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Diphenpipenol Structure.svg
Clinical data
ATC code
  • None
  • 3-[2-[4-(2-methoxyphenyl)piperazin-1-yl]-2-phenylethyl]phenol
CAS Number
PubChem CID
Chemical and physical data
Molar mass388.511 g·mol−1
3D model (JSmol)
  • COc4ccccc4N1CCN(CC1)C(Cc2cccc(O)c2)c3ccccc3
  • InChI=1S/C25H28N2O2/c1-29-25-13-6-5-12-23(25)26-14-16-27(17-15-26)24(21-9-3-2-4-10-21)19-20-8-7-11-22(28)18-20/h2-13,18,24,28H,14-17,19H2,1H3

Diphenpipenol 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 related to compounds such as MT-45 and AD-1211, but diphenpipenol is the most potent compound in the series, with the more active (S) enantiomer being around 105 times the potency of morphine in animal studies.[2] This makes it a similar strength to fentanyl and its analogues, and consequently diphenpipenol can be expected to pose a significant risk of producing life-threatening respiratory depression, as well as other typical opioid side effects such as sedation, itching, nausea and vomiting.

Diphenpipenol has been offered for sale online as a designer drug, though analysis of a sample of supposed diphenpipenol found it to instead contain a structural isomer with much weaker opioid activity, and it is unclear if genuine diphenpipenol has actually been sold.[3]

Alternate isomer sold as diphenpipenol

See also[edit]


  1. ^ US 4080453, Nishimura H, Uno H, Natsuka, Shimokawa N, Shimizu M, Nakamura H, "1-Substituted-4-(1,2-diphenylethyl)piperazine derivatives and compositions containing the same.", issued 21 March 1978, assigned to Dainippon Pharmaceutical Co Ltd 
  2. ^ 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.
  3. ^ Cannaert A, Hulpia F, Risseeuw M, Van Uytfanghe K, Deconinck E, Van Calenbergh S, et al. (June 2020). "Report on a new opioid NPS: chemical and in vitro functional characterization of a structural isomer of the MT-45 derivative diphenpipenol". Journal of Analytical Toxicology. 45 (2): 134–140. doi:10.1093/jat/bkaa066. PMID 32514558.