DISSOLUTION BEHAVIOR OF POLYMORPHS OF CHLORAMPHENICOL PALMITATE AND MEFENAMIC ACID

Relative rates of dissolution and solubilities of three polymorphic forms of chloramphenicol palmitate in 35% tertiary butanol‐water mixture and two polymorphs of mefenamic acid in dodecyl alcohol were measured. The thermodynamic relationships involving the transition of the metastable polymorphs to the stable one were examined. The heats of solution, enthalpy, entropy, free energy differences, and transition temperatures were calculated. The relative stability of the polymorphs in the dissolving media is shown. The significance of free energy differences between the polymorphs and their absorptivity as reflected by blood levels in humans is discussed. Copyright © 1969 Wiley‐Liss, Inc., A Wiley Company