Scientists at the Centres for Disease Control and Prevention (CDC) have adapted a simple low-tech device normally used to examine urine specimens to test and detect counterfeit drugs.
‘Counterfeit malaria drugs are a widespread problem in many parts of the world, especially in Southeast Asia,’ said Michael D. Green, a chemist in the CDC Division of Parasitic Diseases. ‘A survey in Southeast Asia determined that 38% of samples of the malaria drug artesunate purchased at retail outlets contained no active ingredients whatsoever.’ In 1999 at least 30 malaria deaths in Cambodia could be linked to inadequate treatment due to counterfeit drugs.
The device, called a handheld refractometer, has been commonly used by clinics to measure the specific gravity of urine specimens.
Green and his colleagues realised that by measuring the specific gravity of certain dissolved drugs, one could easily determine the amount of active ingredient in a tablet. While not able to conclusively identify an unknown drug, the device could be used as a first line of defence to identify counterfeits.
The test is simple and the refractometer is relatively inexpensive with adequate devices costing less than $100. The tester takes a sample of the medication (usually a tablet), pulverises it, dissolves it in alcohol and filters out any solids left.
A drop of the clear solution is placed on the refractometer, which casts a shadow line giving the refractive index. That index can be converted to specific gravity, which is compared to a standard already established for that particular drug.
‘This is a simple, relatively low-tech approach that people in developing countries who have limited resources can use,’ said Green.
So far, Green and his colleagues have only tested this approach in the lab. He hopes to begin field testing soon. While this study focused only on malaria drugs, the refractometer can be used to detect all sorts of fake drugs.
Green has also studied several tuberculosis drugs and hopes to expand this application to other drugs.
‘This application could be used to test mass batches of drugs imported from overseas. It could also be used to screen drugs sold outside the formal US pharmacy system, such as over the Internet, where counterfeits could be easily pushed on the consumer,’ concluded Green.