Substandard TB drugs probably accelerating resistance - Roger Bate

The World Health Organization released details today that tuberculosis now kills more than HIV/AIDS – approximately one and half million people every year. And the largest worry is that drug resistance versions of medicines to treat TB are becoming more common and deadly. This is a major risk for emerging nations and a costly one for richer nations, where quarantining patients is incredibly expensive.

My colleagues and I published a peer reviewed paper
(Link) nearly three years ago which showed substandard TB medicines were prevalent in most major emerging markets. We updated that paper with previously unanalyzed data from different pharmacies in the same 19 countries covered before (Angola, Brazil, China, Democratic Republic of Congo, Egypt, Ethiopia, Ghana, India (n = 3), Kenya, Nigeria, Russia, Rwanda, Thailand, Turkey, Uganda, United Republic of Tanzania and Zambia).

We assessed the basic quality of two main first-line anti-tuberculosis medicines, isoniazid and rifampicin, procured from private-sector pharmacies, to determine if substandard and falsified medicines are available and if they potentially contribute to drug resistance in cities in low- and middle-income countries.

In the previous paper we had assessed 713 treatment packs from a selection of pharmacies in 19 cities. We now added 392 samples that were procured in 2014 and were tested before expiry in 2014 and 2015. As before these samples were tested for quality using 1) thin-layer chromatography to analyze levels of active pharmaceutical ingredient (API), and 2) disintegration testing.

Of the original 713 samples tested, 9.1% failed basic quality testing for requisite levels of API or disintegration. The failure rate was 16.6% in Africa, 10.1% in India, and 3.9% in other middle-income countries.

Of the new 392 samples, 8% failed basic quality. Once again African failure rates were the highest at 16%, Indian failures rates at 9% and other middle-income nations at 2%.

Overall 8.4% of the total sampled failed.

With more detailed analysis of the packaging, we are confident that 6% of the total sample was not falsified but was substandard with underdosed content that would probably not treat the patient, but would almost certainly drive resistance.

Substandard TB drugs are still readily available in the private marketplace and probably contribute to anti-tuberculosis drug resistance in low- and middle-income countries and possibly the richer world too. This issue warrants further investigation through large-scale studies of drug quality in all markets.
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