The Pharmaceutics and Compounding Laboratory
Extraction of Drugs

Learning Objectives

Upon completion of this exercise, you should be able to:

  • Describe three (3) pharmaceutical applications of the principles of extraction and partition coefficient.
  • Define solvent extraction and describe how it is most efficiently carried out.
  • Given the solvent extraction equations, the partition coefficient for the system, and the relative volumes of original and extracting solvents, calculate the weight or fraction of drug extracted after an number of extractions or calculate the number of extractions required to extract a specified fraction of the drug.
  • To measure the extraction of salicylic acid from aqueous buffer solution into two different organic solvent mixtures.
  • To measure the extraction of salicylic acid (0.02%) from aqueous buffer of various pH's and thereby determine the pKa for salicylic acid.