Role of nicotine receptor partial agonists in tobacco cessation

Abstract

One in three adults in India uses tobacco, a highly addictive substance in one or other form. In addition to prevention of tobacco use, offering evidence-based cessation services to dependent tobacco users constitutes an important approach in addressing this serious public health problem. A combination of behavioral methods and pharmacotherapy has shown the most optimal results in tobacco dependence treatment. Among currently available pharmacological agents, drugs that preferentially act on the α4 β2-nicotinic acetyl choline receptor like varenicline and cytisine appear to have relatively better cessation outcomes. These drugs are in general well tolerated and have minimal drug interactions. The odds of quitting tobacco use are at the very least doubled with the use of partial agonists compared with placebo and the outcomes are also superior when compared to nicotine replacement therapy and bupropion. The poor availability of partial agonists and specifically the cost of varenicline, as well as the lack of safety data for cytisine has limited their use world over, particularly in developing countries. Evidence for the benefit of partial agonists is more robust for smoking rather than smokeless forms of tobacco. Although more studies are needed to demonstrate their effectiveness in different populations of tobacco users, present literature supports the use of partial agonists in addition to behavioral methods for optimal outcome in tobacco dependence.

Galantamine as a Treatment Option for Nicotine Addiction

“…When dopamine is released in a large amounts, it is associated with intense pleasure and a sense of relief leading to nicotine addiction [ 5 ]. Varenicline is a selective partial agonist which acts on nACH receptors including α 4 β 2 [ 6 ]. It is useful to understand the difference between full and partial nicotine agonists.…”

“…A full nicotine agonist will cause substantial dopamine release. However, a partial nicotine agonist such as varenicline will release dopamine to a lesser extent than a full agonist [ 6 ]. Moreover, the partial antagonist action will block the effects of any nicotine entering the system [ 5 ].…”

“…Firstly, the partial agonist action maintains moderate levels of dopamine to counteract the withdrawal symptoms. Secondly, partial antagonist activity reduces smoking satisfaction [ 6 ]. Galantamine is an acetylcholinesterase inhibitor and nicotinic receptor agonist [ 7 ].…”