Sublingual Tropicamide Eye Drops for the Management of Clozapine-Induced Hypersalivation: A Case Series of Seven Patients

Clozapine-induced hypersalivation (CIH) affects 30-80% of patients on clozapine and is a major contributor of non-adherence. Current managements, largely based on systemic anticholinergics, can worsen other clozapine-related side effects. Here sublingual tropicamide 1% eye drops can be a low-cost alternative worth evaluating. We report a case series of seven patients with schizophrenia treated with sublingual tropicamide 1% ophthalmic solution (4-8 drops/day) for CIH. Treatment response was assessed by patient-reported percentage reduction in salivation. All seven patients reported improvement (25-80%). One patient reported a transient bitter taste; no systemic anticholinergic effects occurred. Sublingual tropicamide was associated with patient-reported improvement in CIH and was well tolerated in this small, uncontrolled series. Its short duration of action and local administration may offer practical advantages over systemic anticholinergics, though the mechanism remains unproven. Randomised trials with validated outcome measures are needed to establish its efficacy and safety.