Glycopyrrolate in comparison to hyoscine hydrobromide and placebo in the treatment of hypersalivation induced by clozapine (GOTHIC1): study protocol for a randomised controlled feasibility study

Background Clozapine is the only medication licensed for the treatment of resistant schizophrenia in the UK. Although efficacious, a common and unpopular side effect of clozapine treatment is clozapine-induced hypersalivation (CIH), which can contribute to non-adherence. The standard treatment for CIH in the UK is hyoscine hydrobromide but this may aggravate cognitive deficits in patients with schizophrenia while glycopyrrolate may be an effective alternative with a more tolerable side effect profile. There is currently no convincing evidence for hyoscine, or any other medication, as an effective treatment for CIH.