Opioid analgesics buprenorphine, butorphanol

Among opioids, morphinans (Fig. 1) play an important role as therapeutically valuable drugs. Representative examples of the morphinan class of compounds (Fig. 2) are p-opioid analgesic agents for the treatment of moderate-to-severe pain such as naturally occurring alkaloids (e.g. morphine, codeine), semisynthetic derivatives (e.g. oxycodone, oxymorphone, buprenorphine), and synthetic analogs (e.g. levorphanol, butorphanol) [19-21], Codeine is also an effective antitussive drug. The oxymorphone derivatives naloxone [22] and naltrexone [23] represent... 

Mixed opioid agonist-antagonist analgesics such as buprenorphine, butorphanol, nalbuphine, and pentazocine may theoretically decrease the analgesic... 

Patients who have received hydromorphone for long periods of time or those with confirmed opioid dependency should not receive the so-called agonist/antagonist analgesics, such as nalbuphine, pentazocine, butorphanol, dezocine, and buprenorphine. The use of these drugs in these patients can intensify withdrawal symptoms. 

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