The effect of shelf life on the potency of complex multivitamin preparations

Abstract

Samples of different lots of ten complex multivitamin products, formulated as capsules, tablets, and liquids, were purchased on the retail market in Canada and analyzed for their vitamin content. The potencies of vitamin A, vitamin B12, thiamine, and pantothenic acid were markedly affected by shelf life and storage conditions particularly in certain types of products. Riboflavin, niacinamide, pyridoxine, and ascorbic acid contents were less influenced by these factors. Over one‐third of the products purchased at random were more than one year old and a significant loss of potency in several products was evident at eight to twelve months after manufacture. This situation indicated a serious lack of adequate control of the potency and marketing of such products and a need for closer cooperation between manufacturer, wholesaler, and pharmacist. The use of an expiration date based on actual stability was suggested as an aid in ensuring that the consumer obtain full labeled potency. It would also be mutually helpful to both the conscientious manufacturer and pharmacist.