Effect of Topically Applied Iganidipine Dihydrochloride, a Novel Ca(2+) Antagonist, on Optic Nerve Head Circulation...

Purpose: We studied the effect of topically applied iganidipine dihydrochloride, a novel water-soluble calcium channel blocker on the blood flow of optic nerve head (ONH), intraocular pressure, and blood pressure in rabbits.Methods: (1) 0.1% iganidipine (20 &mgr;l) was instilled into a normal eye. The change in blood flow in the ONH was measured using a hydrogen gas clearance flowmeter. (2) Iganidipine (0.0001%-0.1%) was instilled into a circulation-disordered eye before or after the intravitreal injection of endothelin-1, and change in the blood flow in the ONH was measured. (3) Changes in intraocular pressure and blood pressure after instillation of 0.1% iganidipine were measured. In all experiments, physiological saline was instilled in each contralateral eye as a control.Results: (1) Instillation of iganidipine significantly increased the blood flow in the ONH by 40% at 45 minutes after instillation. (2) Pre-instillation of 0.01 and 0.1% iganidipine almost completely inhibited the decrease of blood flow in the ONH in the circulation-disordered model. The decrease of blood flow in the ONH was corrected with post-instillation of 0.1% iganidipine. These effects were continuous. (3) Instillation of 0.1% iganidipine did not change either intraocular pressure or blood pressure.Conclusion: It was shown that instillation of iganidipine continuously increased and maintained the blood flow in the ONH in normal and circulation-disordered rabbit eye models.