Development of methotrexate-loaded cubosomes with improved skin permeation for the topical treatment of rheumatoid arthritis

Methotrexate-loaded cubosomes (MTCs) were developed to provide relief from pain/joint stiffness, by affording stable methotrexate concentration at the targeting sites through sustained pattern by non-invasive skin route with enhanced permeation upon skin, for the treatment of rheumatoid arthritis. Non-ionic surfactant poloxamer 188 works to enhance the permeation of methotrexate. The results of FT-IR analysis indicates the compatibility nature of methotrexate (MT), poloxamer 188 and cetyl palmitate selected for the formulation. Different ratios of poloxamer 188 and cetyl palmitate were utilized to formulate using emulsification process. The selected MTCs showed particle size of around 626.13 +/- 14.15 nm with charge of around - 6.29 +/- 1.07 mV with cubic morphology. The encapsulation efficiency of MTCs was found to be 92.94 +/- 0.9%. The in vitro MT release from MTCs conducted for 12 h revealed a sustained release pattern. The non-crystalline nature of MTCs was confirmed by XRD analysis. The in vitro anti-inflammatory effect of MTCs showed enhanced anti-inflammatory effect 11.9% compared to diclofenac sodium 10.4%. Ex vivo skin permeation analysis in excised skin of wistar albino rats showed 2.50 +/- 0.3 ng of MT permeation within 2 h followed by 8.80 +/- 5.2 ng within 12 h without any skin irritation. In addition, histopathological evaluation supported with fluorescent microscopic analysis of FITC-labeled MTCs confirmed the superior permeation enhancement of MTCs. The thermal stimulus time (TST) as studied by rat tail flick method indicates the enhancement of TST in case of MTCs (5.63 +/- 0.21 s) compared to standard diclofenac gel (2.70 +/- 0.20 s)/blank formulation (2.45 +/- 0.23 s), which indicates the superior analgesic effect of the developed MTCs. The inflammed paw thicknesses were measured for CFA-induced arthritic rats which get reduced from day 1 (1.47 cm) to (1.03 cm) day 15 for MTCs-treated groups that were imaged by animal imaging system. Thus, the MTCs may act as a promising system for the treatment of RA upon topical application.