A Review of Clinical Efficacy of Topical Vitamin C and Its Derivatives

Abstract

: The last two decades have seen an increase in active-led skin care products in over the counter and retail market places. Consumers have become more knowledgeable about ingredients used in topical products resulting in formulations with vitamins and other active ingredients gaining popularity. Further, the need for instantaneous and short-term benefits, consumers are moving towards high doses of active products. This poses a challenge for formulation scientists to stabilize high active doses and ensure potency over shelf life. Vitamin C or ascorbic acid is one such ubiquitous active commonly found in topical products claiming brightening, skin firming and toning benefits. As humans lack the enzyme required for synthesis of Vitamin C, we obtain it through diet or topical application. Vitamin C consumption results in insignificant benefits due to limited bioavailability, making topical application the major route of delivery. Ascorbic acid is an antioxidant; when applied topically it protects the skin from damaging free radicals produced due to exposure to UV-rays and other environmental stressors. However, ascorbic acid has been reported to be unstable in aqueous systems and readily undergoes oxidation making it inactive. This has led to the generation of multiple pro-drugs and derivatives which dissociate to release free ascorbic acid or its ionic form in the skin. In this review, we have focused on the clinical efficacy of vitamin C and its derivatives, suitable for various applications. This will serve as a ready reckoner for formulators creating vitamin C based products.