Systematic (IUPAC) name
Clinical data
Legal status
CAS number
16291-05-7 (HCl)
ATC code None
Chemical data
Formula C21H25NO4 
Mol. mass 355.428 g/mol

Nalmexone (INN; EN-1620A, UM-592), or nalmexone hydrochloride (USAN), is a semisynthetic, mixed opioid agonist-antagonist with analgesic and narcotic antagonist properties that was never marketed.[1][2][3][4] In clinical studies it was found to have comparable analgesic efficacy to morphine, though with several-fold reduced potency.[5] In addition, nalmexone's side effects, the most common of which were sleepiness and sweating, were reported to be similar to those of morphine, albeit with a noticeably higher degree of incidence.[5]


Nalmexone synthesis: Lowenstein, M. J.; Fishman, J.; 1967, U.S. Patent 3,320,262

See also


  1. ^ Macdonald F (1997). Dictionary of Pharmacological Agents. CRC Press. p. 1395.  
  2. ^ Casy AF, Parfitt RT (1986). Opioid Analgesics: Chemistry and Receptors. Springer. p. 55.  
  3. ^ Loew GH, Berkowitz DS (1978). "Quantum chemical studies of N-substituent variation in the oxymorphone series of opiate narcotics". Journal of Medicinal Chemistry 21 (1): 101–106.  
  4. ^ Forrest WH, Shroff PF, Mahler DL (1972). "Analgesic and other effects of nalmexone in man". Clinical Pharmacology and Therapeutics 13 (4): 520–525.  
  5. ^ a b National Research Council (U.S.). Committee on Problems of Drug Dependence; American Medical Association. Committee on Alcoholism and Drug Dependence; American Medical Association. Council on Mental Health; National Academy of Sciences (U.S.) (1969). Bulletin, problems of drug dependence. National Academies. p. 5873. NAP:10503. Retrieved 11 May 2012.