BackgroundArtemisinin-based combination therapies (ACTs) are the mainstay of the current treatment of uncomplicated Plasmodium falciparum malaria, but ACT resistance is spreading across Southeast Asia. Dihydroartemisinin-piperaquine is one of the five ACTs currently recommended by the World Health Organization. Previous studies suggest that young children (<5 y) with malaria are under-dosed. This study utilised a population-based pharmacokinetic approach to optimise the antimalarial treatment regimen for piperaquine.Methods and FindingsPublished pharmacokinetic studies on piperaquine were identified through a systematic literature review of articles published between 1 January 1960 and 15 February 2013. Individual plasma piperaquine concentration–time data from 11 clinical studies (8,776 samples from 728 individuals) in adults and children with uncomplicated malaria and healthy volunteers were collated and standardised by the WorldWide Antimalarial Resistance Network. Data were pooled and analysed using nonlinear mixed-effects modelling. Piperaquine pharmacokinetics were described successfully by a three-compartment disposition model with flexible absorption. Body weight influenced clearance and volume parameters significantly, resulting in lower piperaquine exposures in small children (<25 kg) compared to larger children and adults (≥25 kg) after administration of the manufacturers’ currently recommended dose regimens. Simulated median (interquartile range) day 7 plasma concentration was 29.4 (19.3–44.3) ng/ml in small children compared to 38.1 (25.8–56.3) ng/ml in larger children and adults, with the recommended dose regimen. The final model identified a mean (95% confidence interval) increase of 23.7% (15.8%–32.5%) in piperaquine bioavailability between each piperaquine dose occasion. The model also described an enzyme maturation function in very young children, resulting in 50% maturation at 0.575 (0.413–0.711) y of age. An evidence-based optimised dose regimen was constructed that would provide piperaquine exposures across all ages comparable to the exposure currently seen in a typical adult with standard treatment, without exceeding the concentration range observed with the manufacturers’ recommended regimen. Limited data were available in infants and pregnant women with malaria as well as in healthy individuals.ConclusionsThe derived population pharmacokinetic model was used to develop a revised dose regimen of dihydroartemisinin-piperaquine that is expected to provide equivalent piperaquine exposures safely in all patients, including in small children with malaria. Use of this dose regimen is expected to prolong the useful therapeutic life of dihydroartemisinin-piperaquine by increasing cure rates and thereby slowing resistance development. This work was part of the evidence that informed the World Health Organization technical guidelines development group in the development of the recently published treatment guidelines (2015).

We evaluated whether sex affects the steady-state pharmacokinetics of the antimalarial drugs, primaquine and doxycycline, in healthy subjects. Seventeen male and 17 female healthy Vietnamese subjects were administered 30 mg (base) of primaquine daily for 14 days. After a 2-week washout period, 14 male and 14 female subjects were administered 100 mg (base) of doxycycline daily for 14 days. Women had significantly higher median values of C(max) (212 versus 122 ng/mL, P< 0.001) and AUC(0-24) (1,909 versus 917 ng . h/mL, P < 0.001) of primaquine compared with men. Other than a longer t(max) in women, no sex-related differences were seen in the pharmacokinetics of doxycycline. The primaquine pharmacokinetic data suggest that women have increased exposure to primaquine, which may put them at increased risk for toxicity when administered the same maintenance dose as men. The similar pharmacokinetics of doxycycline between the two sexes justifies the same maintenance dose.

With the growth of international business and travel, Vietnamese consumers are increasingly confronted with foreign products and services especially children's foods. However, some negative attitudes towards foreign products can arise from several factors such as historic or ongoing political, military, economic, or diplomatic events. Thus, both consumer ethnocentrism and consumer animosity have become important constructs in marketing. The purpose of this study is to investigate whether consumer ethnocentrism and consumer animosity affect Willingness to buy towards Chinese Children's foods and whether this impact is mediated by products judgments. Structural equation modeling was used to analyze the data collected from 846 personal interviews carried out in three Vietnamese cities (Hanoi, Danang, and Ho Chi Minh). The findings of the research indicate that consumer ethnocentrism increases consumer animosity. The present study also denotes that both consumer ethnocentrism and animosity have a negative impact on Willingness to buy toward Chinese children's foods. Product judgments may not be an important mediating factor between consumers' animosity -Willingness to buy and between consumer ethnocentrism -Willingness to buy toward Chinese Children's foods.

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The two fixed-dose combinations of dihydroartemisinin and piperaquine (Artekin and Arterakine) were found to be bioinequivalent in healthy Vietnamese subjects. However, because the peak plasma concentrations and areas under the concentration-time curves of dihydroartemisinin and piperaquine were only marginally different between the two formulations, similar therapeutic efficacies are expected in the treatment of malaria infections.