Can clozapine be used by dental practitioners to increase salivary flow in patients with dry mouth? A scoping review.

OBJECTIVES: Clozapine, an atypical antipsychotic used to treat people with schizophrenia, has been proposed as a possible treatment for salivary gland hypofunction. This scoping review investigated the available literature on clozapine's impact on salivary flow, in order to determine whether it could be used by dental practitioners in low doses as a treatment for dry mouth. DATA SOURCES: An electronic search was completed using Ovid MEDLINE (1996 to Nov 2021). Key MeSH search terms included "clozapine," "Clozaril," "salivation," "salivary flow rate," "sialorrhea," "hypersalivation," and "drooling." Two reviewers independently reviewed eligible articles and extracted the data based on the inclusion and exclusion criteria. RESULTS: The initial search identified 129 studies, six of which were included in this review. Four of them (one cross-sectional and three interventional) described salivary flow rates in schizophrenic patients taking clozapine, while one of those and two others focused on the mechanism of clozapine-induced sialorrhea, with one study covering both. There were mixed findings, with one study observing a moderate association between clozapine dose and salivary flow, and the others reporting no differences. Findings on the putative mechanisms for clozapine-induced sialorrhea (CIS) were inconclusive. CONCLUSION: There is insufficient high-quality information to justify using low-dose clozapine to increase salivary flow in dental patients with salivary gland hypofunction. Well-designed interventional studies and randomized control trials are required.