Evaluation of two doses of etoricoxib, a COX-2 selective non-steroidal anti-inflammatory drug (NSAID), in the treatment of Rheumatoid Arthritis in a double-blind, randomized controlled trial

BACKGROUND: Treatment with non-steroidal anti-inflammatory drugs (NSAID) is a common component of treatment regimens for rheumatoid arthritis (RA). Etoricoxib is a COX-2 selective NSAID that has demonstrated efficacy in the treatment of RA at a dose of 90 mg. The current study further evaluated the efficacy of etoricoxib 60 mg and 90 mg in RA patients with active disease. METHODS: This was a 2-part, double-blind, placebo-controlled study in RA (NCT01208181). Patients were required to have a diagnosis of RA (according to ARA 1987 revised classification criteria) and were to demonstrate symptom flare upon discontinuation of previous NSAID treatment prior to randomization. Part I was a 6-week, placebo-controlled period to assess the efficacy of etoricoxib 90 mg and etoricoxib 60 mg, each compared to placebo, as well as to each other. Part II was a 6-week period to evaluate the potential benefit of dose escalation from etoricoxib 60 mg to etoricoxib 90 mg after 6 weeks exposure to etoricoxib 60 mg in Part I compared to maintaining a steady dose of etoricoxib 60 mg throughout Parts I and II. Primary endpoints were Disease Activity Score evaluating 28 joints and C reactive protein level (DAS28-CRP) index and Patient Global Assessment of Pain (Pain) score (0–100 mm VAS) after 6 weeks of treatment in Part I. Adverse events were monitored throughout the study. RESULTS: In total, 1404 patients were randomized in a 2:7:7:8 ratio; 1228 patients completed Part I and 713 patients continued to Part II. Both etoricoxib doses were superior to placebo on both primary efficacy endpoints (p = 0.004 for 60 mg and p = 0.034 for 90 mg for DAS28-CRP; p < 0.001 for both doses for PGAP) in Part I. Further in Part I, etoricoxib 90 mg was not significantly different from 60 mg for DAS28-CRP, but did demonstrate a small, but statistically significant decrease in baseline PGAP score vs. 60 mg (p = 0.019). In Part II, there was no significant decrease in PGAP score after increasing to 90 mg in subjects with inadequate pain relief on 60 mg as compared to subjects who stayed on 60 mg. The incidence of AEs and SAEs were similar between etoricoxib 60 mg and 90 mg in both Part I and II. CONCLUSION: Both etoricoxib 90 mg and 60 mg are superior to placebo in relieving the symptoms of RA. Etoricoxib 90 mg vs 60 mg resulted in a statistically significant, though small, improvement in PGAP score, but not DAS28-CRP. Dose escalation from 60 mg to 90 mg in pain inadequate responders did not significantly improve efficacy. These results confirm the efficacy and tolerability of etoricoxib 90mg in patients with RA. In addition, this study demonstrated that etoricoxib 60 mg is also efficacious and well-tolerated in RA. CLINICAL TRIAL REGISTRATION: NCT01208181 (registered September 22, 2010). ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12891-016-1170-0) contains supplementary material, which is available to authorized users.