Formulation and stability of ascorbic acid in topical preparations

Abstract

Ascorbic acid (vitamin C) and its derivatives are known to perform various important physiological and metabolic functions in humans. In addition to dietary supplements, a number of topical formulations containing ascorbic acid and derivatives are now available that induce collagen synthesis, strengthening of skin tissues, reduction in pigmentation loss, and improved growth and health activities. It has also been used in a variety of cosmetic preparations as an antioxidant, pH adjuster, anti-aging and photoprotecting agent. Ascorbic acid is highly sensitive to air and light; and to achieve its stabilization in cosmetic preparations, it has been suggested to use ascorbic acid in microencapsulation form, in combination with other chemical moieties such as vitamin-E, by the control of pH and electrolyte concentration and use of stabilizing agents like citric, tartaric, or ferulic acids. A large number of cosmetic creams and lotions are available in the market containing the derivatives of ascorbic acid (e.g., sodium ascorbate, ascorbyl palmitate). Although these preparations are chemically stable, they lack the pharmacological activity of ascorbic acid. In the present review, it has been emphasized to consider the importance of various factors involved in the formulation of such preparations to achieve the stabilization of ascorbic acid as such, to maintain its pharmacological activity.