Chantix (Varenicline) for Smoking Cessation

Tobacco use leads to tobacco dependence and serious health problems. Smoking is the most preventable cause of morbidity and mortality from diseases of lung and heart and cancer. According to World Health Organization (WHO) smokers are at a higher risk of developing COVID-19 and severe COVID-19 complications. Quitting smoking greatly reduces the risk of developing smoking-related diseases. 

The combination of behavioural approaches and pharmacotherapy assist the smokers to quit smoking/tobacco use. Pharmacotherapy interventions approved by the FDA for the treatment of tobacco dependence in adults include:

• Nicotine Replacement Therapy (NRT)
• Bupropion SR
• Varenicline

NRT relieves cravings and reduces nicotine withdrawal symptoms; however, rates of smoking cessation are low. NRT formulations available in the market include transdermal patches, nasal sprays, chewing-gum, sublingual tablets, and lozenges.

Buproprion SR is antidepressant drug, and is more effective in smoking cessation in combination NRT than bupropion alone. Bupropion SR is available as a 150mg oral sustained-release tablet. Dosages for smoking cessation is usually 150mg twice daily.

Chantix (varenicline) is a selective nicotinic receptor partial agonist. It works by reducing cravings and withdrawal symptoms while blocking the binding of nicotine. The pharmacologic effects of nicotine are mediated via nicotinic receptors and the nicotinic cholinergic receptor, and specifically the α4β2 receptor subtype, which is the principal mediator of nicotine dependence. Varenicline binds α4β2 receptor with higher affinity than nicotine, blocking nicotine effects but also acts as a partial agonist.  

Varenicline (Chantix) is safe, well-tolerated and most effective pharmacotherapy for smoking cessation followed by bupropion and NRT. Patients treated with varenicline had better abstinence rates compared to placebo, NRT and bupropion treated patients. Treatment with varenicline for smoking cessation is cost-effective compared to bupropion and NRT.
Chantix therapy gradually increases the dose of varenicline. It starts with a Starter Pack, which contains low doses of 0.5 mg, once a day for 3 days, followed by 0.5 mg, twice a day for 4 days followed by 1 mg twice a day for 3 weeks. Therapy is then continued with Chantix Maintenance Packs with dose of 1 mg twice a day for 4 weeks.

Nausea and insomnia are the most common side effect of varenicline and are largely dose-dependent. Headaches, abnormal dreams, sleep disturbances, dizziness, dry mouth, weight gain, and constipation are less common side effects, and are usually temporary and mild to moderate in severity.