Celecoxib, ibuprofen, and the antiplatelet effect of aspirin in patients with osteoarthritis and ischemic heart disease.

BACKGROUND AND OBJECTIVE: We performed a placebo-controlled, randomized study to address whether celecoxib or ibuprofen undermines the functional range of inhibition of platelet cyclooxygenase (COX)-1 activity by aspirin in patients with osteoarthritis and stable ischemic heart disease. METHODS: Twenty-four patients who were undergoing long-term treatment with aspirin (100 mg daily) for cardioprotection were coadministered celecoxib, 200 mg twice daily, ibuprofen, 600 mg 3 times daily, or placebo for 7 days. RESULTS: The coadministration of placebo or celecoxib did not undermine the aspirin-related inhibition of platelet COX-1 activity, as assessed by measurements of serum thromboxane B(2) (TXB(2)) levels, as well as platelet function. In contrast, a significant (P < .001) increase in serum TXB(2) level was detected on day 7 before drug administration (median, 19.13 ng/mL [range, 1-47.5 ng/mL]) and at 24 hours after the coadministration of aspirin and ibuprofen (median, 22.28 ng/mL [range, 4.9-44.4 ng/mL]) versus baseline (median, 1.65 ng/mL [range, 0.55-79.8 ng/mL]); this was associated with a significant increase in arachidonic acid-induced platelet aggregation (P < .01) and adenosine diphosphate-induced platelet aggregation (P < .05) and a decrease in the time to form an occlusive thrombus in the platelet function analyzer (P < .01). The urinary excretion of 11-dehydro-TXB(2), an index of systemic thromboxane biosynthesis, was not significantly affected by the coadministration of treatment drugs. At steady state, a comparable and persistent inhibition of lipopolysaccharide-stimulated prostaglandin E(2) generation, a marker of COX-2 activity ex vivo, was caused by ibuprofen (>or=80%) or celecoxib (>or=70%) but not placebo. CONCLUSIONS: Unlike ibuprofen, celecoxib did not interfere with the inhibition of platelet COX-1 activity and function by aspirin despite a comparable suppression of COX-2 ex vivo in patients with osteoarthritis and stable ischemic heart disease.

Pharmacodynamic interaction of naproxen with low-dose aspirin in healthy subjects.

OBJECTIVES: We investigated the occurrence of pharmacodynamic interaction between low-dose aspirin and naproxen. BACKGROUND: The uncertainty of cardioprotection by naproxen has encouraged its combination with aspirin in patients with arthritis and cardiovascular disease. METHODS: The incubation of washed platelets with naproxen for 5 min before the addition of aspirin reduced the irreversible inhibition of thromboxane (TX)B(2) production by aspirin. The pharmacodynamic interaction between the two drugs was then investigated in four healthy volunteers who received aspirin (100 mg daily) for 6 days and then the combination of aspirin and naproxen for further 6 days: aspirin 2 h before naproxen (500 mg, twice-daily dosing). After 14 days of washout, naproxen was given 2 h before aspirin for further 6 days. RESULTS: The inhibition of serum TXB(2) production (index of platelet cyclooxygenase [COX]-1 activity) and platelet aggregation ex vivo and urinary 11-dehydro-TXB(2) levels (index of TXB(2) biosynthesis in vivo) by aspirin alone (99 +/- 0.2%, 95 +/- 0.6%, and 81 +/- 4%, respectively) was not significantly altered by the co-administration of naproxen, given either 2 h after aspirin or in reverse order. In a second study, the concurrent administration of a single dose of aspirin and naproxen did not affect platelet TXB(2) production and aggregation at 1 h after dosing, when aspirin alone causes maximal inhibitory effect. Moreover, the rapid recovery of platelet COX-1 activity and function supports the occurrence of a pharmacodynamic interaction between naproxen and aspirin. CONCLUSIONS: Naproxen interfered with the inhibitory effect of aspirin on platelet COX-1 activity and function. This pharmacodynamic interaction might undermine the sustained inhibition of platelet COX-1 that is necessary for aspirin's cardioprotective effects.

Clinical pharmacology of platelet, monocyte, and vascular cyclooxygenase inhibition by naproxen and low-dose aspirin in healthy subjects.

BACKGROUND: The current controversy on the potential cardioprotective effect of naproxen prompted us to evaluate the extent and duration of platelet, monocyte, and vascular cyclooxygenase (COX) inhibition by naproxen compared with low-dose aspirin. METHODS AND RESULTS: We performed a crossover, open-label study of low-dose aspirin (100 mg/d) or naproxen (500 mg BID) administered to 9 healthy subjects for 6 days. The effects on thromboxane (TX) and prostacyclin biosynthesis were assessed up to 24 hours after oral dosing. Serum TXB2, plasma prostaglandin (PG) E2, and urinary 11-dehydro-TXB2 and 2,3-dinor-6-keto-PGF(1alpha) were measured by previously validated radioimmunoassays. The administration of naproxen or aspirin caused a similar suppression of whole-blood TXB2 production, an index of platelet COX-1 activity ex vivo, by 94+/-3% and 99+/-0.3% (mean+/-SD), respectively, and of the urinary excretion of 11-dehydro-TXB2, an index of systemic biosynthesis of TXA2 in vivo, by 85+/-8% and 78+/-7%, respectively, that persisted throughout the dosing interval. Naproxen, in contrast to aspirin, significantly reduced systemic prostacyclin biosynthesis by 77+/-19%, consistent with differential inhibition of monocyte COX-2 activity measured ex vivo. CONCLUSIONS: The regular administration of naproxen 500 mg BID can mimic the antiplatelet COX-1 effect of low-dose aspirin. Naproxen, unlike aspirin, decreased prostacyclin biosynthesis in vivo.