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部分中文安贝生坦信息资料（仅供参考）
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 详细处方信息以本药内容附件PDF文件（200821607363416.pdf）的“原文Priscribing Information”为准
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Ambrisentan是由美国Myogen公司开发的一种内皮素受体拮抗剂(ERA).2006年11月17日美国Gilead Science公司收购Myogen作为子公司,并获得ambrisentan 的所有权.该药物于2007年6月15日获得美国FDA批准,商品名为Letairis,口服用于治疗肺动脉高血压,其片剂具有5mg和10mg两种规格.

吉利德科学(GileadScience)公司的内皮素A型(ET)受体抑制剂安贝生坦片(商品名：Letairis)，用于治疗肺动脉高压。安贝生坦系一新分子实体，其化学名为(+)一(2s)一2一[(4，6一二甲基嘧啶一2一基)氧基卜3一甲氧3,3一二苯丙酸，分子式：c笠H笠N：0，分子量：378．42。薄膜包衣片规格：安贝生坦5mr,／片，10mr,／片。

内皮素一1(ET一1)是一强效自分泌和旁分泌肽。内皮素A型(ET^)和内皮素B型(ET。)两种亚型受体调节血管平滑肌和内皮素的ET一1作用。ETA主要作用是收缩血管和细胞增生，而ET主要作用则是舒张血管、抗内皮增生和清除ET一1。肺动脉高压患者血浆ET一1浓度可增高至10倍．与右心房平均血压和疾患的严重程度相关。肺动脉高压患者肺组织内ET一1和ET一1mRNA浓度可增至9倍，主要在肺动脉的内皮中。这些发现揭示，ET一1在肺动脉高压的病理形成和加重中起着关键作用。
安贝生坦是ETA受体高度亲和性(Ki=0．011nm)的拮抗剂，且对ET的选择性是对E1rB选择性的4000倍以上

对393例肺动脉高压患者进行了12周随机双盲安慰剂对照多中心临床研究，证明了安贝生坦片安全有效。

WARNING: POTENTIAL LIVER INJURY
LETAIRIS (ambrisentan) can cause elevation of liver aminotransferases (ALT and AST) to at least 3 times the upper limit of normal (ULN). LETAIRIS treatment was associated with aminotransferase elevations >3 x ULN in 0.8% of patients in 12-week trials and 2.8% of patients including long-term open-label trials out to one year. One case of aminotransferase elevations >3 x ULN has been accompanied by bilirubin elevations >2 x ULN. Because these changes are a marker for potentially serious liver injury, serum aminotransferase levels (and bilirubin if aminotransferase levels are elevated) must be measured prior to initiation of treatment and then monthly.

In the post-marketing period with another endothelin receptor antagonist (ERA), bosentan, rare cases of unexplained hepatic cirrhosis were reported after prolonged (>12 months) therapy. In at least one case with bosentan, a late presentation (after >20 months of treatment) included pronounced elevations in aminotransferases and bilirubin levels accompanied by non-specific symptoms, all of which resolved slowly over time after discontinuation of the suspect drug. This case reinforces the importance of strict adherence to the monthly monitoring schedule for the duration of treatment.

Elevations in aminotransferases require close attention. LETAIRIS should generally be avoided in patients with elevated aminotransferases (>3 x ULN) at baseline because monitoring liver injury may be more difficult. If liver aminotransferase elevations are accompanied by clinical symptoms of liver injury (such as nausea, vomiting, fever, abdominal pain, jaundice, or unusual lethargy or fatigue) or increases in bilirubin >2 x ULN, treatment should be stopped. There is no experience with the re-introduction of LETAIRIS in these circumstances.

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 详细处方信息以本药内容附件PDF文件（200821607363416.pdf）的“原文Priscribing Information”为准
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