Research Article: Residual Antimalarials in Malaria Patients from Tanzania – Implications on Drug Efficacy Assessment and Spread of Parasite Resistance

Date Published: December 14, 2009

Publisher: Public Library of Science

Author(s): Eva Maria Hodel, Abdunoor Mulokozi Kabanywanyi, Aggrey Malila, Boris Zanolari, Thomas Mercier, Hans-Peter Beck, Thierry Buclin, Piero Olliaro, Laurent Arthur Decosterd, Blaise Genton, Landon Myer.

Abstract: Repeated antimalarial treatment for febrile episodes and self-treatment are common in malaria-endemic areas. The intake of antimalarials prior to participating in an in vivo study may alter treatment outcome and affect the interpretation of both efficacy and safety outcomes. We report the findings from baseline plasma sampling of malaria patients prior to inclusion into an in vivo study in Tanzania and discuss the implications of residual concentrations of antimalarials in this setting.

Partial Text: The intake of antimalarial drugs prior to inclusion in an in vivo study may interfere with the estimation of treatment outcomes (for both efficacy and safety) due to the presence of residual antimalarials. The standard World Health Organization (WHO) protocol for monitoring antimalarial drug efficacy does not exclude patients with a history of previous antimalarial drug use or the presence of antimalarial drugs in the urine or blood [1]. Nonetheless, it is customary in clinical studies to record the occurrence of previous drug intake at screening as reported by the patient, parent or guardian. Two studies in Africa investigated self-reporting of drug intake [2], [3], and both concluded that it is inaccurate. A more objective indication on the drug use in a study population would be obtained by screening the urine or blood for the presence of antimalarial drugs. There are studies on residuals of antimalarials that have been used in past policies, i.e. chloroquine (CQ) or sulfadoxine–pyrimethamine (SP), in urine or blood in the general population or patients [4]–[17]. However, to our knowledge, there is no study on the presence of lumefantrine in malaria patients seeking medical care.

A total of 1672 patients of all age were screened, of whom 389 (23%) had a positive malaria test and 150 were eligible and willing to participate in the in vivo study. Two patients (one from the Kibaoni HC area and one from Kining’ina) were excluded from the analyses (venipuncture unfeasible in one patient; treatment initiated before baseline sampling in the other one), leaving 148 patients with a valid baseline sample, of whom 64 (43.2%) were male and 84 (56.8%) female (3 (2.0%) pregnant in 3rd trimester). Patients’ ages ranged from 1 to 78 years (median 9 years). 51 (34.5%) patients were children under the age of 5, and 94 (63.5%) were <12 years old. This is the first study investigating the presence of a range of antimalarials in the plasma of African malaria patients on enrollment into an in vivo study. The measurement of 14 antimalarial drugs currently in-use allowed a comprehensive assessment of drugs available in the community under study. Source:


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