Abstract: 　Objective] To develop an in vitro method for the assessment of drug response in P falciparum to pyronaridine/sulfadoxine/pyrimethamine(PND/S/P).[Methods]The PND/S/P microtest plate was designed,Rieckmann in vitro microtest(WHO standard kit) was used to test the sensitivity of P falciparum in continuous culture(FCC1/HN strain), and the data obtained were analyzed using a computer programme. Fractional inhibitory concentration (FIC) was calculated to test the possible synergy between PND and S/P. [Results]:The effect of the PND/S/P plates was fairly stable and the ED 50 values of pyronaridine,sulfadoxine and pyrimethamine were 0 11,215 12 and 2 9 pmol,respectively. The FIC obtained confirmed the synergism between PND and S/P. [Conclusion]The in vitro method can be used to assess the sensitivity of P. falciparum to pyronaridine /sulfadoxine/pyrimethamine.

Key words: Plasmodium falciparum, in vitro sensitivity, pyronaridine.