An Effectiveness and Safety Study of Two Doses of Acetaminophen Extended Release Caplets in the Treatment of Osteoarthritis of the Hip or Knee

This is a randomized, double-blind, placebo-controlled study to determine the safety and effectiveness of 650 mg and 1300 mg acetaminophen extended release given three times a day as compared with placebo, for the relief of signs and symptoms of osteoarthritis of the hip or knee for a period of 12 weeks. Propoxyphene Hydrochloride capsules 65 mg are used as rescue medication if subjects experience inadequate pain relief. The primary efficacy assessments are the average change from baseline to the final on-therapy visit for the WOMAN pain subscale score and the WOMAC physical function subscale scare, and the subject's average global assessment of their response to therapy through the final on-therapy visit. Safety assessments at study visits consist of monitoring adverse events, vital signs, study joint assessments and clinical laboratory determinations. The hypothesis is that 1950 mg per day and/or 3900 mg per day acetaminophen extended release are superior to placebo for the relief of the signs and symptoms of osteoarthritis of the hip or knee with respect to all three primary efficacy endpoints. Treatment consisted of either one 650 mg acetaminophen extended release caplet plus one placebo caplet (acetaminophen 1950 mg group); two 650 mg acetaminophen extended release caplets (acetaminophen 3900 mg group); or two placebo caplets administered orally every eight hours for 12 weeks.