• Percent arachidonic acid-induced platelet aggregation; Lanza Mucosal Injury Score of the stomach
  

• Serum thromboxane B2; plasma PGE2; shear-induced platlet aggregation; cyclooxygenase activity in stomach mucosal biopsies as assessed by PGE2 content
  

The purpose of this randomized, multiple-dose, single-blind, parallel-group study is to examine in healthy volunteers the effects of analgesics given in approved daily doses in addition to daily cardio-protective doses of aspirin (81 mg) on the stomach. All subjects are examined endoscopically before receiving study medication, and at the end of treatment on Day 9. Each subject takes 81 mg of aspirin daily plus one of the following treatments to be taken daily on Days 1 through 8: four doses of acetaminophen 1000 mg, three doses of ibuprofen 400 mg, two doses of naproxen sodium (440 mg in the morning and 220 mg in the evening), four doses of aspirin 650 mg, two doses of celecoxib 200 mg, one dose of rofecoxib 25 mg, or no additional study medication. On Day 9, one dose of aspirin 81 mg and only one dose of the assigned treatment drug are taken prior to having an endoscopy. The primary endpoints of the study are the effects of the analgesics on the inhibition of COX-1 activity by aspirin, and any injury to the stomach mucosa, as determined by direct endoscopic observation. Safety assessments consist of routine monitoring for adverse events, as well as endoscopic examination of gastric mucosa for erosions and ulcerations occurring during the treatment phase. The study hypothesis is that the effects of acetaminophen on the stomach do not differ from the effects of ibuprofen, naproxen, aspirin, celecoxib, or rofecoxib.

81 mg aspirin and 1of 7 treatments for 8 days: acetaminophen 1000mg 4xday, ibuprofen 400mg 3xday, naproxen 440mg morning and 220mg evening, no additional study medication, aspirin 650mg 4xday, celecoxib 200mg 2xday,rofecoxib 25mg 1xday. On Day 9, 1 dose aspirin & 1 dose study drug before endoscopy.