In vivo comparative study of ocular vasodilation, a relative indicator of hyperemia, in guinea pigs following treatment with bimatoprost ophthalmic solutions 0.01% and 0.03%.
OBJECTIVE
The objective of this in vivo study was to compare the incidence of vasodilation in guinea pigs following topical administration of bimatoprost ophthalmic solutions 0.01% and 0.03%.


METHODS
The study comprised 20 guinea pigs assigned to 2 treatment groups (10 per treatment group) to receive either bimatoprost 0.01% or bimatoprost 0.03%. Animals were hand-held under 2.75 x magnification to score ocular vasodilation (a measure of hyperemia), using a scoring system developed at Alcon Research, Ltd. Following baseline ocular scoring, each animal received a 30 muL dose to the left eye of either bimatoprost 0.01% (3 mug) or bimatoprost 0.03% (9 mug). Vasodilation was again scored at 1, 2, 3, 4, 5 and 6 hours after dosing. Incidence of vasodilation was calculated as the percent of total eyes in each 2-hour time interval with scores >/=2.


RESULTS
The incidence of vasodilation was higher in the bimatoprost 0.01% treatment group (range, 45.0% to 60.0%) than the bimatoprost 0.03% treatment group (range, 30.0% to 52.2%) at all post-dosing time points.


CONCLUSIONS
The 2 bimatoprost formulations elicited ocular vasodilation of long duration (>6 hours) in the guinea pig model, with the bimatoprost 0.01% treatment group showing a higher incidence of ocular vasodilation than the bimatoprost 0.03% treatment group. Further clinical studies would be needed to determine whether the higher incidence of vasodilation may also be attributed to the increased BAK concentration in the bimatoprost 0.01% formulation.
Ogundele
Abayomi B
AB
Alcon Research, Limited, Fort Worth, TX, USA.
Earnest
David
D
McLaughlin
Marsha A
MA