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.


CONCLUSIONS
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).
Knijff-Dutmer
E A J
EA
Department for Rheumatology, Laboratory for Clinical Chemistry, Medisch Spectrum Twente, Enschede, The Netherlands.
Kalsbeek-Batenburg
E M
EM
Koerts
J
J
van de Laar
M A F J
MA
D000328:Adult; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000188:drug therapy* / Q000201:enzymology; D001760:Bleeding Time; D001792:Blood Platelets / Q000187:drug effects / Q000201:enzymology; D018592:Cross-Over Studies; D016861:Cyclooxygenase Inhibitors / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D000077239:Meloxicam; D008875:Middle Aged; D009288:Naproxen / Q000627:therapeutic use*; D010974:Platelet Aggregation / Q000187:drug effects*; D011897:Random Allocation; D013843:Thiazines / Q000627:therapeutic use*; D013844:Thiazoles / Q000627:therapeutic use*; D013929:Thromboxane B2 / Q000097:blood
D000894:Anti-Inflammatory Agents, Non-Steroidal; D016861:Cyclooxygenase Inhibitors; D013843:Thiazines; D013844:Thiazoles; D013929:Thromboxane B2; D009288:Naproxen; D000077239:Meloxicam