Use of transethosomes for enhancing the transdermal delivery of olmesartan medoxomil: in vitro, ex vivo, and in vivo evaluation

Introduction and aim: Olmesartan medoxomil (OLM) is an antihypertensive drug with low oral bioavailability due to extensive first-pass metabolism. This study aimed to prepare transetho-somes (TEs) for enhancing the transdermal delivery of OLM to avoid its oral problems. Methods: TE formulae were prepared utilizing 5(1).3(1) full factorial design using various surfactants (SAAs) and different phospholipid-to-SAA ratios. The formulae were characterized regarding their entrapment efficiency percentage (EE%), particle size (PS), polydispersity index (PDI), zeta potential (ZP), and the amount of drug released after 6 hours (Q6h). Design Expert (R) software was employed to select the optimum formula. Results: The optimum formula (TE14) had an EE% of 58.50%+/- 1.30%, PS of 222.60 +/- 2.50 nm, PDI of 0.11 +/- 0.06, ZP of -20.80 +/- 0.30 mV, and Q6h of 67.40%+/- 0.20%. In addition, TE14 was compared to transferosomes (TFs) in terms of elasticity and was found to show higher deformability index. Further, evaluation of ex vivo permeation using both rat and shed snake skin showed higher permeability of TE14 compared to TFs and OLM suspension. Confocal laser scanning microscopy confirmed the capability of the fluoro-labeled TE14 to penetrate deep within the skin, while the histopathological study confirmed its safety. TE14 successfully maintained normal blood pressure values of rats up to 24 hours. Moreover, TE14 showed superiority in dermatokinetic study when compared with drug suspension. Conclusion: Taken together, the obtained results confirmed the potential of employing TEs as a successful carrier for the transdermal delivery of OLM.