Effect of topically applied iganidipine dihydrochloride, a novel calcium antagonist, on optic nerve head circulation in rabbits.
OBJECTIVE
To study the effect of topically applied iganidipine dihydrochloride (iganidipine), a novel water-soluble calcium channel blocker, on blood flow in the optic nerve head (ONH), intraocular pressure, and systemic blood pressure in rabbits.


METHODS
After 0.1% iganidipine (20 microL) was instilled into normal eyes, the change in ONH blood flow was measured using a hydrogen gas clearance flowmeter. Iganidipine (0.0001% to 0.1%) was instilled into eyes with impaired ocular circulation before or after the intravitreal injection of endothelin-1, and the change in ONH blood flow was measured. Changes in intraocular pressure and blood pressure after instillation of 0.1% iganidipine were measured. In all experiments, physiological saline was instilled into the contralateral eye as a control.


RESULTS
Iganidipine significantly increased the ONH blood flow in normal eyes with the maximum increment of 31.7% at 45 minutes after instillation. Preinstillation of 0.01% and 0.1% iganidipine significantly inhibited the decrease in ONH blood flow in the eyes with impaired circulation. Moreover, ONH blood flow recovered with postinstillation of 0.1% iganidipine. These effects were persistent. Instillation of 0.1% iganidipine did not change either the intraocular pressure or the blood pressure.


CONCLUSIONS
The instillation of iganidipine persistently increased and maintained the ONH blood flow in rabbit eyes with normal and impaired ocular circulation.
Waki
M
M
Research Laboratories, Senju Pharmaceutical Company, Ltd, Osaka, Japan.
Sugiyama
T
T
Watanabe
N
N
Ogawa
T
T
Shirahase
H
H
Azuma
I
I
D000287:Administration, Topical; D000818:Animals; D001775:Blood Circulation / Q000187:drug effects*; D001783:Blood Flow Velocity / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D019332:Endothelin-1 / Q000494:pharmacology; D018056:Hemorheology; D007267:Injections; D007429:Intraocular Pressure / Q000187:drug effects; D008297:Male; D009883:Ophthalmic Solutions; D009898:Optic Disk / Q000098:blood supply* / Q000187:drug effects; D010879:Piperazines / Q000008:administration & dosage / Q000494:pharmacology*; D011725:Pyridines / Q000008:administration & dosage / Q000494:pharmacology*; D011817:Rabbits; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014822:Vitreous Body
D002121:Calcium Channel Blockers; D019332:Endothelin-1; D009883:Ophthalmic Solutions; D010879:Piperazines; D011725:Pyridines; D014662:Vasoconstrictor Agents; C108540:iganidipine