Table 1.
In vitro IC50 values (nM) of P. falciparum field isolates from the China-Myanmar border to 10 antimalarial drugs.
| Drugs | Median (IQR) | Range | 3D7 (Mean ± SD) |
P* | Cutoff (nM) | # (%) of isolates above cutoff |
|---|---|---|---|---|---|---|
| Chloroquine | 273.4 (154.9–559.2) | 38.7–2563.0 | 17.8 ± 8.1 | <0.0001 | 100# | 92 (86.0%) |
| Piperaquine | 11.0 (6.5–14.9) | 1.7–43.0 | 5.1 ± 2.0 | <0.0001 | 29.0 | 7 (6.5%) |
| Naphthoquine | 10.8 (6.4–14.3) | 1.6–32.0 | 8.5 ± 5.0 | <0.0001 | 25.4 | 5 (4.7%) |
| Mefloquine | 45.4 (34.5–57.7) | 5.7–121.1 | 18.1 ± 7.6 | <0.0001 | 30#; 90.6 | 89 (83.2%); 4 (3.7%) |
| Lumefantrine | 5.1 (3.8–6.7) | 1.7–17.0 | 4.8 ± 2.9 | <0.0001 | 10.6 | 5 (4.7%) |
| Quinine | 464.8 (298.7–605.5) | 30.6–2123.0 | 83.3 ± 41.5 | <0.0001 | 600# | 27 (25.2%) |
| Pyrimethamine | 4129.0 (2698.0–5588.0) | 8.4–10519.0 | 62.5 ± 44.9 | <0.0001 | 100# | 106 (99.1%) |
| Pyronaridine | 10.3 (6.6–17.3) | 2.2–39.3 | 5.6 ± 6.2 | <0.0001 | 15§; 27.4 | 34 (31.8%); 7 (6.5%) |
| Artesunate | 10.7 (8.1–14.2) | 1.6–29.7 | 7.4 ± 4.4 | <0.0001 | 22.2 | 3 (2.8%) |
| Dihydroartemisinin | 4.1 (2.7–6.0) | 1.1–11.0 | 3.0 ± 2.5 | <0.0001 | 8.9 | 4 (3.7%) |
IQR, interquartile range; SD, standard deviation; ND, not defined.
*P values are from Mann-Whitney U test for comparison between field isolates and 3D7.
Cutoffs for resistance are based on earlier report in Ringwald et al. (1996)# and Pradines et al. (1998)§. The rest of the cutoff values were based on calculated based on mean + 2 × SD of IC50s from the field isolates. Note for mefloquine and pyronaridine, the second cutoff value was based on mean + 2 × SD of IC50s from the field isolates in this study.