Packaging for Johnson & Johnson's diabetes drug, Invokana will carry new warnings about the risk of foot and leg amputations as required by the US Food and Drug Administration (FDA).
According to final results from two clinical trials, leg and foot amputations occurred about twice as often in patients with type 2 diabetes treated with Invokana, also known as canagliflozin, as those treated with a placebo, the FDA said in an announcement posted on its website.
The FDA included a new boxed warning to the label of canagliflozin (Invokana, Invokamet, Janssen) to describe the risk for leg and foot amputations.
Invokana belongs to a relatively new class of type 2 diabetes drugs called SGLT-2 inhibitors. The drugs help remove excess blood sugar through urine.
The FDA observed that the results of one clinical trial showed that over the course of a year, the risk of amputation in patients treated with Invokana was equivalent to 5.9 out of 1,000, as against 2.8 out of 1,000 for patients given a placebo.
A second trial revealed the risk of amputation at 7.5 out of every 1,000 patients treated with Invokana compared with 4.2 out of every 1,000 patients given a placebo.
The amputations were most commonly of the toe and middle of the foot, though some involved the leg, below and above the knee.
A number of patients had to undergo more than one amputation, and some of those involved both limbs.
Before prescribing canagliflozin, according to the FDA's advice, healthcare professionals should consider factors that might predispose patients to amputations, including a history of prior amputation, peripheral vascular disease, neuropathy, and diabetic foot ulcers.
Patients taking canagliflozin needed to be monitored for signs and symptoms of those conditions and the drug discontinued if the complications occurred.