Abstract
Abstract: :
Purpose: To determine the efficacy of a newly prepared formulation containing biodegradable calcium phosphate nanoparticles (CAP) with 7-OH-DPAT in pigmented and non-pigmented rabbits using the surrogate end points of IOP and aqueous flow. Methods: IOP (mmHg) was measured utilizing a manometrically calibrated Mentor pneumatonometer. Aqueous humor flow rates were measured using fluorescein dilution by a Fluorotron Master. Results: IOP-lowering effects of topically administrated 7-OH-DPAT (125µg) were markedly diminished in pigmented Dutch Belted rabbits compared to NZW rabbits. However, topical application of 7-OH-DPAT formulated with CAP produced significant dose-related (37.5, 75, 125µg) reduction of IOP accompanied by suppression of aqueous humor flow in pigmented rabbits. Furthermore, in NZW rabbits, the ocular hypotension induced by topical administration of 7-OH-DPAT (75µg) with CAP was more pronounced and sustained than that of 7-OH-DPAT without CAP. Conclusion: The lack of activity by 7-OH-DPAT in pigmented rabbit eyes suggests that 7-OH-DPAT binds to pigment in the anterior segment of the pigmented rabbit eyes and this limits the drug’s action. This lack of activity in pigmented rabbits can be overcome by using CAP as a delivery device. Therefore, CAP may be useful for achieving controlled and targeted drug delivery for treatment of ocular diseases.
Keywords: 444 intraocular pressure • 438 inflow/ciliary body • 389 dopamine