Roxithromycin potentiates the effects of chloroquine and mefloquine on multidrug-resistant Plasmodium falciparum in vitro

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Chloroquine (CQ) and mefloquine (MQ) are no longer potent antimalarial drugs due to the emergence of resistant Plasmodium falciparum. Combination therapy has become the standard for many regimes in overcoming drug resistance. Roxithromycin (ROM), a known p-glycoprotein inhibitor, is reported to have antimalarial activity and it is hoped it will potentiate the effects of both CQ/MQ and reverse CQ/MQ-resistance. We assayed the effects of CQ and MQ individually and in combination with ROM on synchronized P. falciparum (Dd2 strain) cultures. The IC(50) values of CQ and MQ were 60.0+/-5.0 and 16.0+/-3.0 ng/ml; these were decreased substantially when combined with ROM. Isobolograms indicate that CQ-ROM combinations were relatively more synergistic (mean FICI 0.70) than MQ-ROM (mean FICI 0.85) with their synergistic effect at par with CQ-verapamil (VRP) (mean FICI 0.64) and MQ-VRP (mean FICI 0.60) combinations. We conclude that ROM potentiates the CQ/MQ response on multidrug-resistant P. falciparum.


  • Hooi Min Tan Grahn
  • M F M Khairul
  • J H Low
  • C H Che Nasriyyah
  • A Noor A'shikin
  • M N Norazmi
  • M Ravichandran
  • S S Raju
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Cell and Molecular Biology
Original languageEnglish
Pages (from-to)387-392
JournalExperimental Parasitology
Issue number4
Publication statusPublished - 2007
Publication categoryResearch