Mirabegron
Beta-3 Adrenergic Agonist for Overactive Bladder
Quick Facts About Mirabegron
Key Takeaways About Mirabegron
- First-in-class mechanism: Mirabegron is the first beta-3 adrenergic agonist approved for overactive bladder, offering an alternative to antimuscarinic drugs
- No anticholinergic side effects: Unlike antimuscarinics, mirabegron does not typically cause dry mouth, constipation, blurred vision, or cognitive impairment
- Once-daily dosing: Taken as a prolonged-release tablet once daily, with or without food, at the same time each day
- Blood pressure monitoring required: Mirabegron can cause small increases in blood pressure and is contraindicated in severe uncontrolled hypertension
- Allow 4–8 weeks for full effect: Clinical improvement may take several weeks; continue treatment as prescribed even without immediate symptom relief
What Is Mirabegron and What Is It Used For?
Mirabegron is a selective beta-3 adrenergic receptor agonist prescribed for the treatment of overactive bladder (OAB) syndrome. It relieves symptoms of urinary urgency, increased urinary frequency, and urge urinary incontinence by relaxing the detrusor muscle during the bladder filling phase.
Mirabegron belongs to a novel class of medicines known as beta-3 adrenergic agonists. It was the first drug in this class to be approved for the treatment of OAB and represents a fundamentally different approach compared to the long-established antimuscarinic medications such as oxybutynin, solifenacin, and tolterodine. While antimuscarinics block muscarinic receptors to prevent involuntary bladder contractions, mirabegron activates beta-3 adrenoceptors on the detrusor muscle, promoting relaxation during the filling phase without interfering with voiding.
Overactive bladder (OAB) is a common condition characterised by a sudden, compelling desire to urinate (urgency) that is difficult to defer. It is often accompanied by increased daytime urinary frequency (typically more than 8 voids per day) and nocturia (waking at night to urinate). In approximately one-third of patients, OAB is also associated with urge urinary incontinence – involuntary leakage of urine immediately preceded by urgency. OAB affects an estimated 12–17% of the adult population worldwide and significantly impacts quality of life.
Mirabegron is particularly valuable as an alternative to antimuscarinic medications for patients who experience intolerable anticholinergic side effects such as dry mouth, constipation, blurred vision, and cognitive impairment. It is also recommended by the European Association of Urology (EAU) and the International Continence Society (ICS) as a first-line pharmacological option alongside antimuscarinics for the management of OAB.
Mirabegron was first approved for medical use in Japan in 2011 and subsequently in Europe (2012) and the United States (2012). It is marketed under the brand names Betmiga (Europe) and Myrbetriq (USA and other markets). Mirabegron can also be used in combination with the antimuscarinic solifenacin for patients who do not respond adequately to monotherapy.
What Should You Know Before Taking Mirabegron?
Before starting mirabegron, inform your doctor about all your medical conditions, especially uncontrolled high blood pressure, liver or kidney problems, urinary retention, and any other medications you are taking. Mirabegron is contraindicated in severe uncontrolled hypertension and severe hepatic impairment.
Contraindications
You should not take mirabegron if any of the following apply to you:
- Allergy to mirabegron or any of the other ingredients in the tablet – symptoms may include rash, itching, swelling, or difficulty breathing
- Severe uncontrolled hypertension – defined as systolic blood pressure ≥ 180 mmHg and/or diastolic blood pressure ≥ 110 mmHg measured on repeated occasions
- Severe hepatic impairment (Child-Pugh Class C) – mirabegron is extensively metabolised by the liver and drug levels may become dangerously elevated
- End-stage renal disease (eGFR < 15 ml/min/1.73 m² or on dialysis) – insufficient data on safety and efficacy in this population
Warnings and Precautions
Talk to your doctor or pharmacist before taking mirabegron if you have or have had any of the following conditions:
- High blood pressure (hypertension) – mirabegron can increase blood pressure; your doctor should measure your blood pressure before starting treatment and monitor it periodically
- Urinary tract obstruction or benign prostatic hyperplasia (BPH) – there is a risk of urinary retention, particularly in men with bladder outlet obstruction
- Moderate hepatic impairment (Child-Pugh Class B) – the daily dose should not exceed 25 mg
- Severe renal impairment (eGFR 15–29 ml/min/1.73 m²) – the daily dose should not exceed 25 mg
- Concomitant use of drugs that prolong the QT interval – mirabegron has not been extensively studied in patients at risk of QT prolongation
Pregnancy and Breastfeeding
Mirabegron should not be used during pregnancy unless clearly necessary, as there are no adequate data from the use of mirabegron in pregnant women. Animal studies have shown reproductive toxicity at high doses. If you are pregnant, think you might be pregnant, or are planning to become pregnant, consult your doctor before taking mirabegron.
Mirabegron is excreted in breast milk in animal studies. A risk to the breastfed infant cannot be excluded. Your doctor will decide whether to discontinue breastfeeding or discontinue mirabegron therapy, taking into account the benefit of breastfeeding for the child and the benefit of therapy for the mother.
Driving and Operating Machinery
Mirabegron has no known effect on the ability to drive or use machines. However, if you experience dizziness as a side effect, exercise caution when driving or operating machinery until the symptoms resolve.
How Does Mirabegron Interact with Other Drugs?
Mirabegron can increase blood levels of digoxin and CYP2D6 substrates such as metoprolol and desipramine. It may also affect warfarin metabolism, requiring INR monitoring. Always tell your doctor about all medications you are taking, including over-the-counter products and herbal supplements.
Mirabegron is metabolised by multiple enzymes including CYP3A4, CYP2D6, and direct glucuronidation. Importantly, mirabegron is a moderate inhibitor of CYP2D6 and can increase blood levels of drugs metabolised by this enzyme. It is also an inhibitor of P-glycoprotein (P-gp), which affects the absorption and distribution of certain drugs such as digoxin.
Clinically Important Interactions
| Drug | Category | Effect | Recommendation |
|---|---|---|---|
| Digoxin | Cardiac glycoside | Mirabegron inhibits P-gp, increasing digoxin blood levels (AUC increased by 27%) | Use lowest digoxin dose initially; monitor serum digoxin levels closely |
| Metoprolol | Beta-blocker (CYP2D6 substrate) | Mirabegron inhibits CYP2D6, increasing metoprolol exposure (AUC increased by 90%) | Monitor heart rate and blood pressure; dose adjustment of metoprolol may be needed |
| Desipramine | Tricyclic antidepressant (CYP2D6 substrate) | Mirabegron inhibits CYP2D6, increasing desipramine blood levels | Use caution; monitor for increased desipramine side effects; dose reduction may be needed |
| Warfarin | Anticoagulant | Potential increase in warfarin exposure, although clinical studies showed limited interaction | Monitor INR when starting or stopping mirabegron in warfarin-treated patients |
| Thioridazine | Antipsychotic (CYP2D6 substrate) | Risk of increased thioridazine levels, potentially causing QT prolongation | Co-administration is not recommended |
| Ketoconazole | Antifungal (CYP3A4 inhibitor) | Increases mirabegron blood levels (AUC increased by 45%) | In patients with mild-moderate hepatic/renal impairment, avoid co-administration |
| Rifampicin | Antibiotic (CYP3A4 inducer) | Decreases mirabegron blood levels (AUC decreased by 35%) | No dose adjustment required; efficacy should be monitored |
| Solifenacin | Antimuscarinic (OAB treatment) | Additive pharmacological effect; mirabegron may slightly increase solifenacin levels | Approved combination; use under medical supervision |
Mirabegron can also interact with other CYP2D6 substrates with a narrow therapeutic index, such as flecainide and propafenone. If you are taking any of these medications, your doctor may need to adjust the dose or monitor you more closely. Always inform your doctor and pharmacist about all medications, supplements, and herbal products you are using.
What Is the Correct Dosage of Mirabegron?
The recommended starting dose for adults is 25 mg once daily, which may be increased to 50 mg once daily based on clinical response. The prolonged-release tablet should be swallowed whole with water, with or without food, at the same time each day.
Always take mirabegron exactly as your doctor has told you. Do not change your dose without consulting your doctor first. The tablets are prolonged-release and must be swallowed whole – do not crush, chew, or split them, as this would destroy the prolonged-release mechanism and could lead to excessive drug absorption.
Adults
Overactive Bladder (OAB)
Starting dose: 25 mg once daily
Maintenance dose: 50 mg once daily (if tolerated and clinically indicated)
Your doctor may increase the dose from 25 mg to 50 mg after an initial assessment period, typically 4–8 weeks, based on your response and tolerability. The full therapeutic effect may take up to 8 weeks to develop.
Patients with Renal Impairment
Dose Adjustment for Kidney Function
Mild to moderate renal impairment (eGFR 30–89 ml/min/1.73 m²): No dose adjustment is required.
Severe renal impairment (eGFR 15–29 ml/min/1.73 m²): Maximum dose is 25 mg once daily.
End-stage renal disease (eGFR < 15 ml/min/1.73 m² or on dialysis): Mirabegron is not recommended.
Patients with Hepatic Impairment
Dose Adjustment for Liver Function
Mild hepatic impairment (Child-Pugh Class A): No dose adjustment is required.
Moderate hepatic impairment (Child-Pugh Class B): Maximum dose is 25 mg once daily.
Severe hepatic impairment (Child-Pugh Class C): Mirabegron is contraindicated.
Elderly Patients
No dose adjustment is required based on age alone. Clinical trials included patients over 65 and 75 years of age, and mirabegron was well tolerated in these groups. Blood pressure should be monitored periodically in all patients, including the elderly.
Missed Dose
If you forget to take a dose, skip the missed dose and take the next dose at the usual time the following day. Do not take a double dose to make up for the missed one.
Overdose
Single doses of mirabegron up to 400 mg have been studied and were associated with increased pulse rate and elevated blood pressure. Treatment of overdose should be symptomatic and supportive. Monitor heart rate, blood pressure, and ECG in the event of an overdose. Seek immediate medical attention if you suspect an overdose. Contact your local emergency services or poison control centre without delay.
What Are the Side Effects of Mirabegron?
The most common side effects of mirabegron include urinary tract infection, tachycardia (increased heart rate), and hypertension (increased blood pressure). Rare but serious side effects include urinary retention and angioedema. Most side effects are mild to moderate and do not require discontinuation of treatment.
Like all medicines, mirabegron can cause side effects, although not everybody gets them. Clinical trials have shown that mirabegron is generally well tolerated, with a side-effect profile distinctly different from antimuscarinic drugs – notably, dry mouth and constipation are much less common with mirabegron.
- Swelling of the face, lips, tongue, or throat with difficulty breathing or swallowing (signs of angioedema)
- Severe skin reactions with widespread rash, blisters, or peeling skin
- Inability to urinate despite a full bladder (urinary retention)
- Rapid or irregular heartbeat with dizziness or fainting
Common
May affect up to 1 in 10 people
- Urinary tract infection (UTI)
- Tachycardia (increased heart rate)
- Hypertension (increased blood pressure)
- Nasopharyngitis (common cold symptoms)
- Headache
- Constipation
- Nausea
- Diarrhoea
Uncommon
May affect up to 1 in 100 people
- Bladder infection (cystitis)
- Dizziness
- Dyspepsia (indigestion)
- Gastritis (inflammation of the stomach lining)
- Joint swelling
- Vaginal infection
- Elevated liver enzymes (GGT, AST, ALT)
- Pruritus (itching), rash, or urticaria (hives)
Rare and Very Rare
May affect up to 1 in 1,000 people or fewer
- Urinary retention (inability to empty the bladder)
- Angioedema (severe swelling of the face, lips, tongue, or throat)
- Palpitations
- Leukocytoclastic vasculitis (inflammation of small blood vessels)
- Lip swelling
- Purpura (purple spots on the skin)
If you experience any side effects not listed here, or if any side effect becomes severe, contact your doctor or pharmacist. Reporting suspected side effects helps ensure ongoing monitoring of the medicine's benefit-risk balance.
How Should You Store Mirabegron?
Store mirabegron prolonged-release tablets at room temperature (below 30°C), in the original packaging to protect from moisture, out of the reach and sight of children. Do not use after the expiry date printed on the packaging.
No special storage conditions are required other than keeping the medicine below 30°C. Store in the original blister packaging or bottle to protect from moisture. Check the expiry date (marked "EXP" on the carton and blister) before taking any tablets. The expiry date refers to the last day of the stated month.
Do not flush unused tablets down the toilet or throw them in household waste. Return any unused or expired medication to your pharmacy for safe disposal, which protects the environment from pharmaceutical contamination.
What Does Mirabegron Contain?
Each mirabegron prolonged-release tablet contains the active ingredient mirabegron and several inactive ingredients. The 25 mg tablets are brown, oval, and debossed with "325". The 50 mg tablets are yellow, oval, and debossed with "355".
Active Ingredient
The active substance is mirabegron. Each 25 mg prolonged-release tablet contains 25 mg mirabegron. Each 50 mg prolonged-release tablet contains 50 mg mirabegron.
Inactive Ingredients (Excipients)
The other ingredients include: polyethylene oxide, polyethylene glycol, hydroxypropyl cellulose, butylated hydroxytoluene, magnesium stearate, and a film coating containing hypromellose, macrogol, iron oxide yellow (E172), iron oxide red (E172), and titanium dioxide (E171). These excipients ensure proper prolonged-release function, tablet integrity, and identification.
Tablet Appearance and Packaging
25 mg tablets: Brown, oval, film-coated, debossed with "325" on one side.
50 mg tablets: Yellow, oval, film-coated, debossed with "355" on one side.
Available in blister packs of 10, 20, 30, 50, 60, 90, 100, and 200 tablets. Not all pack sizes may be marketed in your country.
How Does Mirabegron Work in the Body?
Mirabegron works by selectively activating beta-3 adrenergic receptors on the detrusor muscle of the urinary bladder. This activation causes the detrusor muscle to relax during the filling phase, increasing bladder capacity and reducing urgency, frequency, and urge incontinence episodes without interfering with normal voiding.
The urinary bladder has two main phases of function: filling (storage) and voiding (emptying). During the filling phase, the detrusor muscle (the smooth muscle layer of the bladder wall) must remain relaxed to allow the bladder to expand and store urine. In overactive bladder, involuntary contractions of the detrusor muscle during filling lead to the characteristic symptoms of urgency, frequency, and incontinence.
Beta-3 adrenergic receptors are the predominant adrenoceptor subtype in the human detrusor muscle, accounting for approximately 97% of all beta-adrenoceptor mRNA. When mirabegron binds to and activates these receptors, it triggers a signalling cascade involving cyclic AMP (cAMP) that leads to relaxation of the detrusor smooth muscle. This relaxation occurs specifically during the filling phase, allowing the bladder to store a greater volume of urine before the sensation of urgency occurs.
Crucially, mirabegron does not inhibit bladder contraction during voiding. The voiding phase is primarily mediated by cholinergic (muscarinic) pathways, which are not blocked by mirabegron. This distinguishes mirabegron from antimuscarinic drugs, which can sometimes impair voiding and lead to urinary retention.
Pharmacokinetic Profile
After oral administration, mirabegron is absorbed from the gastrointestinal tract and reaches peak plasma concentrations approximately 3–4 hours after dosing. The absolute bioavailability is 29% for the 25 mg dose and 35% for the 50 mg dose, and increases when taken with food (although this is not clinically significant enough to mandate administration with food). Mirabegron is approximately 71% bound to plasma proteins.
Mirabegron is extensively metabolised via multiple pathways, including CYP3A4 and CYP2D6 oxidation, amide hydrolysis, and direct glucuronidation. It is a moderate inhibitor of CYP2D6 and an inhibitor of P-glycoprotein. The terminal elimination half-life is approximately 50 hours, supporting once-daily dosing. Approximately 55% of the administered dose is recovered in urine (25% as unchanged drug) and 34% in faeces. Steady-state concentrations are achieved within approximately 7 days of once-daily dosing.
Frequently Asked Questions About Mirabegron
Mirabegron works through a completely different mechanism to antimuscarinics such as oxybutynin, solifenacin, and tolterodine. While antimuscarinics block acetylcholine receptors, mirabegron activates beta-3 adrenergic receptors on the bladder muscle. This means mirabegron does not typically cause the anticholinergic side effects common with antimuscarinics, such as dry mouth, constipation, blurred vision, and cognitive impairment. This makes mirabegron a particularly useful alternative for patients who cannot tolerate antimuscarinics or who are at risk of cognitive side effects, especially elderly patients.
Yes. Mirabegron can cause small increases in blood pressure (typically 1–2 mmHg on average). Your doctor should measure your blood pressure before starting treatment and monitor it periodically during therapy. Mirabegron is contraindicated in patients with severe uncontrolled hypertension (systolic BP ≥ 180 mmHg and/or diastolic BP ≥ 110 mmHg). If you already take blood pressure medication, your doctor will monitor your blood pressure more frequently when starting mirabegron.
Some patients may notice improvement in overactive bladder symptoms within the first few weeks, but the full therapeutic effect of mirabegron typically takes 4 to 8 weeks to develop. Clinical trials showed significant improvements in urgency episodes, urinary frequency, and incontinence episodes by week 4, with continued improvement up to 12 weeks. It is important to continue taking mirabegron as prescribed even if you do not notice immediate improvement.
Yes, mirabegron is generally well suited for elderly patients. No dose adjustment is required based on age alone. Importantly, mirabegron does not have the anticholinergic effects that make many traditional OAB medications problematic in older adults, such as cognitive impairment, confusion, dry mouth, and constipation. Clinical trials included significant numbers of patients over 65 and 75 years of age, and mirabegron was well tolerated in these groups. However, blood pressure monitoring is recommended in all patients.
Yes. The combination of mirabegron 50 mg with solifenacin 5 mg (an antimuscarinic) has been studied in large clinical trials (BESIDE and SYNERGY) and is now an established treatment option for patients who do not respond adequately to monotherapy. This combination provides greater improvements in OAB symptoms compared to either drug alone. However, the combination may increase the risk of urinary retention and should be used under medical supervision, particularly in men with benign prostatic hyperplasia.
Long-term studies of mirabegron lasting up to 12 months have shown that it maintains its effectiveness and is well tolerated over extended periods. The safety profile remains consistent with no new safety signals emerging during prolonged use. The most common long-term side effects are urinary tract infection, hypertension, and nasopharyngitis. Importantly, unlike antimuscarinics, mirabegron has not been associated with cognitive decline during long-term use. Your doctor will review your treatment periodically to ensure continued benefit.
References
This article is based on the following international medical guidelines and peer-reviewed sources. All medical claims have evidence level 1A, the highest quality of evidence based on systematic reviews of randomised controlled trials.
- EAU Guidelines Office. EAU Guidelines on Management of Non-neurogenic Female Lower Urinary Tract Symptoms (LUTS), incl. Urinary Incontinence. European Association of Urology; 2024. Available at: uroweb.org/guidelines
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- Abrams P, Kelleher C, Staskin D, et al. Combination treatment with mirabegron and solifenacin in patients with overactive bladder: efficacy and safety results from a randomised, double-blind, dose-ranging, phase 2 study (Symphony). European Urology. 2015;67(3):577–588.
- National Institute for Health and Care Excellence (NICE). Urinary incontinence and pelvic organ prolapse in women: management. NICE guideline [NG123]. Updated 2019.
- Nitti VW, Auerbach S, Martin N, Calhoun A, Lee M, Herschorn S. Results of a randomized phase III trial of mirabegron in patients with overactive bladder. The Journal of Urology. 2013;189(4):1388–1395. doi:10.1016/j.juro.2012.10.017
- Khullar V, Amarenco G, Angulo JC, et al. Efficacy and tolerability of mirabegron, a beta-3 adrenoceptor agonist, in patients with overactive bladder: results from a randomised European-Australian phase 3 trial. European Urology. 2013;63(2):283–295.
- European Medicines Agency (EMA). Betmiga (mirabegron) – Summary of Product Characteristics. EMA product information database. Accessed February 2026.
- Wagg A, Staskin D, Engel E, Herschorn S, Kristy RM, Schermer CR. Efficacy, safety, and tolerability of mirabegron in patients aged ≥ 65 yr with overactive bladder wet: a phase IV, double-blind, randomised, placebo-controlled study (PILLAR). European Urology. 2020;77(2):211–220.
Editorial Team
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