Beta-3 Adrenoceptor Agonist Pregnancy: Not recommended during pregnancy, and not recommended in women of childbearing potential not using contraception. There are no or limited data in pregnant women and animal studies have shown reproductive toxicity. Should not be used during breast-feeding.

Mirabegron (Overactive Bladder — Elderly)

Brand names: Betmiga

Mirabegron is a beta-3 adrenoceptor agonist used for overactive bladder, offering an alternative to antimuscarinics with a different side-effect profile.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 50 mg once daily (overactive bladder, adults including elderly patients)

Route: Oral (prolonged-release tablet, taken with liquids and swallowed whole — not to be chewed, divided or crushed; may be taken with or without food)

Frequency: Once daily

The SPC states the recommended dose for overactive bladder in adults, including elderly patients, is 50 mg once daily — no separate elderly dose reduction is specified. Not recommended for use in patients with end stage renal disease (eGFR < 15 mL/min/1.73 m2), patients requiring haemodialysis, or patients with severe hepatic impairment (Child-Pugh Class C). Hepatic impairment dosing in adult OAB: mild (Child-Pugh A) 50 mg; moderate (Child-Pugh B) 25 mg; severe not recommended. In patients with mild to moderate renal impairment or mild hepatic impairment concomitantly receiving strong CYP3A inhibitors, the recommended dose is no more than 25 mg; not recommended in patients with severe renal impairment or moderate hepatic impairment concomitantly receiving strong CYP3A inhibitors. Mirabegron can increase blood pressure — measure blood pressure at baseline and periodically during treatment, especially in hypertensive patients. Caution in patients with a known history of QT prolongation or taking QT-prolonging medicines, in clinically significant bladder outlet obstruction, and in patients taking antimuscarinics for OAB (urinary retention reported post-marketing). Missed dose: take unless more than 12 hours have passed, in which case skip it and take the next dose at the usual time. Safety and efficacy in children below 18 years with OAB have not been established; the SPC gives separate weight-based posology for neurogenic detrusor overactivity in patients 3 to less than 18 years. Note: eMC §4.5 (interactions) was truncated in this source bundle; interaction entries below are marked with their source.

Dose adjustments

Renal

Adult OAB daily dosing by renal function: mild/moderate impairment (eGFR 30-89 mL/min/1.73 m2) 50 mg; severe impairment (eGFR 15-29 mL/min/1.73 m2) 25 mg; ESRD (eGFR < 15 mL/min/1.73 m2) or requiring haemodialysis — not recommended. With concomitant strong CYP3A inhibitors: no more than 25 mg in mild to moderate renal impairment, and not recommended in severe renal impairment.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

Mirabegron extended-release tablets and mirabegron for extended-release oral suspension are two different products and they are not substitutable on a milligram-per-milligram basis. Select the recommended product (mirabegron extended-release tablets or mirabegron for extended-release oral suspension) based on the indication. OAB in Adults The recommended starting dose of mirabegron extended-release tablets is 25 mg orally once daily. ( 2.2 ) After 4 to 8 weeks, the mirabegron extended-release tablets dose may be increased to 50 mg orally once daily. ( 2.2 ) Adult Patients with Renal or Hepatic Impairment: Refer to the full prescribing information for recommended dosage. ( 2.4 ) …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2025-09-26. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Contraindications

Hypersensitivity to the active substance or to any of the excipients
Severe uncontrolled hypertension, defined as systolic blood pressure ≥ 180 mmHg and/or diastolic blood pressure ≥ 110 mmHg

Side effects

Tachycardia (1.2% at 50 mg; most common reported adverse reaction)
Urinary tract infection (2.9% at 50 mg)
Headache and dizziness
Nausea, constipation and diarrhoea
Blood pressure increased; atrial fibrillation (serious, 0.2%); urinary retention and angioedema (post-marketing)

Interactions

Strong CYP3A inhibitors — in mild to moderate renal impairment or mild hepatic impairment the dose should be no more than 25 mg; not recommended in severe renal impairment or moderate hepatic impairment (SPC §4.2, §4.4)
Drugs metabolised by CYP2D6 — mirabegron is a CYP2D6 inhibitor; with concomitant CYP2D6 substrates, especially narrow therapeutic index drugs, appropriate monitoring and possible dose adjustment of those drugs may be necessary (US label §7.1)
Digoxin — when initiating the combination, use the lowest dose of digoxin and monitor serum digoxin concentrations to titrate to the desired clinical effect (US label §7.2)
Medicinal products known to prolong the QT interval — caution should be exercised, as such patients were excluded from the clinical studies (SPC §4.4)
Antimuscarinic medicinal products for OAB — administer mirabegron with caution because of the risk of urinary retention (SPC §4.4)

Clinical monograph

How it works

It stimulates β3-adrenoceptors in the bladder to promote detrusor relaxation and increase bladder capacity.

Prescribing in practice

It can raise blood pressure — measure blood pressure before and during treatment, and avoid it in severe uncontrolled hypertension.
It avoids the anticholinergic effects of antimuscarinics, which can suit older patients.
It inhibits CYP2D6, with some resulting interactions.

Monitoring

Monitor blood pressure; review symptom response.

Counselling the patient

It does not cause the dry mouth that antimuscarinic bladder drugs do.
Your blood pressure will be checked.
Report severe headache or palpitations.

Evidence & guidelines

An option for overactive bladder, especially where antimuscarinics are unsuitable, with blood-pressure monitoring (NICE NG123/TA290).

Reference: NICE CG171 (Urinary Incontinence in Women); MHRA Drug Safety Update 2021 (anticholinergic drugs and dementia); AGS Beers Criteria 2023; STOPP/START v3; MHRA SPC Betmiga; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Drugs

Mirabegron · Beta-3 Adrenoceptor Agonist

Pathways