In vivo and in vitro efficacy of amodiaquine monotherapy for treatment of infection by chloroquine-resistant Plasmodium vivax.

Journal article

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.

Authors: Hasugian, A; Tjitra, E; Ratcliff, A; Siswantoro, H; Kenangalem, E

• Publication status: Published
• Journal: Antimicrobial agents and chemotherapy
• Volume: 53
• Issue: 3
• Pages: 1094-1099
• Publication date: 2009-03-01
• DOI: 10.1128/aac.01511-08
• EISSN: 1098-6596
• ISSN: 0066-4804
• Language: English
• Keywords: Age Distribution; Drug Tolerance; Animals; Amodiaquine; Drug Resistance; Plasmodium vivax; Female; Recurrence; Outpatients; Adolescent; Confidence Intervals; Inhibitory Concentration 50; Male; Treatment Failure; Chloroquine; Rural Health; Time Factors; Follow-Up Studies; Parasitemia; Prospective Studies; Treatment Outcome; Humans; Antimalarials