Formulation, Characterization, in vitro Anti-Tubercular Activity and Cytotoxicity Study of Solid Lipid Nano-particles of Isoniazid

The present study was aimed to develop and optimize isoniazid (INZ) loaded solid lipid nanoparticles (SLNs) for exploring in vitro anti-tubercular and cytotoxic activity. The INZ-SLNs were successfully prepared by high pressure homogenization followed by ultrasonication technique and optimized using 2³ full factorial designs. INZ-SLNs were characterized for particle size (PS), zeta potential (ZP), entrapment efficiency percentage (EE%) and cumulative percentage drug release (CDR%). Physicochemical properties were investigated using transmission electron microscopy (TEM), differential scanning calorimeter (DSC), X-ray diffraction and Fourier transmission infrared spectroscopy (FTIR). The average PS, ZP and EE% of the optimized formulation were found to be 167.1 nm, −32.4 mV and 73.17% respectively. The optimized formulation showed a CDR of 79.14% up to 36 h. In vitro anti-tubercular (luciferase reporter phage (LRP) assay in H37Rv viable and resistant strain) and cytotoxicity efficacy (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT) assay in J774A.1 cells) of INZ-SLNs were evaluated and compared with free INZ. Results of LRP assay in H37Rv strain showed that percentage reduction in relative light unit (RLU) for INZ-SLNs and free INZ were 99.75 and 99.898% respectively, whereas in case of INZ resistant strain they were found to be 90.27 and 90.52% respectively, confirming notable antitubercular activity. MTT assay revealed that the percentage of cell viability upon exposure with INZ-SLNs was significantly higher (> 90%) than free INZ (< 80%), confirming its safety. Thus, INZ-SLNs could be an effective dosage form with sustained drug release profile, significant anti-tubercular activity, and reduced normal cell toxicity for achieving better therapeutic activity.