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154 Cancer and tumor pain
(20 mg every 4–6h),IVmethadone (10 mg every 4–6 h), PO codeine (180–
200 mg every 3–4h),IVcodeine (75 mg every 3–4h),POoxycodone (30 mg
every 3–4h). 12 The dosages may seem high to the ED provider, but concerns
about toxicity and addiction tend to be exaggerated, especially in patients who
are not opioid naïve. Physicians in ED should be prepared to prescribe opioids
in dosages that work.
Nearly all studies (28 of 29 RCTs in one review) fail to identify a safety or
efficacy advantage of one route of opioid administration over others. 4 One of
the few major differences is the IV route’s advantage of shorter time to
analgesia onset. 13
Some trials address utility of agents that are not traditionally considered
opioids but which have some opioid agonism. Available data do not support
use of these agents at this time. As an example, proglumide (50 mg/day), a
cholecystokinin (CCK) antagonist with some mu activity, provides no more
pain relief than placebo when assessed as add-on therapy to a baseline
opioid CTP regimen. 14
No data specifically address the efficacy of long-term opioid use. 15 At least
eight clinical trials of PO opioid analgesics have compared controlled-release
with immediate-release morphine. Neither formulation demonstrates analgesic
superiority as defined by pain relief onset or duration. The consistent
finding of decreased dosing frequency accomplished by controlled-release
formulations is the principle advantage of these dosage forms. 16
There is one opioid, methadone, that is less preferred than other mu
agonists. Even though methadone provides useful pain relief and has an
overall side effect profile (when used appropriately) similar to that of other
mu agonists, we do not recommend its use in acute care. The problem, as
highlighted in a 2004 Cochrane review, is that most studies demonstrating
methadone’s safety and efficacy assessed only brief therapeutic courses. 11
Longer-term use is associated with risk of drug buildup and unwanted side
effects. The pharmacokinetics of methadone render use of the drug problematic,
with initiation and titration of the drug best left to those with
experience in its monitoring. 11 There is no evidence to support contentions
that methadone has any effectiveness (compared with other opioids) in CTP,
including neuropathy. 11