Mycophenolic acid isobutanolammonium salt: synthesis, structural characterization, and solubility investigations

Salts of active pharmaceutical components are made to improve the parent drug's solubility and bioavailability. The synthesis and characterization of mycophenolic acid salt are presented in this paper. Mycophenolic acid is a BCS class 2 drug used as a potential immune-suppressing agent. It has potential uses but has solubility issues; converting to salt form can increase solubility and help in formulation development. Thermal methods such as Differential Scanning Calorimetry (DSC), Thermogravimetry, and other methods such as Fourier Transform Infrared Spectroscopy and Powder X-ray Diffraction were used to analyze the produced salt. The DSC curves of the parent drug and its isobutanolammonium salt vary, indicating that the drug and the salt former had undergone a chemical interaction. According to powder X-ray diffraction analysis, the product generated from the reaction was salt, not the parent drug's cocrystal. The salt produced is unreported and has high solubility over the available options. The salt is dissolved at intestinal pH as inferred from the in vitro simulated dissolution experiment, which is an added advantage over the available counterparts. Moreover, the procedure reported is important in drug development and will help researchers with further formulation and development studies.