Platelet function is inhibited by non-selective non-steroidal anti-inflammatory drugs but not by cyclo-oxygenase-2-selective inhibitors in patients with rheumatoid arthritis

BACKGROUND: Interaction with platelet function by non-steroidal anti-inflammatory drugs (NSAIDs) is related to the inhibition of cyclo-oxygenase-1 (COX-1). In patients with rheumatoid arthritis (RA), only one of the COX-2-selective NSAIDs (nabumetone) has been demonstrated to spare platelet function partially. OBJECTIVE: To compare the effects of the COX-2-selective inhibitor, meloxicam, with those of the non-selective NSAID, naproxen, on platelet function and thromboxane levels in RA patients. METHODS: In this randomized, controlled, cross-over trial, 10 RA patients used meloxicam 7.5 mg bid and naproxen 500 mg bid, each during a 2-week period. Washout periods were applied. Before and after each 2-week period of NSAID intake, laboratory studies were performed. RESULTS: Platelet aggregation was significantly less influenced, thromboxane levels were less inhibited (246 vs 117 pg/ml) and bleeding times were less prolonged with meloxicam than with naproxen (3.2 vs 2.3 min). Moreover, the results of all tests during meloxicam exposure were comparable with baseline values. CONCLUSION: In RA patients, meloxicam, a representative of the selective COX-2 inhibitors, does not interfere with platelet function and thromboxane levels, in contrast with naproxen (a non-selective COX inhibitor).