• a topical diclofenac solution (1.5% wt/wt diclofenac sodium in a carrier containing dimethyl sulfoxide [DMSO])
• a vehicle-control solution (the carrier containing DMSO but no diclofenac)
• a placebo solution (a modified carrier with a token amount of DMSO for blinding purposes but no diclofenac).

The authors found that patients who applied the topical diclofenac solution had significantly better PGA scores than those who applied the other 2 solutions (p=0.039 and 0.025, respectively). Thirty of the 84 patients experienced some local skin dryness when using the topical diclofenac solution, leading to discontinuation of treatment in only 6% of the cases. The incidence of GI events did not differ between the treatment groups. No serious GI or renal adverse events were reported or detected by means of laboratory testing.

The authors concluded that topical diclofenac solution can provide safe, site-specific treatment for osteoarthritic pain, with only minor local skin irritation and minimal systemic side effects.

Free full-text article at http://www.cmaj.ca/cgi/content/full/171/4/333

Effect of a topical diclofenac solution for relieving symptoms of primary osteoarthritis of the knee: a randomized controlled trial (PDF file)