Effects of pranidipine, a new calcium antagonist, on circulation in the choroid, retina and optic nerve head.

PURPOSE. To study the effects of pranidipine, a newly developed Ca(2+)-antagonist, on tissue circulation in the optic nerve head (ONH), choroid, and retina in rabbits. METHODS. Pranidipine (5 microg/kg) or vehicle solution was injected intravenously in urethane-anesthetized rabbits and the normalized blur value (NB), a quantitative index of in vivo tissue blood velocity, was measured in the choroid and in an area of the ONH and retina free of visible surface vessels before and for 90 min after injection, using the laser speckle method. Measurements in the ONH and choroid were performed in the same albino rabbit eyes (pranidipine group, n = 10; control group, n = 10) and those in the retina in another group of Dutch rabbits (pranidipine group, n = 10; control group, n = 10). RESULTS. Between 30 and 90 min after injection, the NB in the pranidipine group increased by 24% in the ONH, 19% in the choroid, and 17% in the retina on an average compared to baseline, and was significantly different from that in the control group (P < 0.0001, ANOVA). There were no significant inter-group differences in the systemic parameters, except for a transient decrease in blood pressure in the pranidipine groups. CONCLUSIONS. Pranidipine increased blood velocity and probably blood flow in the ONH, choroid, and retina of rabbits.