title: 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%.
abstract: 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.
authors.affiliation: Alcon Research, Limited, Fort Worth, TX, USA.
authors.forename: Abayomi B
authors.initials: AB
authors.lastname: Ogundele
authors.forename: David
authors.initials: D
authors.lastname: Earnest
authors.forename: Marsha A
authors.initials: MA
authors.lastname: McLaughlin