Kinetics of Hydration of Lyophilised Xerogel of Hydroxypropylmethylcellulose

Overview

The rate of hydration of lyophilised ophthalmic lamellae of graded density of 50 to 56g/l in water or an aqueous solution of sodium chloride was estimated by means of ahydrophilic filtration membrane. With insignificant effect of density, the non-linearcourse of hydration is affected mainly by the diffusion mechanism of penetration of waterinto xerogel while preserving its shape in a time interval of to 20 minutes. In a periodof 10 minutes the rate of hydration of 19.9 mm/min isdecelerated to 15.3 mm/min in the presence of sodium chloride.This contributes to the elucidation of different rates of the release of activeingredients from ophthalmic lamellae of comparable density.

Key words:
xerogel – hydroxypropylmethylcellulose – hydration – kinetics