment with glycopyrrolate 1 mg or placebo. This double-blinded phase was followed by an optional open label extension phase with glycopyrrolate 2 mg. Exposure periods consisted of 6 consecutive days and were separated with 1 washout week. The primary outcome was clinical improvement of nocturnal sialorrhea assessed by the Patient Global Impression of Improvement (PGI-I).


The proportion of patients with a clinical improvement according to PGI-I did not significantly differ between 1 mg and placebo (18.8% vs 6.3%, P = 0.289); however, in patients using glycopyrrolate 2 mg once daily versus placebo, it did (43.5% vs 6.3%, P = 0.039). Glycopyrrolate was not associated with severe adverse events or worsening of cognitive adverse events.


Glycopyrrolate 1 mg was not superior to placebo, whereas 2 mg showed a significant clinical improvement of nocturnal sialorrhea compared with placebo. Glycopyrrolate seemed to be a tolerable anticholinergic agent in the treatment of clozapine-associated sialorrhea.

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