Inexpensive assay detects fake malaria drugs

Chemists from Oregon State University (OSU) have created a simple, inexpensive assay which can tell whether or not one of the primary drugs being used to treat malaria is genuine. Their findings have been published in the journal Talanta.

Artesunate, the most important drug used to treat serious cases of malaria, can cost $1 to $2 per adult treatment, which is considered expensive by the standards of the developing world. This, coupled with the prevalence of malaria in the region, means the market for counterfeit drugs is significant.

In some places in the developing world, more than 80% of outlets are selling counterfeit pharmaceuticals. One survey found that 38-53% of outlets in Cambodia, Laos, Myanmar, Thailand and Vietnam had no active drug in the product that was being sold; according to the OSU researchers, trade in counterfeit artesunate is particularly prevalent in Southeast Asia and sub-Saharan Africa.

“There are laboratory methods to analyse medications such as this, but they often are not available or widely used in the developing world where malaria kills thousands of people every year,” said Vincent Remcho, a professor of chemistry in the OSU College of Science.

“What we need are inexpensive, accurate assays that can detect adulterated pharmaceuticals in the field, simple enough that anyone can use them.”

The researchers developed a colorimetric-based testing kit based on paper microfluidics, in which a film is impressed onto paper that can detect the presence and level of the artesunate drug at a cost of a few cents. A single pill can be crushed and dissolved in water; when a drop of the solution is placed on the paper, it turns yellow if the drug is present. The intensity of the colour indicates the level of the drug.

This approach is used to prepare a paper assay that can tell whether a common drug used to treat malaria is genuine. (Graphic courtesy of Oregon State University.)

“The test can be done within minutes,” said the researchers, “and allows for a semi-quantitative analysis of the artesunate tablets by comparing the developed yellow colour on the paper test to a colour-coded key chart that comes with the kit.” For even higher accuracy, OSU students developed an iPhone app that could be used to measure the colour and, with it, the presence and level of the drug.

The World Health Organization estimates that about 200,000 lives a year may be lost due to the use of counterfeit antimalarial drugs. Additionally, the spread of drugs with sub-therapeutic levels of artesunate can promote the development of new strains of multidrug-resistant malaria. It is thus believed that the assay, when commercialised, could save thousands of lives around the world every year, and similar technology could also be developed for other types of medications and diseases.

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