Archive for March, 2021

Deltamethrin – a polymorphed insecticide.

Wednesday, March 24th, 2021

Deltamethin is a pyrethroid insecticide for control of malaria which has been used for a little while. Perhaps inevitably, mosquitoes are developing resistance to it. So what could be done about countering this? Well, perhaps surprisingly, form a polymorph![1] These crystal structure isomers are often highly undesirable; thus Ritonavir, which changed its polymorphic form during manufacture to become far less active (due it has to be said to insolubility). Now a polymorph of Deltamethin has been discovered, which when applied as a powder, increases its effectiveness more than 10 times against Anopheles mosquitoes and provides a potentially new affordable malaria control solution for countries that are loosing protection.



  1. J. Yang, B. Erriah, C.T. Hu, E. Reiter, X. Zhu, V. López-Mejías, I.P. Carmona-Sepúlveda, M.D. Ward, and B. Kahr, "A deltamethrin crystal polymorph for more effective malaria control", Proceedings of the National Academy of Sciences, vol. 117, pp. 26633-26638, 2020.

The small-molecule antiviral compound Molnupiravir: an exploration of its tautomers.

Sunday, March 14th, 2021

For obvious reasons, anti-viral molecules are very much in the news at the moment. Thus Derek Lowe highlights Molnupiravir which is shown as a hydroxylamine, the representation originating from the Wikipedia page on the molecule.