There is a manufacturer supply problem with hyoscine hydrobromide tablets (Kwells, Kwells Kids and Joy-Rides) and these preparations will be unavailable until at least March 2017. In addition to their licensed indication of motion sickness, they are often used off label to treat hypersalivation associated with clozapine therapy. Hypersalivation is a common and potentially distressing clozapine side effect. It is also occasionally seen with other antipsychotic drugs. Failure to manage it effectively has sometimes resulted in patients stopping clozapine treatment.
The Mental Health Prescribing Management Group has prepared guidance to support Mental Health and Primary Care services manage patients affected by this problem. The majority of patients receive prescriptions for hyoscine hydrobromide tablets from their GP.
The evidence base for any drug used for hypersalivation associated with clozapine therapy is weak. Treatment relies upon the antimuscarinic properties of the drugs recommended. It should be remembered that any drug with antimuscarinic properties may worsen clozapine associated constipation and therefore patients should be regularly asked about their bowel habits and if constipation is found it must be treated.