Effect of Operating Parameters on the Impregnation of Polymers with Drugs

The regulations regarding the use of organic solvents in food and pharmaceutical industries are the key factors for a wider introduction of supercritical fluid technologies. In fact the use of a supercritical fluid reduces to the acceptable limit the residual solvent content in the final product. In this paper the attention is focused to the preparation of a pharmaceutical product for controlled drug release. A polymer and an active drug constitute the final product. The possibility of using supercritical carbon dioxide saturated with the drug for the impregnation of the polymers is investigated. Different nonsteroid anti-inflammatory analgesic drugs, for which solubility data in supercritical carbon dioxide were previously determined, are used. A continuous process is considered for the impregnation of cross-linked polymers. The mechanism of impregnation is essentially based on the partition of the drug between the polymer and the supercritical phase. In this context the experimental apparatus and the experimental data obtained are presented and discussed. Experimental data obtained with different polymers and drugs are discussed in order to evidence the key parameters governing the impregnation process.