Drug maker Boehringer Ingelheim has agreed to pay US$650 million to settle multiple U.S. lawsuits claiming that blood thinner Pradaxa caused serious side effects, including fatal bleeding in some users.

At least four lawsuits over Pradaxa have also been filed in Canada, but it wasn’t immediately clear whether the company’s U.S. settlement will have any effect on the Canadian claims.

In a statement issued Wednesday, Boehringer Ingelheim continued to defend the drug, saying its benefits and safety have been confirmed in “many” clinical trials.

"We continue to stand resolutely behind Pradaxa and believed from the outset that the plaintiffs’ claims lacked any merit,” the head of the Germany-based company’s legal department, Andreas Neumann, said in the statement.

“Notwithstanding our strong belief that we would prevail in these lawsuits, this settlement allows our company to avoid the distraction and uncertainty of protracted litigation over years and years.”

The drug maker said it aims to resolve approximately 4,000 U.S. federal and state claims.

“Boehringer Ingelheim expects most, if not all, of the plaintiffs to accept the terms of the settlement and Boehringer Ingelheim will vigorously defend against those who do not,” it said.

Pradaxa was approved for use in Canada in 2008. It’s used to treat a heart condition called atrial fibrillation and is among a new class of oral anti-coagulants that don’t require regular blood tests.

In the U.S. and several other countries, it has also been approved to prevent and treat deep vein thrombosis and pulmonary embolisms.

Before Pradaxa was introduced, the only oral anti-coagulant available in Canada was warfarin, also known as Coumadin. It’s an older medication that requires regular blood tests and comes with many dietary restrictions.

Pradaxa was heralded as the first drug of its kind that did not require regular testing or diet restrictions. Studies show the drug is effective in stopping clots from forming, lowering the risk of stroke.

Some doctors, however, claim there may be very little that can be done to save someone on Pradaxa who suffers excessive bleeding since there is currently no antidote.

“One of the challenges with Pradaxa in particular is that if someone comes to hospital and they are bleeding we really have no way of turning it off. There is no antidote to the drug and that can sometimes have significant consequences,” Dr. David Juurlink, a drug safety expert at Sunnybrook Health Sciences Centre, told CTV News in April.

While warfarin can also trigger life-threatening bleeding, doctors can administer an antidote containing vitamin K to patients, promoting clotting and counteracting the thinning effect of the drug.

There is no such solution for Pradaxa users.

One of the lawsuits filed against Boehringer Ingelheim in Canada involves the death of 61-year-old Susan Garau, who hemorrhaged from several parts of her body, including her mouth, intestines and brain.

Garau, who had been taking Pradaxa, died at Seven Oaks General Hospital in Winnipeg in January. Her family is now suing Boehringer Ingelheim, claiming they were never told that there is not an effective antidote for the excessive bleeding.

According to the Health Canada Adverse Drug Reaction database, there have been more than 1,700 adverse reaction reports and 281 deaths linked to Pradaxa from the time the drug was approved for use in this country in 2008 up until December 2013.

With files from CTV’s medical specialist Avis Favaro and senior producer Elizabeth St. Philip