This study investigated enhanced bioavailability and sustained delivery of transdermally delivered rifampicin (RIF) in elastic liposomes (ELs). F3, F5, and F7 were optimized formulations comprising of 200, 140 and 80 mg of tween 80, respectively, and Phospholipon^Ⓡ 90 G (300 mg). They were optimized based on in vitro and ex vivo parameters. Using the Franz diffusion cell, an ex vivo study was conducted by utilizing the rat skin for permeation profiles. Also, pharmacokinetic parameters, mechanistic evaluation of penetration, and histopathological investigation were conducted in the rat model for complete dynamic evaluations. Vesicle sizes of suspensions and gels were found to be similar whereas zeta potential of gel attained more negativity due to acidic carbopol. Permeation parameters of gels were significantly (p < 0.05) higher compared to respective ELs due to increased residence time and the composition of the formulations (ethanol, tween 80, d-limonene and lipid). Bioavailability of RIF (F5 gel) was improved by transdermal absorption as evidenced with AUC_0→24 of transdermal F5 gel (56.23±2.7 µg.hr/mL) and oral drug suspension (41.71±5.2 µg.hr/mL). A lower value of transdermal C_max (6.9 ± 0.8 µg/mL) validated sustained delivery for improved tuberculosis management than oral delivery (10.5 ± 1.46.9 ± 0.8 µg/mL). In vivo skin interaction, biopsy and in silico prediction studies corroborated suitable alternative for sustained and prolonged delivery of RIF with high patient compliance to control cutaneous tuberculosis and related infections.

By Afzal Hussain, Mohammad A. Altamimi, Sultan Alshehri, Syed Sarim Imama, Sandeep Kumar Singh