Coartemether produces fast and effective gametocyte clearance in Plasmodium falciparum infection

Gametocytes are the stages in the malaria parasite’s life cycle that give rise to the sexual reproduction phase in the intestine of Anopheles mosquitoes. Since they link the vector and host infectious cycles, they are of key epidemiological importance. The greater the gametocyte carriage rate from human blood to mosquitoes, the more likely that malaria will be transmitted in a particular geographical area. Therefore, eradication of gametocytes will theoretically lead to extinction of malaria. Drugs that are effective against gametocytes are thus important in the fight against the disease.

Unlike various other antimalarials, coartemether has good gametocytocidal properties (Fig. 5). Studies in a hospital setting revealed that gametocyte clearance was significantly faster (p<0.001) with coartemether than with mefloquine in 136 evaluable patients in Thailand (median gametocyte clearance time was 152 hours versus 331 hours).³ Gametocyte clearance time was also faster with coartemether than with chloroquine in a comparative trial in 114 evaluable patients in India.² In this study, median gametocyte clearance time was 120 hours for coartemether, but was not reached with chloroquine. (Note that in compliance with public health policy in India, primaquine treatment was given on Day 8, when approximately 75% of patients on chloroquine had not cleared and had to be censored.)

Coartemether was also superior to sulfadoxine + pyrimethamine in The Gambia, totally clearing gametocytes by Day 15, whereas 28.9% of evaluable children on sulfadoxine + pyrimethamine still had gametocytes at this time (p <0.001).⁶

Figure 5. Faster time to gametocyte clearance with coartemether than comparators
Time to gametocyte clearance was significantly faster with coartemether than mefloquine or chloroquine (p <0.001)