Biodegradable Calcium Phosphate Nanoparticles as a New Vehicle for Delivery of a Potential Ocular Hypotensive Agent

The purpose of this study was to determine the efficacy of a newly prepared formulation containing biodegradable calcium phosphate nanoparticles (CAP) and 7-hydroxy-2-dipropyl-aminotetralin (7-OH-DPAT) in pigmented and non-pigmented rabbits using the surrogate end points of intraocular pressure (IOP) and aqueous flow rate. IOP (mmHg) was measured by utilizing a manometrically calibrated Mentor pneumatonometer. Rates of aqueous humor flow were measured with a Fluorotron Master by estimating the dilution rate of fluorescein. In non-pigmented rabbits, the ocular hypotension induced by topical administration of 7-OH-DPAT (75 μg) with CAP (115 μg) was more pronounced and sustained than that of 7-OH-DPAT without CAP. Furthermore, IOP-lowering effects of topically administered 7-OH-DPAT (125 μg) alone were markedly diminished in pigmented rabbits compared to non-pigmented rabbits. However, topical application of 7-OH-DPAT formulated with CAP produced significant dose-related (37.5, 75, 125 μg) reductions of IOP ...