Masahiro Orihashi1, Yuichiro Shima2, Hiroshi Tsuneki3, Ikuko Kimura1. 1. Department of Clinical Pharmacology, Graduate School of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, Toyama, Japan. 2. Teika Pharmaceutical Company, Toyama, Japan. 3. Department of Clinical Pharmacology, Graduate School of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, Toyama, Japan. htsuneki@ms.toyama-mpu.ac.jp.
Abstract
PURPOSE: To compare the ocular hypotensive effect of nipradilol and timolol in combination with bunazosin in rabbits. METHODS: The intraocular pressure (IOP) in normal rabbits was measured using an applanation pneumatonograph. Nipradilol, timolol, and bunazosin were instilled, individually or in combination, into the inferior conjunctival sac. RESULTS: Nipradilol (0.25%), timolol (0.5%), and bunazosin (0.01%) individually lowered IOP. The IOP-lowering effects of both nipradilol and timolol were significantly enhanced by the combined application of bunazosin (0.01%). In the presence of 5% timolol or 0.1% bunazosin, IOP was further lowered by the addition of nipradilol. The IOP-lowering effect of nipradilol was partly inhibited by pretreatment with c-PTIO (10 mM), a nitric oxide (NO)-trapping agent. CONCLUSIONS: The present study demonstrated that the IOP-lowering effects of nipradilol are due to beta- and alpha1-blocking and NO-donating actions, and bunazosin has an additive effect on the IOP-lowering effect of nipradilol or timolol.
PURPOSE: To compare the ocular hypotensive effect of nipradilol and timolol in combination with bunazosin in rabbits. METHODS: The intraocular pressure (IOP) in normal rabbits was measured using an applanation pneumatonograph. Nipradilol, timolol, and bunazosin were instilled, individually or in combination, into the inferior conjunctival sac. RESULTS:Nipradilol (0.25%), timolol (0.5%), and bunazosin (0.01%) individually lowered IOP. The IOP-lowering effects of both nipradilol and timolol were significantly enhanced by the combined application of bunazosin (0.01%). In the presence of 5% timolol or 0.1% bunazosin, IOP was further lowered by the addition of nipradilol. The IOP-lowering effect of nipradilol was partly inhibited by pretreatment with c-PTIO (10 mM), a nitric oxide (NO)-trapping agent. CONCLUSIONS: The present study demonstrated that the IOP-lowering effects of nipradilol are due to beta- and alpha1-blocking and NO-donating actions, and bunazosin has an additive effect on the IOP-lowering effect of nipradilol or timolol.