Formulation, Characterization, and Optimization of Transethosomes for Enhanced Transdermal Delivery of Methotrexate

Purpose Methotrexate (MTX) is an antineoplastic drug used in the treatment of rheumatoid arthritis (RA). Given that it is a class IV drug with low permeability and solubility, this study aims to improve MTX skin permeation by loading it in transethosomes (TEs) and casting a transethosomal patch that allows for dose quantification to mitigate toxicity. Methods To accomplish this goal, MTX transethosomes (TEs) were developed using the thin film hydration technique and optimized using the Box-Behnken design (BBD) with soya phosphatidylcholine 50, Tween 80, and ethanol as independent variables using the desirability function. Furthermore, zeta potential (ZP) analysis and high-resolution transmission electron microscopy (HR-TEM) were used to confirm the stability and surface morphology of TEs. A transdermal patch was also designed and evaluated from the optimized TE (OPTZ TEs) batch using a solvent casting method with hydroxypropyl methylcellulose (HPMC) as the polymer, dimethyl sulfoxide (DMSO) as a permeation enhancer, and polyethylene glycol (PEG 400) as the plasticizer. Furthermore, ex vivo skin permeation and deposition through rat skin proved that the TE patch had better drug permeation and retention within the skin layers. Results The highest desirability batch had 92.19 ± 3.826 nm vesicle size, 0.35 ± 0.062 PDI, 74.05 ± 5.157% EE and 62.75 ± 4.448% Q8h which were within the predicted results. Furthermore, ZP was found to be more than − 30 mV, and HR-TEM results proved that the TE vesicles were spherical. The results of the evaluation parameters such as weight variation, folding endurance, and thickness were 0.07 ± 0.01 g, 82.3 ± 1.52 folds, and 0.93 ± 0.01, respectively, and were well within the limits. The TE patch incorporated more than 90% of the drug confirmed by the drug content analysis which allowed ex vivo permeation for almost 24 h providing a sustained release action with a permeation flux of 19 ± 1.08 and an enhancement ratio of 3.68 when compared to the MTX solution. Conclusion This study suggests that MTX-loaded transethosomal patch not only enhanced the skin permeation but also provided a 24-h release profile and reduced its toxicity. Graphical Abstract