The role of methadone
Findings
Methadone has often been viewed as an alternative to
oral morphine but its specifi c pharmacokinetic characteristics
and a very long and unpredictable half-life43
require careful individualisation of dosing schedules.
Oral methadone is the drug most frequently considered
as an option in the practice of opioid switching. In a
systematic review by the Cochrane Collaboration,52 which
was updated by Cherny,22 only three RCTs50,53,54 involving
277 patients addressed the comparison of methadone
with another step III opioid (one study had a third group
receiving transdermal fentanyl). The drugs did not diff er
in effi cacy between patients who were treated with step II
opioids or were opioid naive. In one study methadone
was associated with a higher incidence of sedation, which
led to a high percentage of patients dropping out because
of adverse eff ects.53 In a previous study, four (15%) of
26 versus two (8%) of 26 patients in the methadone and
diamorphine plus cocaine groups, respectively, withdrew
because of sedation.55