Trial of Naproxen to Evaluate Various Methods of Measuring Analgesic Effect in Osteoarthritis Pain of the Knee

This study aims to evaluate various methods of measuring pain relief in subjects who have chronic OA of the knee. After a 1 week of wash-out from existing therapy, subjects will be treated in a blinded fashion for 1 week with either naproxen (3 days at 250 mg twice a day followed by 4 days at 500 mg twice a day) or placebo. After the first week of treatment, subjects will have another week of wash-out followed by a second period of 1 week of the alternate treatment. Subjects will not be allowed to use oral non-steroidal anti-inflammatory drugs (NSAIDs) or other oral analgesics, or topical medications on their target knees during the study. Acetaminophen will be allowed as a rescue medication.