NEW YORK (Reuters Health) – In a comparison trial, both the COX-2 inhibitor etoricoxib and the NSAID naproxen proved safe and efficacious for the treatment of osteoarthritis, according to a report in the July issue of the Annals of the Rheumatic Diseases.

Dr. Sean P. Curtis, of Merck Research Laboratories, Rahway, New Jersey, and colleagues studied etoricoxib 60 mg once daily versus naproxen 500 mg twice daily over a 138-week treatment period in patients with osteoarthritis at 80 clinical centers in 19 countries.

The trial consisted of randomized, double-blind, parallel group two-part base studies — part 1 was 12 weeks and part 2 was 40 weeks — followed by an 86-week extension. Patients who took placebo in part 1 received etoricoxib or naproxen in part 2 and the extension. Patients who took etoricoxib or naproxen in part 1 continued to receive the same regimen.

A total of 997 patients entered the base studies. Of these, 838 entered part 2 and 463 entered the extensions. Overall, 161 patients in the etoricoxib group and 152 patients in the naproxen group completed 138 treatment weeks.

Similar efficacy was observed between etoricoxib and naproxen throughout the 138 weeks of treatment.

WOMAC pain assessments for etoricoxib were 67 mm at baseline, 28 mm at 1 year, and 34 mm at 138 weeks. For naproxen, corresponding WOMAC scores were 67 mm, 29 mm, and 33 mm, respectively. Similar results were found between the groups for the other efficacy end points.

Both treatments were generally well tolerated. A similar percentage of patients in all treatment groups experienced any adverse events (AEs) or serious AEs. "In each study period, the naproxen group had a numerically greater percentage of patients discontinuing owing to an AE as well as the greatest percentage of patients with drug-related AEs," Dr. Curtis and colleagues explain.

"Regardless of treatment group, the most common AEs in the three study periods overall were upper respiratory infection and hypertension," they report.

The investigators also note that the study was not powered to evaluate the relative risk of gastrointestinal side effects or cardiovascular events.

Ann Rheum Dis 2007;66:945-951.

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