Low-Tech Handheld Device Detects Counterfeit Drugs

"Counterfeit malaria drugs are a widespread problem in many parts of the world, especially in southeast Asia ," says Michael D. Green, a chemist in the CDC Division of Parasitic Diseases and the presenting author of the study. "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 realized 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 defense to identify counterfeits.

The test is simple and the refractometer is relatively inexpensive with adequate devices costing less than $100. The tester simply takes a sample of the medication (usually a tablet), pulverizes 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," says 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 U.S. pharmacy system, such as over the internet, where counterfeits could be easily pushed on the consumer," says Green.