Mirabegron

Mirabegron is used to treat conditions related to overactive bladder by targeting β3‑adrenergic receptors in the bladder detrusor muscle.

• Overactive bladder: increases functional bladder capacity and reduces urgency episodes.
• Urinary urgency: lessens the sudden, compelling need to void.
• Urinary frequency: decreases the number of daily voids, improving quality of life.

• Mirabegron selectively activates β3‑adrenergic receptors located on detrusor smooth muscle. Receptor activation raises intracellular cyclic AMP, leading to relaxation of the detrusor muscle during the storage phase of the micturition cycle. This relaxation expands bladder capacity and diminishes involuntary contractions, thereby reducing urgency, frequency, and urge incontinence in patients with overactive bladder.

Adverse reactions may occur with Mirabegron use. Patients should be aware of both common and serious possibilities.

Common Side Effects

• Hypertension: elevated blood pressure readings.
• Headache: mild to moderate intensity.
• Nasopharyngitis: inflammation of the nasal passages and throat.
• Urinary tract infection: signs of infection such as dysuria.
• Constipation: reduced bowel movements.
• Dry mouth: decreased salivation.

Serious or Rare Side Effects

• Angioedema: swelling of face, lips, or tongue.
• Severe hypertension: rapid and significant blood pressure rise.
• Urinary retention: difficulty initiating or maintaining urine flow.
• Tachycardia: increased heart rate.
• Allergic reactions: rash, pruritus, or anaphylaxis.
• Myocardial infarction: rare cardiac events.

Before initiating Mirabegron, clinicians should consider several safety measures.

• Blood pressure monitoring: check baseline and periodic readings.
• Renal function assessment: evaluate creatinine clearance in patients with kidney disease.
• Urinary retention evaluation: ensure no pre‑existing obstruction.
• Uncontrolled hypertension: avoid use in patients with severe hypertension.
• Concomitant β‑agonists: use caution when combined with other β‑adrenergic agents.
• Store at ambient temperature: keep in the original pack, protect from moisture.

Mirabegron may interact with other medicines; some combinations require avoidance while others need close monitoring.

Major Interactions (Avoid)

• Strong CYP2D6 inhibitors (e.g., paroxetine, fluoxetine): increase Mirabegron exposure.
• Norepinephrine reuptake inhibitors (e.g., duloxetine): may raise blood pressure.
• Other β‑agonists: additive cardiovascular effects.

Moderate Interactions (Monitor Closely)

• Diuretics: potential alterations in fluid balance.
• Anticholinergics: heightened risk of urinary retention.
• NSAIDs: may affect renal function, especially in susceptible patients.