mirabegron

General

Pronunciation:
mye-ra-beg-ron


Trade Name(s)

  • Myrbetriq

Ther. Class.
urinary tract antispasmodics

Pharm. Class.
beta-adrenergic agonists

Indications

Treatment of symptoms of overactive bladder (OAB) including urge urinary incontinence, urgency, and frequency.

Action

  • Acts as a selective beta-3 adrenergic agonist.
  • Increases bladder capacity by relaxing detusor smooth muscle during storage phase of bladder fill-void cycle.

Therapeutic Effect(s):

Decreased symptoms of OAB.

Pharmacokinetics

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)

ROUTEONSETPEAKDURATION
POunknown3.5 hr†24 hr
†Blood level.

Contraindication/Precautions

Contraindicated in:

  • Hypersensitivity;
  • 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:

  • Hypertension;
  • 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

EENT: nasopharyngitis

CV: ↑ BP, tachycardia

GI: constipation, diarrhea, nausea

GU: urinary tract infection

Misc: ANGIOEDEMA

* CAPITALS indicate life-threatening.
Underline indicate most frequent.

Interactions

Drug-Drug

  • 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).

Route/Dosage

PO: (Adults) 25 mg once daily; may be ↑ to 50 mg once daily based on need/tolerance after 8 wk.

Renal Impairment
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.

Availability

Extended-release tablets: 25 mg, 50 mg

Assessment

  • 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.

Potential Diagnoses

Implementation

  • PO: Administer without regard to food.
    • Swallow tablets whole with water; do not break, crush, or chew.

Patient/Family Teaching

  • 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.

Evaluation/Desired Outcomes

Decreased urinary frequency, urgency, and urge incontinence.

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