Dosing and uses of Myrbetriq (mirabegron)
Adult dosage forms and strengths
tablet, extended-release
- 25mg
- 50mg
Overactive Bladder
Indicated for overactive bladder with symptoms of urge urinary incontinence, urgency, and urinary frequency
25 mg PO qDay
25 mg dose is typically effective within 8 weeks
May increase to 50 mg PO qDay based on individual efficacy and tolerability
Dosage modifications
Renal impairment
- Severe (CrCl 15-29 mL/min): Not to exceed 25 mg/day
- ESRD: Not recommended
Hepatic impairment
- Moderate (Child-Pugh B): Not to exceed 25 mg/day
- Severe (Child Pugh C): Not recommended
Pediatric dosage forms and strengths
Safety and efficacy not established
Myrbetriq (mirabegron) adverse (side) effects
>10%
Elevated BP occurring predominantly in patients with preexisting hypertension (7-11%)
1-10%
Dry mouth (3-9%)
Nasopharyngitis (3-4%)
UTI (3-6%)
Headache (2-4%)
Influenza (2-3%)
Constipation (2-3%)
Dizziness (2%)
Arthralgia (2%)
Cystitis (2%)
Back pain (1-3%)
Sinusitis (1-3%)
URTI (1-2%)
Arthralgia (1-2%)
Diarrhea (1-2%)
Tachycardia (1-2%)
Fatigue (1%)
Abdominal pain (0-1%)
Reports of neoplasms (0-1%)
<1%
Cardiac disorders (eg, palpitations, elevated BP)
Eye Disorders (eg, glaucoma, blurry vision)
GI disorders (eg, dyspepsia, gastritis, abdominal distension)
Rhinitis
Elevations in GGT, AST, ALT, LDH
Renal and urinary disorders (eg, nephrolithiasis, bladder pain)
Reproductive system disorders (eg, vulvovaginal pruritis, vaginal infection)
Skin and subcutaneous tissue disorders (eg, urticaria, leukocytoclastic vasculitis, rash, pruritus, purpura, lip edema)
Stevens-Johnson syndrome associated with increased serum ALT, AST and bilirubin
Postmarketing Reports
Urinary retention
Angioedema of the face, lips, tongue, and larynx, with or without respiratory symptoms
Nausea
Pruritus
Warnings
Contraindications
Hypersensitivity
Cautions
May increase blood pressure; monitor blood pressure periodically, especially in hypertensive patients; not recommended for use in severe uncontrolled hypertensive patients
Urinary retention may occur with bladder outlet obstruction or with concomitant antimuscarinic therapy; administer with caution in these patients
Angioedema of the face, lips, tongue, and/or larynx reported; may occur after the first dose or following multiple doses; promptly discontinue and initiate appropriate therapy to ensure a patent airway
Appropriate monitoring is recommended and dose adjustment may be necessary for narrow therapeutic index CYP2D6 substrates
Pregnancy and lactation
Pregnancy category: C
Lactation: Unknown whether distributed in breast milk; excretion in breast milk possible; discontinue nursing or the drug taking into account the importance of the drug to the mother
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Myrbetriq (mirabegron)
Mechanism of action
Beta-3 adrenergic receptor agonist which causes relaxation of the detrusor smooth muscle of the urinary bladder and increases bladder capacity
Absorption
Bioavailability: 29% for 25 mg dose, 35% for 50 mg dose
Peak Plasma Time: 3.5 hr
Peak Plasma Concentration: ~3-fold increase from 50 mg dose to 100 mg dose
AUC: ~2.5-fold increase from 50 mg dose to 100 mg dose
Distribution
Protein Bound: 71%
Vd: 1670 L
Metabolism
Via multiple pathways including dealkylation, (direct) glucuronidation, amide hydrolysis, and minimal oxidative metabolism in vivo by CYP2D6 and CYP3A4
Possible involvement of butylcholinesterase, uridine diphospho-glucuronosyltransferases (UGT) and alcohol dehydrogenase
Moderate CYP2D6 inhibitor
Elimination
Half-Life: 50 hr
Total body clearance: 57 L/hr (following IV administration)
Excretion: Urine 55%; feces 34%
Administration
Instructions
May take with or without food
Swallow whole with water, do not chew, divide, or crush tablet
