Mental Health  |  OST Drug Issues Pathway - Methadone - Absorption, distribution and half-life




Mental Health

OST Drug Issues Pathway - Methadone - Absorption, distribution and half-life

  • Methadone is rapidly absorbed after oral administration with detectable plasma levels after 30 minutes.

  • It undergoes considerable tissue distribution and crosses the blood brain barrier.

  • Peak level is 3 to 4 hours after consumption.

  • With regular doses the half-life is 6 to 96 hours with a mean of 25 hours.

  • Steady state plasma levels are reached after approximately 4 hours.

  • Methadone accumulates on repeated administration therefore doses should not be increased more often than every 4 days.

*See Appendix 3 Pharmacology and Pharmacokinetics of Methadone and Buprenorphine page 97 of " New Zealand Practice Guidelines for Opioid Substitution Treatment 2014"



Last updated : Wednesday, November 11, 2015
Next review date : Thursday, November 10,2016


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