Membrane transport of hydrocortisone acetate from supersaturated solutions; the role of polymers

Permeation of hydrocortisone acetate (HA) from supersaturated solutions was studied across a model silicone membrane. Supersaturated solutions were pr epared using the cosolvent technique with propylene glycol and water (or aq ueous polymer solutions) as the cosolvents. In the absence of the polymer, the flux of HA was similar at all degrees of saturation and was not signifi cantly different from the value obtained for a saturated solution. Flux enh ancement, as a result of supersaturation, was observed with all the polymer s. The flux increased with increasing polymer concentration, reached a maxi mum and decreased at higher polymer percentages. The amount of polymer requ ired for maximum enhancement differed for each polymer. The decrease of flu x at high polymer concentrations is attributed to changes in microviscosity and a marginal increase in solubility. The infrared spectroscopic and diff erential scanning calorimetry data suggest that HA-polymer interactions occ urred through hydrogen bonding thus explaining the proposed mechanism of th e anti-nucleant properties of the polymers. (C) 2001 Elsevier Science B.V. All rights reserved.