AD-1211 is an opioidanalgesic drug invented in the 1970s by Dainippon Pharmaceutical Co. It is chemically a 1-substituted-4-prenyl-piperazine derivative, which is structurally unrelated to most other opioid drugs. The (S) enantiomers in this series are more active as opioid agonists, but the less active (R) enantiomer of this compound, AD-1211, is a mixed agonist–antagonist at opioid receptors with a similar pharmacological profile to pentazocine, and has atypical opioid effects with little development of tolerance or dependence seen after extended administration in animal studies.
^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. PMID3656354. doi:10.1021/jm00393a017.
^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. PMID6107365. doi:10.1111/j.2042-7158.1980.tb13020.x.
^Nakamura H, Ishii K, Yokoyama Y, Imazu C, Shimoda A, Kadokawa T, Shimizu M (November 1984). "Central actions of AD-1211, an analgesic lacking common opiate features". European Journal of Pharmacology. 106 (2): 345–56. PMID6529980. doi:10.1016/0014-2999(84)90722-2.