Mirabegron Zentiva (Mirabegron)

Mirabegron is used to treat conditions within the overactive bladder disease family, reducing urinary urgency and frequency.

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

• Mirabegron selectively stimulates β3‑adrenergic receptors located in the detrusor smooth muscle of the urinary bladder. Activation of these receptors increases cyclic adenosine monophosphate (cAMP) levels, leading to relaxation of the detrusor during the storage phase of the bladder fill‑void cycle. This relaxation expands functional bladder capacity and reduces involuntary contractions, thereby alleviating symptoms of overactive bladder. The effect is dose‑dependent and does not involve muscarinic pathways, distinguishing it from antimuscarinic agents.

Mirabegron may cause a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Hypertension: increase in blood pressure, often mild.
• Headache: transient headache episodes.
• Nasopharyngitis: upper respiratory tract infection symptoms.
• Constipation: reduced bowel movements.
• Dry mouth: decreased salivation.

Serious or Rare Side Effects

• Severe hypertension or hypertensive crisis: marked elevation of blood pressure requiring medical intervention.
• Tachycardia: rapid heart rate that may be symptomatic.
• Angioedema: swelling of face, lips, tongue or airway.
• Urinary retention: difficulty emptying the bladder, potentially leading to obstruction.
• Allergic reactions: rash, pruritus, or anaphylaxis.

When prescribing Mirabegron, clinicians should observe several safety considerations to minimize risk.

• Monitor blood pressure: check baseline and periodic measurements during therapy.
• Assess renal function: adjust use in patients with severe renal impairment.
• Review cardiovascular history: avoid in uncontrolled hypertension or recent myocardial infarction.
• Avoid concomitant strong CYP2D6 inhibitors: may increase Mirabegron exposure.
• Caution with anticholinergic agents: combined use can increase urinary retention risk.
• Store at room temperature: keep in original container, protect from moisture and light.

Mirabegron can affect the pharmacokinetics of several drugs, requiring attention to potential interactions.

Major Interactions (Avoid)

• Strong CYP2D6 inhibitors (e.g., paroxetine, fluoxetine): may raise Mirabegron plasma levels.
• Digoxin: Mirabegron can increase digoxin concentrations, risking toxicity.
• Antihypertensive agents (e.g., beta‑blockers): additive blood pressure‑lowering effect may cause hypotension.

Moderate Interactions (Monitor Closely)

• Moderate CYP3A4 inhibitors (e.g., erythromycin, ketoconazole): may modestly increase Mirabegron exposure.
• CYP3A4 inducers (e.g., rifampicin, carbamazepine): may reduce efficacy by lowering drug levels.
• Other bladder antimuscarinics: combined therapy may heighten risk of urinary retention.