International pharmacopoeia monographs : antimalarial dosage forms

Abstract

Malaria is a disease affecting millions of people in 109 malarious countries and territories, causing approximately one million deaths annually. In 2004 one of the parasites causing human malaria, Plasmodium falciparum, was among the leading global causes of death from a single infectious agent, especially in Africa (WHO, 2008:23). Treatment of this disease with single active pharmaceutical ingredients has led to the emergence of resistant P. falciparum parasites, resulting in the most severe form of this illness. Alarmingly, the poor quality of commercially available antimalarial products, especially in Africa, has increasingly been reported as a major cause of resistance to antimalarials. In Pakistan it was found that a P. falciparum epidemic that initially was attributed to drug resistance, was actually caused by substandard sulfadoxine/pyrimethamine products, causing a 50 times higher incidence of malaria in these areas than elsewhere (Leslie et al., 2009:1758). Other results indicated that up to 10% of sulfadoxine/pyrimethamine tablets, sampled in six African countries, failed the assay test, whilst up to 40% failed the USP dissolution test. Furthermore, the World Health Organization (WHO) reported that 20 - 90% of products failed quality requirements during 1999 and 2000 in seven African countries (WHO, 2003:263). Cases like these have raised the awareness of the vast number of inferior products that are being distributed. The subsequent need for establishing mechanisms to proactively detect substandard medicines, specifically antimalarials, easily and effectively had indirectly led to the origin of this study, long before it was formally undertaken. Testing monographs for pharmaceutical products are developed to formalise, or standardise, the regulation of pharmaceutical dosage forms. Problems have, however, been reported with regards to the inadequacy of existing antimalarial monographs in assuring quality medicines, fit for their intended use. The WHO had requested the Research Institute for Industrial Pharmacy, incorporating the Centre for Quality Assurance of Medicines (RIIP®/CENQAM®), both operating at the Potchefstroom Campus of the North–West University, to develop monographs for three immediate–release antimalaria dosage forms, namely amodiaquine tablets, sulfadoxine/pyrimethamine fixed–dose combination tablets and mefloquine tablets. The undertaking of these projects, to develop specifications for the quality control of these pharmaceutical products, formed the object of this research study. Data had been accumulated since 2000, as a result of continuous requests by the WHO to help solve problems that had been experienced with analytical test methods, especially from manufacturers. These requests either led to the refinement of existing methods, or to the development of new ones. The success with which these outcomes were implemented worldwide, finally led to the decision to publish these research findings under the umbrella of this project. The proud product is a comprehensive package of tests for three commercial antimalarial products, the outcomes of which are hoped to contribute towards the combat against resistance formation to these important disease fighters.