To compare acetaminophen (Tylenol) with rofecoxib (Viox) for the treatment of Osteoarthritis of the Knee

An initial screening visit was performed in order to assess subject medical history and the potential eligibility of subjects. Following the initial screening visit, all potential subjects underwent a washout period from their usual arthritis medication and returned to the study center for a baseline visit to verify their eligibility.

At the completion of the baseline visit, all eligible subjects were randomly assigned to a treatment group and instructed on the dosing regimen for their assigned study medication.

Subjects returned to the study center for follow-up visits after Week 1 and Week 2 of treatment and a final visit after Week 4 of treatment or upon discontinuation from the study.

Inclusion Criteria:

• Symptomatic idiopathic osteoarthritis of the knee for a minimum of six months duration requiring treatment with either an analgesic or anti-inflammatory agent on a regular basis (greater than or equal to three days/week) for at least three months.
• A history of osteoarthritis of the knee characterized by pain of at least a moderate intensity.
• Demonstrated radiographic evidence of mild to moderate osteoarthritis based on the Kellgren and Lawrence radiographic entry criteria of grade 2 or 3 osteoarthritis.
• Subjects' physical ability was to be either American College of Rheumatology (ACR) Function Class I or II
• At the baseline visit, subjects must have reported a maximum pain intensity experienced over the previous 24 hours of at least moderate on a five-point scale of none(0), mild(1), moderate(2), moderately severe(3), or severe(4) in order to be enrolled in the study.

Exclusion Criteria:

• Medical history, physical examinations, or radiographs suggestive of other types of arthritis, pseudogout, collagen vascular disease or fibromyalgia.
• Medical or psychiatric conditions that may influence absorption, metabolism, or excretion of the study medications or interfere with interpretation of adverse reactions to the study drug.
• History of allergy, sensitivity, contraindication or non-response to acetaminophen, rofecoxib, or drugs classified as NSAIDs including aspirin.
• Use of concomitant medications that might interfere with study drug assessments, including intra-articular corticosteroids.
• Signs of active knee inflammation, morning stiffness of greater than 30 minutes duration.
• Rheumatoid factor quantitative value greater than or equal to 40 IU/mL or a Westergren erythrocyte sedimentation rate greater than or equal to 40 mm/hour.
• ACR functional class III or IV, or unable to walk without assistive devices.
• Pregnancy, lactation, or expect to become pregnant within one month of study completion.