Mirabegron Cf (Mirabegron)

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

• Overactive bladder: improves bladder capacity and reduces urgency episodes.
• Urinary urgency: decreases the frequency of sudden, compelling urges to void.
• Urinary frequency: lowers the number of daily voids.
• Urge urinary incontinence: reduces involuntary leakage associated with urgency.

• Mirabegron selectively stimulates β3‑adrenergic receptors located in the detrusor smooth muscle of the urinary bladder. Activation of these receptors leads to relaxation of the detrusor during the storage phase of the bladder fill‑cycle, thereby increasing functional bladder capacity and reducing involuntary contractions that cause urgency and incontinence.

Adverse reactions reported with mirabegron include both common and less frequent events.

Common Side Effects

• Hypertension: increase in blood pressure, often mild to moderate.
• Nasopharyngitis: inflammation of the nasal passages and throat.
• Headache: mild to moderate intensity.
• Dry mouth: reduced salivation.
• Constipation: decreased bowel motility.
• Dizziness: sensation of light‑headedness.

Serious or Rare Side Effects

• Severe hypertension: marked elevation of blood pressure requiring medical intervention.
• Urinary retention: difficulty emptying the bladder.
• Cardiovascular events: arrhythmias or angina.
• Acute angle‑closure glaucoma: rapid increase in intra‑ocular pressure.
• Allergic reactions: rash, pruritus, or anaphylaxis.
• Hepatotoxicity: abnormal liver function tests.

When prescribing mirabegron, clinicians should consider the following precautions.

• Blood pressure monitoring: check baseline and periodic readings, especially in hypertensive patients.
• Cardiovascular assessment: evaluate for existing heart disease before initiation.
• Renal function: adjust use in patients with severe renal impairment.
• Hepatic function: use cautiously in moderate to severe liver disease.
• Drug interactions: review concomitant medications that affect blood pressure or CYP2D6 metabolism.
• Store below 25°C: keep in the original packaging, protect from moisture and direct sunlight.

Mirabegron may interact with other medicines; notable interactions are grouped below.

Major Interactions (Avoid)

• Strong CYP2D6 inhibitors (e.g., fluoxetine, paroxetine): may increase mirabegron exposure.
• Antihypertensive agents (e.g., beta‑blockers, ACE inhibitors): additive blood‑pressure‑lowering effect.

Moderate Interactions (Monitor Closely)

• CYP3A4 substrates (e.g., midazolam, clarithromycin): potential modest increase in plasma levels.
• Diuretics: may enhance risk of hypertension.
• Anticholinergic drugs: overlapping urinary side‑effect profile.
• NSAIDs: may affect renal function when combined with mirabegron.