Formulation and evaluation of sodium ascorbyl phosphate and kojic acid containing products

Abstract

The skin, our main defence against harmful substances such as wind, dirt, bacteria and ultraviolet radiation has also the important functions of preventing water loss, regulating temperature and receiving external stimuli. Skin colour varies depending on racial background, sex and the season of the year due to the exposure to sunlight. Skin colour is primarily determined by the amount of melanin produced by the melanocytes. For this reason, research for the development of whitening products has focused on reducing melanin production in the melanocytes, rather than bleaching of the skin. Skin-whitening products have been widely used in the cosmetic field and clinic therapy. They either lighten the skin or depigment skin (treatment for abnormal hyperpigmentation of the skin such as freckles and melasma). Whitening agents, such as hydroquinone, kojic acid and ascorbic acid derivatives have shown efficacy in treatment of hyperpigmentation. In this study, sodium ascorbyl phosphate and kojic acid were used as the active ingredients in skin lightening products. Sodium ascorbyl phosphate acts as an in-vivo antioxidant, promotes collagen formation, and lightens the skin. It is a stable vitamin C derivate that protects the skin, promotes its development and improves its appearance. Kojic acid successfully fights age spots and pigmentation on face and body. The product development program started with a literature search and a preformulation study. Existing basic formulations were used and modified to incorporate both active ingredients in a variety of skin lightening products. Stability testing followed, based on the requirements of the South A6ican Medicine Control Council for new products. Six skin lightening products were formulated, i.e. two facial creams, a toner, a gel, a foam bath, and a soap. After formulation these products were tested for their stability over a period of three months at three different storage temperatures and humidity (5ºC,25 ºC + 60% RH and 40ºC + 75% RH).