Quit-smoking pill sparks health warning

22 people experienced depression after taking Champix, a pill designed to help smokers quit. Photo / Kenny Rodger

Health authorities have issued a new warning on the mental health risks of a quit-smoking pill introduced to New Zealand in 2007.

More than 3300 people were prescribed Champix, which contains the chemical varenicline, in the first year of its use in New Zealand.

There were 22 reports of people experiencing depression for the first time after taking Champix. Recurrence or worsening of existing depression, and other psychiatric and neurological symptoms, were also reported.

The majority of the new cases of depression were probably caused by the tablets, according to the Intensive Medicines Monitoring Programme, which collected the data from pharmacists and doctors. Three of these people also thought about suicide and two of these cases were resolved after stopping the medicine, says the programme's director, Dr Mira Harrison-Woolrych, in a Health Ministry newsletter to prescribers.

"Psychiatric reactions have emerged as a potential safety issue with varenicline and patients should be advised accordingly," she says.

Dr Stewart Jessamine, group manager of the ministry's Medsafe unit, said yesterday the monitoring programme's findings reflected international experience with Champix.

"Since the introduction of Champix to New Zealand there have been additional warning statements around neuro-psychiatric side-effects in particular. We knew from clinical trials it could cause neuro-psychiatric side-effects. Their frequency has become more obvious as it has been used in the general population; therefore the data sheet was updated to reflect the increased risks over time."

The international consensus of major drug regulators was that the benefits outweighed the risks, but patients should carefully read the information supplied with the product.

Dr Jessamine said it was not known whether the patients involved in the monitoring were smoking at the time of their adverse reactions.

Dr Harrison-Woolrych's article notes that nicotine withdrawal can itself cause depression and other psychiatric symptoms.

Dr Jessamine said similar psychiatric side-effects had been reported by users of another quit-smoking medicine, Zyban, although it had not been intensively monitored because it was not the first in a new class of drugs.

The Champix data sheet says serious symptoms have continued in some using the medicine even when they continued to smoke.

"Although a causal association between Champix and these symptoms has not been established, in some reports the association cannot be excluded.

"Patients being treated with Champix and their families should be alerted to the need to monitor for neuro-psychiatric symptoms including changes in behaviour, agitation, aggression, depressed mood, suicidal ideation, and suicidal behaviour."