Advice for healthcare professionals:
- carefully monitor patients receiving canagliflozin who have risk factors for amputation, such as poor control of diabetes and problems with the heart and blood vessels
- consider stopping canagliflozin if patients develop foot complications such as infection, skin ulcers, osteomyelitis, or gangrene
- advise patients receiving any sodium-glucose co-transporter 2 (SGLT2) inhibitor about the importance of routine preventive foot care and adequate hydration
- continue to follow standard treatment guidelines for routine preventive foot care for people with diabetes
- report any suspected side effect with SGLT2 inhibitors or any other medicine on a Yellow Card
Sodium-glucose co-transporter 2 (SGLT2) inhibitors are indicated in adults with type 2 diabetes mellitus to improve glycaemic control when diet and exercise alone are inadequate for control.
SGLT2 inhibitors are given alone in patients for whom the use of metformin is considered inappropriate due to intolerance or contraindications. SGLT2 inhibitors can also be given with other glucose-lowering drugs, including insulin, when these drugs do not provide adequate glycaemic control.
The SGLT2 inhibitor-containing medicines marketed in the UK are Invokana▼ (canagliflozin), Vokanamet▼ (canagliflozin and metformin), Forxiga▼ (dapagliflozin), Xigduo▼ (dapagliflozin and metformin), Jardiance▼ (empagliflozin), and Synjardy▼ (empagliflozin and metformin).
Risk of amputation
In June 2016, we published a Drug Safety Update article about an increase in cases of lower-extremity amputation with canagliflozin, compared with placebo, in two clinical trials. A Direct Healthcare Professional Communication was also sent.
The trials, CANVAS and CANVAS-R, are ongoing and involve patients at high risk of cardiovascular disease. As of September 2016, the incidence of lower-limb amputation (mostly affecting the toes) in the CANVAS study was 7 in 1,000 patient-years with canagliflozin 100 mg daily and 5 in 1,000 patient-years with canagliflozin 300 mg daily, compared with 3 in 1,000 patient-years with placebo. The study enrolled around 4,300 patients.
A European review of the risk of lower-limb amputation with all approved SGLT2 inhibitors noted that patients with diabetes (especially those with poorly controlled diabetes and pre-existing problems with the heart and blood vessels) are at increased risk of infection and ulcers (sores), which can lead to amputation. The mechanism by which canagliflozin may increase the risk of amputation is still unclear.
An increased risk of amputation was not seen in studies of dapagliflozin and empagliflozin. However, data are limited and the risk could also apply to these other medicines. Further data are expected from ongoing trials with the approved SGLT2 inhibitors.
The product information for canagliflozin, dapagliflozin, and empagliflozin is being revised to include a warning on the potential increased risk of lower-limb amputation, mostly affecting the toes. For canagliflozin, the prescribing information will also list lower-limb amputation as an uncommon side effect (occurring in fewer than 10 patients in 1,000).
Article citation: Drug Safety Update volume 10 issue 8, March 2017: 1.