Therapeutic doses of codeine have no effect on acetaminophen clearance or metabolism

Eur J Clin Pharmacol. 1988;35(1):109-11. doi: 10.1007/BF00555519.


In nine healthy volunteers, the clearance and metabolism of acetaminophen 1000 mg i.v. was evaluated with and without two concomitant oral doses of codeine in order to investigate a possible interaction. Plasma acetaminophen was followed for 720 min and urine was collected for 24 h after each dose for determination of metabolites. When codeine was coadministered, the average total clearance of acetaminophen and its clearance by glucuronidation, sulphation and mercapturate formation were 0.58 to 1.12-times the control values. It is concluded that therapeutic doses of codeine do not influence the clearance or metabolism of acetaminophen.

MeSH terms

  • Acetaminophen / metabolism
  • Acetaminophen / pharmacokinetics*
  • Adult
  • Codeine / pharmacology*
  • Drug Interactions
  • Female
  • Half-Life
  • Humans
  • Male


  • Acetaminophen
  • Codeine