This is a standard pharmacokinetic interaction study. Subjects will be randomized to be either group A or B. Group A. Subjects will have 3 hospitalizations to complete. Each hospitalization will be about 12-24 hours depends on each regimen. Subjects in A group who receive regimen 1 of primaquine (PQ) on the first admission (visit 2) will receive regimen 2 of primaquine and chloroquine combination (PQ and CQ) on second admission (visit 3) after 1 week wash out period and will finish with regimen 3 of Chloroquine (CQ) on the third admission (visit 4) after 8 weeks wash out period.