Codeine and aspirin analgesia in postpartum uterine cramps: qualitative aspects of quantitative assessments.

The analgesic response to codeine of patients with postpartum uterine-cramp pain has recently met with controversy. To readdress this question, we conducted a new study comparing codeine sulfate, 60 mg (N = 32) and 120 mg (N = 31), with aspirin, 650 mg (N = 34), and placebo (N = 32) in hospitalized women with moderate or severe postpartum uterine cramps treated with single oral doses in a parallel, stratified, randomized, double-blind trial. Subjective reports were used as indices of response, and patients rated pain intensity, pain relief, and side effects at periodic, uniformly conducted interviews for 6 hr. Most measures of analgesia exhibited important differences among the treatments. In patients with undifferentiated pain (N = 129) and in a subset of patients with pure uterine cramps (N = 56; i.e., no concomitant episiotomy), aspirin showed the greatest response, whereas codeine responses were equivocal with no evidence of a positive dose response. In contrast, in a subset of patients with mixed episiotomy-uterine pain (N = 73), 120 mg codeine showed good separation from placebo and compared favorably with aspirin. Codeine, 60 mg, showed a similar trend, and there was a strong suggestion of dose-dependent analgesia. Side effects were not remarkable except for dizziness and drowsiness after 120 mg codeine in all sets and subsets of patients. The new results with codeine in pure postpartum uterine cramps confirm our earlier findings, whereas the previously unrecognized effect of codeine in mixed pain may explain the apparent contradiction in results reported by different investigating teams. Clinical Pharmacology and Therapeutics (1983) 34, 488–495; doi:10.1038/clpt.1983.202