藥物警訊

Ampyra (dalfampridine): Drug Safety Communication - Seizure Risk for Multiple Sclerosis Patients

AUDIENCE: Neurology, Internal Medicine

FDA is updating health care professionals and the public about the risk of seizures in patients with multiple sclerosis (MS) who are starting Ampyra (dalfampridine). Using information received from post-market adverse event reports, FDA recently evaluated seizure risk in MS patients taking Ampyra (dalfampridine). The majority of seizures happened within days to weeks after starting the recommended dose and occurred in patients having no history of seizures. The FDA is updating the Ampyra drug label to clarify recommendations.

BACKGROUND: Ampyra was approved to improve walking in patients with MS. Seizures are a known side effect of Ampyra, and seizure risk increases with higher blood levels of the drug. Ampyra is eliminated from the body through the kidneys, and patients with kidney impairment may develop higher blood levels of the drug, thereby increasing their seizure risk.

RECOMMENDATION: FDA reminds health care professionals that there are age-related decreases in renal function, and mild renal impairment is common after age 50, even when serum creatinine is normal. Renal function should be assessed by estimating creatinine clearance. Ampyra should not be used in patients with a history of seizures or who have moderate to severe renal (kidney) impairment (measured as creatinine clearance [CrCl] less than or equal to 50 mL/min).

Additional information for Patients includes:

* Tell your health care professional if you have kidney problems.
* Your health care professional should order blood tests periodically to evaluate your kidney function.
* Do not take Ampyra if you have ever had a seizure.
* Ampyra tablets should be taken whole and not divided, crushed, chewed, or dissolved.
* Do not take double or extra doses of Ampyra if a dose is missed. Side effects, including seizures, are more frequent at higher doses.

Additional information for Health Care Professionals includes:

* Ampyra is contraindicated in patients with a history of seizures or with moderate to severe renal impairment (CrCl < 50 mL/min).
* The potential benefits of Ampyra treatment should be carefully considered against the risk of seizures before using Ampyra in patients with mild renal impairment (CrCl 51-80 mL/min).
* A patient's CrCl (calculated using the Cockroft-Gault equation) should be known before initiating Ampyra treatment and monitored at least annually whileAmpyra treatment continues, even when serum creatinine levels appear to be normal.
* Tell patients they should not take double or extra doses of Ampyra if a dose is missed. Adverse effects, including seizures, are more frequent at higherdoses.
* Ampyra should be discontinued permanently if a seizure occurs.

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

美國FDA更新有關多發性硬化症(multiple sclerosis, MS)的病人使用Ampyra (dalfampridine)引起癲癇發作(seizure)的風險的資訊。此項資訊是來自藥品上市後的不良反應通報，目前FDA正在評估該風險中。大 部分的案例是在服用Ampyra數天至數週內發生seizure，且病人以前沒有seizure的病史。FDA正在更新Ampyra仿單的相關資訊。

Ampyra被核准用於改善多發性硬化症病人的行走能力，該藥發生seizure副作用的風險與藥品血中濃度成正相關。Ampyra是經由腎臟排除，所以腎功能不佳的病人其藥品血中濃度可能會較高，發生seizure的風險也較高。

建議：FDA提醒醫療人員，腎功能會隨著年紀增長而降低；無論血清肌酐酸(serum creatinine)數值是否為正常，輕微的腎功能不全在年紀大於50歲的人是常見的，故應用creatinine clearance來評估腎功能較恰當。Ampyra不可用於有seizure病史或是中重度腎功能不全的病人(Clcr< 50 mL/min)。

給病人的資訊包括：

> 當您有腎臟問題時請記得告知醫療人員。
> 您的醫療人員應定期評估您的腎功能。
> 如果您曾經發生seizure請不要服用Ampyra。
> Ampyra錠劑須整顆吞服，請勿剝半、壓碎、咀嚼或將其溶解。
> 忘記服藥時，請勿一次吞服2倍或增加額外的藥量，因為當服用較高劑量時，包括seizure等副作用的發生率也較高。

給醫療人員的資訊包括：

> Ampyra對有seizure病史或是中重度腎功能不全的病人(Clcr< 50 mL/min)為禁忌症。
> 對輕微腎功能不全的病人(Clcr 51-80 mL/min)，須審慎評估使用Ampyra的利益與發生seizure風險。
> 在使用Ampyra前，須先評估病人的腎功能，且使用期間每年至少監測一次腎功能，無論serum creatinine是否為正常。
> 告知病人忘記服藥時，不可一次吞服2倍或增加額外的藥量，因為當服用較高劑量時，包括seizure等副作用的發生率也較高。
> 當病人發生seizure時，應永久停用Ampyra。

相關訊息與連結請參考FDA網址：http://www.fda.gov/Safety/MedWatch/SafetyInformation /SafetyAlertsforHumanMedicalProducts/ucm313055.htm
[Posted 07/23/2012]

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