Use of thin-layer chromatography to detect counterfeit sulfadoxine/pyrimethamine tablets with the wrong active ingredient in Malawi.

BACKGROUND: Substandard and falsified anti-malarial medicines pose a serious threat to public health, especially in low-income countries. Appropriate technologies for drug quality analysis in resource-limited settings are important for the surveillance of the formal and informal drug market. The feasibility of thin-layer chromatography (TLC) with different solvent systems was tested using the GPHF Minilab in a study of the quality of sulfadoxine/pyrimethamine tablets in Malawi. METHODS: Twenty eight samples of sulfadoxine/pyrimethamine tablets were collected from randomly selected health facilities of four districts of southern Malawi. A mystery shopper approach was used when collecting samples from illegal street vendors, and an overt approach for the other facilities. Samples were subjected to visual inspection, disintegration testing and TLC analysis. 10 samples were further investigated according to the methods of the US Pharmacopeia using high performance liquid chromatography (HPLC). RESULTS: One sample was found to be falsified, containing a mixture of paracetamol tablets and co-trimoxazole tablets. These had been repackaged into paper strip packs labelled as a brand of sulfadoxine/pyrimethamine. TLC with different solvent systems readily proved that these tablets did not comply with their declaration, and provided strong evidence for the active pharmaceutical ingredients which were actually contained. Full pharmacopeial analysis by HPLC confirmed the results suggested by TLC for this sample, and showed two further samples to be of substandard quality. CONCLUSIONS: Due to the absence of the declared anti-malarial ingredients and due to the presence of other pharmaceutical ingredients, the identified falsified medicine represents a serious health risk for the population. Thin-layer chromatography (TLC) using different solvent systems proved to be a powerful method for the identification of this type of counterfeiting, presenting a simple and affordable technology for use in resource-limited settings.

Are counterfeit or substandard anti-infective products the cause of treatment failure in Papua New Guinea?

Counterfeit and substandard products present a big challenge to any national plan or policy devised to improve public health. Poor quality drug products are especially a problem in lower income countries where product information and drug regulation enforcement are scant or absent. The primary aim of the present study was to evaluate the quality of amodiaquine and amoxicillin formulations sold in Papua New Guinea (PNG) and to detect the presence of counterfeit or substandard drugs in circulation, if any. Fourteen samples, collected from five registered pharmacies in Port Moresby, PNG, were subjected to visual inspection, quality control tests, and verification of product authenticity. The quality control tests included weight variation, content uniformity, thin layer chromatography, and dissolution. None of the products complied with all of the evaluation criteria. Two products, one of which was purportedly distributed by a company which proved to be nonexistent, contained no detectable amodiaquine. The present study confirms that counterfeit and substandard amodiaquine and amoxicillin products are finding their way into the distribution chain in Port Moresby, PNG. This quality problem with anti-infective products is of great concern, as it not only exposes patients to poor quality products but also fosters the development of resistant bacterial strains.