Pharmacokinetics of primaquine in man: identification of the carboxylic acid derivative as a major plasma metabolite

Br J Clin Pharmacol. 1984 Apr;17(4):441-6. doi: 10.1111/j.1365-2125.1984.tb02369.x.


A method is described for the simultaneous determination of the carboxylic acid and N-acetyl-derivatives of primaquine, in plasma and urine. After oral administration of 45 mg primaquine, to five healthy volunteers, absorption was rapid, with peak primaquine levels of 153.3 +/- 23.5 ng/ml at 3 +/- 1 h, followed by an elimination half-life of 7.1 +/- 1.6 h, systemic clearance of 21.1 +/- 7.1 l/h, volume of distribution of 205 +/- 371 and cumulative urinary excretion of 1.3 +/- 0.9% of the dose. Primaquine underwent rapid conversion to the carboxylic acid metabolite of primaquine, which achieved peak levels of 1427 +/- 307 ng/ml at 7 +/- 4 h. Levels of this metabolite were sustained in excess of 1000 ng/ml for the 24 h study period, and no carboxyprimaquine was recovered in urine. N-acetyl primaquine was not detected in plasma or urine. Following [14C]-primaquine administration to one subject, plasma radioactivity levels rapidly exceeded primaquine concentrations. Plasma radioactivity was accounted for mainly as carboxyprimaquine . Though 64% of the dose was recovered over 143 h, as [14C]-radioactivity in urine, only 3.6% was due to primaquine. As neither carboxyprimaquine nor N- acetylprimaquine were detected in urine, the remaining radioactivity was due to unidentified metabolites.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Biotransformation
  • Half-Life
  • Humans
  • Kinetics
  • Male
  • Middle Aged
  • Primaquine / analogs & derivatives*
  • Primaquine / blood
  • Primaquine / metabolism*


  • 8-(3-carboxy-1-methylpropylamino)-6-methoxyquinoline
  • Primaquine