A novel approach to topical acetazolamide/PEG 400 ocular niosomes

To enhance the bioavailability and corneal permeability of acetazolamide (ACZ), niosomes containing Span 60/cholesterol (CH) as well as entrapped ACZ dissolved in 7 % v/v PEG 400 were prepared using thin film hydration method. The prepared vesicles were characterized for entrapment efficiency (%EE), shape, size and in vitro release. The results showed that changing the surfactant/CH ratio altered the %EE and drug release. Niosomes containing Span 60/CH at a 4:2 molar ratio showed the highest entrapment (> 98 %), exhibited a low Q6h (< 20 %), a small particle size (1.60 ± 0.48 μm) and were selected for testing of the intraocular pressure (IOP) lowering activity using Shiøtz tonometer. The tested niosomes produced a significant lowering of the IOP, reaching a value of -15.35 mmHg 1 h after application which was then sustained to reach -3.65 mmHg after 6 h compared to -10.5 mmHg after 4 h and -2.7 mmHg at 6 h from application of the free drug solution.