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

A systematic investigation on the influence of two cellulose polymers, meth yl cellulose (MC) and hydroxypropyl cellulose (HPMC) on supersaturation and permeation of hydrocortisone acetate (HA) is reported. Diffusion of HA fro m a 0.5% Carbopol gel across a model silicone membrane was investigated usi ng the Franz-cell technique. At constant polymer concentration, the flux in creases proportionally with the degree of saturation up to 4.8 x but decrea ses thereafter. For a particular degree of supersaturation (4.8 x), the flu x increases with the concentration of polymer up to 1% and decreases at hig her concentrations. The behaviour is found to be consistent with crystallis ation 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.