Bioavailabilities of rectal and oral methadone in healthy subjects.

Published

Journal Article

AIMS: Rectal administration of methadone may be an alternative to intravenous and oral dosing in cancer pain, but the bioavailability of the rectal route is not known. The aim of this study was to compare the absolute rectal bioavailability of methadone with its oral bioavailability in healthy humans. METHODS: Seven healthy subjects (six males, one female, aged 20-39 years) received 10 mg d(5)-methadone-HCl rectally (5 ml in 20% glycofurol) together with either d(0)-methadone intravenously (5 mg) or orally (10 mg) on two separate occasions. Blood samples for the LC-MS analyses of methadone and it's metabolite EDDP were drawn for up to 96 h. Noninvasive infrared pupillometry was performed at the same time as blood sampling. RESULTS: The mean absolute rectal bioavailability of methadone was 0.76 (0.7, 0.81), compared to 0.86 (0.75, 0.97) for oral administration (mean (95% CI)). Rectal absorption of methadone was more rapid than after oral dosing with Tmax values of 1.4 (0.9, 1.8) vs. 2.8 (1.6, 4.0) h. The extent of formation of the metabolite EDDP did not differ between routes of administration. Single doses of methadone had a duration of action of at least 10 h and were well tolerated. CONCLUSIONS: Rectal administration of methadone results in rapid absorption, a high bioavailability and long duration of action. No evidence of presystemic elimination was seen. Rectal methadone has characteristics that make it a potential alternative to intravenous and oral administration, particularly in cancer pain and palliative care.

Full Text

Duke Authors

Cited Authors

  • Dale, O; Sheffels, P; Kharasch, ED

Published Date

  • August 2004

Published In

Volume / Issue

  • 58 / 2

Start / End Page

  • 156 - 162

PubMed ID

  • 15255797

Pubmed Central ID

  • 15255797

International Standard Serial Number (ISSN)

  • 0306-5251

Digital Object Identifier (DOI)

  • 10.1111/j.1365-2125.2004.02116.x

Language

  • eng

Conference Location

  • England