Information on REVATIO

REVATIO, a therapy for pulmonary arterial hypertension, is the citrate salt of sildenafil, a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type-5 (PDE5). Sildenafil is also marketed as VIAGRA® for erectile dysfunction.

INDICATIONS
REVATIO® is indicated for the treatment of pulmonary arterial hypertension (WHO Group I) to improve exercise ability and delay clinical worsening. The delay in clinical worsening was demonstrated when REVATIO was added to background epoprostenol therapy.

DOSAGE AND ADMINISTRATION
The recommended dose of REVATIO is 20 mg three times a day (TID). REVATIO tablets should be taken approximately 4-6 hours apart, with or without food.
In the clinical trial no greater efficacy was achieved with the use of higher doses. Treatment with doses higher than 20 mg TID is not recommended. Dosages lower than 20 mg TID were not tested. Whether dosages lower than 20 mg TID are effective is not known.

SIDE EFFECTS
The following serious adverse reactions are discussed elsewhere in the labeling:
Hypotension;Vision loss;Hearing loss;Priapism.
At doses higher than the recommended 20 mg TID, there was a greater incidence of some adverse events including flushing, diarrhea, myalgia and visual disturbances. Visual disturbances were identified as mild and transient, and were predominately color-tinge to vision, but also increased sensitivity to light or blurred vision.
The incidence of retinal hemorrhage at the recommended sildenafil 20 mg TID dose was 1.4% versus 0% placebo and for all sildenafil doses studied was 1.9% versus 0% placebo. The incidence of eye hemorrhage at both the recommended dose and at all doses studied was 1.4% for sildenafil versus 1.4% for placebo. The patients experiencing these events had risk factors for hemorrhage including concurrent anticoagulant therapy.

Storage
Store at 25°C (77°F); excursions permitted to 15-30°C (59-86°F).

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详细处方信息以本药内容附件PDF文件（20101610274628.pdf）的“原文Priscribing Information”为准
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                          部分中文瑞肺得处方信息（仅供参考）

药物成分：西地那非   
药理作用：西地那非是一种环状单磷酸鸟苷(cGMP)特异性第五型磷酸二酯酶(phospho-diesterase type 5, PDE5)的选择性抑制剂。PDE5负责分解细胞内的cGMP。西地那非可抑制PDE5，增加肺血管平滑肌细胞内的cGMP，促使血管扩张。   
药物动力学：口服吸收迅速，但经胃肠黏膜与肝脏代谢，绝对生体可用率约40％。在空腹状态下服药，可于30至120分钟(中位数60分钟)内到达最大血中浓度。当与高脂饮食并服，吸收速率减慢，但吸收总量不变。体内分布很广，稳定状态之分布体积为105公升。血浆蛋白结合率约96％。主要经由肝脏酵素CYP3A4和CYP2C9代谢；其主要代谢物对磷酸二酯酶的选择性与西地那非类似，约20％的药理作用来自于此代谢物。主要以代谢物形式经粪便排除(约为口服剂量的80％)，少部份由尿液排除(约为口服剂量的13％)。排除半衰期约4小时。   
适应症： 治疗肺动脉高血压，改善运动能力。   
不良反应： 常见的不良反应包括头痛、潮红、鼻塞、失眠、晕眩、眼睛周围疼痛、消化不良、腹泻、皮疹、肌肉疼痛、视觉异常。视觉异常一般是视觉发生轻微而短暂的变色，对光敏感度增加或视力模糊。   

注意事项
1.　Sildenafil用于有下列患者应特别谨慎：
(1)　最近6个月内发生心肌梗塞、中风或危及生命心律不整的患者。
(2)　发生不稳定型心绞痛之冠状动脉疾病患者。
(3)　严重高血压 (BP>170/110mmHg)或低血压(BP<90/50mmHg) 患者。
(4)　肺静脉阻塞性疾病(PVOD)患者。
(5)　阴茎构造畸形(如阴茎弯曲、海绵体纤维变性或Peyronie氏病)或容易引起阴茎异发性骨髓瘤或白血病) 患者。若发现阴茎持续勃起超过4小时，需立即寻求医疗协助，以免造成组织伤害，丧失勃起能力。
(6)　色素性视网膜炎患者。
(7)　出血性疾病或活动性消化性溃疡患者。
2.　Sildenafil与α阻断剂并用时须小心，可能会对血压下降产生加成效应。3.　在结缔组织继发的肺动脉高血压患者中，使用sildenafil发生鼻出血机率高于原发性肺动脉高血压患者。
4.　合并使用口服维生素K拮抗剂的患者，发生鼻出血的机率较高。
5. 服药期间若出现单眼或双眼视力减退，应立即就医。

禁忌
1.　正在使用任何剂型的有机硝酸盐患者(无论常规或间歇性服用)。
2.　对药品成份过敏者。
3.　同时服用蛋白酶抑制剂ritonavir(强效之CYP-3A4 抑制剂)，会使sildenafil血清浓度大幅升高，故不建议并用。  
  
交互作用
西地那非主要由肝脏酵素CYP3A4和CYP2C9代谢，因此，这类酵素抑制剂(如：itraconazole、ketoconazole、cimetidine、saquinavir、ritonavir…)会减少sildenafil的清除，而酵素诱导剂(如：rifampin、carbamazepine、phenytoin、 bosentan…)则会增加sildenafil的清除。
  
剂量及用法
1.若有特殊情况的病人（如肝肾功能不全、老年人等）需详细说明，密切监测药物的副作用和毒性。注射剂需详细说明给药方法及输注时间。
2.建议剂量：每日三次，每次服用20毫克。每次给药需间隔4到6小时，随餐或空腹服用皆可。肝、肾脏功能不全患者不需调整剂量。

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详细处方信息以本药内容附件PDF文件（20101610274628.pdf）的“原文Priscribing Information”为准
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更新于2010年1月7日