Reported Adverse Drug Reaction Cases
- MHRA & CHM. Drug Safety Update, 2008; vol. 2/4.
Varenicline: The Australian experience so far
Varenicline (Champix) acts to relieve the cravings and withdrawal symptoms of smoking cessation and is used as an aid to stop smoking in adults. To minimise potential adverse reactions, treatment with varenicline is initiated in a gradually increasing dose titration schedule. Since January 2008 varenicline has been available on the Pharmaceutical Benefits Schedule but is restricted to individuals who have entered (or are about to enter) a comprehensive support and counselling program. To date, 210,000 PBS prescriptions for varenicline have been dispensed.
Overseas safety alerts have linked varenicline with the onset of serious neuropsychiatric side-effects, mainly behavioural changes, agitation and depression which may be accompanied by suicidal ideation.1,2 The Australian Product Information alerts prescribers to the possibility of such effects with varenicline treatment.
To October 2008, we have received 339 adverse reaction reports with varenicline, 255 (72%) of which describe psychiatric symptoms including depression, aggression, agitation, abnormal dreams, insomnia, hallucination and anger. There have also been reports of suicidal/self-injurious ideation or behaviour.
While some patients may have experienced these types of symptoms as a result of nicotine withdrawal, it appears increasingly likely with accumulating experience that there is an association between varenicline and serious neuropsychiatric events.
Prescribers are reminded to advise patients of the types of neuropsychiatric symptoms that are outlined in the Champix Product Information and Consumer Medicine Information. Patients who develop these symptoms, including suicidal thoughts, while taking varenicline should seek urgent medical help and cessation of varenicline should be considered. Family and carers should be advised to be vigilant for any changes in behaviour, especially in smokers who have concomitant or previous psychiatric illness.
We have also received 15 reports of seizures in patients using varenicline. It is not known how many of these had a prior history or risk of a seizure disorder and there is no experience from clinical trials of varenicline in patients with epilepsy. Therefore prescribers are also advised to exercise caution when prescribing varenicline to patients with a history of seizure disorder.References
Australian Adverse Drug Reactions Bulletin
Volume 27, Number 6, December 2008