藥物警訊

Kayexalate (sodium polystyrene sulfonate): Drug Safety Communication - FDA Requires Drug Interaction Studies

AUDIENCE: Internal Medicine, Nephrology, Cardiology

ISSUE: FDA is requiring the Kayexalate manufacturer to conduct studies to investigate Kayexalate's potential to bind to other medications administered by mouth – drug interactions that could affect how well the other medications work.

The approved labeling for Kayexalate describes its potential to decrease absorption of lithium and thyroxine; however, extensive drug-drug interaction studies with Kayexalate have not been performed. During FDA's review of another potassium-lowering drug, Veltassa (patiromer), we found that Veltassa bound to about half of the medications tested, some of which are commonly used in patients who require potassium-lowering drugs. Such binding could decrease the effects of these medications. The label for Veltassa contains a warning not to take other orally administered medications within 6 hours of taking Veltassa.

Similar to Veltassa, Kayexalate may also bind to other medications administered by mouth. To reduce this potential risk, prescribers and patients should consider separating Kayexalate dosing from other medications taken by mouth by at least 6 hours. This includes both prescription medications, such as antibiotics, blood pressure lowering agents and blood thinners, and those purchased over-the-counter without a prescription, such as antacids and laxatives. Health care professionals should monitor blood levels or clinical response to the other medications when appropriate.

If the studies conducted by the Kayexalate manufacturer, Concordia Pharmaceuticals, confirm significant interactions with other medications, FDA will require all manufacturers of sodium polystyrene sulfonate products to update the drug labels to include information about these drug interactions.

BACKGROUND: Kayexalate (sodium polystyrene sulfonate) and generic brands Kionex and SPS are used to treat hyperkalemia, a serious condition in which the amount of potassium in the blood is too high. They work by binding potassium in the large intestine so it can be removed from the body.

RECOMMENDATION: Prescribers and patients should consider separating Kayexalate dosing from other medications taken by mouth by at least 6 hours. Health care professionals should monitor blood levels or clinical response to the other medications when appropriate. Patients should not stop taking their potassium-lowering drugs without talking to their health care professional.

Read the MedWatch safety alert, including a link to the Drug Safety Communication, at:
http://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHuma...

Kayexalate (sodium polystyrene sulfonate)為治療高血鉀的藥品，此藥於大腸與體內鉀離子結合，藉此將鉀離子由體內排除。Kayexalate仿單中有提及服用此藥時可能降低lithium和thyroxine的吸收，但未有與其他藥物的交互作用報告。美國FDA在評估另一種降鉀藥品VeltassaTM (patiromer)時發現，VeltassaTM和其他藥品會產生交互作用並降低其療效，其中也包含常與降鉀藥品併用的藥物。在VeltassaTM仿單中有加註不可與其他口服藥品一起給予，應間隔6小時以上服用。美國FDA要求Kayexalate之廠商應進行交互作用研究以確認Kayexalate是否也會與其他口服藥品產生交互作用。

若研究結果證實Kayexalate與其他藥品會產生交互作用，美國FDA將要求所有sodium polystyrene sulfonate之廠商於仿單中新增此項訊息。

為了減少此風險，醫療人員和病人應將Kayexalate和其他口服藥品至少間隔6小時服用，包含處方藥及非處方藥。必要時醫療人員也應監測病人服藥後之血中濃度或臨床反應。在未經醫療人員評估前，病人不得自行停用正在服用之降鉀藥品。

相關訊息與連結請參考FDA網址：
http://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHuma...
[Posted 10/22/2015]

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