There are approximately 1 million deaths annually due to malaria worldwide. The World Health Organization estimates that approximately 20% of these deaths are associated with counterfeit antimalarial drugs.
Although this is not a new problem, it is widespread and fake drugs have become increasingly difficult to distinguish from the real thing. Avarice-driven criminals have become highly skilled in replicating the look and feel of real drugs and their packaging. More sophisticated counterfeits contain a small amount of the real active ingredient, so they can deceive crude tests of authenticity.
Artesunate is the drug of choice for severe or drug-resistant Plasmodium falciparum infections. It is also the most commonly reported drug to be counterfeited. As a response, the US Centers for Disease Control and Prevention has developed a rapid, low cost, colorimetric lab test for artesunate. The reaction of an alkali decomposition product of artesunate with Fast Red TR in a solution at a specific pH yields a yellow solution. The concentration of the drug is quantifiable based on how yellow the solution becomes.
A study recently published in Talanta demonstrates how a simplified mobile test kit can be used to reach the same outcome. To use the kit, the drug just needs to be dissolved in a sodium hydroxide solution and dropped onto the test paper. The various dry chemicals on the test paper take care of the reaction with Fast Red TR and maintaining the correct pH.
In addition to simplifying the test, the researchers demonstrated that an iPhone can be used to detect the color of the result and accurately translate that to the concentration of the artesunate in the solution.
Researchers were able to demonstrate that the kit is effective in identifying artesunate and quantifying the concentration of the drug. They tested various concentrations of the drug and analyzed it with an iPhone app called ColorAssist. Drugs were incubated on the test kit for 5 minutes and then analyzed by the app with the iPhone held at a standard distance from the chip. The RGB value for the color was converted to a gray scale intensity and compared to the known concentration being tested.
They found that the gray scale intensity correlated well with the actual drug concentrations. The researchers that created the test kit are currently developing an app that can analyze the yellow color produced by the test and display the concentration of the drug being tested.
There are a few limitations to this study. The study doesn’t include any actual data (other than the graphs shown). Based on what was published, it’s impossible to determine exactly how accurate the test truly is. At this point, the publication simply demonstrates a proof of concept.
Without the app, the yellow result has to be compared manually to a printed color strip (similar to a pH litmus test). A well-developed app would potentially decrease user error by including clear instructions and leaving the analysis to the mobile device. Then the user just has to drop the solution on the test kit, wait five minutes, and let the app tell them what the concentration is. Simplifying the solution could enable improved testing and potentially save lives .
Sources: Talanta, Malaria Journal, Smithsonian Magazine, World Health Organization
