How does adding other anti-malarial drugs to artemisinin, to obtain a "combined" therapy result in reducing the frequency of emergence of resistance?

And it is given in the form of artemisinin combination therapy, combined with another anti-malarial drug, with the goal of reducing the frequency of emergence of resistance. (Cf source).


The idea is rather simple. When an antibiotic is used, it becomes a driver to select for a mutant that has resistance towards the antibiotic. Let say the probability for that happening is P1 (Lets say 1 in 10, 0.1).

When you use two antibiotics with different modes of attack, the probability of acquiring resistance to both is P1 x P2. (Let say P1 =0.1 and P2 = 0.15). So P1 x P2 = 0.1 x 0.15 = 0.015

Hence the probability of becoming resistant to both antibiotics at the same time is very much lower. And as the antibiotics are always used together, the time a bug needs to develop resistance to the therapy becomes longer. The duration which you can use the drug is increased.

  • $\begingroup$ When was this discovered? $\endgroup$ – Vincent Mia Edie Verheyen Jun 3 '18 at 2:56
  • $\begingroup$ From Google, the concept has been around since the 1960s. I found an article in New England Journal of Medicine, 1960. However, it appears we only start to start considering antibiotic-antibiotic combination in the 1990s when MR started appearing at high frequency. $\endgroup$ – JayCkat Jun 3 '18 at 14:51

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