Cytisine - From the Past to the Future.

Introduction: 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.

Current Indication: 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.

Potential Indications: 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.

Summary: 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.