The US Food and Drug Administration has issued a warning regarding the relatively new diabetes 2 drug most notably known as Invokana regarding leg and toe amputations.
The warning states:
Based on new data from two large clinical trials, the FDA has concluded that the type 2 diabetes medicine canagliflozin (Invokana, Invokamet, Invokamet XR) causes an increased risk of leg and foot amputations. FDA is requiring new warnings, including the most prominent Boxed Warning, to be added to the canagliflozin drug labels to describe this risk.
The FDA further advises that anyone taking the medication consult with their doctor immediately should they experience any pain or tenderness, sores, ulcers or infections in the lower limbs. They do not recommend stopping the medication without first consulting with a physician or other healthcare provider.
Healthcare professionals are advised to consider any factors that may predispose a patient to amputations before starting the medication, which may include issues such as:
- Any prior amputations
- Peripheral vascular disease
- Diabetic ulcers in the feet
The two clinical trials referenced in the FDA safety announcement include results from the Canagliflozin Cardiovascular Assessment Study (CANVAS) and A Study of the Effects of Canagliflozin on Renal Endpoints in Adult Participants With Type 2 Diabetes Mellitus (CANVAS-R). Both studies published findings that indicated “leg and foot amputations occurred about twice as often in patients treated with canagliflozin compared to patients treated with placebo, which is an inactive treatment. The CANVAS trial showed that over a year’s time, the risk of amputation for patients in the trial were equivalent to:
- 9 out of every 1,000 patients treated with canagliflozin
- 8 out of every 1,000 patients treated with placebo
The CANVAS-R trial showed that over a year’s time, the risk of amputation for patients in the trial were equivalent to:
- 5 out of every 1,000 patients treated with canagliflozin
- 2 out of every 1,000 patients treated with placebo”
The most common amputations were of toe or middle foot but also included the leg and knee areas. Some patients required amputations involving more than one area, or more than one surgery.