Single dose dextropropoxyphene, alone and with paracetamol (acetaminophen), for postoperative pain.

BACKGROUND

Patient surveys have shown that postoperative pain is often not managed well, and there is a need to assess the efficacy and safety of commonly used analgesics as newer treatments become available. Dextropropoxyphene is one example of an opioid analgesic in current use, and is widely prescribed for pain relief in combination with paracetamol under names such as Co-proxamol and Distalgesic.

OBJECTIVES

To determine the analgesic efficacy and adverse effects of single dose oral Dextropropoxyphene alone and in combination with paracetamol (acetaminophen) for moderate to severe postoperative pain.

SEARCH STRATEGY

Published reports were identified from: Medline (1966 - November 1996), Biological Abstracts (1985 - 1996), Embase (1980 - 1996), the Cochrane Library (Issue 4 1996), and the Oxford Pain Relief Database (1954 - 1994). Additional studies were identified from the reference lists of retrieved reports. Date of the most recent searches: July 1998.

SELECTION CRITERIA

The inclusion criteria used were: full journal publication, postoperative pain, postoperative oral administration, adult patients, baseline pain of moderate to severe intensity, double-blind design, and random allocation to treatment groups which included dextropropoxyphene and placebo or a combination of dextropropoxyphene plus paracetamol and placebo.

DATA COLLECTION AND ANALYSIS

Data were extracted by two independent reviewers, and trials were quality scored. Summed pain intensity and pain relief data were extracted and converted into dichotomous information to yield the number of patients with at least 50% pain relief. This was used to calculate the relative benefit and number-needed-to-treat (NNT) for one patient to achieve at least 50% pain relief.

MAIN RESULTS

Six trials (440 patients) compared dextropropoxyphene with placebo and five (963 patients) compared dextropropoxyphene plus paracetamol 650 mg with placebo. For a single dose of dextropropoxyphene 65 mg in postoperative pain the NNT for at least 50% pain relief was 7.7 (95% confidence interval 4.6 to 22) when compared with placebo over 4-6 hours. For the equivalent dose of dextropropoxyphene combined with paracetamol 650 mg the NNT was 4.4 (3.5 to 5.6) when compared with placebo. These results were compared with those for other analgesics obtained from equivalent systematic reviews. Pooled data showed increased incidence of central nervous system adverse effects for dextropropoxyphene plus paracetamol compared with placebo.

REVIEWER'S CONCLUSIONS: The combination of dextropropoxyphene 65 mg with paracetamol 650 mg shows similar efficacy to tramadol 100 mg for single dose studies in postoperative pain but with a lower incidence of adverse effects. The same dose of paracetamol combined with 60 mg codeine appears more effective but, with the slight overlap in the 95% confidence intervals, this conclusion is not robust. Adverse effects of both combinations were similar. Ibuprofen 400 mg has a lower (better) NNT than both dextropropoxyphene 65 mg plus paracetamol 650 mg and tramadol 100 mg.