- Associated Press - Monday, May 23, 2016

Europe’s main drug regulator has lifted a 7-year-old warning about possible suicidal risks from Chantix, Pfizer’s smoking-cessation pill.

The European Medicines Agency’s ruling could boost sales of Champix, the drug’s name in Europe, by reassuring doctors and would-be ex-smokers that the prescription medicine doesn’t have dangerous psychiatric side effects.

The EMA’s decision, announced Monday by New York-based Pfizer Inc., comes after an 8,144-patient, 16-country study found users had no elevated risk of suicides, suicide attempts or suicidal thoughts.

Anecdotal reports of such risks led both the EMA and the U.S. Food and Drug Administration in 2009 to slap their most-stringent warnings -a black triangle and a black box, respectively - on both Chantix and GlaxoSmithKline PLC’s Zyban. The EMA now has removed the black triangle and changed the detailed prescribing information for Champix to state that a large patient study didn’t find any increased risk.

Zyban is an antidepressant that reduces symptoms of nicotine withdrawal. Chantix, known chemically as varenicline, binds to brain receptors, blocking the ability of nicotine to bind to those sites and produce the feel-good chemical dopamine.

Quitting smoking, with or without medication, can cause significant withdrawal symptoms, including irritability, mood swings and depression. In addition, psychiatric conditions are more common in smokers than nonsmokers.

Many doctors and smokers trying to quit were scared off by warnings on Chantix and Zyban, about “changes in behavior, hostility, agitation, depressed mood, and suicidal thoughts or actions” in some patients.

That hurt sales of Zyban, which has long been available as an inexpensive generic called bupropion, and Chantix, which has a monopoly until its patent expire - in 2020 in the U.S. and in 2021 in Europe.

With the new research, it’s clear they are far safer than smoking, which each year kills about 440,000 people in the U.S. alone.

The FDA said in an email Monday that it’s “reviewing the findings of this study and substantial supporting documentation from the clinical trial, along with additional published medical literature, as we continue to evaluate this issue.”

A GlaxoSmithKline spokeswoman could not immediately say whether the EMA is lifting its warning on Zyban.

GlaxoSmithKline and Pfizer jointly funded the huge safety study, ordered by the FDA. It ended late last year. It compared psychiatric side effects of those two medicines, nicotine replacement patches and dummy pills, with participants treated for 12 weeks and then followed for another 12.

Half had existing psychiatric problems: depression, anxiety, post-traumatic stress, obsessive-compulsive disorder or schizophrenia. In that group, suicidal thoughts or behavior or other serious mental health issues were reported in about 6.5 percent given Chantix or Zyban and 5 percent given the nicotine patch or dummy pills.

Among participants without psychiatric problems, the risk was lower - and the same for all four groups. No participants committed suicide, though two taking dummy pills and one taking Zyban attempted it. However, the drugs can cause other side effects: nausea, insomnia, abnormal dreams and headaches.

The study also found Chantix was the most-effective quitting method, with about 22 percent of Chantix users still not smoking after six months, compared to 16 percent each for Zyban and the patch, and 9 percent for dummy pills.

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Follow Linda A. Johnson https://twitter.com/lindaj_onpharma

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