Ten deaths including a suicide have been tracked by health authorities monitoring an anti-smoking drug that is in line for massive public rollout with taxpayer funding.
The deaths were reported to a special monitoring unit tracking side-effects associated with Champix, a hugely successful drug used to quit smoking.
Government drug funder Pharmac has previously refused to subsidise Champix because of "safety concerns". But it has now agreed to help fund it in a massive drug deal with pharmaceutical giant Pfizer.
Anti-smoking advocates have welcomed Pharmac's backing, saying the benefits of the drugs outweigh the risks.
The deal will bring the price of the $200-a-month drug down to about $130 a month. It is estimated to be successful in up to half the cases in which people use it to try to stop smoking.
Champix will be available under tight restrictions after Pharmac agreed to take a package of four drugs from Pfizer. The other drugs were sought after by Pharmac, but it had previously been caught up on the price Pfizer demanded and its insistence it owned the patent to one of the drugs.
The package deal of drugs comes after Pharmac stepped aside from its concerns over Champix.
The other drugs in the package include one to treat arthritis, an antidepressant and an expensive kidney cancer drug.
Pharmac medical director Peter Moody said medical advisers had "cautiously endorsed" the use of Champix.
The agency is calling for public submissions on the package deal from Pfizer before the taxpayer subsidy kicks in on November 1.
"Quite often [drug] companies will offer as a package a number of medications at the same time. We will look at the total deal and look at the benefits we're getting."
He said package deals meant all the drugs from the company had to be taken. "You can't cherry pick."
A Pharmac spokesman said the price reduction on Champix had been agreed and "in return for that we get two new products and wider access to one other product".
A spokeswoman for Pfizer said the package deal was suggested by Pharmac, rather than the other way around. The drug company had submitted four separate applications to get the drugs funded.
She said the benefits of Champix outweighed the risks. The subsidy meant "more people will be able to access Champix to improve their chances of quitting smoking".
Pharmac had twice considered backing Champix but rejected the move because of safety concerns.
Pharmac papers stated that it "appears increasingly likely that there is an association between varenicline [Champix] and serious neuro-psychiatric events".
It also questioned whether Champix was as successful as nicotine replacement therapies.
"The committee considered that the safety signal is real, the number of adverse events is increasing, there are concerns with the safety profile of varenicline, and there is limited evidence that varenicline is more effective than NRT," stated minutes from a meeting last year.
Champix has been subject to a special monitoring system arranged by Medsafe, the Ministry of Health unit. Data on prescriptions of Champix - and only one other drug - are collected by the Intensive Medicines Monitoring Programme at the University of Otago.
Medsafe principal clinical advisor Dr Enver Yousuf said Champix had been reported to the programme in connection with 10 patients who had died within 100 days of stopping varenicline.
One of those was reported to have been taking varenicline at the time, and this patient had committed suicide.
He said this gave an estimate of risk of completed suicide of "one in 3415 for the first year of use in NZ".
The programme had now recorded almost 12,000 patients between May 2007 and June this year having used the drug, with nausea and depression the most common side effects.