BACKGROUND A total dose of chloroquine of 25 mg/kg is recommended by the World Health Organization (WHO) to treat malaria by Plasmodium vivax. In several endemic areas, including the Brazilian Amazon basin, anti-malarial drugs are dispensed in small plastic bags at a dosing regimen based on age. This practice can lead to suboptimal dosing of the drug, which can impact treatment outcomes. The aim of the present study was to estimate the extent of sub-dosing of chloroquine in children and adolescents with vivax malaria using an age-based dose regimen, in addition to investigating the influence of age on the plasma concentrations of chloroquine and desethylchloroquine. METHODS A study of cases was conducted with male patients with a confirmed infection by P. vivax, ages 2 to 14 years, using a combined regimen of chloroquine and primaquine. Height, weight and body surface area were determined at admission on the study. The total dose of chloroquine administered was estimated based on the weight and on the body surface area of the study patients. Chloroquine and desethylchloroquine were measured on Day 7 in each patient included in the study by a high-performance liquid chromatographic method with fluorescence detection. RESULTS A total of 81 patients were enrolled and completed the study. The median age was 9 years (2-14 years). All patients presented negative blood smears at 42 days follow-up. The total dose of chloroquine ranged from 13.1 to 38.1 mg/kg. The percentage of patients with a total dose of the drug below 25 mg/kg ranged from 29.4 to 63.6%. The total dose of chloroquine administered based on BSA ranged from 387 to 1079 mg/m2, increasing with age. Plasma chloroquine concentrations ranged from 107 to 420 ng/ml, increasing with age. For desethylchloroquine, the plasma concentrations ranged from 167 to 390 ng/ml, with similar values among age-groups. CONCLUSION The data demonstrated the widespread exposure of children and adolescents to suboptimal doses of chloroquine in the endemic area investigated.

中文翻译：

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使用氯喹治疗巴西亚马逊盆地 2 至 14 岁患者间日疟原虫疟疾的剂量。

背景 世界卫生组织 (WHO) 建议使用 25 mg/kg 的氯喹总剂量来治疗间日疟原虫引起的疟疾。在包括巴西亚马逊河流域在内的几个流行地区，抗疟疾药物以基于年龄的给药方案分配在小塑料袋中。这种做法可能导致药物剂量不理想，从而影响治疗结果。本研究的目的是除了调查年龄对氯喹和去乙基氯喹血浆浓度的影响之外，还使用基于年龄的剂量方案来评估间日疟儿童和青少年中氯喹分剂量的程度。方法 对确诊间日疟原虫感染的 2 至 14 岁男性患者进行病例研究，使用氯喹和伯氨喹联合方案。高度，体重和体表面积在研究入院时确定。氯喹的总剂量是根据研究患者的体重和体表面积估算的。在第 7 天，通过具有荧光检测的高效液相色谱法测量了研究中每位患者的氯喹和去乙基氯喹。结果 共有 81 名患者入组并完成了研究。中位年龄为 9 岁（2-14 岁）。所有患者在随访 42 天时均呈阴性血涂片。氯喹的总剂量范围为 13.1 至 38.1 毫克/公斤。药物总剂量低于 25 mg/kg 的患者百分比范围为 29.4% 至 63.6%。基于 BSA 的氯喹总剂量范围为 387 至 1079 mg/m2，随着年龄的增长而增加。血浆氯喹浓度范围为 107 至 420 ng/ml，随年龄增加。对于去乙基氯喹，血浆浓度范围为 167 至 390 ng/ml，各年龄组的值相似。结论 数据表明，在所调查的流行地区，儿童和青少年普遍暴露于次优剂量的氯喹。