Evaluation of the QT effect of a combination of piperaquine and a novel anti-malarial drug candidate OZ439, for the treatment of uncomplicated malaria

AimsThe aim was to investigate the QT effect of a single dose combination regimen of piperaquine phosphate (PQP) and a novel aromatic trioxolane, OZ439, for malaria treatment. MethodsExposure-response (ER) analysis was performed on data from a placebo-controlled, single dose, study with OZ439 and PQP. Fifty-nine healthy subjects aged 18 to 55years received OZ439 alone or placebo in a first period, followed by OZ439 plus PQP or matching placebos in period 2. OZ439 and PQP doses ranged from 100-800mg and 160-1440mg, respectively. Twelve-lead ECG tracings and PK samples were collected serially pre- and post-dosing. ResultsA significant relation between plasma concentrations and placebo-corrected change from baseline QT(c)F (QT(c)F) was demonstrated for piperaquine, but not for OZ439, with a mean slope of 0.047ms per ng ml(-1) (90% CI 0.038, 0.057). Using an ER model that accounts for plasma concentrations of both piperaquine and OZ439, a largest mean QT(c)F effect of 14ms (90% CI 10, 18ms) and 18ms (90% CI 14, 22ms) was predicted at expected plasma concentrations of a single dose 800mg OZ439 combined with PQP 960mg (188ngml(-1)) and 1440mg (281ngml(-1)), respectively, administered in the fasted state. ConclusionsPiperaquine prolongs the QT(c) interval in a concentration-dependent way. A single dose regimen combining 800mg OZ439 with 960mg or 1440mg PQP is expected to result in lower peak piperaquine plasma concentrations compared with available 3day PQP-artemisinin combinations and can therefore be predicted to cause less QT(c) prolongation.