Abstract
Clozapine has proven to be an effective antipsychotic agent, particularly for patients who are unresponsive to other antipsychotic drugs. However, it has a number of side-effects that impact adversely on patient compliance and quality of life. Hyper-salivation is common and can be unpleasant and socially disabling. Initial studies with clozapine reported hypersalivation in 31% of patients [1], but more recent studies suggest that the incidence is generally higher than this. A double-blind trial comparing clozapine and haloperidol reported hyper-salivation in 74% of the patients taking clozapine and 15% of the patients taking haloperidol [2].
Clozapine has a complex pattern of receptor affinities, and the pathophysiology of the hypersalivation is unclear. There is reported to be no difference in average saliva flow rates between patients taking clozapine and controls [3]. A single case study found decreased pharyngeal peristalsis in a patient with severe clozapine-induced hypersalivation [4]. While treatment with anticholinergic drugs such as benztropine or tricyclic antidepressants is often recommended, these tend not to be very effective and have the added disadvantage of increasing the already considerable anticholinergic effect of clozapine. Clonidine has also been suggested, but is potentially hypotensive.
We report a case in which sublingual atropine eye drops [5] were successful in treating clozapineinduced hypersalivation:
A is a 44-year-old female with chronic schizophrenia and associated depression who has made many high-lethality suicide attempts. She was treated with clozapine following a poor response to other antipsychotic drugs. Clozapine has been highly effective in controlling her schizophrenia and suicidality. However, she began to suffer severe hypersalivation, which she found intolerable.
A reduction of the clozapine dose and addition of benztropine had minimal effect. The prescription of 1% atropine eye drops, with 1–2 drops administered sublingually in the morning, has resulted in resolution of the hypersalivation, persisting throughout the day. There have been no adverse effects from this treatment.
The local administration of atropine would appear more desirable than giving systemic agents. Further research is required to evaluate the efficacy of sub-lingual atropine in the treatment of clozapineinduced hypersalivation.