The U.S. Food and Drug Administration is requiring a prominent boxed warning for the drug, which is sold under the brand names Invokana, Invokamet and Invokamet XR.
Final results from two clinical trials showed that leg and foot amputations occurred about twice as often in patients treated with canagliflozin compared to patients treated with placebo, which is an inactive treatment.
Amputations of the toe and middle of the foot were the most common; however, amputations involving the leg, below and above the knee, also occurred. Some patients had more than one amputation, some involving both limbs.
If you are taking canagliflozin, you should notify your doctor 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 physician.
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.
Canagliflozin is a prescription medicine used with diet and exercise to lower blood sugar in adults with type 2 diabetes. It lowers blood sugar by causing the kidneys to remove sugar from the body through the urine. Untreated, type 2 diabetes can lead to serious problems, including blindness, nerve and kidney damage, and heart disease.
"Canagliflozin is an important treatment option for people with type 2 diabetes," said the drug's manufacturer, Janssen. The company said that while the incidence of amputation observed in the trials was low, "the highest incidence of amputations across all treatments was seen in patients with prior amputation."