Effect of maximum OTC doses of naproxen sodium or acetaminophen on low-dose aspirin inhibition of serum thromboxane B₂

47 healthy male and female volunteers (37 evaluable), mean age 40.2 years.

Enteric-coated aspirin 81 mg once daily for 5 days, followed by 5 days of enteric-coated aspirin 81 mg once daily co-administered with either naproxen sodium 220 mg three times daily or acetaminophen 1 g four times daily.

Enteric-coated aspirin 81 mg once daily for 5 days, followed by 5 days of enteric-coated aspirin 81 mg once daily alone.

Inhibition of serum thromboxane B2 (TXB2), as a marker of platelet cyclooxygenase-1 (COX-1) inhibition, measured on Day 11.surrogate