COMPLEXATION STUDY OF GLIMEPIRIDE WITH Mg

Objective: The present work describes complexation study of sulfonylurea based drug, glimepiride with divalent metal ions (Mg2+, Ca2+, Cu2+and Zn2+ Methods: The stoichiometry of resulting metal ion-glimepiride complexes were ascertained by molar conductance vs. mole ratio of glimepiride/metal ion plots, Job’s method of continuous variation and liquid chromatography-mass spectrometric analysis. The values of enthalpy and entropy of complexation reactions in methanol were obtained from van’t Hoff plots. ) in methanol by conductometry, spectrophotometry and liquid chromatography-mass spectrometry. Results: The formation constants of 1:1 (M2+: glimepiride) complexes at different temperatures followed the order Mg2+>Cu2+>Zn2+>Ca2+ Conclusion: The stability of complexes increased with temperature suggesting endothermic nature of complexation reactions. The thermodynamic data showed that all the complexes formed were entropy stabilized and enthalpy destabilized. A good linear relationship between ∆H and T∆S values suggests existence of entropy–enthalpy compensation in the complexation of these four cations with glimepiride. by conductometry as well as spectrophotometry. High molar conductivities were observed for all the complexes indicating formation of charged complex and the results were supported by the presence of protonated precursor complex ions in the mass spectral study.