Cytisine, also known asbaptitoxine,cytisinicline, orsophorine, is analkaloid that occurs naturally in several plant genera, such asLaburnum andCytisus of the familyFabaceae. It has been used medically to help withsmoking cessation.[1] It has been found effective in several randomizedclinical trials, including in the United States and New Zealand,[1] and is being investigated in additional trials in the United States and anon-inferiority trial in Australia in which it is being compared head-to-head with the smoking cessation aidvarenicline (sold in the United States as Chantix).[2] It has also been usedentheogenically viamescalbeans by some Native American groups, historically in theRio Grande Valley predating evenpeyote.[3]
Cytisine has been available inpost-Soviet states for more than 40 years as an aid to smoking cessation under the brand nameTabex from the Bulgarian pharmaceutical company Sopharma AD.[4] In 1961, Bulgarian pharmacist Strashimir Ingilizov synthesized Tabex using the alkaloid Cytisine which was derived from the seeds of the yellow acacia (Cytisus laburnum), a European decorative shrub prevalent in Bulgaria and commonly referred to as "golden rain".[5] It was first marketed in Bulgaria in 1964 and then became widely available in the Soviet Union.[6] In Poland, it is sold under the brand nameDesmoxan, and it is also available in Canada under the brand nameCravv.[7][8]
Its molecular structure has some similarity to that ofnicotine, and it has similar pharmacological effects. Like the smoking cessation aidvarenicline, cytisine is a partialagonist ofnicotinic acetylcholine receptors (nAChRs).[9] Cytisine has a shorthalf-life of 4.8 hours.[10] As a result, the extract provides smokers with satisfaction similar to smoking a cigarette, alleviating the urge to smoke and reducing the severity of nicotinewithdrawal symptoms, while also reducing the reward experience of any cigarettes smoked.[11]
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.[12] A 2013meta-analysis of eight studies demonstrated that cytisine has similar effectiveness tovarenicline but with substantially lower side effects.[13] A 2014systematic review andeconomic evaluation concluded that cytisine was more likely to be cost-effective for smoking cessation thanvarenicline.[14]
Plants containing cytisine, including thescotch broom andmescalbean, have also been usedrecreationally. Positive effects are reported to include a nicotine-like intoxication.[12]
(−)-Cytisine extracted fromLaburnum anagyroides seeds was used as a starting material for the preparation of "(+)-sparteine surrogate", for the preparation ofenantiomerically enriched lithium anions of oppositestereochemistry to those anions obtained from sparteine.[15]
Cytisine has been found to interfere with breathing and cause death in test mice;LD50 i.v. in mice is about 2 mg/kg.[16] Cytisine is alsoteratogenic.[17]
Māmane (Sophora chrysophylla) can contain amounts of cytisine that are lethal to most animals. Thepalila (Loxioides bailleui, a bird),Uresiphita polygonalis virescens andCydia species (moths), and possiblysheep andgoats are not affected by the toxin for various reasons, and consume māmane, or parts of it, as food.U. p. virescens caterpillars are possibly able to sequester the cytisine to give themselves protection from predation; they haveaposematic coloration which would warn off potentialpredators.[18]
^Dallanoce C, Frigerio F, Martelli G, Grazioso G, Matera C, Pomè DY, et al. (June 2010). "Novel tricyclic Delta(2)-isoxazoline and 3-oxo-2-methyl-isoxazolidine derivatives: synthesis and binding affinity at neuronal nicotinic acetylcholine receptor subtypes".Bioorganic & Medicinal Chemistry.18 (12):4498–4508.doi:10.1016/j.bmc.2010.04.065.PMID20478710.
^Jeong SH, Newcombe D, Sheridan J, Tingle M (June 2015). "Pharmacokinetics of cytisine, an α4 β2 nicotinic receptor partial agonist, in healthy smokers following a single dose".Drug Testing and Analysis.7 (6):475–482.doi:10.1002/dta.1707.PMID25231024.S2CID45441989.
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