FDA warns about popular diabetes drugs

In alarming news for diabetic patients taking canagliflozin (Invokana, Invokamet) medications, FDA is warning that interim safety results from an ongoing clinical trial found an increase in foot and leg amputations with the drugs.

“We have not determined whether canagliflozin increases the risk of leg and foot amputations,” FDA said in a Drug Safety Communication. “We are currently investigating this new safety issue and will update the public when we have more information.”

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FDA said patients should not stop taking the medications. Instead, health professionals should monitor patients for symptoms such as new pain or tenderness, sores or ulcers or infections in their legs or feet.

The warning about Invokana and Invokamet, both manufactured by Janssen Biotech, was based on the ongoing Canagliflozin Cardiovascular Assessment Study (CANVAS) clinical trial. The trial’s independent data monitoring committee (IDMC) identified an increased risk of leg and foot amputations.

“The amputations occurred about twice as often in patients treated with canagliflozin compared to patients treated with placebo, which is an inactive treatment,” FDA said.

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An interim analysis showed that over a year’s time, the risks of amputation for patients in the trial were equivalent to: 7 out of every 1,000 patients treated with 100 mg. daily of canagliflozin, 5 out of every 1,000 patients treated with 300 mg. daily of canagliflozin and 3 out of every 1,000 patients treated with placebo.

Patients in the CANVAS trial have been followed for an average of 4.5 years to date, and the IDMC has recommended that the trial continue.

The IDMC has also reported that a second, similar trial evaluating canagliflozin, the CANVAS-R trial, has not shown the same risks of increased leg and foot amputations to date. Patients in the CANVAS-R trial have been followed for an average of 9 months.

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