Abstract
Abstract: :
Purpose: To compare the ocular bioavailability of brimondine tartrate administered as ALPHAGAN® (brimonidine tartrate 0.2% preserved with benzalkonium chloride, pH 6.4), BRIMONIDINE PURITETMbrimonidine tartrate 0.2% preserved with PURITE®, pH 7.2), and ALPHAGAN®PF (brimonidine tartrate 0.2%, preservative-free, pH 6.4). Methods: In cross-over fashion, on three separate study days, New Zealand albino rabbits (n=20) were administered a single 35-µl drop of test formulation in each eye. Aqueous humor samples were collected pre-dose and at 10, 20, and 40 minutes and 1, 1.5, 2, 3, 5, and 8 hours post-dose and brimonidine concentrations measured by a specific, sensitive LC-MS/MS method. Results: Aqueous humor concentrations were quantifiable up to 5 hours post-dose. Brimonidine was rapidly absorbed from all three formulations with maximal aqueous humor concentrations being reached within 1 hour. Ocular absorption of BRIMONIDINE PURITETM, ALPHAGAN®PF, and ALPHAGAN® was assessed through these pharmacokinetic parameters, Cmax (2.69 ± 0.72, 1.74 ± 0.13 and 1.24 ± 0.22 µg/ml respectively) AUC (3.78 ± 0.38, 2.49 ± 0.22 and 2.77±0.22 µg.h/ml respectively) and t1/2 (0.75, 0.75, and 0.92 hours respectively). A statistical comparison of the AUC values indicates a significantly higher ocular bioavailability for BRIMONIDINE PURITETM when compared to ALPHAGAN®PF, and ALPHAGAN®. The enhanced ocular bioavailability from BRIMONIDINE PURITETM may be related to either the PURITE® preservative or to the elevated pH. Conclusion: Brimonidine was rapidly absorbed into rabbit eye following topical administration as BRIMONIDINE PURITETM, ALPHAGAN®PF, or ALPHAGAN®. The ocular bioavailability of brimonidine was enhanced when administered as BRIMONIDINE PURITETM.
Keywords: 316 animal model • 318 anterior segment • 390 drug toxicity/drug effects