Study reveals scale of quality issues with antimalarials

The first results from a large-scale study of key antimalarial medicines in 10 sub-Saharan African countries reveal that a high percentage of these circulating on national markets are of substandard quality, according to the US Pharmacopoeial Commission (USP).

USP says this may contribute to the growth of drug-resistant strains of Plasmodium falciparum, the most virulent form of malaria.

The study found that 44 per cent of all antimalarials in Senegal were substandard, while Madagascar had a rate of 33 per cent and in Uganda it was 26 per cent. It focused on artemisinin-based combination (ACT), currently the most effective form of treatment, as well as sulfadoxine-pyrimethamine (SP) products used mainly for preventative treatment of malaria during pregnancy.

A total of 491 samples were underwent basic testing, and 197 were sent for 'full-scale quality control testing," according to USP. The study did not examine whether the substandard medicines were counterfeit, although earlier studies would indicate this is likely at least in a proportion of cases.

"It is noteworthy that all the samples (ACTs and SPs) passed their respective identification test requirements and no products lacking the active ingredients were identified," notes the report. It goes on to give examples of a number of anomalies that could point to counterfeiting activity.

For instance, differences in the colour intensity of packaging materials were observed in samples from the same brand but from different lots. Testing of one SP brand - called Maloxine - found that those with a darker blue box passed dissolution testing, while those with lighter blue packaging consistently failed.

"This suggests that, at a very basic level, a careful visual inspection of the packaging and product can be useful in identifying products for further testing and confirmation of the product quality," it notes.

Beyond the overall failure rates, other noteworthy findings across the three countries were that SP products were most likely to fail dissolution tests (35 per cent), while ACTs were most likely to fail impurity tests (29 per cent).

The authors of the note that the analysis provides an opportunity to mount a risk-based campaign against substandard and counterfeit antimalarials, based on the individual brands which failed quality testing.

"Although alarming, this study offers extremely valuable information that has already been shared with those countries in the hope that local regulatory bodies will focus their attention on products, brands and geographical locations where substandard medicines were found to pose the biggest threats," said Patrick Lukulay, director of the Promoting the Quality of Medicines (PQM) Programme, a venture between USP and US government agency USAID.


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