Interaction of cefadroxyl monohydrate with hexadecyltrimethyl ammonium bromide and sodium dodecyl sulfate

Interaction of a cephalosporin antibiotic drug, cefadroxyl monohydrate (CFM) with hexadecyltrimethyl ammonium bromide (CTAB), a cationic surfactant, and sodium dodecyl sulfate (SDS), an anionic surfactant, has been studied in aqueous medium by conductivity measurement over a range of temperatures and salt concentrations. Values of critical micelle concentration (c(center dot)), degree of micelle ionization (alpha), and thermodynamic parameters have been determined for both the systems in pure water as well as in aqueous NaCl solution. For both (CFM + CTAB) and (CFM + SDS) systems. Delta G(m)(center dot) values are negative which indicate that the drug mediated ionic micelle formation processes are thermodynamically spontaneous. For (CFM + CTAB) system, the micellization is entropy controlled at lower temperatures whereas at higher temperatures it becomes both entropy and enthalpy controlled. The micellization of (CFM + SDS) system is entropy controlled over the range of temperatures studied and more so at lower temperature. In the presence of NaCl, enhancement of hydrophobic interaction is observed for both the systems at lower temperatures. A significant decrease of c(center dot) values in the presence of NaCl for both the surfactant systems indicates that CFM supported ionic micelle formation is much favoured in NaCl compared to that in pure water. (C) 2008 Elsevier Ltd. All rights reserved.