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Systematic overview of co-proxamol to assess analgesic effects of addition of dextropropoxyphene to paracetamol

BMJ 1997; 315 doi: https://doi.org/10.1136/bmj.315.7122.1565 (Published 13 December 1997) Cite this as: BMJ 1997;315:1565
  1. A Li Wan Po, professor of clinical pharmaceuticsa,
  2. W Y Zhang, research fellowa
  1. a Centre for Evidence Based Pharmacotherapy, Department of Pharmaceutical Sciences, University of Nottingham, Nottingham NG7 2RD
  1. Correspondence to: Professor Li Wan Po
  • Accepted 5 August 1997

Abstract

Objective: To evaluate the comparative efficacy and tolerability of paracetamol-dextropropoxyphene combination and paracetamol through a systematic overview of randomised controlled trials.

Design: Systematic retrieval of trials of paracetamol-dextropropoxyphene, paracetamol, and placebo to allow pooling of results from head to head comparison trials and single active placebo controlled trials.

Subjects:2231 patients with postsurgical pain, arthritis, and musculoskeletal pain reported in 26 randomised controlled trials.

Main outcome measures: Sum of difference in pain intensity; response rate ratio and difference in response rate with response defined as moderate to excellent pain relief; and rate ratio and rate difference of side effects.

Results: The difference in pain intensity between paracetamol-dextropropoxyphene and paracetamol was 7.3% (95% confidence interval −0.2 to 14.9). The response rate ratio for the combination and paracetamol was 1.05 (0.8 to 1.3) on the basis of the head to head trials. Indirect comparisons produced quantitatively consistent results. Compared with placebo, the combination produced more dizziness (3.1; 1.1 to 8.9) whereas paracetamol resulted in more drowsiness (1.8; 1.1 to 2.9).

Conclusion: On the basis of data on analgesic efficacy and acute safety in both head to head and indirect comparisons, there is little objective evidence to support prescribing a combination of paracetamol and dextropropoxyphene in preference to paracetamol alone in moderate pain such as that after surgery.

Key messages

  • Combinations of paracetamol with centrally acting analgesics are widely used, accounting for 73% of all prescriptions for paracetamol in a recent hospital survey in the United Kingdom

  • The combination of paracetamol (650 mg) with dextropropoxyphene hydrochloride (32.5 mg) is particularly popular

  • In both head to head and indirect comparisons of paracetamol and the combination, the combination was no better than paracetamol on its own

  • Since the total number of patients in the few published head to head comparisons was modest, small differences in effect cannot be excluded but these are unlikely to be of clinical importance

Footnotes

  • Accepted 5 August 1997
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