title: In vitro sensitivity of Plasmodium falciparum to eight antimalarials in China-Myanmar and China-Lao PDR border areas.
abstract: In 1991-1995 by using the Rieckmann in vitro micro-method, susceptibilities of Plasmodium falciparum to eight antimalarials in the China-Lao PDR and China-Myanmar border areas were tested. The resistant rates of P. falciparum to chloroquinine were 95.0%-100%; IC50 114-240nmol/l. P. falciparum resistant rates to amodiaquine resistance accounted for 83.5%-100%, IC50 52-72nmol/l. All cases were sensitive to quinine, IC50 470-608nmol/l. P. falciparum isolates from the Lao PDR frontier were highly sensitive to artesunate, dihydroartemisinin, and arteether. Resistant rates from other areas were 0-11%. P. falciparum from China-Myanmar and Lao PDR border areas were also sensitive to mefloquine, IC50 68-88nmol/l. A longitudinal survey of the sensitivity of P. falciparum in vivo on the China-Lao PDR border showed that the average defervescent time of falciparum malaria was treated by pyronaridine increased from 32.7 +/- 16.0 hours during 1984-85 to 56.2 +/- 27.4 hours in 1995; the recrudescence rate rose up from 15.2% to 37.5%. The results monitored in vitro showed that all cases assessed in 1988 for response to pyronaridine were sensitive, but 36.4% of cases had emerging resistance, IC50 increased from 13nmol/l to 40 nmol/l. The above results suggested that P. falciparum in these areas has expressed resistance to chloroquine and amodiaquine. However, the parasites are still sensitive to artemisinin, pyronaridine, mefloquine, quinine, but with a declining sensitivities.
authors.affiliation: Yunnan Institute of Malaria Control, Simao, People's Republic of China.
authors.forename: H L
authors.initials: HL
authors.lastname: Yang
authors.forename: D Q
authors.initials: DQ
authors.lastname: Liu
authors.forename: Y M
authors.initials: YM
authors.lastname: Yang
authors.forename: K G
authors.initials: KG
authors.lastname: Huang
authors.forename: Y
authors.initials: Y
authors.lastname: Dong
authors.forename: P F
authors.initials: PF
authors.lastname: Yang
authors.forename: M Z
authors.initials: MZ
authors.lastname: Liao
authors.forename: C Y
authors.initials: CY
authors.lastname: Zhang
mesh_terms: D000655:Amodiaquine / Q000494:pharmacology; D000818:Animals; D000962:Antimalarials / Q000494:pharmacology*; D037621:Artemisinins; D000077332:Artesunate; D002681:China; D002738:Chloroquine / Q000494:pharmacology; D004353:Drug Evaluation, Preclinical; D004351:Drug Resistance; D006801:Humans; D007812:Laos; D008826:Microbial Sensitivity Tests; D002052:Myanmar; D009287:Naphthyridines / Q000494:pharmacology; D010963:Plasmodium falciparum / Q000187:drug effects*; D011803:Quinine / Q000494:pharmacology; D012717:Sesquiterpenes / Q000494:pharmacology
chemical_list: D000962:Antimalarials; D037621:Artemisinins; D009287:Naphthyridines; D012717:Sesquiterpenes; D000655:Amodiaquine; D000077332:Artesunate; C039060:artenimol; D002738:Chloroquine; D011803:Quinine; C027871:pyronaridine; C055141:artemotil