Drug Guide
Mirabegron
Classification
Therapeutic: Urinary bladder modifier, antispasmodic
Pharmacological: Beta-3 adrenergic agonist
FDA Approved Indications
- Overactive bladder (OAB) with symptoms of urge urinary incontinence, urgency, and frequency
Mechanism of Action
Mirabegron selectively stimulates beta-3 adrenergic receptors in the detrusor muscle of the bladder, leading to relaxation of the muscle during the storage phase of the urinary cycle, which increases bladder capacity.
Dosage and Administration
Adult: Start with 25 mg once daily; may increase to 50 mg once daily based on response and tolerability.
Pediatric: Not approved for pediatric use.
Geriatric: Use with caution; consider starting at lower doses due to possible increased sensitivity.
Renal Impairment: Adjust dose for severe impairment—start at 25 mg, monitor closely.
Hepatic Impairment: No specific dose adjustment recommended.
Pharmacokinetics
Absorption: Rapidly absorbed, with maximum plasma concentrations reached in about 3 hours.
Distribution: 70% bound to plasma proteins.
Metabolism: Metabolized mainly by CYP3A4 and CYP2D6 pathways.
Excretion: Excreted primarily via urine (66%) and feces (20%).
Half Life: Approximately 50 hours, allowing once-daily dosing.
Contraindications
- Known hypersensitivity to mirabegron or any components.
- Severe uncontrolled hypertension.
Precautions
- Use cautiously in patients with hypertension, urinary retention, or gastric retention issues; monitor blood pressure regularly.
Adverse Reactions - Common
- Hypertension (Increased risk)
- Nasopharyngitis (Common)
- Urinary tract infection (Common)
Adverse Reactions - Serious
- Angioedema (Rare)
- Arrhythmias or tachycardia (Rare)
- Hemorrhage (Rare)
Drug-Drug Interactions
- Other antihypertensives, CYP2D6 inhibitors, substrates of CYP3A4
Drug-Food Interactions
- No specific interactions noted
Drug-Herb Interactions
- No specific interactions noted
Nursing Implications
Assessment: Monitor blood pressure, heart rate, and urinary symptoms.
Diagnoses:
- Risk of hypertension or cardiovascular issues.
- Impaired urinary elimination.
Implementation: Administer once daily, preferably with or without food. Educate patient on reporting side effects.
Evaluation: Assess for reduction in overactive bladder symptoms and monitor blood pressure and heart rate.
Patient/Family Teaching
- Take medication exactly as prescribed.
- Report new or worsening symptoms, especially hypertension, urinary retention, or allergic reactions.
- Avoid sudden discontinuation.
- Maintain regular follow-up appointments.
Special Considerations
Black Box Warnings:
- None currently noted for mirabegron.
Genetic Factors: No specific genetic considerations well-documented.
Lab Test Interference: May slightly increase blood pressure readings.
Overdose Management
Signs/Symptoms: Severe hypertension, tachycardia, dizziness, or chest pain.
Treatment: Discontinue medication, provide supportive care, monitor cardiovascular status, and treat symptoms accordingly.
Storage and Handling
Storage: Store at room temperature, 20°C to 25°C (68°F to 77°F).
Stability: Stable for the shelf life indicated on the package when stored properly.