Cytisine - From the Past to the Future

Neuronal nicotinic acetylcholine receptors are ligand-gated ion channel receptors, distributed throughout central nervous system, as well as in peripheral ganglia and some non-neuronal cells. Cytisine, a qulinolizidine alkaloid, could be considered a high affinity ligand of those receptors. It is a partial agonist of β2*-containing receptors and a full agonist of α7 and β4*-containing receptors.

At present, pharmacodynamic properties of cytisine are leveraged only in a few European countries where it is available as medicinal product (Desmoxan and Tabex) indicated in the pharmacotherapy of nicotine addiction. Cytisine mimics the influence of nicotine on α4β2* receptors, but with higher affinity and lower activity. It lowers rewarding and reinforcing effects of nicotine in smoking persons and reduces withdrawal symptoms and craving in quitting ones.

The results of non-clinical studies suggest that cytisine could affect ethanol consumption, has an antidepressant and neuroprotective effect and could be useful in reducing body mass and preventing weight gain. Although there is a lack of research on cytisine in the treatment of areca nuts usage, the preliminary data suggest its usefulness. The combination of cytisine and Trolox C was selected as a possible effective treatment for type 2 diabetes. Though these drugs alone are not effective, their theoretical usefulness was confirmed in animal models.

Treatment with cytisine is an effective, cost-efficient, affordable and well tolerated nicotine addiction therapy. Potential new indications for cytisine include the treatment of alcoholism, areca nuts usage, Parkinson's disease, an autonomic-system failure. Further studies are necessary.