prostaglandin f2 alpha isopropyl ester versus iloprost phenacyl ester in rabbit and beagle eyes one and 2 micrograms of prostaglandin f2 alpha isopropyl ester pgf2 alpha ie applied topically to the rabbit eye caused a biphasic response the hypotensive phase was dosedependent with a maximum reduction in intraocular pressure iop of 94 17 mmhg at a dose of 2 micrograms in beagles 04 to 2 micrograms topical pgf2 alphaie resulted in a sustained iop reduction 2 micrograms produced the maximum reduction of 79 mmhg no initial hypertensive response was observed iloprost phenacyl ester iloprostpe caused a greater decrease in iop when dissolved in 05 hydroxypropyl methylcellulose at than in saline in rabbits doses of 01 to 1 microgram in at caused a biphasic response with a sustained iop decrease fluctuating between 7 and 8 mmhg in beagles 1 and 2 micrograms iloprostpe resulted in a mean iop reduction of 58 04 mmhg and 58 05 mmhg p less than 0005 respectively the decrease persisted for 5 hrs no initial hypertensive response was observed in beagles pgf2 alphaie induced a strong miosis lasting more than 6 hours iloprostpe had no effect on pupil size both pgesters induced a slight hyperemia in rabbit and beagle eyes in rabbits iloprostpe affects the bloodaqueous barrier more than pgf2 alphaie since higher protein concentrations are seen in the aqueous humor after application of iloprostpe neither pgester had a noticeable effect on aqueous protein in beagles in rabbits both pgesters led to slightly increased aqueous humor cyclicamp concentrations in beagles aqueous humor cyclicamp was elevated only after iloprostpeabstract truncated at 250 words