This is a randomized, double-blind study to compare the long term safety profile and effectiveness of acetaminophen, given at a dose of 1000 mg every four to six hours, and naproxen, given at a dose of 375 mg twice daily (with matching placebo given four times daily to maintain the blind), in the treatment of osteoarthritis of the hip or knee. There are two groups of subjects. Group 1 has approximately 480 subjects randomized and a treatment duration of 12 months. Group 2 has approximately 80 subjects randomized and a treatment duration of 6 months. The primary measure of efficacy is the change from baseline in the WOMAC Osteoarthritis Index pain subscale at month 6. Safety evaluations, throughout the course of the study, include monitoring adverse events, laboratory tests and assessments of vital signs including respiration rate, pulse, blood pressure, and body weight. Subjects are instructed to take a dose of medication orally, every 4-6 hours. The acetaminophen subjects take a total daily dose of 4 g of acetaminophen. The naproxen subjects a total daily dose of 750 mg of naproxen. The treatment duration is 12 and 6 months in Group 1 and Group 2, respectively.
The purpose of this study is to compare the long-term safety and effectiveness of acetaminophen (4000 mg per day) and naproxen (750 mg per day) in the treatment of osteoarthritis of the hip or knee.