The Comparison of the Efficacy and Gastrointestional side Effects of Tylenol-ER(Extended Relief) and Naproxen in the Treatment of Osteoarthritis of Knee: Multicenter Trial

Objectives: The symptomatic treatment for knee pain due to osteoarthritis(OA) often involves drugs with antiinflammatory and/or analgesic effects, but the needs for antiinflammatory agents has been argued because of serious gastrointestinal adverse events. Accordingly, we compared the efficacy and gastrointestinal side effects of a nonsteroidal antiinflammatory agent, naproxen with those of Tylenol-ER, a newly developed sustained release form of acetaminophen. Methods: One hundred six patients with OA of the knee were enrolled in a single blinded short term 8-week multicenter trial, randomly assigned to receive Tylenol-ER(acetaminophen 3900mg/day, 52 cases) or naproxen(1000mg/day, 54 cases). They were evaluated for pain score(visual analog scale, 0-10cm) and Lequesne index after 4, 8 weeks of treatment as well as the physician`s and patient`s global assessment at the end of study. Gastrointestinal side effects were evaluated by questionnaire for various gastrointestinal symptoms and total ingestion of antacids during the study. Results: After 4 weeks of therapy, both Tylenol-ER(TYR) and naproxen(NPX) group had significant improvement in pain score and Lequesne index. Among studied patients, 33 patients(31.1%) did not complete 8 weeks of treatment for various reasons such as side effects and patient`s intolerance, but the withdrawal rate was similar in each group. The improvement in patient`s and physician`s global assessment was seen in 65.7% of TYR group, 60.5% of NPX group. Gastrointestinal adverse events such as epigastric pain and dyspepsia were slightly more frequent in NPX group(29.6% vs 23.1%), and mean ingestion of antacids was slightly more in NPX group than in TYR group. Abnormal transaminase elevation was noted in minority of patients(TYR: 2, NPX: 1 case). Conclusion: In short-term trial, the efficacy of high dose Tylenol-ER(3900mg/day), an simple analgesics, in the control of knee pain due to OA of knee was similar to that of naproxen. The frequencies of gastrointestinal side effects tended to be lower in Tylenol-ER group than in naproxen.ope