Purpose: The purpose of this study is to determine the highest tolerable dose of primaquine within 0.75 mg/kg. A tolerable dose is defined as one in which:~Two or fewer participants (< 30%) experience hemolysis;~No participant experiences a drug-related serious adverse event; and~No participant requires a blood transfusion.~Design:~This is an open-label, phase 2, dose-adjustment study.~The initial primaquine dose will be 0.40 mg/kg. Subsequent dose groups will be selected depending on the occurrence of adverse events in the previous dose group. Once the highest tolerable dose in G6PD-deficient (G6PDd) individuals is established, a control group of G6PD normal malaria-free men will be enrolled and evaluated under the highest tolerable dose of primaquine.~Study Population:~Malian men aged 18-50 years without malaria infection.~The majority of study participants will be G6PDd.~Study Size: This study will enroll 7 participants per dose group. If all dose groups are tested, this study will enroll approximately 28 participants.~Study visit and duration:~Each participant will be followed for 28 days.~Participants will be evaluated for hemolysis and adverse events on Days 1-10, 14, and 28 following their assigned primaquine dose.~Primary objective:~To measure the change in hemoglobin among G6PD deficient west-African men following a single low-dose of primaquine not to exceed 0.75 mg/kg.~Secondary objectives:~To measure the occurrence of adverse events, graded by severity, at each primaquine dose among G6PD deficient men~To measure the occurrence of markers of acute hemolytic anemia (AHA), at each primaquine dose among G6PD deficient men. AHA markers will include:~Absolute and fractional change in hemoglobin on day 7 vs. baseline~Urine color~Reticulocyte count~Bilirubin (both total and direct)~Methemoglobin concentration~Development of physical signs or symptoms of hemolytic anemia~To compare the change in hemoglobin, frequency and severity of adverse events, and occurrence of markers of AHA between G6PD deficient and non-deficient participants receiving the highest tolerable primaquine dose~To measure G6PD enzyme activity (semiquantitative testing, U / gHb)~To measure the pharmacokinetics of primaquine, carboxyprimaquine, and other metabolites according to plasma concentrations.~To genotype participant blood samples for cytochrome P450 2D6 (CYP2D6) single nucleotide polymorphisms (SNPs), to determine if potential hemolysis in G6PDd individuals is affected by CYP2D6 metabolizer status (e.g. weak metabolizers and/or intermediate metabolizers)
The purpose of this study is to determine the highest tolerable dose of primaquine within 0.75 mg/kg. A tolerable dose is defined as one in which:~Two or fewer participants (< 30%) experience hemolysis;~No participant experiences a drug-related serious adverse event; and~No participant requires a blood transfusion.