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Invokana has recently come under fire after a series of FDA clinical trials revealed that those who were prescribed Invokana were twice as likely to suffer from a lower-body amputation than those who were taking the placebo. As a result of these trials, the FDA required Invokana to place a ‘black box warning’ on its packaging, warning patients of the increased risk of such a serious side effect.

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Reasons For Testing

Neither of the clinical trials intended to study the rate of amputation associated with the drugs. Originally, the FDA created the CANVAS program (Canagliflozin Cardiovascular Assessment Study) to determine the scope, if any, of the effects that drugs containing the ingredient canagliflozin had on the cardiovascular health of diabetes patients. The CANVAS-R program was aimed at the renal effects of the drug. The trials were designed to determine what the relationship was between the cardiovascular safety of the drug, as well as the potential benefits versus risks associated with it. Both studies revealed that leg and foot amputations occurred twice as often in patients treated with canagliflozin over patients receiving a placebo.

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Basics of the Testing

In total, the two trials studied 10,142 patients and were randomized into groups. Some received 100 mg each day of canagliflozin, and others received 300 mg each day. Over 667 testing centers in 30 countries examined the effects of the drug. The first round occurred over a period of 126 weeks, with an average follow-up time of 188 weeks. The average age of the test participants was 63, with the vast majority being men. Nearly 80 percent of participants were white with a history of coronary disease.


In CANVAS, the risk of lower body amputations occurred in 5.9 of every 1,000 patients per year if they were on canagliflozin. In comparison, those on placebos suffered amputations at the rate of 2.8 per 1,000 patients each year. The CANVAS-R study was even starker: the risk of lower limb amputations rose to 7.5 amputations per 1,000 patients each year compared with 4.2 per 1,000 patients on the placebo.

Both studies confirm that amputations of the toe and mid-foot were most common, although there were additional amputations which involved the leg – both above and below the knee. Prior to amputations, patients most often suffered lower limb infections, diabetic foot ulcers, and ischemia, which led to gangrene and ultimately, the amputations. The study revealed that individuals on canagliflozin with the highest risk of amputation were those that had already had a prior amputation, peripheral heart disease, and neuropathy (or nerve damage).

The Aftermath and Current Invokana Amputee Lawsuits

First, the FDA issued new requirements to add the Boxed Warning to canagliflozin drug labels to include the increased risk of lower body amputations. The FDA also issued warnings to patients to notify their doctors if any pain, tenderness or sores developed in their feet. However, they have not removed the drug from the market and do not recommend the cessation of taking the medication without instructions from the doctor.

Of course, this has also led to a series of lawsuits against the manufacturer of Invokana, Janssen Pharmaceuticals. Currently, there are over 1,000 lawsuits pending against the Johnson and Johnson subsidiary, with many having filed over claims that the drug caused their amputation. Litigation has expanded into Canada, with patients filing a class-action lawsuit against the manufacturer. And while there have not been any further cases filed, Janssen recently cut a deal with U.K. company Mundipharma to distribute the drug to the British and European market.

Litigants across the United States assert that the manufacturers negligently made the drug, and then lied about the risks and side effects without properly warning the doctors and public. Had they known about the increase in risk for amputation, they would not have taken the drug. Patients have requested compensation for pain and suffering, medical costs, attorney’s fees and even punitive damages in some cases.

What is Canagliflozin?

Marketed as Invokana, Invokamet, or Invokamet XR, canagliflozin is a prescription drug used in conjunction with diet and exercise to lower the amount of glucose in the blood levels of adults who suffer from Type 2 diabetes. It has been one of the highest selling prescription drugs for Type 2 diabetic patients, netting Janssen Pharmaceuticals over $1 billion in profits from Invokana alone in one year.  The class of drug it belongs to is SGLT-2 inhibitors. It works by removing blood sugar from the kidneys through the urine.

Other side effects of Invokana

As you can tell from the initial purpose of the CANVAS and CANVAS-R studies, Invokana carries with it multiple other side effects aside from potential amputation. Because Invokana works in increasing filtration through the kidneys, there have been serious problems with patients who have taken Invokana and their renal systems. In some cases, kidney failure has occurred, with patients now having to resort to dialysis in addition to regular treatments for their diabetes. Since 2013, when the FDA initially approved Invokana, the FDA has received 101 reports of acute injury – 4 cases resulted in a fatality. In the majority of cases, the acute kidney injury occurred within a month of starting the drug.

Ketoacidosis is also another side effect of Invokana, all of which require visits to the hospital. The drug has also been linked to frequent urinary tract infections, blood clots, and blood infections. Interestingly enough, the risks for cardiac events (such as heart attacks) appears to have been lowered in patients taking canagliflozin than those taking the placebo.

The black box warning for the risk of amputation was added to Invokana packaging in May 2017; therefore, anyone who suffered some sort of lower limb amputation before that date might have the standing to file their own action against the manufacturer. There is still time to file. The first ‘bellwether’ trial is slated to begin in September 2018. If you or a loved one have suffered an injury from Invokana, particularly a lower limb amputation, you deserve to be compensated for what you have lost. Contact the law offices of Paul Schiffer at 713-269-6828

Invokana™ is a registered trademark of Janssen Pharmaceuticals, Inc. The use of any trademarks marks are solely for informational and product identification purposes