EVALUATION OF PILOCARPINE-LOADED ALBUMIN PARTICLES AS DRUG-DELIVERY SYSTEMS FOR CONTROLLED DELIVERY IN THE EYE .1. IN-VITRO AND IN-VIVO CHARACTERIZATION

The loading of pilocarpine on albumin microspheres and nanospheres was optimised. Optimal loading conditions were obtained with 2% pilocarpine and a particle concentration of 20 to 40 mg particles/ml. Due to their high surface area nanoparticles exhibited the highest loading. The in vitro release of the albumin particle carrier systems differing in size was measured by simulating the rapid drug dilution as occurring in the eye. All particle fractions released pilocarpine completely within a few minutes. The systems were further tested in vivo by determination of their miotic and IOP-lowering properties. Independent of the size, pilocarpine-loaded albumin particles increased the bioavailability of pilocarpine by about 50-90% (miosis), and 50-70% (IOP) respectively, compared to a pilocarpine reference solution. The best results were obtained with albumin nanoparticles with 2% pilocarpine (total concentration) at a particle concentration of 40 mg/ml.