Methadone: Radioimmunoassay and pharmacokinetics in the rat

Geoffrey Ling, J. G. Umans, C. E. Inturrisi

Research output: Contribution to journalArticle

Abstract

A radioimmunoassay for the quantitation of methadone in biofluids is described. The antiserum was prepared by using an albumin conjugate of N-methyl-N-(1-methyl-3,3-diphenyl-4-oxohexyl)aminoethanol succinate. By employing tritium-labeled dl-methadone as the radioligand and a sample volume of 0.05 ml, the method has a lower limit of sensitivity of 3 ng/ml. The ability of the antiserum to detect methadone was not influenced by the presence of the metabolites of methadone or members of the methadol series. Morphine, codeine, levorphanol, meperidine, l, α-acetylmethadol and d-propoxyphene do not cross-react. After the i.v. administration of 0.90 or 1.5 mg/kg of methadone to male rats, plasma methadone levels decline biexponentially and elimination is independent of dose. The mean volume of distribution is 7.58 ± 0.87 liters/kg; the mean elimination T 1/2 is 88.6 ± 1.9 min and the plasma clearance is 59.3 ± 1.4 ml/min/kg. These results demonstrate that methadone is eliminated by the rat much more rapidly than previously suspected.

Original languageEnglish (US)
Pages (from-to)147-151
Number of pages5
JournalJournal of Pharmacology and Experimental Therapeutics
Volume217
Issue number1
StatePublished - Jan 1 1981
Externally publishedYes

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Methadone
Radioimmunoassay
Pharmacokinetics
Methadyl Acetate
Immune Sera
Ethanolamines
Levorphanol
Dextropropoxyphene
Codeine
Meperidine
Tritium
Succinic Acid
Morphine
Albumins

ASJC Scopus subject areas

  • Pharmacology

Cite this

Methadone : Radioimmunoassay and pharmacokinetics in the rat. / Ling, Geoffrey; Umans, J. G.; Inturrisi, C. E.

In: Journal of Pharmacology and Experimental Therapeutics, Vol. 217, No. 1, 01.01.1981, p. 147-151.

Research output: Contribution to journalArticle

Ling, G, Umans, JG & Inturrisi, CE 1981, 'Methadone: Radioimmunoassay and pharmacokinetics in the rat', Journal of Pharmacology and Experimental Therapeutics, vol. 217, no. 1, pp. 147-151.
Ling, Geoffrey ; Umans, J. G. ; Inturrisi, C. E. / Methadone : Radioimmunoassay and pharmacokinetics in the rat. In: Journal of Pharmacology and Experimental Therapeutics. 1981 ; Vol. 217, No. 1. pp. 147-151.
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