Characterization and drug-permeation profiles of microporous and dense cellulose acetate membranes: influence of plasticizer and pore forming agent.

The use of pore forming agents and plasticizers are efficient ways to obtain membranes for controlled drug permeation through polymeric membranes. The challenge of the present study was to combine these two strategies to obtain cellulose acetate (CA) membranes, where poly(caprolactone triol) (PCL-T) was used as a plasticizer and water, dissolved in a casting solution, was used as a pore forming agent. First, the influence of water on membrane morphology, porosity and the permeation coefficient of a model drug (paracetamol) was analyzed. The influence of different amounts of PCL-T on the permeation coefficient of the CA membranes was then evaluated. Finally, both strategies were combined to obtain porous CA/PCL-T membranes. The membrane microstructure was analyzed using scanning electron microscopy (SEM), the CA crystallinity was determined via differential scanning calorimetry (DSC), and membrane permeability was investigated using paracetamol. The addition of water, a non-solvent, during the membrane casting process was found to be a simple and effective way to change membrane porosity and consequently the drug-permeation profile. When small quantities of non-solvent were used to obtain low porosity membranes, the presence of a plasticizer agent could be used to better modulate drug permeation. Combining the addition of PCL-T with the use of a non-solvent resulted in a series of CA membranes with paracetamol-permeation coefficient values in the range of ca. 10(-7) to 10(-5) cm s(-1). Copyright 2004 Elsevier B.V.