Resisting arrest

16 May 2023
Will the world lose another miracle cure? Fifty years ago chloroquine seemed to be an unbeatable malaria remedy. But as the popularity spread of this synthetic form of quinine (a tree extract), the biological backlash began in the form of drug resistance. Today it is not recommended even for use in Africa, which suffers most of the world's malarial deaths.

In the past few years artemisinin, derived from Artemisia annua, a bush common in China, seemed equally promising. Alarmingly, though, signs of resistance to it have started to appear in South-East Asia. A large part of the reason for the build-up of resistance is the use of the drug by itself, as a monotherapy, rather than in combination with another drug. Experts agree that the use of Artemisinin Combination Therapies (ACTs) can greatly delay drug resistance in Africa. The World Health Organisation recommends their use. The leading ACT today is Coartem, which combines artemether, a derivative of the Chinese drug, with lumifantrine, another anti-malarial remedy.

The snag is that unscrupulous manufacturers peddle substandard ACTs and monotherapies. Roger Bate, of the American Enterprise Institute and his colleagues, examined the malarial remedies sold by the private sector in six African countries. Their study, recently published in the Public Library of Science (PLoS), found that many were substandard and that a third were artemisinin monotherapies. This, the researchers concluded, "places the future of malaria treatment at risk globally".

What is to be done? Widespread testing and surveillance would help. But Ramanan Laxminarayan of Resources for the Future, a think-tank, has another idea: rather than rely on just one "front-line" therapy he argues for the use of several ACTs and points to research that suggests the use of multiple therapies can dramatically extend the useful life of artemisinin.

Something like that may yet happen. A consortium led by Farmanguinhos, a state-run drugs firm in Brazil, recently launched ASMQ, which combines artesunate, a derivative of artemisinin, with mefloquine, another anti-malarial, in a convenient single-pill that does not need refrigeration and has shown good results in field trials. The developers want it to be widely available, so they will not seek a patent.

But that does not guarantee success, says Rachel Nugent of the Centre for Global Development. As she points out,ACTs are complex and costly to develop and make. The new Brazilian pill will sell for about $2.50 per adult dose. That is cheaper than buying the drugs separately, but much more expensive than the dodgy monotherapies uncovered by the researchers. It is also pricier than Coartem, which Novartis sells for under $1 a dose.

Even so, the new ACT is welcome. Resources for the Future suggests that the benefit ASMQ will bring in delaying drug resistance will greatly outweigh its higher cost. But are people suffering from malaria now prepared to pay the price to help future generations? Dr Laxminarayan reckons governments and big donors could help by providing extra money to subsidise the widespread use of a new ACT, rather than lose another promising drug needlessly soon.;=RSS