Effect of topically applied iganidipine dihydrochloride, a novel calcium antagonist, on optic nerve head circulation in rabbits

Purpose: To study the effect of topically applied iganidipine dihydrochlori de (iganidipine), a novel water-soluble calcium channel blocker, on blood f low in the optic nerve head (ONH), intraocular pressure, and systemic blood pressure in rabbits. Methods: After 0.1% iganidipine (20 muL) was instilled into normal eyes, th e change in ONH blood now was measured using a hydrogen gas clearance flowm eter. Iganidipine (0.0001% to 0.1%) was instilled into eyes with impaired o cular circulation before or after the intravitreal injection of endothelin- 1, and the change in ONH blood flow was measured. Changes in intraocular pr essure and blood pressure after instillation of 0.1% iganidipine were measu red. In all experiments, physiological saline was instilled into the contra lateral eye as a control. Results: Iganidipine significantly increased the ONH blood flow in normal e yes with the maximum increment of 31.7% at 45 minutes after instillation. P reinstillation of 0.01% and 0.1% iganidipine significantly inhibited the de crease in ONH blood flow in the eyes with impaired circulation. Moreover, O NH blood now recovered with postinstillation of 0.1% iganidipine. These eff ects were persistent. Instillation of 0.1% iganidipine did not change eithe r the intraocular pressure or the blood pressure. Conclusion: The instillation of iganidipine persistently increased and main tained the ONH blood flow in rabbit eyes with normal and impaired ocular ci rculation. Jpn J Ophthalmol 2001;45:76-83 (C) 2001 Japanese Ophthalmology S ociety.