Based on two recent studies, the U.S. Food and Drug Administration (FDA) has issued a warning against type 2 diabetes medicine canagliflozin, sold commercially as Invokana, Invokamet, and Invokamet XR.

Apparently, the drug causes an increased risk of leg and foot amputations. The FDA is now issuing guidelines to have it come with a warning on its label.

Image credit: Prescription Drug Journal
Image credit: Prescription Drug Journal

Diabetes drug increases risk of amputation

Canagliflozin is prescribed alongside diet and exercise to help patients with type 2 diabetes lower their blood sugar. It inhibits the sodium-glucose cotrasporter-2, and its effects are measured through the amount of sugar in the patient’s urine, as the drug focuses its effects on the kidneys. Although it is usually sold under its commercial name Invokana, it is also combined with metformin in Invokamet and Invokamet XR.

The study was focused on determining how canagliflozin affected the renal endpoints in adults with type 2 diabetes. Researchers discovered that leg and foot amputations were twice as likely to occur in patients treated with the drug compared to those who were given a placebo.

The most common amputations were those involving the tow and the middle of the foot, although amputations including the leg up to the knee also became more frequent. In some cases, both limbs had to undergo amputation.

Results showed that 5.9 out of every 1,000 patients treated with canagliflozin were amputated, compared to 2.8 out of every 1,000 patients treated with placebo who were also amputated. 99 out of 140 amputated patients receiving the drug had their toe or mid-foot removed, while amputations involving the leg and the knee accounted for 41 out of 140 amputations. Some patients underwent more than one amputation.

If you or one of your acquaintances use canagliflozin, you should contact a health specialist immediately if there’s any pain or soreness in legs or feet. Even if ulcers are present, the patient should not stop taking the drug unless a physician indicates otherwise.

Before prescribing the medication, the doctor should check the patient’s medical history to see if there’s anything that could increase the risk of amputation. Factors that increase the risk of amputation include a history of a peripheral vascular disease, previous amputations, and neuropathy. If left untreated, type 2 diabetes can lead to kidney damage, heart disease, and blindness. The doctor should also inform the patient how canagliflozin is associated with a higher risk of amputations.

On the other hand, canagliflozin does have its side effects. It can cause hypotension, ketoacidosis, kidney problems, a large amount of potassium in the blood, urinary infections, high cholesterol, yeast infections, bone fractures, and low blood sugar if combined with other drugs for treating diabetes.

Immediately after the press release, Lilly, Invokana’s manufacturer, saw its stocks drop 1.6 percent after a Goldman Sachs analyst removed the stock from one of its lists.

The full results of the medical trials are yet to be released, as the higher risk of amputation was only a collateral discovery.

Source: FDA