A new ciprofibrate calcium salt with improved solubility and intrinsic dissolution rate

Ciprofibrate (CIP) is an active pharmaceutical ingredient (API) classified as class II on the basis of biopharmaceutical classification system (BCS), what indicates that it has low solubility in aqueous solvents. The use of API salts has attracted attention due to their improvements in solubility, tolerability, higher rate and extent of absorption, and faster onset of the therapeutic effect. In this work, a new crystalline CIP monohydrated calcium salt (Ca(CIP)₂.H₂O) was successfully obtained and its crystal structure determined by single crystal X-ray diffraction analysis (SCXRD). Additionally, Ca(CIP)₂.H₂O was widely characterized by powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and submitted to solubility, intrinsic dissolution and accelerated stability studies. Ca(CIP)₂.H₂O exhibited higher solubility and dissolution rate than CIP-free form and was stable up to 6 months at 40 °C (75 %RH). Therefore, Ca(CIP)₂.H₂O may be a viable alternative for use in solid dosage forms.