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dose and can be given in equal divided doses by SC or IM injection 2 to 4 times daily (Alford et
al, 2006) or by continuous infusion.
Buprenorphine
Buprenorphine is a partial opioid agonist used in the treatment of opioid addiction and is
commonly prescribed in doses of 8 to 32 mg (Roberts & Meyer‐Witting, 2005). Administered
sublingually, it has a mean terminal half‐life of 28 hours (Johnson et al, 2005). It is usually given
once every day or two, which again is often enough to suppress symptoms of opioid
withdrawal; like methadone the duration of any analgesic effect from the dose is likely to be
much shorter (Alford et al, 2006). Preparations that combine buprenorphine and naloxone
(poorly absorbed by the sublingual route) are available (Harris et al, 2004). The addition of
naloxone to buprenorphine is said to reduce potential parenteral abuse of the drug (Johnson
et al, 2005).
While patients in methadone maintenance programs have been shown to be hyperalgesic
when assessed with cold pressor testing (Compton et al, 2000 Level III‐2; Doverty et al, 2001
Level III‐2; Athanasos et al, 2006 Level III‐2), much less information is available for the effects of
experimental pain stimuli in patients in buprenorphine maintenance programs. In a very small
study comparing methadone‐maintained (n = 5) and buprenorphine‐maintained (n = 7)
subjects with opioid‐naive controls, both methadone‐maintained and buprenorphine‐
maintained were more sensitive to cold‐pressor pain than the controls although to a lesser
degree in those taking buprenorphine (Compton et al, 2001 Level III‐2). In opioid‐naive subjects,
administration of buprenorphine resulted in decreased hyperalgesia following transcutaneous
pain stimuli compared with those given a placebo, suggesting that unlike morphine and
methadone, buprenorphine may exert an anthyperalgesic effect (Koppert et al, 2005 Level III‐2).
There are no good data on which to base the management of patients on buprenorphine
maintenance programs requiring pain relief. If shorter‐acting opioid agonists will be required,
a decision needs be made whether or not to continue buprenorphine. Suggestions for
management vary from withholding the buprenorphine and substituting an alternative opioid
(eg methadone), to continuing the buprenorphine as usual (Roberts & Meyer‐Witting, 2005;
Alford et al, 2006). However, in practice, there appears to be little problem if the buprenorphine
is continued and acute pain managed with the combination of a short‐acting pure opioid
agonist as well as other multimodal analgesic strategies (Macintyre & Schug, 2007). As with
methadone, dividing the daily doses on a temporary basis may take advantage of the analgesic
properties of the buprenorphine (Alford et al, 2006).
Close liaison with all treating clinicians and drug and alcohol services should occur. If
CHAPTER 11 buprenorphine has been ceased, its reintroduction should be managed in consultation with

the prescribing practitioner.
Naltrexone
Naltrexone is a pure opioid antagonist used in the management of patients with opioid or
alcohol addiction. The usual oral maintenance dose is up to 25 to 50 mg daily; long acting
implantable pellets are also available in some countries (Roberts & Meyer‐Witting, 2005; Vickers
& Jolly, 2006). Orally administered, naltrexone has an apparent half‐life of about 14 hours and
binds to opioid receptors for over 24 hours following a single dose (Vickers & Jolly, 2006), which
can create difficulties in the acute pain setting.
It has been recommended that, where possible, naltrexone be stopped for at least 24 hours
before surgery (Mitra & Sinatra, 2004; Vickers & Jolly, 2006). In these patients and in patients
requiring surgery within this 24‐hour period, multimodal analgesic regimens (eg NSAIDs,
paracetamol, ketamine, tramadol and regional analgesia) should also be employed.

432 Acute Pain Management: Scientific Evidence