Spectral and chromatographic characterization of fixed dose combination norfloxacin and metronidazole interacting with cetyltrimethylammonium bromide

•Biophysical probing of combinational drugs in cationic micelle is explained.•Binding parameters of each drug interacting with cationic surfactant are estimated.•The drug surfactant interaction may be useful to elucidate the drug delivery system.•The result indicates solubilization of each drug in peripheral region of micelles.

Surfactant molecular self-assemblies solubilize and shelter the drugs from adverse conditions. As membrane mimetic they serve as a powerful tool to understand the consequences of drug membrane interactions. In this study the interaction modulation of fixed dose combination (FDC) having norfloxacin (NOR) and metronidazole (MET) with quaternary ammonium disinfectant (cetyltrimethylammonium bromide) has been described at physiological condition (pH 7.4). The spectral and physiochemical characteristic of NOR and MET interacting with cationic micelles were investigated by electronic spectroscopy as function of cetyltrimethylammonium bromide (CTAB) concentration from pre-micellar to post-micellar region. Magnitudes of binding constant and related Gibbs free energies were optimized using differential absorption spectrometry and micellar liquid chromatography (MLC). The results indicate potential solubilization of drugs in the peripheral region of micelles that may be helpful to their control release. The values of the binding capacities of drug-micelle system have verified these results.

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