A colorimetric field method to assess the authenticity of drugs sold as the antimalarial artesunate

Artesunate is the most widely used of the artemisinin derivatives. These dr ugs are being used increasingly throughout the tropical world, and are an e ssential component of the treatment of multi-drug resistant malaria. The re cent and widespread appearance of counterfeit artesunate tablets in several countries in Southeast Asia poses a serious threat to health in this regio n. We have developed a simple, inexpensive colorimetric test to determine a rtesunate authenticity in tablets. The test is based on a reaction between an alkali decomposition product of artesunate and a diazonium salt, fast re d TR (FRTR). The appearance of a yellow color indicates the presence of art esunate. The specificity of the test is dependent on the pH of the reaction . Among other antimalarials tested, (i.e. artemisinin, artemether, chloroqu ine, quinine, primaquine, sulfadoxine, and pyrimethamine) only artesunate p roduced a positive color reaction at pH 4. The assay requires only 1% of th e total weight of a standard tablet containing 50 mg of artesunate and can be completed within 10 min. The method was tested on six genuine artesunate tablets and six counterfeit artesunate tablets obtained in Southeast Asia. The average amount of artesunate in the genuine tablets was determined to be 50.8 +/- 2.9 mg while the counterfeit tablets were found to contain no a rtesunate. (C) Published by Elsevier Science B.V.