Anticholinergic medication for non-clozapine neuroleptic-induced hypersalivation in people with schizophrenia

Treatment of schizophrenia depends heavily on neuroleptic drugs. Hypersalivation is a common side effect when people with schizophrenia are treated with neuroleptic drugs. Hypersalivation can be an embarrassing and stigmatising problem, can affect quality of life and can result in discontinuation of neuroleptic treatment. It can also be difficult to treat.

To summarise the best available evidence of the effects of anticholinergic drugs in the treatment of non-clozapine neuroleptic-induced hypersalivation in people with schizophrenia. Clozapine-induced hypersalivation has been addressed in another Cochrane review.

We searched the Cochrane Schizophrenia Group Trials Register (15 November 2012) and inspected references of all identified studies for further relevant studies. We were to contact the first author of each included study for information regarding unpublished trials.

All randomised controlled trials comparing an anticholinergic drug with placebo, no treatment, another anticholinergic drug or any other intervention.

We inspected the results of the search to identify relevant studies. We were to extract data onto standard, simple forms. Disagreements were resolved through discussion. The risk of bias was to be assessed using the Cochrane risk assessment tool. For binary outcomes, we were to calculate a standard estimation of the risk ratio (RR) and its 95% confidence interval (CI). For continuous outcomes, we were to estimate the mean difference between groups.

The search resulted in four potential studies; after inspection, all were excluded. Three studies were excluded because they involved people with clozapine-induced hypersalivation - a topic covered in another Cochrane review. The fourth study was excluded because it involved people with schizophrenia, mood disorders or other mental disorders who were suffering from clozapine- and non-clozapine induced hypersalivation and were treated with Chinese medicines with unknown anticholinergic properties. People in the control group received an anticholinergic drug (artane) or an antihistamine (phenergan). It was not possible to separate clozapine- from non-clozapine-treated people in the intervention group, or to separate artane-treated people from phenergan-treated people in the control group.

We have been unable to locate any studies addressing the question raised in this review. Accordingly, this empty review points out an important clinical problem that needs to be investigated via well-designed and well-conducted randomised trials. Clinicians and patients are likely to continue with their current dependence on clinical judgement and personal experience. Policy makers have no trial-based evidence upon which to base guidelines for the treatment of hypersalivation induced by neuroleptics other than clozapine. They are likely to continue to rely on opinion and habit when making recommendations. Funders of studies may wish to make this important subgroup of people a priority in future research.