Aspirin is a medication commonly used to relieve minor pains. Aspirin has also been used to prevent heart attacks and strokes. Aspirin, however, can also cause damage to the stomach and/or intestinal lining leading to the development of erosions ("small sores") and/or ulcers ("large sores"). Erosions may cause bleeding ("bleeding ulcers") and/or perforations ("holes in the stomach"). Acetaminophen, often referred by the brand name, Tylenol, is also used to treat minor pains but is not commonly recognized to cause damage to the stomach lining.

Many patients often take both of these medications together. While the effects on the stomach lining of each medication, when used alone, are known, the effects of both medications, when used together, are not.

The purpose of this study is to show whether or not the collective effects of both aspirin and acetaminophen, when used together, increase the damage on the stomach lining when compared to either medication alone.

Low dose aspirin is used for the primary and secondary prevention of cardiovascular thromboembolic events. As a non-selective inhibitor of cyclooxygenase, aspirin use results in irreversible COX-1 inhibition leading to impaired platelet aggregation. However, aspirin also inhibits COX-1 activity in the gastric mucosa by suppressing the synthesis of protective prostaglandins. In doing so, this creates a state of propensity for the development of aspirin-associated gastrointestinal ulcers and ulcer complications.

A high proportion of aspirin users also require concomitant use of anti-inflammatory medications for the treatment of pain and arthritis. However, evidence suggests that the risk of developing gastroduodenal ulcers and ulcer complications is significantly increased when aspirin is co-administered with other nonselective NSAIDs. In a previous study, concomitant aspirin (325 mg daily) in healthy subjects taking naproxen (500mg bid) was associated with endoscopic ulcer rates of 27.3% as compared to aspirin alone (7.6%). In a separate and independent trial of similar design, patients using 81 mg of aspirin in conjunction with daily naproxen also resulted in a higher incidence of gastric and duodenal ulcers than aspirin therapy alone. Beyond endoscopic ulcer rates, the risk of upper gastrointestinal hemorrhage has been reported to be substantially increased with concurrent administration of low-dose aspirin with nonselective NSAIDS. These data suggest that the gastrointestinal toxicity of combined aspirin with other NSAIDs may be more than additive.

• Drug: Acetaminophen - 4 grams per day + Placebo
• Drug: Aspirin - 325 mg per day + Placebo
• Drug: Acetaminophen 4 gram per day + Aspirin 325 mg per day

• Active Comparator: Acetaminophen - 4 grams per day + Placebo
• Active Comparator: Aspirin - 325 mg per day + Placebo
• Experimental: Acetaminophen 4 gram per day + Aspirin 325 mg per day

• Antithrombotic Trialists' Collaboration. Collaborative meta-analysis of randomised trials of antiplatelet therapy for prevention of death, myocardial infarction, and stroke in high risk patients. BMJ. 2002 Jan 12;324(7329):71-86. Erratum in: BMJ 2002 Jan 19;324(7330):141.
• Patrono C, García Rodríguez LA, Landolfi R, Baigent C. Low-dose aspirin for the prevention of atherothrombosis. N Engl J Med. 2005 Dec 1;353(22):2373-83. Review. No abstract available.
• Weil J, Colin-Jones D, Langman M, Lawson D, Logan R, Murphy M, Rawlins M, Vessey M, Wainwright P. Prophylactic aspirin and risk of peptic ulcer bleeding. BMJ. 1995 Apr 1;310(6983):827-30.
• Derry S, Loke YK. Risk of gastrointestinal haemorrhage with long term use of aspirin: meta-analysis. BMJ. 2000 Nov 11;321(7270):1183-7.
• Goldstein JL, Lowry SC, Lanza FL, Schwartz HI, Dodge WE. The impact of low-dose aspirin on endoscopic gastric and duodenal ulcer rates in users of a non-selective non-steroidal anti-inflammatory drug or a cyclo-oxygenase-2-selective inhibitor. Aliment Pharmacol Ther. 2006 May 15;23(10):1489-98.
• Sørensen HT, Mellemkjaer L, Blot WJ, Nielsen GL, Steffensen FH, McLaughlin JK, Olsen JH. Risk of upper gastrointestinal bleeding associated with use of low-dose aspirin. Am J Gastroenterol. 2000 Sep;95(9):2218-24.
• Cryer B, Feldman M. Cyclooxygenase-1 and cyclooxygenase-2 selectivity of widely used nonsteroidal anti-inflammatory drugs. Am J Med. 1998 May;104(5):413-21.
• Lanza FL, Codispoti JR, Nelson EB. An endoscopic comparison of gastroduodenal injury with over-the-counter doses of ketoprofen and acetaminophen. Am J Gastroenterol. 1998 Jul;93(7):1051-4.
• Jick H. Effects of aspirin and acetaminophen in gastrointestinal hemorrhage. Results from the Boston Collaborative Drug Surveillance Program. Arch Intern Med. 1981 Feb 23;141(3 Spec No):316-21.

Inclusion Criteria:

1. Be a cooperative, healthy male or female between the ages of 18-75 inclusive.
2. Have a physical examination which reveals no clinically significant abnormalities at the screening visit.
3. Have fewer than 6 gastric or duodenal erosions visible on nasal endoscopy at Visit 2.
4. If the subject is female and of childbearing potential, she has been using effective contraception since the last date of her menses, will continue to use effective contraception during the study period, is not breast-feeding or lactating at screening and has had a negative urine pregnancy test at screening. Women who have been post-menopausal for less than 2 years will also require a urine pregnancy test at screening.
5. Have provided written informed consent prior for admission to this study.
6. H. pylori negative serologic exam prior to baseline nasal EGD.

Exclusion Criteria:

1. Active GI disease (e.g. IBD), or a history of GI ulcers or bleeding
2. History of gastric or intestinal surgery
3. Use of ASA, NSAIDs, coxibs, or acetaminophen at any dose within 2 weeks prior to the randomization visit of the study.
4. Positive FOBT at baseline.
5. Use of over-the-counter or prescription: sucralfate, antacids, H2-receptor antagonists, misoprostol, or proton pump inhibitors 4 weeks prior to enrollment and/or during the study
6. A known allergy to the topical anesthetic, lidocaine.