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.
About 50% of an oral dose of griseofulvin passes through the gastro-intestinal tract unabsorbed and is excreted in faeces. Short residence time of the low soluble griseofulvin, in stomach and small intestine, limits its dissolution. Griseofulvin is highly soluble in acidic pH, and so a gastro-retentive floating matrix system was developed to control dissolution rate and thereby enhance solubility to develop an improved and convenient dosage form. Preformulation studies included selection of excipients and evaluation of compatibility with griseofulvin. Tablets were prepared by wet granulation technique with varying ratios of Methocel™, Accurel MP and Polyvinylpyrrolidone as determined by Design Expert software. Buoyancy capability and dissolution studies were carried out to assess the influence of the tablet components. Tablets that float immediately upon contact with dissolution medium and continue floating for over 12 h were achieved with at least 28% of Accurel MP. An increase in tablet hardness reduced the rate of griseofulvin release only up to 120 min. Methocel™ had the most significant influence on griseofulvin release, with an indirect proportion to the rate of griseofulvin release. Using Design Expert software, optimized formulation was achieved with 1% Polyvinylpyrrolidone, 30% Methocel™, 60% Accurel MP and hardness ranging between 8 and 9 N. Tablets produced floated immediately upon contact with the medium and remained floating for at least 12 h. Griseofulvin was released from the optimized tablets in a near zero order fashion, with a total of 80.8% griseofulvin released at the end of the 12-h dissolution test period.
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