Assay of aspirin and naproxen analgesia.

To establish the relative potency of naproxen and aspirin for oral analgesia, a 4-point, noncrossover bioassay with placebo control was undertaken with 197 patients. Subjective-response methods were used to determine two measures of postoperative analgesia over a period of 6 hr. With reasonable confidence for an oral analgesic assay, we found 220 mg of naproxen to be equivalent to 600 mg of aspirin for pain relief and 330 mg of naproxen to be equivalent to 600 mg of aspirin for decreased pain intensity.