Estimation of Ibuprofen solubilization in cationic and anionic surfactant media: Application of micelle binding model

Abstract

Drug solubility is an important parameter for efficient drug delivery and absorption. Ibuprofen, <img src='/image/spc_char/alpha.gif'>-methyl-4-[2-methyl­propyl] benzene acetic acid is a NSAID group of drug with antipyretic and analgesic properties. It has poor solubility in water. Its solubilisation properties in presence of cetyltrimethylammonium bromide (CTAB) and sodiumdodecyl sulphate (SDS) have been studied. Saturation solubilities in aqueous and aqueous-micellar media have been studied spectrophotometrically by measuring absorbance at 264 nm. Plot of solubility versus [SDS] shows a maximum in the pre-micellar region followed by the linear relationship between the variables in the region past critical micellar concentration (cmc). With CTAB, the solubility- [surfactant] profile shows double maxima, one each in pre- and post- micellar region. Appropriate explanation has been forwarded and the nature of solubilizate-surfactant interaction suggested. The p<i style="">K</i>_a values of ibuprofen determined <i>p</i>H-metrically in aqueous and aqueous-SDS media have been used to supplement the inference. The association constant values and free energy change of solubilisation are reported.