Plasma codeine and morphine concentrations after a single oral dose of codeine phosphate

J Clin Pharmacol. 1990 Aug;30(8):764-6. doi: 10.1002/j.1552-4604.1990.tb03641.x.

Abstract

Plasma concentrations of codeine and its O-demethylated metabolite morphine were determined, by a sensitive and specific high performance liquid chromatography (HPLC) method, following a single oral dose of 60 mg codeine phosphate. Ten healthy volunteers received a single dose of 60 mg codeine phosphate. The plasma concentrations were analyzed for codeine and morphine at the 0.5, 1, 3, and 6 hours postdosing. The mean peak codeine plasma concentrations and tmax (time to reach maximum plasma codeine concentrations) were 88.1 ng/mL and 1.2 hours. Mean maximum concentrations of metabolically produced morphine was 2.7 +/- 0.6 ng/mL. The mean ratio of areas under the plasma concentration-time curves for morphine and codeine was 0.027. Thus, free morphine represented only about 2.7 +/- 1.8% of the free codeine area in each case.

MeSH terms

  • Administration, Oral
  • Adolescent
  • Adult
  • Chromatography, High Pressure Liquid
  • Codeine / administration & dosage*
  • Codeine / blood*
  • Codeine / pharmacokinetics
  • Drug Administration Schedule
  • Humans
  • Male
  • Morphine / blood*
  • Morphine / pharmacokinetics

Substances

  • Morphine
  • Codeine