Pilot study of the metabolism of codeine to morphine and a possible modification by benzodiazepines

After administration of high-dose codeine we found that in two cases 20-40% of the total morphine-equivalents in the 24-hour urine sample were free morphine. After another 24 hours the proportion of free morphine was up to 70% and after roughly 96 hours even went up to 96%. Although 10% of the admin...

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Bibliographic Details
Published inBeitrage zur gerichtlichen Medizin Vol. 49; p. 253
Main Authors Friedrich, G, Allgaier, B, Schneider, T, Schwarzkopf, G
Format Journal Article
LanguageGerman
Published Austria 1991
Subjects
Biotransformation - drug effects
Codeine - administration & dosage
Codeine - pharmacokinetics
Diazepam - pharmacology
Humans
Metabolic Clearance Rate - drug effects
Morphine - pharmacology
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Summary:After administration of high-dose codeine we found that in two cases 20-40% of the total morphine-equivalents in the 24-hour urine sample were free morphine. After another 24 hours the proportion of free morphine was up to 70% and after roughly 96 hours even went up to 96%. Although 10% of the administered codeine was eliminated as morphine. In contrast to the values reported in literature we found that even with codeine/morphine ratios greater than 0.5 and morphine concentrations of up to 2000 ng/ml urine one cannot naturally conclude that morphine/diamorphine has been consumed. The short half-life of codeine in serum was 2-4 hours, the final half-life was 9-11 hours. In urine we found a short half-life of 1-6 hours as well as a long half-life of 7-12 hours. When diazepam was administered simultaneously with codeine the expected half-life in serum was up to 1.5 times and in urine 2.5 times. The codeine/morphine ratios were hardly affected so far as evidence goes which they give of preceding drug-intake.
ISSN:0067-5016