Options in managing alternatives to hyoscine in clozapine-induced hypersalivation: a survey of secure services consultants

Clozapine-induced hypersalivation is socially embarrassing and potentially life threatening. It can lead to poor medication adherence, which is of concern for patients in secure settings.

Hyoscine hydrobromide is widely used as a first-line treatment, despite little available evidence. ¹ Alternatives are limited, but 19 different agents are listed in the Maudsley Prescribing Guidelines, ¹ including antipsychotics, anti-depressants and other drugs with antimuscarinic properties. There are few meaningful trials. Within the north-west of England, obtaining hyoscine has been difficult at times due to supply shortages and so alternatives have been sought.

Partnerships in Care have over 50 consultant psychiatrists nationwide caring for over 1000 in-patients, mostly within secure conditions, with a fair proportion prescribed clozapine. To examine prescribing alternatives to hyoscine, all consultants with clinical responsibilities were contacted regarding their prescribing practices and experiences. Responses were sent back in the form of a patient non-identifiable response via email.

Just under 50% of consultants replied (n=23). In the absence of hyoscine hydrobromide, there was overall little confidence in alternatives, but clinicians tended to advocate one or two. Atropine, either sublingually or via eye drops was relatively popular and the 8 clinicians that supported its use had some confidence in it. Four clinicians each supported the use of amitriptyline, pirenzepine and trihexyphenidyl. All the medication recommendations received were in the latest Maudsley Prescribing Guidelines in Psychiatry, except for procyclidine. Most options consisted of drugs with antimuscarinic properties such as pirenzepine and trihexyphenidyl. Dose reduction of clozapine was recommended by 1 consultant. The author and another two consultants have had some success with glycopyrrolate syrup, but this is a very expensive option.

Clozapine-induced hypersalivation is a condition potentially difficult to manage. The wide range of options and lack of evidence does not support clinicians in their attempts to continue treatment. In circumstances where patients do not respond to hyoscine, the most popular choice was sublingual atropine. National guidance and further trials are required. The shortage of hyoscine raises legal and ethical questions for patients subject to certification by second-opinion doctors and whether clinicians are likely to request further certification for alternative classes of drugs for hypersalivation.