Global Insight Perspective | |
Significance | Varenicline tops the list in terms of occurrences of adverse drug events in the fourth quarter of 2007, linked with 78 deaths in the United States, according to a report from non-governmental organisation (NGO) the Institute for Safe Medication Practices. |
Implications | Although previously known neuropsychiatric disorders such as depression feature as adverse events of the drug in the report, heart rhythm disturbances, seizures, abnormal muscle spasms and diabetes are more notable inclusions. |
Outlook | On account of the public attention on the drug's adverse events, Chantix's short-term sales prospects are expected to be affected. |
Damning Report on Champix/Chantix
The Institute of Safe Medication Practices (ISMP) has issued a report tracking the adverse events of U.S. firm Pfizer's smoking cessation drug Chantix (varenicline) since its launch in May 2006. The impetus for the report came from a pilot programme aimed at identifying emerging drug risks and new medication errors through the U.S. FDA's adverse events reports. The study findings have indicated a rise in adverse events related to the product in the fourth quarter of 2007, accounting for 988 serious injuries compared with five reports of serious injuries for 769 drugs in the same quarter. Between the drug's launch in May 2006 and December 2007, the study noted neuropsychiatric symptoms including 227 acts thoughts or behaviours of suicide, 397 cases of possible psychosis, 525 reports of hostility or paranoia, and 55 cases of hallucination. The neuropsychiatric symptoms are consistent and support the FDA's recent action to issue new warnings on Chantix's label.
Worryingly for Pfizer, the report indicated:
- 173 cases of accident and injuries
- 148 cases of vision disturbance
- 224 cases of heart rhythm disturbances
- 86 cases of seizures
- 372 cases of abnormal muscle spasms or movements
- 338 cases of moderate and severe skin reactions
- 544 reports suggesting relation to loss of glycaemic control or link to diabetes
The study has put the drug at the top of a list of suspect drugs in the fourth quarter of 2007 ahead of interferon beta, and noting that there were just 35 drugs with more than 100 adverse event reports.
Leading Suspect Drugs, Q4 2007 | |
Drug | Number of Cases Reported |
Varenicline | 988 |
Interferon Beta | 640 |
Etanercept | 555 |
Infliximab | 554 |
Fentanyl | 404 |
Oxycodone | 372 |
Source: Institute For Safe Medication Practices | |
Outlook and Implications
The findings in the report will most certainly put the spotlight back on Chantix in the short term, potentially prompting increased scrutiny of the post-marketing surveillance data on the drug. This may affect Chantix's near-term sales prospects in the United States. Media reports indicate that some regulatory agencies, such as the Federal Motor Carrier Safety Administration and the Federal Aviation Administration, have issued warnings on the use of the drug following the findings highlighted in the ISMP report. The report itself notes a high degree of adverse events in the fourth quarter, which could be related to increased awareness following the emergence of psychiatric symptoms related to the drug in an early communication by the FDA in November 2007. The reporting of adverse drug events is voluntary, and the high incidence of these events could be further reflected in the first quarter of 2008 following a public health warning issued by the FDA on the potential risk of suicide in patients taking this anti-smoking drug. Additionally, the report does not provide details of causality, recommending a wider study by the FDA and the manufacturer to resolve the safety issues concerning varenicline. It should be noted that the FDA has resolved to persist with the current focus on neuropsychiatric disorders after the ISMP report is published. Pfizer has, meanwhile, indicated that the warnings on the label adequately support the events noted in the report. Chantix currently garners US$883 million annually for Pfizer and is on course to become a billion-dollar drug soon.
Related Articles
- United States: 5 May 2008: Pfizer to Launch New Ad Campaign for Chantix Following FDA Talks
- United States: 4 February 2008: FDA Issues Public Health Warning over Pfizer's Chantix