Re: “Medical management of osteoarthritis of the knee and hip joints”, a Clinical Update article by Grainger R and Cicuttini FM in the 1 March 2004 issue of the Journal (Med J Aust 2004: 180; 232-236). The authors have requested a correction because their statement “both diclofenac and celecoxib are more COX-2 selective than meloxicam” is incorrect, and should read “both meloxicam and celecoxib are more COX-2 selective than diclofenac.”

The html and pdf versions of the article on the eMJA website were corrected on 28 April 2004.

The COX-2 selectivity of meloxicam over diclofenac has been demonstrated in vitro using Human Whole Blood Assay and William Harvey Modified Human Whole Blood Assay (WHMA). In an in-vitro analysis assessing the degree of inhibition of COX-2 relative to COX-1 for over 40 non-steroidal anti-inflammatory drugs using the WHMA, both meloxicam and celecoxib demonstrated fivefold to 50-fold selectivity for COX-2 over COX-1, while less than fivefold selectivity for COX-2 over COX-1 was observed with diclofenac. Analysis of the percent inhibition of COX-1 seen when COX-2 is inhibited by 80% showed that the concentration of meloxicam sufficient to inhibit COX-2 isoenzymes by 80% produces only 25% inhibition of COX-1 isoenzymes. By contrast, the concentration of diclofenac necessary to produce 80% inhibition of COX-2 produced almost 70% inhibition of COX-1.1