Treatment of Clozapine-Induced Hypersalivation
Excess saliva (hypersalivation or siallorrhoea) is a distressing clozapine side effect which can occur in about 30% of patients. The usual treatment is hysoscine hydrobomide tablets (Kwells®, or Joy-Rides®) but there is a national shortage, so alternative treatments are required.
Reducing the clozapine dose can help, which can be achieved by augmenting with another antipsychotic such as sulpiride.
Some of the following options are unlicensed, or involve off-label use, so it is recommended to discuss the treatment with the pharmacist before prescribing. These drugs would need to be included on MHA treatment forms if prescribed.
The alternatives include:
- Pirenzepine (25-100mg/day) is the most frequently preferred alternative. It is an unlicensed drug, but there is evidence to support its use
- Atropine 1% eye drops (BNF 11.5) can be used either sublingually or in solution as a mouthwash
- Glycopyrrolate oral solution (unlicensed) is usually well tolerated without causing a reduction in cognitive function which can be a problem with other options
- Amitriptyline (75-100mg, BNF 4.3.1) has been used effectively, although side effects are often a problem
- Antimuscarinics (BNF 4.9.2), such as procyclidine, are commonly tried, but are not usually effective. Trihexyphenidyl (5-15mg/day) is the best option
- Hyoscine patches (Scopoderm TTS®, BNF 4.6) should be kept on constantly, replacing every 3 days
Closely monitor the effects on the patient after switching treatment, as all these options have the potential to cause adverse effects such as severe constipation, drowsiness and loss of cognitive function.
Matthew Roberts, Clinical Pharmacist