EVALUATION OF PILOCARPINE-LOADED ALBUMIN PARTICLES AS CONTROLLED DRUG-DELIVERY SYSTEMS FOR THE EYE .2. COADMINISTRATION WITH BIOADHESIVE AND VISCOUS POLYMERS

The aim of the present investigation was to investigate the influence of various polymers at different concentrations on the in vivo activit y of pilocarpine-loaded albumin nanoparticles. It was speculated that co-administration with viscous or bioadhesive polymers would increase the time of residence in the eye of the drug-loaded particle systems, and hence the drug bioavailability. For this purpose, different formul ations containing bioadhesive (hyaluronic acid, mucin, sodium carboxym ethylcellulose, and polyacrylic acid) or viscosity-enhancing polymers (methylcellulose, polyvinyl alcohol, and hydroxypropylmethylcellulose) were tested in rabbits for miotic effect and reduction of intraocular pressure (IOP, betamethasone model). In the presence of some polymers , the nanoparticles induced a significantly improved pharmacological r esponse when compared with particle dispersions in buffer or with part icle-free polymeric vehicles. Bioadhesive polymers exhibited superior effects with respect to viscous polymers: the best results for miotic response and IOP reduction were observed with mucin. It can be assumed that coadministration of particles with these polymers leads to an im proved adhesion to the precorneal/conjunctival mucin layer and hence t o a prolongation of the residence time of the medication in the eye.