Methaemoglobin results from the oxidation of ferrous to ferric iron in the centre of the haem moeity of haemoglobin. The production of dose-dependent methaemoglobinaemia by 8-aminoquinoline antimalarial drugs appears to be associated with, but is not directly linked to therapeutic efficacy against latent vivax and ovale malarias. Iatrogenic methaemoglobinaemia may be a useful pharmacodynamic measure in 8-aminoquinoline drug and dose optimization.
The deployment of artesunate for severe malaria and the artemisinin combination therapies (ACTs) for uncomplicated malaria has been a major advance in antimalarial therapeutics. These drugs have reduced treated mortality, accelerated recovery, and reduced treatment failure rates and transmission from the treated infection. These drugs remain highly effective against falciparum malaria in most malaria endemic areas but significant resistance has emerged in the Greater Mekong subregion of Southeast Asia. Resistance to artemisinin was followed by resistance in the ACT partner drugs, and fit multidrug resistant parasite lineages have now spread widely across the region. ACTs are highly effective against P. vivax and the other malaria species. Recent studies show that radical curative regimens of primaquine (to prevent relapse) can be shortened to seven days, and that the newly introduced single dose tafenoquine is an alternative, although the currently recommended dose is insufficient in Southeast Asia and Oceania. Targeted malaria elimination using focal mass treatments with dihydroartemisinin-piperaquine have proved safe and effective malaria elimination accelerators, but progress overall towards malaria elimination is very slow. Indeed since 2015 overall malaria case numbers globally have risen.