In the present investigation, imiquimod (IMQ) was coupled to oleic acid (OLA; IMQ-OLA) to synthesise prodrug to reduce crystallinity that later amalgamated with oil-in-water (o/w) emulsion cream (IMQ-OLA cream) for the treatment of melanoma tumour. The synthesis of IMQ-OLA prodrug was verified by FT-IR, 1HNMR and mass spectroscopy. The crystalline lattice of IMQ was transformed to somewhat amorphous structure in IMQ-OLA prodrug. IMQ-OLA cream retained 35.6% of IMQ within skin, significantly (p < 0.05) higher than 22.3% and 10.6% retained by marketed IMQ cream and IMQ solution, respectively. IMQ-OLA cream suppressed the melanoma tumour to 70.3 mm3 in C57BL6J mice as compared to 72.6 mm3 tumour, reduced by marketed IMQ cream with no significant difference (p > 0.05) at day 32 over 17-day period of treatment. IMQ-OLA cream followed the multiple mechanisms of cell death. IMQ-OLA cream warrants further in depth investigations for translating in to a clinically viable topical dermal product.
Keywords: Imiquimod; melanoma; oleic acid; permeation enhancer; prodrug; topical delivery.