Abstract:
Micro-heterogeneous surfactant assemblies solubilize and encapsulate the active drug
molecules and consequently protect them from the adverse environmental conditions.
As pseudomodel of biomembranes, the associative structures of surfactant molecule
are very useful for researchers to determine their role in cellular interactions. The
present study reveals the molecular interactions of potential antibiotics (fixed dose
combinations as well as single drugs) with cetyltrimethylammonium bromide (CTAB,
a quaternary ammonium surfactant). Micellar liquid chromatography (MLC),
differential absorption and emission spectrometry were performed to probe the drug–
CTAB association whereas interaction modes of drug–surfactant were quantified by
determining binding capacities and related Gibb’s free energies at various pH
conditions. The binding values of drug–CTAB obtained from micellar liquid
chromatography measurements are found to be in good agreement with as measured
by electronic spectroscopy. The fixed dose combination (FDC) drugs, (norfloxacin +
metronidazole), (ofloxacin + ornidazole) and single drug sparfloxacin were studied at
physiological condition pH 7.4. Gatifloxacin and levofloxacin were also studied at
two pH values pH 7.4 and pH 5.5. Most fluoroquinolones solubilize in the aqueous
medium. However for better bioavailability, improved efficacy and to overwhelm the
lipophilic barrier, a physiological medium (pH 7.4) is useful for diffusion through
phospholipid membrane. The spectral-luminescent measurements of these drugs
interacting with cationic micelles were investigated as function of CTAB
concentration from pre micellar to post micellar region. The results indicated potential
solubilization of drugs in the peripheral region of micelles that may facilitate their
controlled release. The values of the binding capacities of drug-micelle system have
verified these results.
