What is the recommended treatment and dosage for overactive bladder using Myrbetriq (mirabegron)?

Mirabegron (Myrbetriq) Treatment for Overactive Bladder

The recommended treatment for overactive bladder using Myrbetriq (mirabegron) is to start with 25 mg extended-release tablets once daily, which can be increased to 50 mg once daily after 4-8 weeks if needed for symptom control. 1

Dosing Algorithm

• Start with mirabegron extended-release tablets 25 mg orally once daily 1
• After 4-8 weeks, if needed, increase to maximum dosage of 50 mg orally once daily 1
• For adult patients, tablets should be swallowed whole with water and can be taken with or without food 1
• For patients with renal impairment:
  • eGFR 30-89 mL/min/1.73 m²: Start with 25 mg, maximum 50 mg 1
  • eGFR 15-29 mL/min/1.73 m²: Start with 25 mg, maximum 25 mg 1
  • eGFR <15 mL/min/1.73 m² or requiring dialysis: Not recommended 1
• For patients with hepatic impairment:
  • Child-Pugh Class A (mild): Start with 25 mg, maximum 50 mg 1
  • Child-Pugh Class B (moderate): Start with 25 mg, maximum 25 mg 1
  • Child-Pugh Class C (severe): Not recommended 1

Efficacy and Benefits

• Mirabegron significantly reduces incontinence episodes, micturition frequency, and urgency episodes compared to placebo 2, 3
• Improvements in symptoms can be observed as early as 4 weeks after treatment initiation 4
• Mirabegron has demonstrated safety and efficacy in older patients with overactive bladder and multiple comorbidities 5, 6
• Cardiovascular safety analysis has shown no significant concerns with mirabegron treatment 5, 6

Advantages Over Antimuscarinic Agents

• Mirabegron has a different mechanism of action as a β3-adrenoreceptor agonist compared to antimuscarinic agents 4
• The incidence of dry mouth with mirabegron is similar to placebo (0.5-2.1%) and significantly lower than with antimuscarinic agents like tolterodine (8.6%) 2, 4, 3
• Mirabegron may be an effective alternative for patients who are poor responders to antimuscarinic agents or intolerant of their adverse effects 7

Combination Therapy

• Combination therapy with mirabegron 50 mg plus solifenacin 5 mg (an antimuscarinic) has demonstrated superior efficacy compared to either monotherapy alone for reducing urinary incontinence episodes and micturitions 8, 5
• The combination of solifenacin/mirabegron 50 mg was statistically significantly superior to both monotherapies for urgency urinary incontinence episodes, urgency episodes, and nocturia 8
• Treatment-emergent adverse events were reported more frequently in the combination group (49%) than in the mirabegron monotherapy group (41%) or solifenacin monotherapy group (44%) 8

Common Side Effects and Monitoring

• Most common adverse events include hypertension, nasopharyngitis, and urinary tract infection 4, 6
• Dry mouth incidence is similar to placebo, making mirabegron a good option for patients who experienced this side effect with antimuscarinic agents 2, 4
• Regular monitoring of blood pressure is recommended, especially in patients with pre-existing hypertension 6

Treatment Approach

• First-line therapy should include behavioral interventions such as bladder training, pelvic floor exercises, and fluid management 5, 9
• For pharmacological treatment, mirabegron 25-50 mg is recommended as an effective option with fewer anticholinergic side effects 10
• In men with both BPH and OAB symptoms, alpha blockers are first-line therapy, with mirabegron added if storage symptoms persist 9

Mirabegron represents an effective treatment option for overactive bladder with a favorable tolerability profile, particularly for patients who cannot tolerate the anticholinergic side effects of traditional OAB medications.