NEW YORK ( TheStreet) -- A Pfizer ( PFE) stop-smoking drug increases the risk of cardiovascular events such as heart attacks, according to researchers who analyzed multiple trials involving the drug.

After reviewing 14 trials of the drug Chantix (varenicline), the researchers wrote that the drug's use was associated with a 72% risk of "serious adverse cardiovascular events."

The trials involved 8,216 participants and ranged in duration from seven to 52 weeks.

The researchers concluded that their analysis raises safety concerns about the use of the drug by tobacco users.

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They published their findings in the Canadian Medical Association Journal.

The Food and Drug Administration recently placed a warning in the information that comes with the drug about additional cardiovascular risks for people already suffering from heart disease, according to a report by the BBC.

A Pfizer representative said the company "disagreed with the interpretation of the data" used by the researchers," the BBC report said.

Shares of Pfizer closed Friday up 15 cents at $20.75. U.S. stock markets were closed Monday in observance of Independence Day.
This article was written by a staff member of TheStreet.