Polymeric ocular hydrogels and ophthalmic inserts for controlled release of timolol maleate

Ophthalmic drug delivery systems are the challenging subject for the researchers because of delicate nature of ocular membrane and preventive barriers leading to less than 1 % of Bioavailability. Reasons for reduced bioavailability are due to rapid pre corneal elimination, tear turnover, lacrimal drainage, blinking and degradation by enzymes. Less bioavailability causes short duration of action and increased frequency of administration.

Timolol maleate was used as model drug. Dynamic drug release studies were used to study the polymeric hydrogels and ophthalmic inserts. Rheological studies were carried out by Brookfield Viscometer LVDV- II+.

Viscosity value lies in the range of 4.08 to 31.8 cps. Drug release data was fitted to various kinetic equations such as First order plots, Higuchi plots, Peppa's exponential plots. The results shows fairly linear curve and the slope value of the Peppa's equation is less than 0.5 and hence follows the fickian diffusion.

The developed hydrogels and inserts were therapeutically effacious, stable, non irritant and provide a sustained release of drug over 8 hours time period.