Invokana: Diabetes Drug Gets Black Box Warning for Amputation Risks
Invokana (canagliflozin), an SGLT-2 drug for use in type 2 diabetes and off-label in those with type 1 diabetes has been required by the FDA to carry the prominent boxed warning due to a higher risk for leg and foot amputations.
This new requirement is a result of two clinical trials whose data revealed these elevated risks. Canagliflozin is the drug present in the marketed products: Invokana, Invokamet, and Invokamet XR.
The clinical trials called CANVAS (Canagliflozin Cardiovascular Assessment Study) and CANVAS-R (A Study of the Effects of Canagliflozin on Renal Endpoints in Adult Participants With Type 2 Diabetes Mellitus) revealed that leg and foot amputations happened about twice as often in those taking canagliflozin compared to those taking a placebo.
Over the span of a year the amputation risk for CANVAS trial patients was equal to 5.9 out of every 1,000 patients taking canagliflozin and 2.8 out of every 1,000 patients taking a placebo.
Over the span of a year the amputation risk for CANVAS-R trial patients was equal to 7.5 out of every 1,000 patients taking canagliflozin and 4.2 out of every 1,000 patients taking a placebo.
Most common was toe and middle the foot amputations but below and above the knee leg amputations were also observed. Some patients needed multiple amputations, “some involving both limbs.”
This warning is in addition to last year’s FDA strengthened warning to users of canagliflozin for an increased risk of acute kidney injury and in 2015 the strengthened “warning for canagliflozin related to the increased risk of bone fractures,”
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