Cytisine, also known as baptitoxine and sophorine, is an alkaloid that occurs naturally in several plant genera, such as Laburnum and Cytisus of the family Fabaceae. It has been used medically to help with smoking cessation. Its molecular structure has some similarity to that of nicotine and it has similar pharmacological effects. Like varenicline, cytisine is a partial agonist of nicotinic acetylcholine receptors (nAChRs). Cytisine has a short half-life of 4.8 hours, and is rapidly eliminated from the body. The use of cytisine for smoking cessation remains relatively unknown outside Eastern Europe, however, it is currently being investigated in clinical trials in the United States, being conducted by Achieve Life Sciences.
Plant species that contain cytisine are found in several genera of the subfamily Faboideae of the family Fabaceae, including Laburnum, Anagyris, Thermopsis, Cytisus, Genista, Retama and Sophora. Cytisine is also present in Gymnocladus of the subfamily Caesalpinioideae.
As a pharmaceutical preparation called Tabex, cytisine has been used in Eastern Europe available for the treatment of tobacco smoking. Cytisine has some structural and pharmacological similarities to the smoking cessation drug varenicline.
Cytisine is an acetylcholine agonist, and has strong binding affinity for the nicotinic acetylcholine receptor. It is extracted from the seeds of Cytisus laborinum L. (Golden Rain acacia) and has been available in former socialist economy (FSE) countries for more than 40 years as an aid to smoking cessation under the brand name Tabex produced by the Bulgarian pharmaceutical company Sopharma. It was first marketed in Bulgaria in 1964 and then became widely available in FSE countries. In Poland it is sold under the brand name Desmoxan.
In 2011, a randomized controlled trial with 740 patients found cytisine improved 12-month abstinence from nicotine from 2.4% with placebo to 8.4% with cytisine. A 2013 meta-analysis of eight studies demonstrated that cytisine has similar effectiveness to varenicline but with substantially lower side effects. A 2014 systematic review and economic evaluation concluded that cytisine was more likely to be cost-effective for smoking cessation than varenicline.
Plants containing cytisine, including the scotch broom and mescalbean, have also been used recreationally. Positive effects are reported to include a nicotine-like intoxication.
Reagent for organic chemistry
Cytisine extracted from Laburnum anagyroides seeds was used as a starting material for the preparation of “(+)-sparteine surrogate,” for the preparation of enantiomerically enriched lithium anions of opposite stereochemistry to those anions obtained from sparteine.
Cytisine can interfere with breathing and cause death; LD50 i.v., in mice is about 2 mg/kg. Cytisine is also teratogenic.
Māmane (Sophora chrysophylla) can contain amounts of cytisine that are lethal to most animals. The palila (Loxioides bailleui, a bird),Uresiphita polygonalis virescens and Cydia species (moths), and possibly sheep and goats are not affected by the toxin for various reasons, and use māmane, or parts thereof, as food. U. p. virescens caterpillars are possibly able to sequester the cytisine to give themselves protection from getting eaten; they have aposematic coloration which would warn off potential predators.
IUPAC name: (1R,5S)-1,2,3,4,5,6-Hexahydro-1,5-methano-8H-pyrido[1,2a][1,5]diazocin-8-one
Other names: Cytisine, Baptitoxine, Sophorine
CAS Number: 485-35-8
3D model (JSmol): Interactive Image
ECHA InfoCard: 100.006.924
PubChem CID: 10235
CompTox Dashboard (EPA): DTXSID00883395
Chemical formula: C11H14N2O
Molar mass: 190.24 g/mol
Melting point: 152 to 153 °C (306 to 307 °F; 425 to 426 K)
Boiling point: 218 °C (424 °F; 491 K) at 2 mmHg
ATC code: N07BA04 (WHO)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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- Leaviss, Joanna; Sullivan, William; Ren, Shijie; Everson-Hock, Emma; Stevenson, Matt; Stevens, John; Strong, Mark; Cantrell, Anna (2014). “What is the clinical effectiveness and cost-effectiveness of cytisine compared with varenicline for smoking cessation? A systematic review and economic evaluation”. Health Technology Assessment. 18 (33): 1–120. doi:10.3310/hta18330. PMC 4780997. PMID 24831822.
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