Preformulation study of pelrinone hydrochloride

Pelrinone HCl is essentially nonhygroscopic. The pH-solubility profile exhibits a U-shaped curve, while the octanol-water partition coefficient-pH profile shows a bell-shaped curve. Two ionizable functions, with a pKa1 value of 4.71 and a pKa2 value of 8.94, produce the cationic and anionic forms, respectively. A weak ionic strength effect on solubility of the compound is observed: at pH 3.9 (0.1 M acetate buffer), the solubility increases with increasing ionic strength, while at pH 7.5 (Tris HCl buffer), the solubility decreases with increasing ionic strength. No gross incompatibility of the compound is seen with the 13 excipients selected, except povidone. The solubility phase diagram, X-ray diffraction pattern, and IR spectroscopy demonstrate the presence of polymorphs. The compound in solution is stable at various pH conditions under 500-foot-candle (ft-c) light at room temperature and at 80 degrees C for 64 d. In the solid state, no decomposition is observed at 80 degrees C and on exposure to 500-ft-c light for at least 112 d.