Ocular hypotensive effect of topical ketanserin in timolol users

Background: Ketanserin is a specific antagonist of 5-HT2 and 5-HT1c receptors. These receptors are linked to the stimulation of phosphoinositide metabolism and are involved in IOP controls. Orally and topically administered ketanserin reduces IOP in normotensive and glaucomatous eyes. Methods: Ketanserin 0.5% eye drops were administered to 20 patients with primary open-angle glaucoma in a randomised, crossover, double-masked fashion to evaluate the effect of ketanserin in glaucomatous patients already receiving timolol who did not have controlled IOP (>21 mmHg). Mean and range of IOP curve (8.00 a.m.-8.00 p.m.), pupil diameter, Schirmer I, basal secretion test and BUT values were recorded at baseline and after 2 weeks of topical administration of ketanserin or placebo twice daily. The alternative treatment was given 2 weeks later and the same protocol was repeated. Results: When patients received placebo no significant variations were found in the analysed parameters. Ketanserin significantly reduced mean IOP (19.5%) and was effective for up to 12 h without inducing variations of tear secretion or pupil diameter. No systemic side effects were observed, and no significant variations in ocular symptoms and signs were reported. Conclusion: These results indicate that topical administration of ketanserin may be useful to reduce IOP in patients not controlled with beta-blockers.