2012年6月28日，安斯泰来制药宣布，美国食品药品管理局(FDA)已批准Myrbetriq(米拉贝隆)缓释片治疗伴急迫性尿失禁、尿急、尿频症状的膀胱过度活动症(OAB)。Myrbetriq是一种β3肾上腺素受体激动剂，每日服药1次。使用这种药物可使逼尿肌平滑肌松弛在膀胱充盈-排尿周期的存储期变得松弛，从而促进增加膀胱容量。
Myrbetriq的推荐起始剂量为25 mg，1次/d，可与食物同服也可在非进食时服用。Myrbetriq 25 mg通常会在开始治疗后8周内起效。根据个体的疗效和耐受性，剂量可增加至50 mg，1次/d。
研究者在一个以白人女性为主、平均年龄59岁的人群中对Myrbetriq进行了评估。受试者中52%此前曾使用抗毒蕈碱药物治疗OAB。Myrbetriq获得批准是基于3项安慰剂对照3期研究的安全性和有效性数据，在这些研究中，Myrbetriq 25 mg和50 mg可显著改善尿失禁和减少每24 h排尿次数。
在研究受试者中最常报告的不良反应包括高血压、鼻咽炎、泌尿系统感染和头痛。
使用Myrbetriq可增加血压。建议定期检测血压，特别是对于高血压患者。不建议对严重失控的高血压患者使用Myrbetriq。
上市后已有膀胱出口梗阻(BOO)患者和服用抗毒蕈碱药物者接受Myrbetriq治疗期间发生尿潴留的报告。对于临床显著性BOO患者应慎用Myrbetriq，对于正在服用抗毒蕈碱药物的OAB患者使用Myrbetriq也应谨慎。
Myrbetriq是一种温和的CYP2D6抑制剂，如果将Myrbetriq与美托洛尔、地昔帕明合用，CYP2D6的系统性暴露量会增加。因此，合理监测和调整剂量可能是必要的，尤其是在合用经CYP2D6代谢且治疗指数范围窄的药物时(如硫利达嗪、氟卡尼和普罗帕酮)。
INDICATIONS AND USAGE
Myrbetriq (mirabegron) is a beta-3 adrenergic agonist indicated for the treatment of overactive bladder (OAB) with symptoms of urge urinary incontinence, urgency, and urinary frequency.
IMPORTANT SAFETY INFORMATION
Myrbetriq can increase blood pressure. Periodic blood pressure determinations are recommended, especially in hypertensive patients. Myrbetriq is not recommended for use in severe uncontrolled hypertensive patients (defined as systolic blood pressure ≥ 180mm Hg and/or diastolic blood pressure ≥ 110mm Hg).
Urinary retention in patients with bladder outlet obstruction (BOO) and in patients taking antimuscarinic medications for the treatment of OAB has been reported in postmarketing experience in patients taking mirabegron. A controlled clinical safety study in patients with BOO did not demonstrate increased urinary retention in Myrbetriq patients; however, Myrbetriq should be administered with caution to patients with clinically significant BOO. Myrbetriq should also be administered with caution to patients taking antimuscarinic medications for the treatment of OAB.
Myrbetriq is a moderate CYP2D6 inhibitor, the systemic exposure to CYP2D6 substrates such as metoprolol and desipramine is increased when co-administered with Myrbetriq. Therefore, appropriate monitoring and dose adjustment may be necessary, especially with narrow therapeutic index drugs metabolized by CYP2D6, such as thioridazine, flecainide, and propafenone.
When initiating a combination of Myrbetriq and digoxin, prescribe the lowest dose of digoxin; monitor serum digoxin concentration to titrate digoxin dose to the desired clinical effect.
Most commonly reported adverse reactions (> 2% and
> placebo) were hypertension, nasopharyngitis, urinary tract infection and headache.