Clinical Inquiries

Does topical diclofenac relieve osteoarthritis pain?

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EVIDENCE-BASED ANSWER:

Yes, at least in the short term. Topical diclofenac, with and without dimethyl sulfoxide (DMSO), modestly improves pain and function scores (by 4%-8%) for as long as 12 weeks in patients with osteoarthritis (OA) of the knee (strength of recommendation [SOR]: A, meta-analyses of multiple randomized controlled trials [RCTs]).

Topical diclofenac modestly decreases pain scores in patients with OA of the hand in the short term (by 9% at 6 weeks) but no more than placebo at 8 weeks (SOR: B, RCT).

Both topical diclofenac with DMSO and oral diclofenac produce similar pain and function scores in patients with OA of the knee. In addition to minor skin dryness, topical diclofenac causes gastrointestinal (GI) adverse effects in about a third of patients (SOR: B, RCT).

EVIDENCE SUMMARY

Diclofenac gel ($260-$330 per 150-mL bottle) and diclofenac with DMSO solution are the only topical nonsteroidal anti-inflammatory drugs (NSAIDs) available in the United States.

Topical diclofenac with DMSO beats placebo

In a meta-analysis of 3 RCTs (697 patients, mean age 63.2, 37% male) with knee OA, topical diclofenac solution with DMSO (Pennsaid, 40 drops applied 4 times daily) demonstrated superiority to vehicle-controlled placebo at 4 to 12 weeks (mean 8.5 weeks) using the Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index.1 The WOMAC is a standardized patient questionnaire measuring 5 items for pain (score range 0-20), 2 for stiffness (score range 0-8), and 17 for functional limitation (score range 0-68).

Topical diclofenac, with and without dimethyl sulfoxide, modestly improves pain and function scores for as long as 12 weeks in patients with knee OA. Compared with placebo, topical diclofenac with DMSO resulted in 1.6 units greater reduction in pain (8% difference), 0.6 units greater reduction in stiffness (7.5% difference), and 5.5 units greater improvement in physical function (8% difference). Patients using diclofenac reported more minor skin dryness than patients using placebo (number needed to harm [NNH]=6).

Diclofenac gel is also effective, but may cause dermatitis

A pooled analysis of 3 12-week randomized, double-blind, parallel-group, multicenter trials of 1426 patients with OA of the knee compared topical diclofenac gel (4 g applied 4 times a day) with vehicle placebo for patients older than 25 years and patients older than 65 years.2 Investigators evaluated 972 patients who suffered a symptom flare at 1, 4, 8, and 12 weeks after a one-week washout period.

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