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98 Arthritis
for patients with high risk for NSAID-related side effects. Cochrane review
finds acceptable efficacy for acetaminophen for OA, although pain relief is
better with NSAIDs. 21 Acetaminophen’s main advantage is its safety and side
effect profile. Even in patients with liver disease, acetaminophen has fewer
risks than other systemic OA analgesics. 22 Finally, acetaminophen has additional
utility as a rescue medication for patients taking NSAIDs. 23
While the available evidence is limited, some commentators endorse
combination therapy with acetaminophen plus tramadol as a relatively
low-risk analgesic approach for OA. 24 Overall, there seems to be little role
for opioids in OA pain management. Most expert reviews and meta-analyses
find an unfavorable risk-to-benefit ratio, although some commentators do
report occasional utility of the opioids for OA. 25–27
When acetaminophen is not an option, the NSAIDs constitute the best
choice for short-term therapy of acute OA flares. 28 As is the case with other
conditions, for treatment of OA there is little difference (in either risks or
efficacy) between comparably dosed NSAIDs. For example, diclofenac in a
dose of 25 mg PO is at least as safe (and equally effective) as ibuprofen 400 mg
PO. 29 Cochrane review concludes that the NSAIDs are a reasonable firstchoice
therapy for OA, given their relatively reliable relief of moderate pain
and the overall side effect profile. 21 The evidence upon which the Cochrane
recommendations are based includes head-to-head comparisons. One such
trial finds diclofenac (combined with misoprostol) clearly superior to
acetaminophen. 30
Meta-analysis of four RCTs assessing a topical diclofenac preparation
found the evidence to be of high quality and to consistently favor the use of
the topical NSAID. 31 Other than localized skin reactions, which are mild and
usually limited to dryness, topically applied diclofenac (1.5%) is much better
tolerated than the same agent administered orally, and the level of pain relief
appears to be similar with the two approaches. 31 A gel form of diclofenac
(diclofenac diethylamine 1.16%, 4 g QID for three weeks) is also significantly
better than placebo for pain relief, with no safety problems identified over a
three week course. 23 Another preparation of topical diclofenac (a bio-adhesive
plaster containing diclofenac epolamine) provides significantly better pain
relief than placebo, with a pooled analysis finding 50% pain reduction