mirabegron

General

Pronunciation:
mye-ra-beg-ron


Trade Name(s)

  • Myrbetriq

Ther. Class.
urinary tract antispasmodics

Pharm. Class.
beta-adrenergic agonists

Indications

  • Overactive bladder (OAB), including urge urinary incontinence, urgency, and frequency (either as monotherapy or in combination with solifenacin).
  • Pediatric neurogenic detrusor overactivity (NDO).

Action

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

Therapeutic Effect(s):

  • Decreased symptoms of OAB.
  • Improved bladder capacity in NDO.

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: Adults– 50 hr;  Children– 26–31 hr.

TIME/ACTION PROFILE (effects on bladder)

ROUTEONSETPEAKDURATION
POunknown3–4 hr†24 hr
†Blood level.

Contraindication/Precautions

Contraindicated in:

  • Hypersensitivity;
  • Severe uncontrolled hypertension;
  • End-stage renal disease (eGFR <15 mL/min/1.73 m2  or requiring dialysis);
  • Severe hepatic impairment (Child-Pugh Class C).

Use Cautiously in:

  • Hypertension;
  • Bladder outlet obstruction/concurrent antimuscarinics (↑ risk of urinary retention);
  • Concurrent use of antimuscarinics used to treat OAB;
  • OB:  Safety not established in pregnancy;
  • Lactation: Safety not established in breastfeeding
  • Pedi:  Children <3 yr (safety and effectiveness not established).

Adverse Reactions/Side Effects

CV: ↑ BP, tachycardia

EENT: nasopharyngitis

GI: constipation, diarrhea, nausea

GU: urinary tract infection

Neuro: dizziness, headache

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 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

The extended-release tablets and extended-release oral suspension are NOT interchangeable and should NOT be combined.

Overactive Bladder

PO (Adults): 25 mg once daily; may ↑ to 50 mg once daily, if needed, after 4–8 wk.

Renal Impairment 
PO (Adults): eGFR 15–29 mL/min/m2 – 25 mg once daily (max dose = 25 mg/day).

Hepatic Impairment 
PO (Adults): Moderate hepatic impairment (Child-Pugh Class B)– 25 mg once daily (max dose = 25 mg/day).

Neurogenic Detrusor Overactivity

PO (Children ≥3 yr and ≥35 kg): Extended-release tablets– 25 mg once daily; may ↑ to 50 mg once daily, if needed, after 4–8 wk.  Extended-release oral suspension (granules)– 48 mg once daily; may ↑ to 80 mg once daily, if needed after 4–8 wk.

PO (Children ≥3 yr and 22–<35 kg): Extended-release oral suspension (granules)– 32 mg once daily; may ↑ to 64 mg once daily, if needed after 4–8 wk.

PO (Children ≥3 yr and 11–<22 kg): Extended-release oral suspension (granules)– 24 mg once daily; may ↑ to 48 mg once daily, if needed after 4–8 wk.

Renal Impairment 
PO (Children ≥3 yr and ≥35 kg): eGFR 15–29 mL/min/m2 – Extended–release tablets: 25 mg once daily (max dose = 25 mg/day); Extended-release oral suspension (granules): 48 mg once daily (max dose = 48 mg/day).

Renal Impairment 
PO (Children ≥3 yr and 22–<35 kg): eGFR 15–29 mL/min/m2 – Extended–release oral suspension (granules): 32 mg once daily (max dose = 32 mg/day).

Renal Impairment 
PO (Children ≥3 yr and 11–<22 kg): eGFR 15–29 mL/min/m2 – Extended–release oral suspension (granules): 24 mg once daily (max dose = 24 mg/day).

Hepatic Impairment 
PO (Children ≥3 yr and ≥35 kg): Moderate hepatic impairment (Child-Pugh Class B)– Extended–release tablets: 25 mg once daily (max dose = 25 mg/day); Extended-release oral suspension (granules): 48 mg once daily (max dose = 48 mg/day).

Hepatic Impairment 
PO (Children ≥3 yr and 22–<35 kg): Moderate hepatic impairment (Child-Pugh Class B)– Extended–release oral suspension (granules): 32 mg once daily (max dose = 32 mg/day).

Hepatic Impairment 
PO (Children ≥3 yr and 11–<22 kg): Moderate hepatic impairment (Child-Pugh Class B)– Extended–release oral suspension (granules): 24 mg once daily (max dose = 24 mg/day).

Availability

Extended-release tablets: 25 mg, 50 mg

Extended-release oral suspension (granules): 8 mg/mL

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.

Implementation

  • Tablets and granules are different products. Do not interchange, substitute, or combine.

OAB

  • PO 

    Administer without regard to food.

    •  DNC: Swallow tablets whole with water; do not break, crush, or chew.

NDO

  • Pediatric patients weighing ≥35 kg may use tablets or granules. Administer as an extended-release oral suspension once daily.

    •  DNC: Swallow tablets whole with water; do not break, crush, or chew.
    • Administer granules for patients weighing <35 kg. Granules are prepared as an extended-release oral suspension with a concentration of 8 mg/mL. Shake bottle for 1 min then let stand until foam on top of suspension is gone (about 1–2 min). Administer within 1 hr after preparation with food once daily; do not save dose for later.

Patient/Family Teaching

  • Instruct patient to take mirabegron as directed. If a dose is missed, take as soon as remembered unless >12 hrs since missed dose. If >12 hrs since missed dose, omit dose and take next dose at scheduled time. 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 females of reproductive potential to notify health care professional if pregnancy is planned or suspected or if breastfeeding.

Evaluation/Desired Outcomes

Decreased urinary frequency, urgency, and urge incontinence.

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