Mirabegron Doc (Mirabegron)

Mirabegron is used to manage symptoms of overactive bladder and related urinary disorders.

• Overactive bladder: reduces urgency episodes and increases bladder capacity.
• Urinary urgency: lessens the sudden need to void.
• Urge urinary incontinence: decreases involuntary leakage episodes.
• Frequency: lowers the number of daily voids.
• Nocturia: improves nighttime bladder control.
• Detrusor overactivity: relaxes detrusor muscle to improve storage.

• Mirabegron selectively activates β3‑adrenergic receptors located on detrusor smooth muscle cells in the urinary bladder. Stimulation of these receptors increases intracellular cyclic adenosine monophosphate (cAMP), leading to relaxation of the detrusor muscle during the storage phase of the micturition cycle. This relaxation expands functional bladder capacity and reduces involuntary contractions that cause urgency and urge incontinence. The effect is dose‑dependent and does not involve cholinergic pathways.

Common and serious adverse reactions have been reported with mirabegron use.

Common Side Effects

• Hypertension: mild to moderate increase in blood pressure.
• Headache: transient and usually resolves without intervention.
• Nasopharyngitis: upper respiratory tract infection symptoms.
• Constipation: reduced bowel motility.
• Dry mouth: decreased salivation.

Serious or Rare Side Effects

• Severe hypertension: marked elevation requiring medical attention.
• Urinary retention: inability to void, may need catheterization.
• Tachycardia: rapid heart rate that can be symptomatic.
• Angioedema: swelling of face, lips or airway.
• Elevated hepatic enzymes: abnormal liver function tests.

Before initiating mirabegron, clinicians should consider several safety aspects.

• Assess blood pressure: monitor baseline and periodic readings due to risk of hypertension.
• Review cardiac history: use cautiously in patients with arrhythmias or uncontrolled heart disease.
• Evaluate renal function: dose adjustment may be needed in severe impairment.
• Consider drug interactions: avoid concomitant use with strong CYP2D6 inhibitors.
• Pregnancy and lactation: safety not established; prescribe only if benefit outweighs risk.
• Store at ambient temperature: keep below 25 °C, in original packaging, protected from moisture and light.

Mirabegron may interact with several medication classes.

Major Interactions (Avoid)

• Strong CYP2D6 inhibitors (paroxetine, fluoxetine, quinidine): may increase mirabegron exposure.
• Co‑administration with other β‑adrenergic agonists (e.g., albuterol): may potentiate cardiovascular effects.

Moderate Interactions (Monitor Closely)

• Moderate CYP2D6 inhibitors (duloxetine, sertraline): may modestly raise mirabegron levels.
• Antihypertensive agents (ACE inhibitors, ARBs): mirabegron may attenuate blood‑pressure‑lowering effect.
• Diuretics: monitor for additive changes in blood pressure.