In Vivo and In Vitro Efficacy of Amodiaquine Monotherapy for Treatment of Infection by Chloroquine-Resistant Plasmodium vivax

A HASUGIAN, E TJITRA, A RATCLIFF, H SISWANTORO, Enny Kenangalem, R WUWUNG, H PURBA, Kim Piera, Ferryanto Chalfein, Jutta Marfurt, P PENTTINEN, Bruce Russell, Nicholas Anstey, Ric Price

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    Amodiaquine retains efficacy against infection by chloroquine-resistant Plasmodium falciparum; however, little information is available on its efficacy against infection by chloroquine-resistant Plasmodium vivax. Patients presenting to a rural clinic with a pure P. vivax infection that recurred after recent antimalarial treatment were retreated, this time with amodiaquine monotherapy, and the risk of further recurrence within 4 weeks was assessed. Of the 87 patients with pure P. vivax infection, 15 patients did not complete a full course of treatment, 4 of whom were intolerant to treatment. In the 72 patients completing treatment, 91% (63 of 69) had cleared their parasitemia within 48 h with no early treatment failure. Follow-up to day 28 or recurrent parasitemia was achieved for 56 patients (78%). The cumulative incidence of treatment failure by day 28 was 22.8% (95% confidence interval, 7.3 to 38%). The in vitro sensitivity profile was determined for a separate set of isolates from outpatients with pure P. vivax infection. The median 50% inhibitory concentration of amodiaquine was 11.3 nM (range, 0.37 to 95.8) and was correlated significantly with that of chloroquine (Spearman rank correlation coefficient, 0.602; P < 0.001) Although amodiaquine results in a rapid clinical response, the risk of recurrence by day 28 is unacceptably high, reducing its suitability as an alternative treatment of infection by chloroquine-resistant P. vivax in this region. Copyright � 2009, American Society for Microbiology. All Rights Reserved.
    Original languageEnglish
    Pages (from-to)1094-1099
    Number of pages6
    JournalAntimicrobial Agents and Chemotherapy
    Issue number3
    Publication statusPublished - 2009


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