Canagliflozin (Invokana, Invokamet): Drug Safety Communication - Increased Risk of Leg and Foot Amputations
AUDIENCE: Internal Medicine, Family Practice, Pharmacy, Patient
ISSUE: 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.
Final results from two clinical trials – the 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) – showed that 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. Amputations of the toe and middle of the foot were the most common; however, amputations involving the leg, below and above the knee, also occurred. Some patients had more than one amputation, some involving both limbs. See the FDA Drug Safety Communication for additional information, including a data summary.
BACKGROUND: This information is an update to the May 18, 2016 MedWatch safety alert. Canagliflozin is a prescription medicine used with diet and exercise to lower blood sugar in adults with type 2 diabetes. It belongs to a class of drugs called sodium-glucose cotransporter-2 (SGLT2) inhibitors. Canagliflozin lowers blood sugar by causing the kidneys to remove sugar from the body through the urine. It is available as a single-ingredient product under the brand name Invokana and also in combination with the diabetes medicine metformin under the brand name Invokamet.
RECOMMENDATION: Patients taking canagliflozin should notify your health care professionals right away if you develop new pain or tenderness, sores or ulcers, or infections in your legs or feet. Talk to your health care professional if you have questions or concerns. Do not stop taking your diabetes medicine without first talking to your health care professional.
Health care professionals should, before starting canagliflozin, consider factors that may predispose patients to the need for amputations. These factors include a history of prior amputation, peripheral vascular disease, neuropathy, and diabetic foot ulcers. Monitor patients receiving canagliflozin for the signs and symptoms described above and discontinue canagliflozin if these complications occur.
Read the MedWatch safety alert, including a link to the FDA Drug Safety Communication, at:
https://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm558605.htm
Canagliflozin為用於治療第二型糖尿病之降血糖藥品。其機轉為藉由抑制sodium-glucose cotransporter 2 (SGLT2)，減少腎臟對已過濾之糖分的再吸收作用，增加糖分經由尿液的排泄。在美國有canagliflozin單方及複方製劑上市。
美國FDA從兩個大型的臨床試驗發現，服用含canagliflozin成分藥品之病人相較於服用安慰劑者，發生下肢截肢（主要影響腳趾）的機率較高。有些病人不只一個部位截肢；有些病人則雙腳皆有影響，因此美國FDA要求新增此資訊於仿單之加框警語中。
病人若於服用canagliflozin後，出現下肢疼痛、觸痛、痠痛、潰瘍或感染等情形，請立即與醫療專業人員連繫。若有任何疑問請諮詢醫療人員，切勿於諮詢醫療人員前自行暫停或改變治療糖尿病的藥物。
醫療專業人員在處方canagliflozin前，應考量病人是否有其它因素導致其有截肢之較高風險。例如：先前有截肢、周邊血管疾病、神經病變或糖尿病足(diabetic foot)之病史。開立處方後，需監控病人服藥後之反應，若出現上述症狀，請立即停藥。
相關訊息與連結請參考FDA網址：
https://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm558605.htm
[Posted 5/16/2017]
資料來源：美國FDA之藥物安全警訊
資料提供：台大醫院藥劑部
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