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Analytical method development for post-marketing evaluation of classical antimalarials and novel artemisinin-derivative medicines

Wednesday, 20 June, 2007 - 18:00
Campus: Brussels Health Campus
Faculty: Medicine and Pharmacy
auditorium R. Vanden Driessche
Magnus Ajong Atemnkeng
phd defence

Malaria is the world’s highest killer disease with at least 300 million yearly clinical cases occurring mainly in Africa.

The classical antimalarial drugs such as chloroquine (CQ), quinine (Q) and sulfadoxine-pyrimethamine (SP) although less effective due to resistance are still widely used. Novel compounds such as the artemisinin-derived (AR) drugs are more potent and no resistance to them is yet to be reported. In Africa, the malaria burden is exacerbated by the presence of poor quality medicines and few studies have been performed on this topic. In addition, there are insufficient analytical methods for health officials to check the quality of these drugs.

The first aim was to develop simple and less expensive methods which are suitable for developing countries. UV spectrophotometry was used to verify the content of CQ, Q and proguanil in tablets and syrups. An HPLC-UV assay was developed for artemether and the preservatives, methyl paraben (MP) and propylparaben (PP) in a dry suspension. TLC was used to identify the preservatives in the CQ and Q syrups, and to determine artemisinin in plant extracts. The second aim was to assess the proportion of low quality anti malarials in two endemic countries: Kenya and DR Congo. The study found that 29% (4/14) of CQ and Q tablets failed to meet the 95-105% content requirements of the European Pharmacopoeia (Ph. Eur.). All batches of SP were underdosed while 9 of the 24 AR drugs did not conform. We compared the efficacy of an infusion made from Artemisia annua plant leaves in curing infected mice to the WHO required regimen for artemisinin. All mice treated with the tea died while WHO treated mice survived.

The presence of substandard and counterfeit antimalarials on the market is detrimental to public health. Hence, rapid field methods are necessary to determine drug quality.