INVERSE SUPERCRITICAL EXTRACTION OF ACETAMINOPHEN FROM SUPPOSITORIES

The use of supercritical CO2 for the isolation of acetaminophen from t he non-polar matrix of a suppository is demonstrated. Since acetaminop hen is not soluble in pure CO2 at low pressure, but the waxy matrix is , the later can be extracted, leaving the acetaminophen behind. After studies on acetaminophen solubility as a function of pressure, tempera ture flow and supercritical fluid volume, optimal extraction condition s were determined. In this method, the matrix is removed using pure CO 2 at 1500 psi and 40 degrees C, and the remaining acetaminophen is the n removed from the extraction cell using ultrasound in warm water. Thi s method is an alternative to the US Pharmacopoeia's (USP) method for this kind of formulation, which involves the dissolution of the matrix in hexane with the subsequent liquid-liquid extraction of the acetami nophen into water. (C) 1998 Elsevier Science B.V. All rights reserved.