Pharmacokinetics of intrarectal nalbuphine in children undergoing general anaesthesia

Fundam Clin Pharmacol. 1997;11(2):133-7. doi: 10.1111/j.1472-8206.1997.tb00180.x.


The pharmacokinetics of nalbuphine (0.3 mg/kg) administered by the rectal route were studied in ten children undergoing general anaesthesia for minor surgery. Blood sampling was carried out for 8 h after rectal administration and plasma drug concentrations were measured by high performance liquid chromatography using electrochemical detection after an optimized solid-phase extraction procedure. The mean time to achieve the maximum plasma concentration (Cmax = 24 +/- 15 ng/mL) was 25 +/- 11 min and the elimination half-life was 2.7 +/- 0.7 h. The coefficients of variation for Cmax and the concentration-time curve (AUC) were 62 and 68%, respectively. Although rectal absorption is considered irregular, the large intersubject variability is also explainable by a variable hepatic bypass for a drug, like nalbuphine, that undergoes extensive first-pass metabolism. No problem of analgesic efficacy or of local tolerance was reported. In conclusion, the rectal route of administration provides a rapid and reliable absorption of nalbuphine.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Rectal
  • Analgesics, Opioid / administration & dosage
  • Analgesics, Opioid / pharmacokinetics*
  • Anesthesia, General*
  • Area Under Curve
  • Child
  • Child, Preschool
  • Female
  • Humans
  • Male
  • Nalbuphine / administration & dosage
  • Nalbuphine / pharmacokinetics*


  • Analgesics, Opioid
  • Nalbuphine