ST LOUIS (MD Consult) - On May 26, 2009, United Therapeutics Corporation announced that the US Food and Drug Administration (FDA) has approved Adcirca (tadalafil) for the treatment of pulmonary arterial hypertension (PAH). Adcirca is a phosphodiesterase type 5 (PDE5) inhibitor. It is indicated to improve exercise ability in patients with PAH whose disease falls into the World Health Organization's (WHO's) group I category, which encompasses patients with multiple forms of the disease including etiologies such as idiopathic and familial PAH as well as PAH associated with scleroderma and congenital heart disease.

In a randomized, double-blind, 16-week, placebo-controlled, phase 3 clinical trial of Adcirca for PAH, patients taking Adcirca 40 mg (administered as two 20-mg tablets) once daily achieved a 33-meter improvement in 6-minute walk distance compared with patients assigned to placebo. In addition, patients taking Adcirca 40 mg experienced less clinical worsening than patients in the placebo group. The most common adverse events in the trial were generally transient and were considered mild to moderate in intensity. These events included headache, flushing, nasopharyngitis, muscle pain, stomach upset, nasal congestion, respiratory tract infection, and pain in the arms, legs, or back.

PDE5 inhibitors, including tadalafil, have mild systemic vasodilatory properties that may result in transient decreases in blood pressure. Before prescribing Adcirca, physicians should carefully consider whether their patients with underlying cardiovascular disease could be adversely affected by such effects. Pulmonary vasodilators may significantly worsen the cardiovascular status of patients with pulmonary venoocclusive disease, and administration of Adcirca to these patients is not recommended. In addition, the drug should not be prescribed for patients taking nitrates because the combination could cause a sudden, unsafe drop in blood pressure.

In rare instances, some patients taking PDE5 inhibitors (including tadalafil) have reported a sudden decrease or loss of vision or hearing, and some men taking the drug have experienced an erection lasting longer than 4 hours. Patients taking Adcirca should be instructed to seek immediate medical attention if they experience any of these adverse effects. 

圣路易斯（MD Consult）——2009年5月26日，联合治疗公司（United Therapeutics Corporation）宣布，美国食品药品管理局（FDA）已经批准他达拉非（Adcirca）用于治疗肺动脉高压（PAH）。他达拉非是一种磷酸二脂酶5（PDE5）抑制剂。PAH已归入世界卫生组织（WHO）I类疾病中，根据病因学可分为多种类型，诸如先天性和家族性PAH，以及硬皮病相关性PAH和先天性心脏病相关性PAH。他达拉非适用于改善上述PAH患者的运动能力。

在一项历时16周、随机、双盲、安慰剂对照、III期临床试验中，为了探讨他达拉非对PAH的疗效，试验组患者服用他达拉非，每日1次，剂量为40mg（20mg片剂2片）；与安慰剂对照组患者相比，试验组患者6min行走距离提高了33m。此外，服用40mg 他达拉非的试验组患者临床病情恶化次数亦少于安慰剂对照组。试验中最常见的不良事件基本上为暂时性，在严重程度上可视为轻度至中度， 其中包括头痛、面部潮红、鼻咽炎、肌肉疼痛、腹部不适、鼻塞、呼吸道感染，以及双臂、双下肢或背部的疼痛。

他达拉非等PDE5抑制剂有轻度的全身性扩血管效应，可导致血压一过性下降。因此，对于有潜在的心血管疾病的患者，医生在开他达拉非处方前，应慎重考虑患者是否会因这种效应而受到不利影响。在患有肺静脉闭塞症的患者，应用肺血管扩张剂可能会使其心血管状态明显恶化，故这类患者不适宜应用他达拉非。此外，鉴于该药与硝酸盐类药物联用可能会导致血压骤然、不安全地下降，所以也不适用于服用硝酸盐类药物的患者。

某些服用PDE5抑制剂（包括他达拉非）的患者中有极少数报告了视力或听力突然下降或丧失，而某些服用该药的男性勃起曾长达4h以上。医生应告知患者，若其出现上述任何不良反应，要立即去就诊。

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