Determination of the physicochemical properties of pyronaridine - a new antimalarial drug
Adegoke, O.A.; Babalola, C.P.; Oshitade, O.S.; Famuyiwa, A.A.
Pakistan Journal of Pharmaceutical Sciences 19(1): 1-6
2006
ISSN/ISBN: 1011-601X PMID: 16632444 Document Number: 602413
The physicochemical properties of pyronaridine, a new antimalarial drug, have been determined for the first time in this study, since these parameters are comprehensively not available in literature. UV-Vis spectral analysis of both pyronaridine and its tetraphosphate salt were carried out in various solvents, in addition to the solubility of the 2 drugs in these solvents. Partition coefficient was done in n-octanol-water mixture using the Leo-Hansch method as well as hydrophobicity index determination. pKa determination was carried out on the tetraphosphate. UV-Vis spectral characteristics showed that both the base and the tetraphosphate salt have significant light absorption in the range 190-380 nm. Solubility in different solvents showed that pyronaridine base is sparingly soluble in chloroform (1.34%) while it is slightly soluble in methanol (0.29%) and ethanol (0.42%) and very slightly soluble in octanol and distilled water. The tetraphosphate salt was sparingly soluble in water (1.46%) while it is only very slightly soluble in other solvents. The higher aqueous solubility of the salt was further revealed by a greater Rm value on extrapolation to 100% water concentration in hydrophobicity index determination. Log P value determination showed that the base (log P of 0.26+or-0.02) is more liposoluble than the salt {log P of -(1.24+or-0.21)}. Four prominent pKa values were obtained for the tetraphosphate titrated which when extrapolated to the base gave values of 7.08+or-0.05, 7.39+or-0.05, 9.88+or- 0.05 and 10.30+or-0.10. The results should guide in the formulation of appropriate dosage forms to improve bioavailability of the drug especially from oral routes.