INFORMATION FOR HEALTH PROFESSIONALS
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Dr Mira Harrison-Woolrych, Director, Intensive Medicines Monitoring Programme
Web site: May 2009
Prescriber Update 2009;30(2):9
Varenicline (Champix) is the newest smoking cessation medicine available in New Zealand and has been monitored by the Intensive Medicines Monitoring Programme (IMMP) since its introduction here in 2007. The IMMP has recently analysed results for 3389 patients who were dispensed a prescription for varenicline in the first year (1 April 2007 to 31 March 2008) of marketing in New Zealand.
In this interim analysis the IMMP identified a total of 293 reports (for 284 patients) with a total of 538 adverse events occurring while the patient was taking varenicline. These events have been identified from follow-up questionnaires sent to doctors in June 2008 and spontaneous reports submitted to the New Zealand Pharmacovigilance Centre (NZPhvC). The most frequently reported adverse events were psychiatric effects, with a total of 169 events (31% of all events). The most common psychiatric adverse events reported were depression (22 events), insomnia (22), sleep disturbance (13), fatigue (12), vivid/strange dreams (10), nightmares (10), and anxiety (9). There have also been four reports of depersonalisation, four reports of mood swings, four of panic attacks, and two of hypomania/ mood elevation.
Depression and Suicidal Ideation
Of the 22 reports of new-onset depression while taking varenicline, 15 were assessed as having a 'probable' relationship (i.e. there was evidence of positive dechallenge) with varenicline and 7 were assessed as having a 'possible' relationship.1 Three of the patients who experienced depression while taking varenicline also reported suicidal ideation and in two cases this resolved on cessation of the medicine. A further 10 patients experienced a worsening or recurrence of existing depression while taking varenicline. Of these, four recovered on withdrawal of varenicline, with the other six assessed as having a 'possible' relationship with the medicine.
Regarding psychiatric adverse effects, the New Zealand data sheet for Champix includes the following advice: "Patients and their families should be advised that the patients should stop taking CHAMPIX and contact a health care professional immediately if changes in behaviour, agitation or depressed mood, that are not typical for the patients are observed, or if the patient develops suicidal ideation or suicidal behaviour".2
Withdrawal Symptoms
The IMMP has identified six reports of symptoms following cessation of varenicline which appear to be withdrawal effects. Two patients experienced a withdrawal depression and one of these patients also experienced anxiety. In other patients withdrawal symptoms included agitation, mood swings, cravings, night sweats, insomnia, and taste disturbance. The New Zealand data sheet for Champix includes mention of withdrawal effects and prescribers should advise patients of this possibility.2
Prescribers are reminded that patients may also experience psychiatric symptoms such as depression and irritability for many reasons including nicotine withdrawal. Information provided by prescribers in the IMMP follow up questionnaires will help us to evaluate the significance of these possible confounding factors.
Summary of Key Messages for Prescribers:
References