Clinical observations of agonist-antagonist analgesic dependence.
The agonist-antagonist opioids are clinically effective analgesics with generally low abuse potential. Four agonist-antagonists are currently available for use as analgesics. Pentazocine, butorphanol and nalbuphine produce morphine-like effects in low doses and, to varying degrees, dysphoric effects as the dose is increased. Buprenorphine, an antagonist opioid of slow onset but long duration of action, produces morphine agonist effects at lower doses, and as the dose is increased, antagonist effects with minimal or no dysphoria. Clinical experience with pentazocine indicates that abuse is possible and consists of two main types: misuse (and abuse) of the drug alone by patients during treatment for pain and, abuse of the drug, often taken together with other psychoactive agents, as a substitute for the preferred drug of abuse. Few reports of abuse have appeared for butorphanol, nalbuphine and buprenorphine; however, considerable care is recommended in their use in patients, especially where there is the possibility for abuse as might occur in patients who require long-term treatment, with a history of drug abuse, and where the drug is easily obtained.