Benefit-risk ratio of agonist-antagonist analgesics.

Many agonist-antagonist analgesic substitutes for morphine have been synthesized and their safety and efficacy evaluated in animals, humans or both. Several drugs in this class have achieved regulatory approval and have reached the marketplace. Agonist-antagonist analgesics have proved clinically acceptable and are in some respects superior to the standard narcotic analgesics, most markedly in their diminished addiction liability. In other respects, however, agonist-antagonist analgesics are inferior to morphine; they probably have lower analgesic ceiling efficacy, are more likely to produce psychotomimetic effects, and can precipitate abstinence in patients physically dependent on opioids.