Concerns over Chantix side effects were reportedly ignored by the Food & Drug Administration (FDA) last year when they were raised by a doctor who is a top expert in smoking cessation. John Spangler, director of Tobacco Intervention Programs at the Wake Forest University School of Medicine in Winston-Salem, N.C., says that a study that was used to demonstrate that Chantix was safe for long-term use was not thorough enough to assure the drug’s safety.
Chantix, approved in the US in 2006, works by blocking nicotine receptors to the brain. Chantix is the first such nicotine receptor partial agonist approved by the FDA. It was heralded as an alternative to other smoking cessation drugs and nicotine replacement therapy. Since its approval, over 6 million Chantix prescriptions have been written.
In the US, 34 Chantix users have reportedly committed suicide. In February, the FDA said “it appears increasingly likely that there may be an association between Chantix and serious neuropsychiatric symptoms.” The agency said that it had asked Pfizer to elevate the prominence of safety information regarding suicidal thoughts and other psychiatric problems to the warnings and precautions section of the Chantix prescribing information, or labeling. However, many consumer advocates, including the group Public Citizen, want the FDA to go further and highlight the Chantix suicide risk with black box warning – the agency’s highest safety alert.
Last month, the non-profit Institute for Safe Medication Practices issued a report detailing Chantix adverse event repots to the FDA. The report specifically cited 224 reports of potential heart-rhythm disturbances, 372 reports of possible movement disorders and 544 reports of likely glycemic problems, including diabetes. There were also reports of a dozen traffic accidents linked to Chantix. The report caused the Federal Aviation Administration to ban the use of Chantix by pilots and air traffic controllers.
Dr. Spangler is one person who is not surprised that questions have arisen about the safety of Chantix. According to report on ABC News, last year, he raised concerns about heart and vision effects in people who took the drug for at least one year. Spangler told ABC that a safety study by researchers employed by Pfizer and published in a relatively obscure medical journal looked at far too few subjects — a total of only 251 taking the drug — to determine whether or not the drug is safe when used over that duration. Yet, the researchers concluded that Chantix could be safely administered for up to one year.
Dr. Spangler also did his own analysis of the Chantix study, and told ABC News that the authors failed to mention that study subjects who took the drug were 2.5 times as likely to experience a serious adverse event. Dr. Spangler said the small size of the study made it impossible to determine if the adverse events were the results of chance, or were caused by Chantix.
It is Dr. Spangler’s contention that a bigger study must be conducted to determine the safety of Chantix. Until it is done, doctors who prescribed the drug must consider the possibility that an increased risk exists. To date, the FDA has not asked Pfizer to conduct such a long-term study.