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L.R. Bartholomew, A.R. Kent, L. King; Vitreous Concentration of Topically Applied Brimonidine–Purite 0.15% . Invest. Ophthalmol. Vis. Sci. 2005;46(13):1325.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine the vitreous brimonidine concentration of topically applied brimonidine–Purite (Alphagan–P®). Methods: Patients scheduled for pars plana vitrectomy were invited to participate in this study after IRB approval was obtained. Patients were asked to place brimonidine 0.15%–Purite (Alphagan–P®) in the operated eye either bid or tid for at least one week, and 12 or 8 hours respectively prior to the vitrectomy. Four patients served as controls and did not receive any drops. Vitreous (∼ 0.5 – 1.0 cc) was aspirated prior to opening the infusion line. Three blank vitreous specimens from cadaver eyes were included in the samples as controls. The vitreous was sent to an independent lab in a masked fashion for analysis. Results: Nine and ten patients received brimonidine 0.15%–Purite in a bid and tid dosing respectively. The mean concentration of brimonidine in the bid patients was 18.5 nM (range 2.14 – 36.4, median 18.1, Std Dev 10.3), and in the tid patients was 20.1 nM (range 1.77 – 37.5, median 18.7, Std Dev 16.2). The concentration of brimonidine in blank vitreous specimens was below the lower limit of quantitation (1.72 nM). The presence of a posterior chamber lens may decrease the resistance of penetration of topically applied brimonidine–Purite 0.15%: brimonidine concentration was statistically significantly higher in patients with posterior chamber lenses with the tid patients (N= 7; p = 0.043), but not with bid patients (N= 5; p = 0.21). Conclusions: Brimonidine 0.15%–Purite topically applied both bid and tid obtain vitreous concentrations at or above the 2 nM concentration known to activate the alpha–2 receptor. Supported in part by an unrestricted research grant from Allergan, Inc.
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