The influence of buffer composition on the solubility of baclofen and sulfadoxine

Abstract

The drug discovery process has developed immensely during the last couple of decades. The Biopharmaceutical Classification System (BCS) is a drug development tool that is based on correlation of solubility and membrane permeability with bioavailability in the human body. It allows estimation of the contributions of three major factors namely, dissolution, solubility, and intestinal permeability; which affect oral drug absorption from immediate release (IR) solid oral drugs. In the introduction, the impact and importance of the BCS are discussed. Since its use, many drugs have been classified according to BCS, however, there still remain drugs such as sulfadoxine and baclofen that have not been assigned a class yet. Sulfadoxine in conjunction with pyrimethamine is recommended for the use of intermittent preventative treatment of malaria in pregnant women, and baclofen is approved by the Food and Drug Administration (FDA) for the treatment of muscle spasticity. During this study, sulfadoxine and baclofen were investigated with regards to their solubility and the impact that buffer and / or solution composition (over a pH range of 1.2 to 6.8) might have on the solubility of these drugs. Furthermore, since neither of the above-named drugs have been classified according to BCS, in vitro intestinal permeability studies using the Caco-2 cell line were performed to establish BCS classification of these drugs.