Beta-3 adrenoceptor agonist (bladder relaxant) Pregnancy: Not recommended during pregnancy — no or limited data in pregnant women and animal studies show reproductive toxicity. Not recommended in women of childbearing potential not using contraception. Should not be used during breast-feeding.

Mirabegron

Brand names: Betmiga

Mirabegron is an oral beta-3 adrenoceptor agonist used to treat the symptoms of overactive bladder, namely urgency, increased frequency and urgency urinary incontinence, offering an alternative to antimuscarinics.

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)

Route: Oral (prolonged-release tablet — swallow whole with liquid; not to be chewed, divided or crushed; with or without food in adults)

Frequency: Once daily

§4.2: for overactive bladder in adults (including elderly patients) the recommended dose is 50 mg once daily. Paediatric NDO (neurogenic detrusor overactivity, 3 to less than 18 years): dosing is by BODY-WEIGHT BAND, not per kg — prolonged-release tablets may be used at 35 kg or more, granules for prolonged-release oral suspension are recommended below 35 kg; recommended starting dose of the tablets is 25 mg once daily WITH FOOD, increased if needed to a maximum of 50 mg once daily with food after 4 to 8 weeks; patients on 6 ml oral suspension may switch to the 25 mg tablet and those on 10 ml to the 50 mg tablet; safety and efficacy below 3 years not established. Because the paediatric regimen is banded rather than per-kg, paedDose is null. Paediatric OAB: safety and efficacy below 18 years not established — no posology recommendation can be made. Missed dose: take unless more than 12 hours have passed, then skip and take the next dose at the usual time. During long-term therapy review at least annually for continuation and potential dose adjustment.

Dose adjustments

Renal

Adult OAB (§4.2 Table 1): mild/moderate renal impairment (eGFR 30–89 ml/min/1.73 m2) 50 mg; severe renal impairment (eGFR 15–29) 25 mg; ESRD (eGFR < 15) or requiring haemodialysis — not recommended. With strong CYP3A inhibitors: no more than 25 mg in mild/moderate impairment, and not recommended in severe renal impairment. Hepatic: mild (Child-Pugh A) 50 mg, moderate (Child-Pugh B) 25 mg, severe (Child-Pugh C) not recommended.

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.

Contraindications

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

Side effects

Urinary tract infection (common)
Tachycardia (common; 1.2% at 50 mg)
Headache and dizziness
Nausea, constipation and diarrhoea
Blood pressure increased / hypertensive crisis (post-marketing)
Atrial fibrillation (rare, serious)

Interactions

US label §7 (the fetched UK SPC extract truncates before §4.5 content): drugs metabolised by CYP2D6 — mirabegron is a CYP2D6 inhibitor; monitor and consider dose adjustment of the co-administered drug, especially narrow therapeutic index drugs
US label §7: digoxin — when initiating the combination use the lowest digoxin dose and monitor serum digoxin concentrations to titrate to effect
UK SPC §4.2/§4.4: strong CYP3A inhibitors — in mild/moderate renal impairment or mild hepatic impairment the recommended dose is no more than 25 mg; not recommended in severe renal impairment or moderate hepatic impairment
UK SPC §4.4: caution when co-administered with antimuscarinic medicines for OAB (risk of urinary retention) and in patients taking medicines known to prolong the QT interval

Clinical monograph

How it works

It stimulates beta-3 adrenoceptors in the detrusor smooth muscle, promoting bladder relaxation during the storage phase and increasing functional bladder capacity.

Prescribing in practice

Mirabegron can raise blood pressure and is contraindicated in severe uncontrolled hypertension, so measure blood pressure before and during treatment.
It inhibits CYP2D6, so it can increase exposure to substrates with a narrow margin such as some antiarrhythmics and certain antidepressants; review interacting medicines.
Dose reduction or avoidance applies in significant renal or hepatic impairment per the SPC.

Monitoring

Monitor blood pressure regularly, particularly in patients with pre-existing hypertension, and review symptom response.

Counselling the patient

Take once daily, swallowing the tablet whole with water.
Have your blood pressure checked, and seek urgent help for the rare symptoms of urinary retention (inability to pass urine) or facial/throat swelling.

Evidence & guidelines

Mirabegron is recommended by NICE as an option for overactive bladder, supported by randomised trials showing reduced incontinence episodes and frequency.

Reference: NICE NG123; EAU Guidelines; NICE TA290; 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

Pathways