Abstract

Dietary supplements, particularly nutraceuticals, are an expanding sector on the South African market, especially since the beginning of the COVID-19 pandemic. However, regulatory authorities do not regulate nutraceuticals and concern arose regarding safety, quality and efficacy of the product reaching the end-user. The aim of the study was to evaluate the pharmaceutical quality, specifically the physical and the in-vitro release properties of two commonly marketed L-lysine products in South Africa. An experimental design was used. Two L-lysine products, a tablet and a capsule, available on the South African market were evaluated for pharmaceutical quality. Tests performed were: Weight variation test, dimensions test, friability test, hardness test, assay, and drug release studies. The quality of products was compared to official USP standards. Tablets were of consistent diameter, length and thickness. Not more than 2 tablets had weights outside the 5% deviation range for each sample. Tablets had an average friability of 17.56%, although their hardness was greater than the acceptable range. All tablets disintegrated within the 15 min. Two out of three samples had amount of lysine below the acceptable range. Tablets sampled released just about 70% of the contained L-lysine by 45 min. Capsules had inconsistent powder weight and contained an amount of L-lysine less than the label claim. Capsules disintegrated within 4 min and released just over 75% of drug by 45 min. There seems to be inconsistences in the characteristics of L-lysine products and their quality cannot be guaranteed. More investigations on other marketed L-lysine products are suggested, to further advice on the necessity of a relook of their quality assurance procedures and labelling.

Key words: Nutraceuticals, pharmaceutical quality, L-lysine.