Product Description

Mirabegron Extended-Release Tablets 50 mg is an oral beta-3 adrenergic agonist (not a broad sympathomimetic) approved by the FDA in 2012 for treating overactive bladder (OAB) in adults, including symptoms of urinary urgency, frequency, and urgency incontinence. 

It relaxes the detrusor muscle of the bladder, increasing storage capacity without the anticholinergic side effects (e.g., dry mouth, constipation) common in antimuscarinics like solifenacin or tolterodine. 

It is also indicated for neurogenic detrusor overactivity (NDO) in adults and children ≥3 years (in some formulations). Prescription-only; provides symptomatic relief but does not cure underlying causes of OAB/NDO (e.g., neurological conditions like multiple sclerosis or spinal cord injury).

Uses

• Treatment of OAB in adults: Reduces urinary urgency, increased daytime frequency, and urge urinary incontinence

• Management of NDO in adults and children ≥3 years with neurological conditions (e.g., spina bifida, spinal cord injury) to reduce incontinence episodes and improve bladder capacity

• Adjunctive therapy when antimuscarinics are ineffective or intolerable

• Not indicated for stress incontinence, urinary retention without overflow, or acute urinary tract infections (UTIs)

How it works

Mirabegron is a selective beta-3 adrenergic receptor agonist that targets the detrusor smooth muscle in the bladder wall:

• During the storage phase, beta-3 receptors relax the detrusor muscle, increasing bladder capacity and volume before the first involuntary contraction.

• This reduces the micturition reflex, alleviating urgency and frequency without affecting bladder contraction during voiding (minimal impact on emptying).

• Unlike antimuscarinics, it does not block acetylcholine, preserving cognitive/salivary functions. Onset: Symptom improvement in 3–8 weeks; peak plasma levels in 3–5 hours; extended-release ensures 24-hour coverage.

Benefits

• Effectively reduces OAB symptoms: Decreases micturition episodes by 1–2/day, urgency incontinence by 1–2 episodes/day, and nocturia (per trials like SCORING).

• Improves quality of life by enhancing bladder control, reducing pad usage, and minimizing disruptions (e.g., sleep, social activities).

• Well-tolerated alternative to antimuscarinics, with lower rates of dry mouth (3–5% vs. 20–30%) and constipation.

• Beneficial for NDO: Increases maximum cystometric capacity by 30–50 mL and reduces detrusor pressure, preventing complications like vesicoureteral reflux.

• Long-term use (up to 12 months) maintains efficacy without tachyphylaxis; modest BP increase (~2–4 mmHg systolic) is generally manageable.

How to use

Swallow the tablet whole with water/with or without food. Do not crush, chew, or divide the tablet, as this will cause the drug to be released too quickly and may increase side effects. The extended-release tablet is designed to release the medication slowly over 24 hours. If you forget a dose, take it as soon as you remember.

Side Effects

Common side effects (usually mild and transient):

• Cardiovascular: Increased blood pressure (systolic ~2–4 mmHg; monitor in hypertensives)

• General: Headache, nasopharyngitis (upper respiratory infection), dizziness

• Gastrointestinal: Constipation, diarrhea, nausea

• Urinary: UTI (5–10%), bladder pain

Rare but serious side effects (seek immediate medical attention):

• Tachycardia or palpitations (beta-agonist effect; ~1%)

• Urinary retention (especially with antimuscarinics; contraindicated in outflow obstruction)

• Hypersensitivity: Rash, angioedema, pruritus

• Other: Fatigue, arthralgia; rare QT prolongation at high doses

Side effects often resolve with continued use; report persistent BP rise or urinary issues.

Safety Advice

Inform your doctor if you have a history of severe, uncontrolled high blood pressure Also, report any severe liver or kidney disease, or urinary retention, as these may affect the dose or suitability of the medication. Mirabegron can interact with certain drugs, including some heart medications and antidepressants. Crushing or chewing the extended-release tablet releases the medicine too quickly and can increase side effects. Do not stop taking Mirabegron without consulting your doctor. Mirabegron can cause dizziness. Be cautious when driving or operating heavy machinery until you know how the medication affects you. Mirabegron can increase blood pressure. If you have high blood pressure or blood pressure increases during treatment, your doctor may adjust your dose or stop the medication. Inform your doctor that you are taking Mirabegron if you are scheduled for any type of surgery.

Storage Conditions

Store at a temperature below 86°F (30 °C). Protect from light and moisture.

FAQs

How long does it take for Mirabegron to work?

While you may notice some effects within a few hours, it can take up to 4 to 8 weeks to experience the full benefits of the medication.

Is Mirabegron safe for long-term use?

Yes, Mirabegron is generally considered safe for long-term use under a doctor's supervision.

What happens if you stop taking Mirabegron?

Do not stop taking Mirabegron without consulting a doctor. Overactive bladder symptoms may return or worsen if discontinued.

Can Mirabegron be taken with other OAB medications?

Mirabegron can sometimes be combined with other OAB medications, such as anticholinergics. However, this should be done only under a doctor's supervision to avoid unwanted side effects.

Will Mirabegron affect blood pressure?

Mirabegron can increase blood pressure. Regular monitoring is important, especially for those with existing hypertension. It is not recommended for patients with severe, uncontrolled hypertension.

Can you drink alcohol or other beverages with Mirabegron?

Alcohol does not affect how Mirabegron works, but it can worsen OAB symptoms. Limiting drinks with caffeine or artificial sweeteners is also recommended, as they can irritate the bladder.

Should you avoid certain foods while taking Mirabegron?

There are no specific foods to avoid, but be mindful of drinks that may irritate the bladder.

Can Mirabegron cause weight gain?

Weight gain is not a common side effect. Consult a doctor if you experience unexplained weight changes.

Does Mirabegron affect fertility or contraception?

Mirabegron does not affect contraception, and there is no direct evidence that it affects fertility.

Is Mirabegron safe for the elderly?

Yes, but blood pressure should be monitored regularly, especially in older adults.

Can children take Mirabegron?

The effectiveness and side effects of Mirabegron in children under 18 have not been fully studied.