Abstract:
Pyronaridine is a partner drug in, Pyramax®, a combination of artesunate (ASN)-pyronaridine (PRD) which
was recently prequalified by WHO drug as a potential alternative for treatment of malaria in African
setting. Pyronaridine is a mannich base, with a long half-life, thus predisposed to resistance. In this
study, we selected pyronaridine resistance by submitting Plasmodium berghei ANKA line in vivo to
increasing pyronaridine concentration for 20 successive passages over a period of six months. The
effective doses that reduce parasitaemia by 50% (ED50) and 90% (ED90) determined in the standard fourday suppressive test for the parent line were 1.83 and 4.79 mgkg-1, respectively. After 20 drug pressure
passages, the ED50 and ED90 increased by 66 and 40 fold, respectively. After dilution cloning, the
parasites were grown in the absence of drug for five passages and cryo-preserving them at -80°C for at
least one month, the resistance phenotypes remained stable. Thus, the resistant phenotype line could
be used to explore genetic determinants associated with pyronaridine resistance; therefore, this strain
represents a vital tool to study the mechanisms of resistance.
