Some physicochemical properties of mefenamic acid

Mefenamic acid is a problematic drug in granulation, tableting, and dissolu tion due to its poor solubility, hydrophobicity, and tendency to stock to s urfaces. In most cases, the specifications of a drug by the pharmacopoeia i nclude identification and purity, but they do not describe the physicochemi cal drug properties precisely. To characterize the mefenamic acid particle size, surface area measurements, X-ray pattern, differential scanning calor imetry (DSC), wettability, crystal habit, and compression behavior of diffe rent batches from two manufacturers were investigated. Due to larger partic le size and better wettability, mefenamic acid of il Yang type was easier t o handle in a granulation process. The compression behavior of both types w as nearly the same, although particle size, crystal habit, and wettability were very different.