1. Ocular and systemic pharmacokinetics of brimonidine and brinzolamide after topical administration in rabbits: comparison between fixed-combination and single-drug formulations.
- Author
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Suzuki G, Kunikane E, Shigemi W, Shinno K, Kozai S, Kurata M, and Kawamura A
- Subjects
- Administration, Topical, Adrenergic alpha-2 Receptor Agonists administration & dosage, Adrenergic alpha-2 Receptor Agonists pharmacokinetics, Animals, Aqueous Humor drug effects, Brimonidine Tartrate administration & dosage, Carbonic Anhydrase Inhibitors administration & dosage, Carbonic Anhydrase Inhibitors pharmacokinetics, Chromatography, High Pressure Liquid, Disease Models, Animal, Drug Compounding, Drug Therapy, Combination, Glaucoma metabolism, Male, Ophthalmic Solutions, Rabbits, Sulfonamides administration & dosage, Tandem Mass Spectrometry, Thiazines administration & dosage, Vitreous Body drug effects, Aqueous Humor metabolism, Brimonidine Tartrate pharmacokinetics, Glaucoma drug therapy, Sulfonamides pharmacokinetics, Thiazines pharmacokinetics, Vitreous Body metabolism
- Abstract
Aim: The aim of this study was to compare the ocular and systemic absorption of brimonidine (BMD) and brinzolamide (BZM) in rabbits after the topical administration of a fixed-combination ophthalmic suspension of 0.1% BMD tartrate and 1% BZM (FCBB) with that after the administration of the respective single-drug formulations., Materials and Methods: Ocular and systemic drug absorption was estimated by determining BMD and BZM concentrations in the aqueous humor, retina/choroid, vitreous body, and blood/plasma by liquid chromatography/tandem mass spectrometry after the administration of FCBB, 0.1% BMD tartrate ophthalmic solution (0.1% BMD), or 1% BZM ophthalmic suspension (1% BZM) to rabbits., Results: In concomitant administration, instilling 0.1% BMD and 1% BZM successively without interval lowered aqueous humor concentrations of both drugs compared to those observed with a 5-min interval. After FCBB administration, BMD and BZM concentrations in the aqueous humor were comparable with those observed after the administration of 0.1% BMD and 1% BZM, whereas BMD concentrations in posterior ocular tissues were equal to or higher than those observed after 0.1% BMD. Plasma BMD concentrations following the administration of FCBB were 0.8-fold lower than those after 0.1% BMD; no remarkable differences were observed in blood BZM concentrations for both formulations., Conclusions: FCBB achieved drug distribution in the aqueous humor and systemic exposure that were comparable to those for the single-drug formulations. The viscosity of FCBB may increase BMD distribution in the retina/choroid. The administration interval affects ocular drug absorption with the concomitant administration of 0.1% BMD and 1% BZM, which can be overcome by using the fixed-combination of both drugs.
- Published
- 2021
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