Single dose oral naproxen and naproxen sodium for acute postoperative pain.

BACKGROUND: Postoperative pain is often poorly managed. Treatment options include a range of drug therapies such as non-steroidal anti-inflammatory drugs (NSAIDs) of which naproxen is one. Naproxen is used to treat a variety of painful conditions including acute postoperative pain, and is often combined with sodium to improve its solubility for oral administration. Naproxen sodium 550 mg (equivalent to 500 mg of naproxen) is considered to be an effective dose for treating postoperative pain but to date no systematic review of the effectiveness of naproxen/naproxen sodium at different doses has been published.

OBJECTIVES: To assess the efficacy, safety and duration of action of a single oral dose of naproxen or naproxen sodium for acute postoperative pain in adults.

SEARCH STRATEGY: We searched The Cochrane Library, MEDLINE, EMBASE and the Oxford Pain Relief Database for relevant studies. Additional studies were identified from the reference list of retrieved reports. The most recent search was undertaken in July 2004.

SELECTION CRITERIA: Included studies were randomised, double blind, placebo-controlled trials of a single dose of orally administered naproxen or naproxen sodium in adults with moderate to severe acute postoperative pain.

DATA COLLECTION AND ANALYSIS: Pain relief or pain intensity data were extracted and converted into dichotomous information to give the number of patients with at least 50% pain relief over four to six hours. Relative risk estimates (RR) and the number-needed-to-treat (NNT) for at least 50% pain relief were then calculated. Information was sought on the percentage of patients experiencing any adverse event, and the number-needed-to-harm was derived. Time to remedication was also estimated.

MAIN RESULTS: Ten trials (996 patients) met the inclusion criteria: nine assessed naproxen sodium; one combined the results from two small trials of naproxen alone. Included studies scored well for methodological quality. Meta-analysis of six trials (500 patients) that compared naproxen sodium 550 mg with placebo gave a RR for at least 50% pain relief over 4 to 6 hours of 4.2 (95% confidence interval (CI) 2.9 to 6.0) and an NNT of 2.6 (95% CI 2.2 to 3.2). Three trials (334 patients) assessed naproxen 400 mg and naproxen sodium 440 mg, giving a RR of 4.8 (95% CI 2.75 to 8.38). Two small studies indicated that naproxen 200 mg and naproxen sodium 220 mg may provide effective postoperative pain relief. There was no significant difference between the number of patients experiencing any adverse event on treatment compared with placebo. Weighted mean time to remedication for naproxen sodium 550 mg was 7.6 hours compared with 2.6 hours for placebo.

REVIEWERS' CONCLUSIONS: Naproxen sodium 550 mg, naproxen 400 mg and naproxen sodium 440 mg administered orally are effective analgesics for the treatment of acute postoperative pain in adults. A low incidence of adverse events was found but reporting was not consistent.