Enhanced solubilization and In-Vitro release of rifampicin in mixed aggregates of surface active ionic liquid and conventional surfactants

• Physicochemical characterisation of binary mixtures of C 12 mimBr with cationic (C 12 BzCl and DTAB) and non-ionic surfactants (Igepal CO 720 and Tween 20). • Solubility of rifampicin enhanced in binary mixed micelles of C 12 mimBr + Tween 20 and C 12 mimBr + C 12 BzCl. • DLS measurements show the presence of rifampicin in micellar core. • Sustained in-vitro release of rifampicin by C 12 mimBr + Tween 20 and C 12 mimBr + C 12 BzCl, follows zero order kinetics. Rifampicin is a very important drug used in the treatment of tuberculosis, but its low solubility in aqueous medium leads to its lesser bioavailability. The present work is focused on enhancing the solubility of rifampicin in aqueous medium employing mixed micellar assembly of the surface active ionic liquids (SAILs), i.e., 1-dodecyl-3-methylimidazolium bromide (C 12 mimBr), with conventional cationic surfactants, viz., dodecylbenzyldimethylammonium chloride (C 12 BzCl) and dodecyltrimethylammonium bromide (DTAB), and non-ionic surfactants, viz., Igepal CO 720 (ICO 720) and Tween 20. The physicochemical behaviour of mixed micelles has been investigated using conductivity, UV-visible spectroscopy, fluorescence spectroscopy, and dynamic light scattering (DLS) measurements. Interactions between the components of mixed micelles are illustrated by the evaluation of different micellar parameters, i.e ., β (degree of counterion binding), Δ G m i c ∘ (Gibb’s free energy of micellization), hydrodynamic diameter ( D h ), β m (interaction parameter), cmc* (ideal cmc ) , X ideal (mole fraction in mixed micelle in an ideal state), and activity coefficients ( f 1 and f 2 ) using regular solution theory. The mixtures of C 12 mimBr + C 12 BzCl, C 12 mimBr + ICO 720, and C 12 mimBr + DTAB have been found to behave non-ideally with synergistic interactions in the first two cases and antagonistic interactions in the case of C 12 mimBr + DTAB. However, the mixture of C 12 mimBr + Tween 20 exhibits ideal behaviour. Employing UV-visible spectroscopy, these mixtures have been further investigated for enhancing the rifampicin solubility. The molar solubilization capacity (χ) is observed to be more for mixed micellar media of C 12 mimBr + Tween 20 and C 12 mimBr + C 12 BzCl than their pure components and decreased in the case of C 12 mimBr + DTAB. Further, in vitro drug release studies were performed using the dialysis method, which illustrates the sustained release of rifampicin by the proposed binary mixtures.