Take this FDA-approved diabetes drug, and you might have to amputate your leg, warns the FDA

The U.S. Food and Drug Administration (FDA) has recently issued a black box warning against Johnson & Johnson’s Type 2 diabetes drug Invokana as the medication was found to increase the risk of amputation in patients. Data from two clinical trials showed that patients taking canagliflozin, the drug’s generic name, had higher incidence of amputations than those who did not. According to the FDA, amputations of the toe and middle of the foot were the most common effects seen in patients. However, some patients also experienced amputations of the leg, below and above the knee. In addition, the FDA noted that some patients even had more than one amputation, with certain cases involving both limbs.

According to the FDA, canagliflozin reduces blood sugar levels in patients with Type 2 diabetes by prompting the kidneys to flush out sugar from the body through urination. Canagliflozin belongs to a class of diabetes drugs called sodium-glucose cotransporter-2 (SGLT2) inhibitors, and is used as an adjunct treatment to diet and exercise to lower blood sugar in adult patients with Type 2 diabetes.

“Based on new data from two large clinical trials, the U.S. Food and Drug Administration (FDA) has concluded that the Type 2 diabetes medicine canagliflozin (Invokana, Invokamet, Invokamet XR) causes an increased risk of leg and foot amputations. We are requiring new warnings, including our most prominent Boxed Warning, to be added to the canagliflozin drug labels to describe this risk. Patients taking canagliflozin should notify your health care professionals right away if you develop new pain or tenderness, sores or ulcers, or infections in your legs or feet. Talk to your health care professional if you have questions or concerns. Do not stop taking your diabetes medicine without first talking to your health care professional. Health care professionals should, before starting canagliflozin, consider factors that may predispose patients to the need for amputations. These factors include a history of prior amputation, peripheral vascular disease, neuropathy, and diabetic foot ulcers. Monitor patients receiving canagliflozin for the signs and symptoms described above and discontinue canagliflozin if these complications occur,” the FDA statement read.

The FDA cautioned that untreated Type 2 diabetes may lead to a plethora of adverse medical conditions such as heart disease, blindness, and nerve and kidney damage. The agency urged patients and health care professionals to report side effects associated with canagliflozin and other diabetes drugs to the FDA MedWatch program.

Trials confirm that Invokana may cause amputations in patients

The FDA warning was based on two clinical trials demonstrating the detrimental effects of the drug on patients with Type 2 diabetes. Data from the Canagliflozin Cardiovascular Assessment Study (CANVAS) revealed that the prevalence of leg and foot amputation was twice as high in the canagliflozin group than those in the placebo group. According to the CANVAS trial, nearly six out of every 1,000 patients who took the drug were at an increased risk of amputation one year after treatment, compared with nearly three out of every 1,000 patients in the placebo group.

In addition, the CANVAS-R trial, which examined the renal endpoints in patients, found that nearly eight out of every 1,000 canagliflozin-treated patients were at an increased risk of amputation a year after taking the drug. In contrast, 4.2 out of every 1,000 patients in the placebo group had the same risk. (Related: Johnson & Johnson in hot water for Invokana, vaginal yeast risk)

While the amputation warning is a first for Invokana, the drug has already been noted by the FDA as having several dangerous side effects. In 2015 alone, the FDA released two warnings against the drug: first in May for a serious condition called diabetic ketoacidosis, and the second one in December for urinary tract infections. In 2016, the FDA added kidney injury warnings against Invokana.

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