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By: Marilyn McGoldrick, Esq.

UPDATE: The U.S. Food and Drug Administration (FDA) removed the boxed warning about the risk of leg and foot amputations for the diabetes drug canagliflozin (Invokana, Invokamet, Invokamet XR) on August 26, 2020. The FDA explained removing the boxed warning thusly:

FDA reviews of new clinical trial data demonstrated additional heart- and kidney-related benefits, which led to additional approved uses.  Specifically, in 2018, canagliflozin was approved to reduce the risk of major heart-related events such as heart attack, stroke, or death in patients with type 2 diabetes who have known heart disease; and, in 2019, it was approved to reduce the risk of end-stage kidney disease, worsening of kidney function, heart-related death, and being hospitalized for heart failure in certain patients with type 2 diabetes and diabetic kidney disease.

Collectively, these newly identified effects of canagliflozin on heart and kidney disease show significantly enhanced benefit of this medicine.  Safety information from recent clinical trials also suggests that the risk of amputation, while still increased with canagliflozin, is lower than previously described, particularly when appropriately monitored.  Based upon these considerations, FDA has concluded that the boxed warning should be removed.

Published on May 16, 2017

The FDA has added a boxed warning to the label of  diabetes drugs containing canagliflozin (Johnson & Johnson’s brand names Invokana and Invokamet) to warn that these drugs carry an elevated risk of leg and foot amputations.

FDA Confirms Doubled Risk of Lower Limb Amputation When Taking Canagliflozin Drugs

Today’s FDA Drug Safety Communication confirms the approximately doubled risk of  lower limb amputations for patients taking Invokana (canagliflozin) or Invokamet (canagliflozin with metformin). The warning is based on new data from two large clinical trials. CANVAS (Canagliflozin Cardiovascular Assessment Study) and CANVAS-R (A Study of the Effects of Canagliflozin on Renal Endpoints in Adult Participants With Type 2 Diabetes Mellitus) showed about double the rate of amputations from diabetes patients on canagliflozin drugs, as compared to patients taking a placebo. Amputations mostly affect the toes and the middle of the foot. Amputations of the leg, below and above the knee, and to both limbs were also observed.

Europe Requires Amputation Warning on All SGLT2 Inhibitor Drugs, Not Just Canagliflozin

Invokana and Invokamet are classified as sodium glucose cotransporter-2 (SGLT2) inhibitor drugs. SGLT2s trigger the kidneys to release blood glucose into the urine, thereby lowering blood sugar levels.  The European Medicines Agency issued a requirement in February of 2017 (PDF link) that the labels of every drug in the SGLT2 inhibitor class carry the amputation warning.  The other drugs included as well as canagliflozin (brand names Invokana, Invokamet) are dapagliflozin (brand names Farxiga, Xigduo XR) and empagliflozin (brand names Jardiance, Glyxambi, Synjardy).

FDA Recommendations for Diabetes Patients and Their Health Care Providers When Using Canagliflozin

The FDA issued the following recommendations to patients, and to health care providers:

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.

Reporting Adverse Events While Taking Invokana and Invokamet

The FDA encourages patients health care professionals and patients to report adverse events or side effects related to the use of canagliflozin and other medicines to the FDA’s MedWatch Safety Information and Adverse Event Reporting Program. You can do this   by calling  800-332-1088 to request a reporting form; by using their online reporting form; by downloading an online form and submitting by mail, or by faxing the form to 1-800-FDA-0178.

What Can You Do?

If you have taken the canagliflozin-containing diabetes drugs Invokana or Invokamet, or any other SGLT2 inhibitor drug, and suffered an amputation, you may have a claim for damages. Contact the defective drug attorneys at Thornton Law Firm for a free, thorough evaluation of your legal rights at 1-888-341-1405. Or tell us your story using our online contact form. Like all lawsuits, Invokana claims must be filed within short time limits. Seek legal advice as soon as possible to protect your rights.