Bioactive polymers XXXIX. Retarded ophthalmic drugs base on pilocarpine and xanthan derivatives

Polycomponent Ophthalmic Inserts with Polysaccharide Support

Ophthalmic inserts, based on xanthane modified with pilocarpine, adrena line and hydrocortisone have been prepared. The drugs were fixed in the insert by ionic bonds and gel entrapment. The in vitro release rate of pilocarpine de pended on the degree of xanthane modification and on the drug content in the polymer matrix. Inserts show a high ophthalmic tolerance indicating the potential for treatment of glaucoma.

Bioactive polymers 53: synthesis of poly(vinyl alcohol) and nalidixic acid based pro-drugs

The present paper studies the process of esterification of nalidixic acid on poly(vinyl alcohol). The influence of time, dilution and concentration of the reactants on the efficiency of esterification with dicyclohexylcarbodiimide has been followed. By experiment scheduling according to a centered, rotatory, compound, second order program, optimum conditions for the system under study have been found. On the other hand, the evolution of reaction of esterification of the nalidixic acid on poly(vinyl alcohol) was followed by using the activator-catalyst (4-pirolidinopyridine) system. An increase of the esterification yield up to 37% has been observed.

Bioactive polymers 66. Theophylline retardation in xanthan-based hydrogels

Xanthan has been reticulated with epichlorohydrin to obtain a hydrogel for use in drug retardation. The obtained gel shows swelling degrees up to 1000. Theophylline has been inserted by diffusion into this gel; concentrations around 150 mg theophylline/g dry hydrogel being obtained. Controlled release of theophylline has been established by elution in a close recirculation system. Zero-order kinetics has been obtained in the diffusion process of theophylline into the eluent, within a 14 h time interval.

Bioactive polymers. LX. Kinetics of delayed release neomycin-xanthan complex

The kinetics of delayed release neomycin-xanthan complex, and its antimicrobial activity, were studied. Delayed release neomycin (53.13% free neomycin) had zero-order release kinetics, when artificial tear solution was used as eluent. Microbiological tests revealed an activity of 380 units/mg, 10% higher than neomycin in its free form.