Spectroscopic, conductivity and voltammetric investigations of interaction of sulfamethoxazole alone and in combination with trimethoprim with self-assembled structures

The demand and urgency of new drug design and discovery is facing new challenges in the wake of spread and persistence of serious global threat of antibiotic resistance. One of the major hurdles in the development of new drugs that are more aqueous soluble and passively diffusible is the paucity of knowledge regarding their physicochemical interactions with biological membranes. Being chemical-mimics of biomembranes, surfactant-based micellar systems present excellent pseudo-membrane models to study biophysical interactions of drugs with biological membranes in vitro. The present research focuses on physicochemical interaction of sulfamethoxazole (SMZ) alone and in combination with trimethoprim (TMP) with cationic surfactant cetyltrimethylammonium bromide (CTAB) and anionic surfactant sodium dodecyl sulfate (SDS). UV-visible spectroscopy, electrical conductivity and cyclic voltammetric techniques were employed to quantitate different drug-surfactant interaction parameters. UV-visible spectroscopic was used to evaluate critical micelle concentration (CMC) of CTAB and SDS in the presence of SMZ, TMP and their binary mixture in aqueous medium (pH 7.0). Differential absorption technique was used to determine partition coefficient (K-c) and binding constant (K-b) of SMZ and (SMZ + TMP) mixture with ionic micelles. Thermodynamic parameters of micellization such as Delta H-m degrees, Delta S-m degrees, and Delta G(m)degrees, m of CTAB and SDS in the presence SMZ and its mixed form with TMP were calculated in deionized water. Further, voltammetric investigations depict the strong binding of SMZ and its TMP mixture with CTAB micelles relative to SDS micelles. [GRAPHICS] .