Quest for cheap, easy medicine monitor may be over as scientists develop simple home dosage test

Scientists have created a molecule that glows red or blue, depending on drug levels in blood, as the basis for a home test to prevent patients accidentally overdosing.

After contact with a drop of blood, the molecule's colour could be observed with the aid of a digital camera, its Swiss and American developers wrote in the journal Nature Chemical Biology.

"The process does not require any laboratory instruments and is so simple that the patients can do it themselves," Rudolf Griss from the Swiss Federal Institute of Technology in Lausanne said in a video explaining the invention, which is being refined for commercial use.

People who use medicine for conditions such as cancer, heart disease and epilepsy, or immunosuppressants to prevent organ rejection after a transplant, risk possible poisoning from overdosage, or the drugs not having an effect if the dose is too small.

But tests to monitor dosage are expensive, time-consuming and have to be done by trained experts.

A cheap, easy method has long been sought to monitor drug dosage at the patient's home or bedside, especially in remote areas where there are limited medical services.