Levallorphan Explained

Levallorphan (INN, BAN) (brand names Lorfan, Naloxifan, Naloxiphan), also known as levallorphan tartrate (USAN), is an opioid modulator of the morphinan family used as an opioid analgesic and opioid antagonist/antidote.^{[1] [2] [3]} It acts as an antagonist of the μ-opioid receptor (MOR) and as an agonist of the κ-opioid receptor (KOR),^[4] and as a result, blocks the effects of stronger agents with greater intrinsic activity such as morphine whilst simultaneously producing analgesia.^[5]

Levallorphan was formerly widely used in general anesthesia, mainly to reverse the respiratory depression produced by opioid analgesics and barbiturates used for induction of surgical anaesthesia whilst maintaining a degree of analgesia (via KOR agonism). It is now less commonly employed for this purpose as the newer drug naloxone tends to be used instead. Levallorphan was also used in combination with opioid analgesics to reduce their side effects, mainly in obstetrics, and a very small dose of levallorphan used alongside a full agonist of the MOR can produce greater analgesia than when the latter is used by itself.^[6] The combination of levallorphan with pethidine (meperidine) was indeed used so frequently, a standardized formulation was made available, known as Pethilorfan.^[7]

As an agonist of the KOR, levallorphan can produce severe mental reactions at sufficient doses including hallucinations, dissociation, and other psychotomimetic effects, dysphoria, anxiety, confusion, dizziness, disorientation, derealization, feelings of drunkenness, delusions, paranoia, and bizarre, unusual, or disturbing dreams.^{[8] [9] [10]}

See also

• Butorphanol
• Cyclorphan
• Dextrallorphan
• Levomethorphan
• Levorphanol
• Nalbuphine
• Nalodeine
• Nalorphine
• Oxilorphan
• Proxorphan
• Samidorphan
• Xorphanol

Notes and References

1. Book: Elks J . The Dictionary of Drugs: Chemical Data: Chemical Data, Structures and Bibliographies. 14 November 2014. Springer. 978-1-4757-2085-3. 731–.
2. Book: Swiss Pharmaceutical Society . Index Nominum 2000: International Drug Directory (Book with CD-ROM) . Medpharm Scientific Publishers . Boca Raton . 2000 . 978-3-88763-075-1 .
3. Book: Morton IK, Hall JM . Concise Dictionary of Pharmacological Agents: Properties and Synonyms. 6 December 2012. Springer Science & Business Media. 978-94-011-4439-1. 164–.
4. Book: 602 . Goodman & Gilman . The Pharmacological Basis of Therapeutics . 10th . McGraw Hill Medical Publishing . 978-0-07-135469-1 . 2001 .
5. Codd EE, Shank RP, Schupsky JJ, Raffa RB . Serotonin and norepinephrine uptake inhibiting activity of centrally acting analgesics: structural determinants and role in antinociception . The Journal of Pharmacology and Experimental Therapeutics . 274 . 3 . 1263–70 . September 1995 . 7562497 .
6. Bullough J . Use of premixed pethidine and antagonists in obstetrical analgesia; with special reference to cases in which levallorphan was used . British Medical Journal . 2 . 5156 . 859–62 . October 1959 . 13805887 . 1990381 . 10.1136/bmj.2.5156.859 .
7. Williams G, Cope I . An evaluation of a combination of pethidine and levallorphan ("pethilorfan") in labour . The Medical Journal of Australia . 49 . 2 . 499–503 . September 1962 . 10.5694/j.1326-5377.1962.tb20494.x . 14000851 .
8. Book: Hall RC . Psychiatric Presentations of Medical Illness: Somatopsychic Disorders. 6 December 2012. Springer Science & Business Media. 978-94-011-7677-4. 364–.
9. Book: American Hospital Formulary Service Drug Information. 1984. authority of the Board of Directors of the American Society of Hospital Pharmacists. 664.
10. Book: Williams, John B. . Narcotics. 1963. Wm. C. Brown Company. 203.