Tafenoquine Thorough QTc Study in Healthy Subjects

SB-252263 (tafenoquine, TQ) is a new 8-aminoquinoline antimalarial drug being developed by GlaxoSmithKline (GSK) and the Medicines for Malaria Venture with the assistance and historical support of the Walter Reed Army Institute of Research. Tafenoquine has been shown to be effective in the treatment of plasmodial infections in vitro, in pre-clinical models in vivo, and during early phase clinical studies for radical cure and eradication of liver hypnozoites in patients infected with Plasmodium vivax. This study is designed to compare the effects of tafenoquine mono-therapy, administered as a single dose or administered on 3 consecutive days, on the changes in QT duration to those observed in subjects dosed with either Avelox (moxifloxacin hydrochloride) or placebo. This will be a randomized, single-blind, placebo controlled, parallel group study. Parallel group design is chosen because tafenoquine has a long half-life, about 14 to 19 days, and therefore a cross-over design is not a practical alternative. Moxifloxacin will be used as a positive control in order to validate the sensitivity of the study in detecting QTc change. Moxifloxacin has been shown to prolong the QT interval in a dose-dependent manner in patients and healthy volunteers, and the QTc prolongation has been well quantified.