urinary tract antispasmodics
Treatment of symptoms of overactive bladder (OAB) including urge urinary incontinence, urgency, and frequency.
- Acts as a selective beta-3 adrenergic agonist.
- Increases bladder capacity by relaxing detusor smooth muscle during storage phase of bladder fill-void cycle.
Decreased symptoms of OAB.
Absorption: 29–35% absorbed following oral administration.
Distribution: Widely distributed.
Metabolism and Excretion: Extensively metabolized, 6% excreted unchanged in urine (25 mg dose), remainder excreted in urine and feces as metabolites.
Half-life: 50 hr.
TIME/ACTION PROFILE (effects on bladder)
|PO||unknown||3.5 hr†||24 hr|
- Severe uncontrolled hypertension;
- End-stage renal disease or severe hepatic impairment (Child-Pugh Class C);
- Lactation: Probably enters breast milk and may cause adverse reactions in infant.
Use Cautiously in:
- Bladder outlet obstruction/concurrent antimuscarics (↑ risk of urinary retention);
- Concurrent use of antimuscarinics used to treat OAB;
- OB: Use only if potential maternal benefit outweighs risk to etus;
- Pedi: Safety and effectiveness not established.
Adverse Reactions/Side Effects
CNS: dizziness, headache
CV: ↑ BP, tachycardia
GI: constipation, diarrhea, nausea
GU: urinary tract infection
* CAPITALS indicate life-threatening.
Underline indicate most frequent.
- Acts as a moderate inhibitor of the CYP2D6 enzyme system.
- May ↑ levels and risk of adverse reactions of drugs metabolized by the the CYP2D6 enzyme system including desipramine, flecainide, metoprolol, propafenone, and thioridazine.
- May ↑ levels and risk of toxicity with digoxin; use lowest effective level of digoxin/monitor serum levels).
PO: (Adults) 25 mg once daily; may be ↑ to 50 mg once daily based on need/tolerance after 8 wk.
PO: (Adults) CCr 15–20 mL/min–Dose should not exceed 25 mg/day.Hepatic Impairment
PO: (Adults) Moderate hepatic impairment (Child-Pugh Class B)–Dose should not exceed 25 mg/day.
Extended-release tablets: 25 mg, 50 mg
- Assess patient for urinary urgency, frequency, and urge incontinence periodically during therapy.
- Monitor BP prior to starting and periodically during therapy; may cause ↑ BP.
- Monitor for signs and symptoms of angioedema (swelling of face, lips, tongue and/or larynx). Discontinue mirabegron and treat symptomatically.
- PO: Administer without regard to food.
- Swallow tablets whole with water; do not break, crush, or chew.
- Instruct patient to take mirabegron as directed. If a dose is missed, omit dose and begin taking next day; do not take 2 doses on the same day. Advise patient to read Patient Information sheet prior to starting and with each Rx refill in case of changes.
- Inform patient that mirabegron may cause an increase in BP. Advise patient to have BP checked periodically during therapy.
- May cause dizziness. Caution patient to avoid driving or other activities requiring alertness until response to medication is known.
- Advise patient to notify health care professional if difficulty emptying bladder occurs.
- Advise patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult with health care professional before taking other medications.
- Advise female patients to notify health care professional if pregnancy is planned or suspected or if breast feeding.
Decreased urinary frequency, urgency, and urge incontinence.
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