Mirabegron Doc (Mirabegron)

Mirabegron is indicated for conditions affecting bladder storage function and is used in the management of overactive bladder.

• Overactive bladder: increases bladder capacity and reduces urgency episodes.
• Urinary urgency: lessens the sudden need to void.
• Urinary frequency: decreases the number of daily voids.
• Urge urinary incontinence: reduces involuntary leakage episodes.

• Mirabegron selectively stimulates β3‑adrenergic receptors in the detrusor smooth muscle of the bladder. Activation of these receptors triggers cyclic AMP production, leading to relaxation of the detrusor during the storage phase, thereby increasing functional bladder capacity and reducing involuntary contractions associated with overactive bladder.

Adverse reactions may occur with mirabegron therapy and are categorized by frequency.

Common Side Effects

• Hypertension: elevated blood pressure readings.
• Nasopharyngitis: mild upper respiratory tract infection symptoms.
• Headache: persistent or intermittent head pain.
• Constipation: reduced bowel movements.
• Dry mouth: decreased salivation.
• Urinary retention: difficulty initiating or completing voiding.

Serious or Rare Side Effects

• Severe hypertension: markedly high blood pressure requiring medical attention.
• Tachycardia: rapid heart rate that may be symptomatic.
• Angioedema: swelling of face, lips, or tongue.
• Acute urinary retention leading to bladder outflow obstruction.
• Myocardial infarction: rare cardiac event.
• Anaphylactic reaction: severe allergic response.

Before initiating mirabegron, clinicians should evaluate patient-specific risk factors and monitor for potential complications.

• Cardiovascular assessment: check baseline blood pressure and heart rate.
• Monitor blood pressure: regularly assess during therapy.
• Renal function review: adjust use in patients with impaired renal clearance.
• Hepatic impairment: consider dose modification for liver disease.
• Avoid use in uncontrolled hypertension: contraindicated in patients with markedly elevated BP.
• Store at below 25°C: keep in the original pack, protect from moisture.

Mirabegron can affect the pharmacokinetics of several co‑administered drugs, requiring attention to interaction severity.

Major Interactions (Avoid)

• Strong CYP2D6 inhibitors (e.g., paroxetine, fluoxetine): may increase mirabegron exposure.
• Potent CYP3A4 inhibitors (e.g., ketoconazole, itraconazole): can raise plasma concentrations.
• Co‑administration with other β3‑adrenergic agonists: risk of additive cardiovascular effects.

Moderate Interactions (Monitor Closely)

• CYP2D6 substrate drugs (e.g., metoprolol): may have altered levels.
• CYP3A4 substrate drugs (e.g., midazolam): monitor for increased effects.
• Antihypertensive agents: possible additive blood pressure lowering.
• Diuretics: monitor fluid balance and electrolytes.
• NSAIDs: watch for renal function changes.