Agonist/Antagonist Opioid Analgesics. When a patient has Beforehand been given or is presently undergoing a class of therapy with a pure opioid agonist analgesic like Dilaudid, agonist/antagonist analgesics like pentazocine, nalbuphine, butorphanol, and buprenorphine, really should be used with caution.When this medication is used to get a long t