Twin Crossover Relative Potency Analgesic Assays in Man. I. Morphine Vs. Morphine

Abstract

Although the 4-point relative potency assay using crossover design proved to be a powerful technique for the clinical evaluation of analgesics in patients with chronic pain, excessive dropouts have made this design impractical in postoperative pain. The "twin crossover" design, however, coupled with a sequential decision-making process that expedites choosing the doses of the test medication which are most closely equianalgesic with the standard, yielded excellent analgesic assay sensitivity and made efficient use of the population of postoperative patients studied. Each subject receives only 2 of the 4 possible treatments.