Tissue distribution of primaquine in the rat

The distribution of primaquine was measured in seven rat tissues at 15-180 min after the intraperitoneal injection of the antimalarial 8-aminoquinoline. The half-life of unmetabolized primaquine was 4.0 h in lung, 1.7-1.9 h in blood, spleen, kidney and heart, and 1.2 h in liver. At each interval, the concentrations of unmetabolized primaquine were (in order): lung greater than liver, kidney, spleen greater than heart greater than brain greater than or equal to blood. At 3 h after the injection of [6-O-methyl-3H]primaquine, unmetabolized primaquine constituted 10% of the total 3H in blood and 40-60% of the total 3H in liver, brain, heart and kidney.