Nearly a third of anti-malaria medicines available in Cameroon, Ethiopia, Ghana, Kenya, Nigeria and Tanzania are substandard and possibly counterfeit, according to the latest WHO survey of antimalarials, released today (25 February).
One in ten samples shows "extreme'" deviations in active ingredients or other standards — which could have life-threatening implications, says the survey.
The highest incidence of failure was in Nigeria, with two-thirds of all samples failing WHO quality tests.
"That means in Nigeria a patient is more likely to be treated with a substandard drug than one which meets quality specifications," said Lembit Rägo, the WHO's coordinator for quality assurance and medicines safety.
Ghana and Cameroon, with failure rates of 39 per cent and 37 per cent respectively, are not doing particularly well either.
Ethiopia, Kenya and Tanzania fared better, with failure rates of below 11 per cent. In these countries the WHO regards the quality of antimalarials to be reasonably under control. In Ethiopia no samples failed, in part because of a tight regulatory regime.
Kenya's failure rate of five per cent was a big improvement from studies carried out in 2003 when the failure rate for some samples was as high as 54 per cent.
Countries with domestic production of antimalarials fared slightly worse.
"It seems that regulators are focusing mainly on the quality of imports," said Jitko Sabatova, the WHO's technical officer responsible for pre-qualification of quality control labs.
Sabatova told SciDev.Net that countries with the smallest number of suppliers to the market tended to have lower failure rates.
Although the health implications of failing drugs was not examined in the survey, and the WHO did not distinguish between counterfeit and substandard drugs in its overall statistics, the organisation said the results should not be regarded as "catastrophic" in health terms.
But it pointed to important gaps in regulation and quality control within countries.
And Rägo said that international funds that are providing funding for a large proportion of antimalarials on the continent are exacerbating the situation. The Global Fund to Fight AIDS, Tuberculosis and Malaria and other charities "were [until recently] driven by price — the cheaper the better".
But now they have a better defined quality assurance policy," he said.
Elodie Jambert, pharmaceutical coordinator for the international medical charity Médicins Sans Frontiéres' Campaign for Access to Essential Medicines, in Geneva, told SciDev.Net: "Many donors and countries with weak NMRA [national medicines regulatory authorities] delegate the quality assurance function to procurement agencies.
"Procurement agencies may have the technical knowledge to assess the quality of the medicines but often have pressure from the market to buy medicines of the lowest possible price and their commercial interests may conflict with quality assurance policy."
She added: "The WHO must help to strengthen the national medicines regulatory authorities".