Objective: To conduct the first Canadian study of the comparative efficacy and safety of nabumetone and diclofenac SR in patients with primary osteoarthritis (OA) of the hip, knee and shoulder.
Methods: Nabumetone 1000-1500 mg po daily was compared to diclofenac SR 100-150 mg po daily in a 6-month, double blind, randomized, controlled, multicenter, parallel trial. Initial starting doses were nabumetone 1000 mg daily and diclofenac SR 100 mg daily, with optional subsequent one-level dose titration permitted after 2 weeks on lower dose up to 1500 mg nabumetone and 150 mg diclofenac SR. The primary outcome measures were overall pain and disease activity as assessed by physician and patient. Secondary efficacy measures included tenderness, swelling, limitation of motion, duration of morning stiffness, acetaminophen consumption, physician and patient global assessment, and patient evaluation of efficacy and tolerability. Following an initial screening visit and a 2 to 7 day nonsteroidal antiinflammatory drug free washout period (i.e., randomization), patients were assessed at Weeks 2, 8, 14, 20, and 26.
Results: In all, 382 patients [nabumetone (n = 192), diclofenac SR (n = 190)] participated in the trial. Improvement in all efficacy variables was noted, but there was no statistically significant difference between drugs. Significantly fewer (p = 0.01) patients reported upper gastrointestinal (GI) adverse experiences in the nabumetone group. Significantly fewer (p < 0.04) patients withdrew from the study for adverse experiences in the nabumetone (14%) than the diclofenac SR (23%) group, particularly from upper abdominal pain (p < 0.04) and dyspepsia (p = 0.02). Three patients treated with diclofenac SR and none with nabumetone developed upper GI ulcers or bleeds. The number of patients experiencing clinically important elevations in transaminases (p < 0.04) or BUN/creatinine (p < 0.03) was significantly lower in the nabumetone group.
Conclusion: Nabumetone is efficacious and well tolerated in patients with OA of the hip, knee or shoulder. In this group of patients it was similar in efficacy and superior in tolerability to diclofenac SR.