@ serious adverse events occurred in @ ( @ % ) of @ patients ; QT prolongation was the most common serious adverse event ( @ -LSB- @ % -RSB- of @ ) , occurring in five ( @ % ) of @ patients receiving tafenoquine , four ( @ % ) of @ patients receiving primaquine , and two ( @ % ) of @ patients receiving chloroquine alone , with no evidence of an additional effect on QT of chloroquine plus tafenoquine coadministration .