Authors
Dr. Binu Krishnan, MD, DTCD, Consultant Pulmonologist, Pulmonary, Critical care and Sleep Medicine, PRS Hospital, Thiruvananthapuram.
Abstract
Introduction: Varenicline (Chantix/Champix) is a prescription medication approved in 2006 for smoking cessation, functioning as a nicotinic receptor partial agonist. It was introduced as an alternative to existing nicotine replacement therapies (NRTs) and bupropion.
Mechanism of Action: Varenicline acts as an α4β2 nicotinic receptor partial agonist, which both reduces cravings and diminishes the pleasurable effects of cigarettes and other tobacco products. It is primarily excreted renally with an elimination half-life of approximately 24 hours.
Efficacy and Trials: Clinical trials demonstrated Varenicline’s greater efficacy compared to NRTs, yielding average one-year quit rates of around 22-23%. A 2008 study showed a 52-week abstinence rate of 26.1% for Varenicline users versus 20.3% for NRT users, alongside significant reductions in craving and withdrawal symptoms. However, the article notes that these results were achieved under highly controlled and supportive clinical conditions and may not reflect real-world outcomes.
Adverse Event Profile: Nausea is the most common side effect (37.2%). Significant safety concerns have emerged regarding neuropsychiatric adverse events, including suicidal ideation, erratic behavior, and drowsiness, leading to an FDA alert in 2008 and a subsequent ban by the FAA for pilots and air traffic controllers. The potential for physical dependence also requires further evaluation.
Conclusion: While Varenicline offers considerable economic and health benefits for smoking cessation, especially for individual patients and communities, further long-term evaluation is crucial to definitively determine if its benefits outweigh the observed and potential neuropsychiatric risks. The drug has not been tested in adolescents or pregnant women, and its efficacy and safety in difficult-to-treat smoker populations, often excluded from trials, remain unknown.