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Acute Pain | Chronic Pain | General

Naproxen in postoperative pain

Clinical bottom line:

Naproxen is an effective analgesic. A single dose of 550 mg naproxen sodium versus placebo had an NNT of 2.7 (2.3 to 3.3) for at least 50% pain relief over 4-6 hours in patients with moderate or severe pain compared with placebo. Naproxen sodium 220 mg and 440 mg were also more effective than placebo.


Naproxen

Naproxen is a non-steroidal anti-inflammatory (NSAID) and anti-pyretic agent. Naproxen sodium is allegedly absorbed more rapidly than naproxen.

Systematic review

Lorna Mason et al.Single-dose oral naproxen for acute postoperative pain: a quantitative systematic review. BMC Anesthesiology 2003, 3:4 http://www.biomedcentral.com/1471-2253/3/4 .

Updated review prepared summer 2007, with planned publication 2008.

Inclusion criteria were full journal publication of trials of naproxen in acute postoperative pain; single oral dose; randomised; placebo-controlled; double-blind; moderate to severe baseline pain; adult populations; group sizes at least 10; sufficient data to calculate the area under the curve for pain relief (TOTPAR).

For each trial the mean TOTPAR values for naproxen and placebo groups were converted to the percent of maximum total pain relief based on the categorical pain scales (%maxTOTPAR). These values were then converted to dichotomous information on the proportion, and then the number of patients, who achieved at least 50%maxTOTPAR. A number-needed-to-treat for at least 50% pain relief and the relative benefit of the treatment were then calculated. Adverse effects frequency data were used to calculate numbers-needed-to-harm and relative risk.

Trials of naproxen and naproxen sodium were pooled if the doses were pharmacokinetically equivalent.

Findings

The results for the main doses of naproxen tested are shown in Table 1. There was indufficient information to make any firm conclusions regarding dose-response.

Table 1: Results for naproxen in acute pain trials

Number of
Percent with at least 50% pain relief
Dose
(mg)
Trials
Patients
Naproxen
Placebo
Relative benefit
(95% CI)
NNT
(95% CI)
200/220
2
202
45
16
2.9 (1.6 to 5.1)
3.4 (2.4 to 5.8)
400/440
2
197
51
14
4.0 (2.1 to 7.6)
2.7 (2.1 to 4.0)
500/550
9
784
52
15
3.4 (2.6 to 4.4)
2.7 (2.3 to 3.3)

 

Adverse effects

Eight included studies reported adverse events for single dose data . Only five trials using naproxen sodium 550 mg contained sufficient evaluable data to pool results. Forty-seven out of 197 patients (24%) given naproxen sodium 550 mg reported at least one adverse event. Fifty-two out of 195 patients (27%) given placebo reported at least one adverse event. There was no significant difference between treatment and placebo, relative risk 0.89 (0.6 to 1.3).