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

BACKGROUND: Clozapine-induced hypersalivation (CIH) is a common side effect of clozapine treatment and is disliked by clozapine patients, potentially threatening adherence to clozapine treatment. We proposed a trial of alternative medications, hyoscine and glycopyrrolate, for the treatment of CIH and the primary objective of the feasibility study was to assess the recruitment and retention of community clozapine patients as well as assess the metrics of the primary hypersalivation measure. METHODS: This 11-month trial took place in two NHS trusts in northwest UK. Participants were community-dwelling clozapine patients aged 18–65 years who were suffering from CIH, and were recruited from community mental health clinics. They were randomised using a telephone randomisation service to receive either hyoscine (1 week at 0.6 mg daily, 3 weeks at 0.9 mg daily), glycopyrrolate (1 week at 2 mg daily, 3 weeks at 3 mg daily) or placebo. Participants and investigators were blinded to which study arm the participants had been randomised to. We collected data on salivation levels and side effects on a weekly basis and also assessed cognition at the beginning and end of the trial. We also interviewed a sample of participants after the trial to gather information on their experience of having taken part. RESULTS: One hundred and thirty-eight potential participants agreed to being contacted by researchers about participation in the trial and of these, 29 participants were randomised. Of these, four participants exited the trial before taking any trial medication, and two participants left the study owing to concerns of side effects. Data from four participants was missing, and complete data was available for 19 participants who completed the trial. The mean recruitment rate overall was 1.3 participants per site per month, and the overall retention rate was 76%. Interview data suggested that participants’ experiences of trial participation were overwhelmingly positive. CONCLUSIONS: The feasibility study demonstrated that a trial of alternative medications in the treatment of CIH is feasible; patients were willing to be randomised to the trial and retention rate was high. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02613494, registered 24 November 2015