ADR that result in revision of patient information
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| The United States: Drug Safety Communication: FDA updates label for stop smoking drug Chantix (varenicline) to include potential alcohol interaction, rare risk of seizures, and studies of side effects on mood, behaviour, or thinking |
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The U.S. Food and Drug Administration (FDA) is warning that the prescription smoking cessation medicine Chantix (varenicline) can change the way people react to alcohol. In addition, rare accounts of seizures in patients treated with Chantix have been reported. The FDA has approved changes to the Chantix label to warn about these risks. Until patients know how Chantix affects their ability to tolerate alcohol, they should decrease the amount of alcohol they drink. Patients who have a seizure while taking Chantix should stop the medicine and seek medical attention immediately.
The FDA reviewed the case series submitted by Pfizer, the manufacturer of Chantix, as well as the cases in the FDA Adverse Event Reporting System (FAERS) database describing patients who drank alcohol during treatment with Chantix and experienced adverse reactions. Some patients experienced decreased tolerance to alcohol, including increased drunkenness, unusual or aggressive behaviour, or they had no memory of things that happened.
The FDA also reviewed FAERS and the medical literature for cases of seizures with Chantix and identified cases in which the patients who had seizures while taking Chantix either had no history of seizures or had a seizure disorder that had been well-controlled. In most of these cases, the seizures occurred within the first month of starting Chantix. Information about these risks has been added to the Warnings and Precautions section of the drug label and to the patient Medication Guide.
The FDA also updated the Warnings and Precautions section of the label to include information about several studies that investigated the risk of neuropsychiatric side effects on mood, behaviour, or thinking occurring with Chantix. These included observational studies, as well as analyses that Pfizer conducted of randomized controlled clinical trial data. These studies did not show an increased risk of neuropsychiatric side effects with Chantix; however, they did not examine all types of neuropsychiatric side effects, and they had limitations that prevented the FDA from drawing reliable conclusions. Pfizer is conducting a large clinical safety trial of Chantix to investigate the risk of possible neuropsychiatric side effects and results from this study are expected in late 2015. The FDA will update the public as appropriate when this new information becomes available.
Healthcare professionals are advised of the following:
• Interactions between alcohol and Chantix (varenicline) have resulted in some patients experiencing increased intoxicating effects of alcohol, sometimes associated with aggressive behaviour and/or amnesia.
• Advise patients to reduce the amount of alcohol they consume while taking Chantix until they know whether the drug affects their tolerance for alcohol.
• Seizures have been reported in patients treated with Chantix.
• Weigh the potential risk of seizures against the potential benefits before prescribing Chantix in patients with a history of seizures or other factors that can lower the seizure threshold.
• Advise patients to discontinue Chantix and seek medical attention immediately if they experience a seizure while on treatment.
• Advise patients to immediately stop taking Chantix if they develop agitation, hostility, aggressive behaviour, depressed mood, or changes in behaviour or thinking that are not typical for them, or if they develop suicidal ideation or behaviour.
Please refer to the following website in FDA for details:
http://www.fda.gov/Drugs/DrugSafety/ucm436494.htm
In Hong Kong, there are three registered pharmaceutical products containing varenicline, namely Champix Tab 1mg (HK-55437), Champix Tab 0.5mg & 1mg (HK-55462) and Champix Tab 0.5mg (HK-55479). All of them are prescription-only medicines and registered by Pfizer Corporation Hong Kong Limited. Related news on the risk of neuropsychiatric adverse events has been reported by the FDA, and was posted on the Drug Office website on 25 October 2011. So far, the Department of Health has not received any adverse drug reaction report on varenicline. In view of the FDA's announcement, letters to healthcare professionals will be issued to draw their attention to the updates, and the matter will be discussed on the meeting of the Registration Committee of the Pharmacy and Poisons Board.
Ends/ Tuesday, March 10, 2015
Issued at HKT 13:00
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