Effect of cellulose polymers on supersaturation and in vitro membrane transport of hydrocortisone acetate

A systematic investigation on the influence of two cellulose polymers, methyl cellulose (MC) and hydroxypropyl cellulose (HPMC) on supersaturation and permeation of hydrocortisone acetate (HA) is reported. Diffusion of HA from a 0.5% Carbopol gel across a model silicone membrane was investigated using the Franz-cell technique. At constant polymer concentration, the flux increases proportionally with the degree of saturation up to 4.8 x but decreases thereafter. For a particular degree of supersaturation (4.8 x), the flux increases with the concentration of polymer up to 1% and decreases at higher concentrations. The behaviour is found to be consistent with crystallisation experiments. The results suggest that optimisation of supersaturation and polymer content is necessary to achieve both high permeation rates and inherent stability. (C) 2000 Published by Elsevier Science B.V. All rights reserved.