Ginger oil-based microemulsion as a strategy to improve the topical therapy of imiquimod

The Imiquimod (IMQ) formulation for cutaneous administration is challenging due to its very low solubility and its poor penetration properties. The purpose of this study was to develop medium or high fluidity microemulsions (ME) to increase the solubility and modulate the release for the topical administration of Imiquimod (IMQ), thus increasing the therapeutic efficacy of the drug. Ginger oil was selected as the oil phase, Polysorbate 80/Triton X100 1:1 as the surfactant system, and water as the aqueous phase. From the construction of a pseudo-ternary phase diagram, it was possible to obtain ME in a wide range of combinations with medium to high density. Five ME were subjected to conductivity, drug incorporation, and in vitro release assays. From conductivity determinations, it was established that ME exhibited a characteristic profile of percolative conductivity, suggesting a phase inversion of W/O to direct micelles O/W. The release assay demonstrated the ability of the ME to deliver IMQ, where the ME1-3 had a high rate of release as a function of time, and the ME4-5, released the drug in a sustained manner. These results indicate that the ME studied may be a promising vehicle for increasing the effectiveness of IMQ in topical dosage forms.