title: In vitro susceptibility of Plasmodium vivax to antimalarials in Colombia.
abstract: The in vitro susceptibilities of 30 isolates of Plasmodium vivax to a number of antimalarials (chloroquine [CQ], mefloquine, amodiaquine, quinine, and artesunate [AS]) were evaluated. The isolates came from the region of Urabá in Colombia, in which malaria is endemic, and were evaluated by the schizont maturation test. The 50% inhibitory concentration (IC50) was 0.6 nM (95% confidence interval [CI], 0.3 to 1.0 nM) for artesunate, 8.5 nM (95% CI, 5.6 to 13.0 nM) for amodiaquine, 23.3 nM (95% CI, 12.4 to 44.1 nM) for chloroquine, 55.6 nM (95% CI, 36.8 to 84.1 nM) for mefloquine, and 115.3 nM (95% CI, 57.7 to 230.5 nM) for quinine. The isolates were classified according to whether the initial parasites were mature or immature trophozoites (Tfz). It was found that the IC50s for chloroquine and artesunate were significantly different in the two aforementioned groups (P < 0.001). The IC50s of CQ and AS were higher in the isolates from mature Tfz (CQ, 39.3 nM versus 17 nM; AS, 1.4 nM versus 0.3 nM), and 10% of the isolates showed lower susceptibilities to one of the antimalarial drugs, 13.3% to two antimalarial drugs, and 3.3% to more than three antimalarial drugs. It should be highlighted that despite the extensive use of chloroquine in Colombia, P. vivax continues to be susceptible to antimalarials. This is the first report, to our knowledge, showing in vitro susceptibilities of P. vivax isolates to antimalarials in Colombia.
authors.affiliation: Grupo Malaria, Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia.
authors.forename: Diana
authors.initials: D
authors.lastname: Fernández
authors.affiliation: Grupo Malaria, Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia.
authors.forename: César
authors.initials: C
authors.lastname: Segura
authors.affiliation: Instituto Colombiano de Medicina Tropical, Universidad CES, Apartadó, Colombia.
authors.forename: Margarita
authors.initials: M
authors.lastname: Arboleda
authors.affiliation: Departamento de Farmacia, Facultad de Ciencias, Universidad Nacional de Colombia, Bogota, Colombia.
authors.forename: Giovanny
authors.initials: G
authors.lastname: Garavito
authors.affiliation: Grupo Malaria, Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia.
authors.forename: Silvia
authors.initials: S
authors.lastname: Blair
authors.affiliation: Grupo Malaria, Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia Programa de Biología, Facultad de Ciencias Básicas, Universidad del Atlántico, Barranquilla, Colombia apabon72@gmail.com.
authors.forename: Adriana
authors.initials: A
authors.lastname: Pabón
mesh_terms: D000655:Amodiaquine / Q000494:pharmacology; D000962:Antimalarials / Q000494:pharmacology*; D037621:Artemisinins / Q000494:pharmacology; D000077332:Artesunate; D002738:Chloroquine / Q000494:pharmacology; D003105:Colombia; D004351:Drug Resistance; D016780:Malaria, Vivax / Q000188:drug therapy* / Q000469:parasitology; D015767:Mefloquine / Q000494:pharmacology; D021261:Parasitic Sensitivity Tests; D010966:Plasmodium vivax / Q000187:drug effects* / Q000302:isolation & purification; D011803:Quinine / Q000494:pharmacology
chemical_list: D000962:Antimalarials; D037621:Artemisinins; D000655:Amodiaquine; D000077332:Artesunate; D002738:Chloroquine; D011803:Quinine; D015767:Mefloquine
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