Evaluation of Upper GI Ulceration Induced by PL2200 Versus Aspirin in At-Risk Subjects

Inclusion Criteria: * Healthy volunteers, ≥50 and ≤75 years of age. * No endoscopically observed baseline gastrointestinal lesions. Exclusion Criteria: * Baseline gastrointestinal lesions or abnormal screening/baseline laboratory parameters deemed clinically significant by the Investigator. * Significant history of substance abuse or uncontrolled acute or chronic medical illness. * Active H. pylori infection. * Current use of low-dose aspirin for cardioprevention, or other ulcerogenic medications, gastroprotective, or anti-platelet agents. * Hypersensitivity to aspirin or other NSAIDs.