A feasibility study of Glycopyrrolate in comparison to Hyoscine hydrobromide and placebo in the Treatment of Hypersalivation Induced by Clozapine

GOTHIC1 is a multicentre, randomised double blind, placebo controlled feasibility trial, looking to recruit, 42 patients across Lancashire and Merseyside who have been prescribed Clozapine and who experience hypersalivation.

Hypersalivation is one of the most debilitating side effects of Clozapine use, occurring in 80% of patients. Clozapine Induced Hypersalivation (CIH) can cause profound social stigma and embarrassment, lowering self-esteem, increasing social isolation and exacerbating psychological problem.

The most commonly used medication for CIH is Hyoscine Hydrobromide, in spite of the limited evidence base, though there is promising evidence to show that Glycopyrrolate, an anti-muscarinic  may be more successful in the treatment of CIH causing fewer cognitive side effects.


Assess the feasibility of recruiting community care patients, and to ascertain whether the interventions are acceptable, and indicate likely attrition rates and tolerability.


5-week study consisting of a 1-week wash-out period followed by a 4-week study drug treatment period. Participants will be randomised to one of three study arms. Self-report measures of salivation and side effects will be taken weekly and measures of cognition and will be assessed on two occasions during the study.


Results from the feasibility trial will allow for a further main study to be carried out, the results of which will be published in peer reviewed journals, on behalf of all collaborators.


The management of debilitating side effects of clozapine could help increase the adherence clozapine use for patients.