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MT-45 svg.svg
Systematic (IUPAC) name
Clinical data
Legal status
Routes of
oral administration
CAS Number 52694-55-0 N 52694-52-7 (S) enantiomer
ATC code None
PubChem CID: 431865
ChemSpider 381935 N
Synonyms MT-45, IC-6
Chemical data
Formula C24H32N2
Molecular mass 348.523 g/mol
 N (what is this?)  (verify)

MT-45 (IC-6) is an opioid analgesic drug invented in the 1970s by Dainippon Pharmaceutical Co.[1] It is chemically a 1-substituted-4-(1,2-diphenylethyl)piperazine derivative, which is structurally unrelated to most other opioid drugs. Racemic MT-45 has around 80% the potency of morphine, with almost all opioid activity residing in the (S) enantiomer (the opposite stereochemistry from the related drug lefetamine).[2][3] It has been used as a lead compound from which a large family of potent opioid drugs[4] have been developed, including full agonists, partial agonists, and antagonists at the three main opioid receptor subtypes.[5][6][7][8][9][10]

Recreational use of MT-45 has been associated with hearing loss and unconsciousness.[11]

MT-45 became a class A drug in the UK on 11 March 2015[12]

See also[edit]


  1. ^ US patent 3957788, Haruki Nishimura, Hitoshi Uno, Kagayaki Natsuka, Noriaki Shimokawa, Masanao Shimizu, Hideo Nakamura, "1-Substituted-4-(1,2-diphenylethyl)piperazine derivatives and their salts", published 1975-15-01, issued 1976-18-05 
  2. ^ Natsuka K, Nakamura H, Uno H, Umemoto S (December 1975). "Studies on 1-substituted 4-(1,2-diphenylethyl)piperazine derivatives and their analgesic activities. 1". Journal of Medicinal Chemistry 18 (12): 1240–4. doi:10.1021/jm00246a014. PMID 1195277. 
  3. ^ Nakamura H, Shimizu M (May 1976). "Comparative study of 1-cyclohexyl-4-(1,2-diphenylethyl)-piperazine and its enantiomorphs on analgesic and othe pharmacological activities in experimental animals". Archives Internationales De Pharmacodynamie Et De Thérapie 221 (1): 105–21. PMID 962421. 
  4. ^ US Patent 4080453
  5. ^ Natsuka K, Nakamura H, Negoro T, Uno H, Nishimura H (December 1978). "Studies on 1-substituted 4-(1,2-diphenylethyl)piperazine derivatives and their analgesic activities. 2. Structure-activity relationships of 1-cycloalkyl-4-(1,2-diphenylethyl)piperazines". Journal of Medicinal Chemistry 21 (12): 1265–9. doi:10.1021/jm00210a017. PMID 722735. 
  6. ^ Shimokawa N, Nakamura H, Shimakawa K, Minami H, Nishimura H (January 1979). "Studies on analgesic agents. 1.1a Preparation of 1,2-diphenyl-2-(4-substituted 1-piperazinyl)ethanol derivatives and structure-activity relationships". Journal of Medicinal Chemistry 22 (1): 58–63. doi:10.1021/jm00187a014. PMID 106119. 
  7. ^ Nakamura H, Ishii D, Yokoyama Y, Motoyoshi S, Natsuka K, Shimizu M (September 1980). "Analgesic and other pharmacological activities of a new narcotic antagonist analgesic (−)-1-(3-methyl-2-butenyl)-4-[2-(3-hydroxyphenyl)-1-phenylethyl]-piperazine and its enantiomorph in experimental animals". The Journal of Pharmacy and Pharmacology 32 (9): 635–42. doi:10.1111/j.2042-7158.1980.tb13020.x. PMID 6107365. 
  8. ^ Nozaki M, Niwa M, Imai E, Hori M, Fujimura H (1983). "(1,2-Diphenylethyl) piperazines as potent opiate-like analgesics; the unusual relationships between stereoselectivity and affinity to opioid receptor". Life Sciences. 33 Suppl 1: 431–4. doi:10.1016/0024-3205(83)90534-9. PMID 6319898. 
  9. ^ Natsuka K, Nakamura H, Nishikawa Y, Negoro T, Uno H, Nishimura H (October 1987). "Synthesis and structure-activity relationships of 1-substituted 4-(1,2-diphenylethyl)piperazine derivatives having narcotic agonist and antagonist activity". Journal of Medicinal Chemistry 30 (10): 1779–87. doi:10.1021/jm00393a017. PMID 3656354. 
  10. ^ Natsuka K, Nishikawa Y, Nakamura H (December 1999). "Roles of two basic nitrogen atoms in 1-substituted 4-(1,2-diphenylethyl)piperazine derivatives in production of opioid agonist and antagonist activities". Chemical & Pharmaceutical Bulletin 47 (12): 1790–3. doi:10.1248/cpb.47.1790. PMID 10748722. 
  11. ^ A. Helander, M. Bäckberg, and O. Beck (2014). "MT-45, a new psychoactive substance associated with hearing loss and unconsciousness". Clinical Toxicology 52 (8): 901–904. doi:10.3109/15563650.2014.943908. 
  12. ^ "Circular 003/2015: a change to the Misuse of Drugs Act 1971: control of MT-45 and 4,4’-DMAR". UK Home Office. 20 February 2015. Retrieved 11 March 2015.