MICROENCAPSULATION: A STRATEGY TO SURPASS PHOTO INSTABILITY AND LOW PENETRABILITY OF SKIN LIGHTENING AGENTS

Objective: Kojic acid and arbutin are potent agents for effective treatment of hyperpigmentation. However, low photostability, low permeability and high irritancy exhibited by them make topical delivery a challenge. The aim of this study was to develop novel photostable and highly penetrable formulation of kojic acid and arbutin to combat hyper-pigmentation effectively at lower concentrations in comparison to marketed conventional formulations. Methods: Kojic acid and arbutin loaded micro-emulsion based crème’ gel was formulated by the generation of water in oil system by spontaneous formation technique followed by incorporation into a gel. Thus manufactured by simple industry feasible technique and evaluated for effective reduction of skin irritancy, improvement in photostability, the penetrability of the hydrophilic drugs and anti-tyrosinase potential. Results: Comparative in-vitro and ex-vivo release study showed that microemulsion based crème’ gel not only provided sustained effect up to 24 h but also retained approximately 10 folds higher drug concentration of drugs in the skin as against conventional gel formulation. This novel formulation was not associated with any irritation potential and had a higher tyrosinase inhibitory effect when compared against conventional gel. Furthermore, microemulsion based crème’ gel when subjected to photostability studies was found to be stable over a period of 7-8 h of sun exposure, thus allowing day time use of the formulation. Conclusion: Microemulsion based crème’ gel can be easily used in daylight, thus, surpassing the limitation of photodegradation of actives to some highly irritant products when exposed to sunlight.