ST LOUIS (MD Consult) - On August 21, 2009, Lundbeck Inc announced that the US Food and Drug Administration (FDA) has approved tablet and oral solution formulations of Sabril (vigabatrin). Sabril is approved for the treatment of infantile spasms and as adjunct therapy for adults with refractory complex partial seizures.

The precise mechanism of Sabril's antiseizure effect is unknown, but it is believed to be the result of its action as an irreversible inhibitor of gamma-aminobutyric acid transaminase (GABA-T), the enzyme responsible for the metabolism of the inhibitory neurotransmitter GABA. This action results in increased levels of GABA in the central nervous system. No direct correlation between plasma concentration and efficacy has been established. The duration of drug effect is presumed to be dependent on the rate of enzyme resynthesis rather than on the rate of elimination of the drug from the systemic circulation.

Sabril can cause permanent vision loss in infants, children, and adults. Sabril-induced vision loss includes progressive and permanent bilateral, concentric, visual field constriction in 30% or more of patients receiving therapy. This vision loss can range in severity from mild to severe—including tunnel vision to within 10 degrees of visual fixation—and can result in disability. Reports have also indicated that Sabril can damage the central retina and decrease visual acuity. The onset of visual disturbance is unpredictable and can occur within weeks of starting treatment (or sooner) or at any time during treatment, even after months or years.

Lundbeck and the FDA have established a comprehensive Risk Evaluation and Mitigation Strategy (REMS) to manage the risk of permanent vision loss associated with the product. The Sabril REMS specifies elements, such as restricted product distribution, required vision testing, and mandatory risk-benefit assessments, to manage the risk of vision loss associated with Sabril. As with all other antiepileptic drugs, the REMS also addresses the risk for suicidality associated with the class.

Lundbeck plans to launch Sabril in the United States during the third quarter of 2009. The medication will be available in 500-mg tablets for use in adults and in 500-mg packets of powder for oral solution for use in infants.

圣路易斯（MD Consult）——2009年8月21日，灵北制药有限公司宣布，美国食品药品管理局（FDA）已批准Sabril（中文商品名为喜保宁）（氨己烯酸）片剂和口服液上市。喜保宁获准作为婴儿痉挛治疗药和成人难治性癫痫局部复杂发作的辅助治疗药。

喜保宁抗癫痫作用的确切作用机制尚不清楚，但据认为是通过不可逆性抑制γ氨基丁酸氨基转移酶(GABA-T)的作用所致，此酶是参与抑制性神经递质GABA代谢的酶。这种抑制作用会导致中枢神经系统内GABA水平升高。尚未证实血浆浓度与疗效之间是否存在直接相关性。药效时程可能依赖于酶再合成速率而非药物自全身循环中清除的速率。

喜保宁可导致婴儿、儿童和成人永久性视力丧失。在接受喜保宁治疗的患者中，有逾30%出现双侧视野进展性或永久性向心性缩小等该药治疗所引发的视力丧失现象。视力丧失的严重程度可为轻度至重度——其中包括注视视野在10度内的隧道视野——可致残。报告也表明，喜保宁可破坏中央视网膜，降低视力。视觉紊乱的发病难以预测，可在开始治疗后的数周内（或更早）或治疗期内任何时间发生，甚至还可在数月或数年后发生。

灵北制药公司和FDA已形成了一个综合性风险评估和降低策略（REMS），控制与该药品使用相关的永久性视力丧失的风险。喜保宁REMS强调了一些要素，诸如限制药品分销，必要的视力检查，以及强制性风险获益评估，以便控制喜保宁关联的视力丧失风险。与其他抗癫痫药相同，REMS也阐明了与疾病相关的自杀风险。

灵北制药有限公司拟于2009年第三季度在美国推出喜保宁。届时，将有2种剂型上市：成人用的500 mg片剂和婴儿用的500mg粉剂包（冲成口服液服用）。

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