In vitro susceptibility of Plasmodium falciparum isolates to halofantrine in the Central Province of Papua New Guinea.

Halofantrine is a newer antimalarial drug which has not been approved for clinical use in Papua New Guinea. We assessed 21 Central Province isolates of Plasmodium falciparum for their in vitro susceptibility to halofantrine. The concentration required to inhibit 50% of parasite growth (IC50) ranged from 0.05 to 7.0 nM with a mean of 1.90 nM and a median of 1.50 nM. The minimum inhibitory concentration (MIC) values ranged from 2.5 to 50 nM with a median of 5.0 nM. All but one isolate had an MIC of 10 nM or less. These results indicate that halofantrine would be a suitable alternative for the treatment of P. falciparum malaria in the region in the future, if and when the need arises, provided that its use was carefully monitored.