Mirabegron Avansor (Mirabegron)

Mirabegron acts on the β3‑adrenergic receptors of the bladder detrusor muscle, addressing overactive bladder and related symptoms.

• Overactive bladder: increases bladder capacity and reduces urgency and frequency.
• Urinary urgency: lessens sudden urge to void, improving control.
• Urinary frequency: decreases the number of daily voids, enhancing daily activities.

• Mirabegron selectively stimulates β3‑adrenergic receptors located on the detrusor smooth muscle of the urinary bladder. Activation of these receptors raises intracellular cyclic adenosine monophosphate (cAMP) levels, leading to relaxation of the detrusor during the storage phase. This relaxation expands functional bladder capacity, thereby diminishing involuntary contractions that cause urgency and frequency. The effect is dose‑dependent and persists throughout the dosing interval, providing continuous symptom control without directly affecting the sphincter or causing anticholinergic activity.

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

Common Side Effects

• Hypertension
• Nasopharyngitis
• Headache

Serious or Rare Side Effects

• Severe hypertension
• Urinary retention requiring catheterisation
• Angioedema

When prescribing Mirabegron, consider the following precautions:

• Renal impairment: assess renal function and consider dose adjustment.
• Hepatic impairment: use with caution in patients with moderate hepatic dysfunction.
• Hypertension: monitor blood pressure regularly during therapy.
• Concomitant use with strong CYP2D6 inhibitors: may increase mirabegron exposure.
• Pregnancy: safety not established; avoid unless benefits outweigh risks.
• Store at ambient temperature: keep in original container, protect from moisture and light.

Mirabegron can interact with several drug classes; awareness of these interactions helps optimise therapy.

Major Interactions (Avoid)

• Strong CYP2D6 inhibitors (e.g., paroxetine, fluoxetine): may markedly increase mirabegron plasma concentrations.
• Strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole): can raise exposure and risk of adverse events.
• Co‑administration with anticholinergic agents for bladder: may reduce therapeutic benefit.

Moderate Interactions (Monitor Closely)

• Diuretics: may enhance hypotensive effect, monitor blood pressure.
• Nitrates: additive vasodilatory effect, observe for dizziness.
• Other β3‑adrenergic agonists: potential additive pharmacodynamic effect.