Invokana Amputation Problems Involving Feet, Legs Result in FDA Safety Investigation

In the latest of a string of potential problems linked to Invokana side effects, federal regulators indicate that they are reviewing whether the new-generation diabetes drug may increase the risk of leg, foot and toe amputations. 

In a drug safety communication issued on May 18, the FDA notified the public and medical community about leg and foot amputation problems with Invokana and Invokamet, mostly affecting the toes among patients treated with the new diabetes drugs that contain the active ingredient canagliflozin.

Invokana was just introduced by Johnson & Johnson and its Janssen Pharmaceuticals subsidiary in March 2013, as the first member of a new class of diabetes drugs, known as sodium-glucose co-transporter 2 (SGLT2) inhibitors. Invokamet is a version that combines the drug with metformin.

Although the medication has been aggressively marketed as a superior diabetes treatment, as more and more individuals are switched to this new treatment, a number of serious safety risks with Invokana have emerged in post-marketing adverse event reports, including diabetic ketoacidosis, kidney failure, bone fractures and now amputation problems.

The FDA states that interim data from an ongoing clinical trial indicates that there is a higher incidence of Invokana amputation problems, with individuals treated with the medication requiring leg, foot or toe amputations twice as often as those treated with a placebo. The agency indicates that it is continuing to evaluate the safety issue, and urges healthcare providers to report any adverse events involving Invokana amputations.

“We have not determined whether canagliflozin increases the risk of leg and foot amputations,” the FDA cautioned. “We are currently investigating this new safety issue and will update the public when we have more information.”

The warning comes about a month after European regulators voiced similar concerns. The European Medicines Agency (EMA) announced it was also launching an Invokana safety review regarding reports of amputations, due to findings from the same clinical trial, known as CANVAS.

Individuals taking Invokana or Invokamet have been told not to stop or change their diabetes medicines without first talking to their healthcare provider. However, the FDA warns patients to notify their healthcare professional immediately if they begin to notice new pain, tenderness, sores, ulcers or infections in their legs and feet, which may be signs or symptoms of problems that could lead to the need for an amputation on Invokana.

Invokana Risks

The warning comes as Johnson & Johnson faces a growing number of Invokana lawsuits and Invokamet lawsuits filed by individuals throughout the U.S. who have suffered diabetic ketoacidosis, kidney failure and other injuries. The complaints allege that the drug maker failed to adequately research the side effects of Invokana before introducing the medication, and that it recklessly promoted the medication without providing sufficient warnings for consumers and the medical community.

Only two years after the drug was introduced in the United States, the FDA launched an investigation into a link between Invokana and ketoacidosis, which involves a dangerously high concentration of acid levels in the blood. In May 2015, the agency indicated that it had identified at least 20 reports of individuals being hospitalized due to acid problems with the drug or other members of the SGLT2 inhibitor class of diabetes medications.

Following a safety review, the FDA ultimately required Johnson & Johnson to add new Invokana warnings about ketoacidosis in December 2015, urging users to stop taking the drug and seek immediate medical attention if they experience symptoms like abdominal pain, fatigue, nausea, respiratory problems or vomiting.

In September 2015, the FDA required new Invokana bone fracture warnings, indicating that the drug may also lead to decreased bone density.

A detailed review of adverse event reports submitted to the FDA during the first year Invokana was on the market, which was conducted by the Institute of Safe Medication Practices (ISMP), identified a potential risk of kidney damage with Invokana and other SGLT2 inhibitors.

These new-generation diabetes treatments work in a unique way, by impacting the normal function of the kidneys. However, investigators identified reports of kidney failure and other problems that they suspected were caused by the medication.

There are currently a few dozen product liability lawsuits pending nationwide, but as Invokana injury lawyers continue to review and file cases for individuals who have experienced problems, it is ultimately expected that hundreds, if not thousands, of claims may be presented against Johnson & Johnson over their new-generation diabetes drugs.