Invokana Amputation Risk Seen In Heart Study

Although a recent study that looked at the potential side effects of Invokana provided positive findings about the cardiovascular benefits, the data also appears to confirm growing concerns about the increased amputation risks associated with the new-generation diabetes drug.

Johnson & Johnson widely hailed the findings of recent research published in the New England Journal of Medicine, which found that Invokana may decrease the risk of cardiovascular death and non-fatal heart attacks and strokes. However, the study also highlights the increased risk of leg and foot amputations users may face.

Invokana (canagliflozin) belongs to a new class of diabetes drugs, known as sodium-glucose cotransporter 2 (SGLT2) inhibitors, which works in a unique way by impacting some normal kidney functions. Other members of this class include Invokamet, Jardiance, Farxiga, Xigduo and others, but Invokana has remained the biggest seller since it hit the market in March 2013.

As more and more diabetics have switched to Invokana, in response to aggressive marketing efforts by Johnson & Johnson, a steady stream of serious health concerns have emerged from post-marketing adverse event reports, leading the FDA to require several warning label updates over the past few years. In addition to the Invokana heart attack risks, the medication has previously been linked to reports of diabetic ketoacidosis, kidney failure and amputations.

Last month, the FDA required an Invokana warning update regarding the risk of leg and foot amputation, which manufacturers of other SGLT2 inhibitors claim is a unique risk with Invokana, not seen with their competing drugs.

The study, known as CANVAS, looked at integrated data from two clinical trials involving 10,142 subjects with type 2 diabetes and high risks of heart problems. The participants were either given Invokana or a placebo for a mean of 188.2 weeks.

According to the findings, there was an increased risk of amputation, with 6.3 amputations per 1,000 patient years, compared to 3.4 among those given the placebo. The researchers calculated that Invokana use increased the risk of amputations by 97%, which were primarily toe or metatarsal (foot).

“The increased rate of amputation is a new finding for which the mechanism is unknown, and care is warranted in the use of canagliflozin in patients at risk for amputation,” the researchers warned.

In addition to the recent warning update about the Invokana amputation risk, the FDA has required the drug makers to change the label several times since originally approving the new diabetes treatment.

In December 2015, diabetic ketoacidosis warnings were added to Invokana and other SGLT2 inhibitors, indicating for the first time that users may face of risk of developing this serious condition. Prior Invokana warnings failed to alert consumers about the importance of seeking immediate medical attention if they experience symptoms like abdominal pain, fatigue, nausea, respiratory problems or vomiting, which is critical for avoiding serious complications from diabetic ketoacidosis.

Concerns about a potential link between Invokana and kidney failure have also emerged since the drug hit the market. In June 2016, the FDA required that new information be added to the drug label about the risk of acute kidney injury and other kidney issues.

While Johnson & Johnson continues to defend the safety of their diabetes drug and highlight the positive findings of the heart study, the drug maker faces hundreds of Invokana lawsuits filed over failure to adequately warn about the risk of diabetic ketoacidosis, kidney failure, amputations and other serious health risks when the medication was introduced.