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WASHINGTON -- Labels for type 2 diabetes drugs containing canagliflozin (Invokana, Ivokamet, Invokamet XR) will now carry a , the FDA said Tuesday.
The warning comes after the agency reviewed data from two randomized, placebo controlled trials (CANVAS and CANVAS-R) that showed rates of lower-extremity amputations were doubled in the active drug groups, irrespective of dose.
Among nearly 6,000 patients receiving canagliflozin in the two trials, rates of amputations were 5.9 and 7.5 per 1,000 patient-years, compared with 2.8 and 4.2 per 1,000 patient-years in the placebo groups. The differences were statistically significant.
CANVAS was the FDA-required study investigating cardiovascular outcomes; CANVAS-R assessed renal endpoints.
Lower-limb infections, gangrene, diabetic foot ulcers, and ischemia were the most common precipitating factors for amputations in the studies, the FDA said. Patients with previous amputations were more likely than others to need additional ones during the trial.
Notably, patients in the two trials were included only if they had cardiovascular disease or risk factors for it other than type 2 diabetes. However, the new warning applies to all patients regardless of cardiovascular risk.
The FDA urged prescribers to consider individual patients' risks for amputation before initiating canagliflozin. Patients currently on the drug should be monitored closely for conditions such as infections and foot ulcers that may lead to amputation; the drug should be discontinued if these appear.
Almost exactly 1 year ago, the FDA issued an that suggested the increased amputation risk, and promised an update when fuller data were available.
Canagliflozin is one of the new class of SGLT-2 inhibitors that reduce blood glucose levels by inducing sugar to be excreted in urine. The FDA has not said other SGLT-2 inhibitors may have the same risk of amputations, but in February, the . Other SGLT-2 inhibitors include dapagliflozin (Farxiga) and empagliflozin (Jardiance).