Development and evaluation of microemulsion foam formulation for topical delivery of betamethasone dipropionate

Betamethasone dipropionate (BDP) is widely recognized as a therapeutic agent for psoriasis. However, the current topical formulations exhibit certain limitations, including significant systemic absorption and substantial residue on the skin surface post-application. Thus, this study aimed to develop a novel microemulsion (ME) foam system, which can enhance the targeting and bioavailability of BDP at the diseased skin. Through the pseudo-ternary diagrams, it was determined that when the ratio of surfactant to cosurfactant was 6:1, the ME region reached its maximum. The optimized formulation was composed of 0.064% BDP, medium-chain triglyceride (oil phase), Labrasol/polyglyceryl-3 dioleate NF (surfactant/co-surfactant), and water (aqueous phase). In vitro permeation studies on normal and exfoliated porcine skin, the ME foam could significantly increase the R/Q (ratio of intradermal retention to permeation) of BDP compared to the two commercial formulations (Diansong cream and Xamiol gel). The in vivo studies on rats showed that compared to the commercially cream, the ME foam significantly increased the 24-hour intradermal retention of the drug, and the T_max of plasma pharmacokinetics was also longer. This further demonstrated the intradermal targeting and sustained-release properties of the ME foam. Overall, the ME foam developed in this study is a promising, safe and effective drug vehicle for the topical delivery of BDP.