Varencilne is a prescription medicine used to help adults quit smoking that works by blocking the effects of nicotine (from smoking) on the brain. It increases the likelihood of abstinence from smoking for as long as one year compared to treatment with placebo. The drug is available as Chantix IN US and marketed by Pfizer.

In a drug safety announcement, FDA has warned that a higher occurrence of major adverse cardiovascular events (a combined outcome of cardiovascular-related death, nonfatal heart attack, and nonfatal stroke) was observed in patients using Chantix compared to placebo.

The number of such events were uncommon in both groups though and the risk determined cannot be said to be statsically significant.

Still, the agency said clinicians need to weigh the risks of the drug against the benefits of its use, noting that smoking is itself already a risk factor for heart disease.

FDA asks health care professionals  to weigh the risks of Chantix against the benefits of its use.

[Smoking itself is a major risk factor for cardiovascular disease]

Patients taking Chantix should contact their health care professional if they experience new or worsening symptoms of cardiovascular disease, such as chest pain, shortness of breath, calf pain when walking, or sudden onset of weakness, numbness, or difficulty speaking. Patients should also contact their health care professional if they have any questions or concerns about Chantix.

Patients on Chantix should contact their healthcare professional if there is

• Shortness of breath or trouble breathing
• New or worsening chest pain
• New or worse pain in legs when walking
• Sudden onset of weakness, paralysis, numbness, or difficulty speaking or understanding speech