Supercritical fluid extraction of active components in a drug formulation.

Sulfamethoxazole and trimethoprim have been extracted from a drug formulation, Septra Infusion, with pure supercritical carbon dioxide. Both direct extraction of the aqueous-based matrix and indirect extraction of the formulation immobilized onto Celite were studied. Exhaustive analytical extraction was achieved when active components were less than 1.0 mg. A number of co-extractants were found, but each was blind to the HPLC/UV assay.