Mirabegron belongs to the family of medications called antispasmodics. Mirabegron is used to treat symptoms associated with an overactive bladder, such as urinary urgency (a need to urinate right away), urinary frequency (having to urinate more often than usual), or urge incontinence (leaking or wetting caused by an unstoppable urge to urinate).

This medication works by relaxing the bladder muscles. This helps to increase how much urine the bladder can hold and to reduce the involuntary loss of urine, the urge to pass urine, and the frequency of urination.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are using this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The usual starting dose of mirabegron is 25 mg once daily. Your doctor may increase the dose to a maximum of 50 mg once daily, if necessary to control symptoms. Mirabegron may be taken with or without food. Swallow the tablet whole with some water. Do not chew, crush, or divide the tablet.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are using the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, skip the missed dose and continue with your regular dosing schedule. If you miss several doses, talk to your doctor. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature and keep it out of reach of children.

25 mg
Each oval, brown, film-coated, extended-release tablet debossed with "325" and the Astellas logo, contains 25 mg of mirabegron. Non-medicinal ingredients: polyethylene oxide, polyethylene glycol, hydroxypropyl cellulose, butylated hydroxytoluene, magnesium stearate, hypromellose, yellow ferric oxide, and red ferric oxide.

50 mg
Each oval, yellow, film-coated, extended-release tablet debossed with "355" and the Astellas logo, contains 50 mg of mirabegron. Non-medicinal ingredients: polyethylene oxide, polyethylene glycol, hydroxypropyl cellulose, butylated hydroxytoluene, magnesium stearate, hypromellose, and yellow ferric oxide.

Do not use mirabegron if you:

• are allergic to mirabegron or any ingredients of the medication
• are pregnant
• have severe, uncontrolled hypertension (high blood pressure)

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• constipation
• diarrhea
• dizziness
• headache
• increased blood pressure
• itching
• nausea
• symptoms of a cold (e.g., congestion, runny nose, sore throat)

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• symptoms of a urinary tract infection (e.g., pain when urinating, urinating more often than usual, low back or flank pain)

Stop taking the medication and seek immediate medical attention if any of the following occur:

• fast and irregular heartbeat
• hives or rash
• signs of angioedema (e.g., swelling of the face, mouth, hands, or feet; difficulty breathing)
• signs and symptoms of a stroke (e.g., sudden numbness or weakness in face, arm, or leg; slurred speech, vision changes, headache)
• urinary retention (not able to urinate)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin taking a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should take this medication.

Abnormal heart rhythms: This medication can cause abnormal heart rhythms. Certain medications (e.g., sotalol, quinidine, thioridazine, chlorpromazine, pimozide, moxifloxacin, mefloquine, pentamidine, arsenic trioxide, tacrolimus) can increase the risk of a type of abnormal heart rhythm called QT prolongation, and should not be used in combination with mirabegron. You are more at risk for this type of abnormal heart rhythm and its complications if you:

• are female
• are older than 65 years of age
• have a family history of sudden cardiac death
• have a history of heart disease or abnormal heart rhythms
• have a slow heart rate
• have congenital prolongation of the QT interval
• have diabetes
• have had a stroke
• have low potassium, magnesium, or calcium levels
• have nutritional deficiencies

If you have heart disease and abnormal heart rhythms, or are taking certain medications (e.g., verapamil, atazanavir), discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Bladder obstruction: If you have bladder obstruction (blockage) or are taking any other medications, such as anticholinergics, for the treatment of overactive bladder, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Glaucoma: If you have glaucoma, discuss with your doctor how this medication may affect your medical condition, and how your medical condition may affect the dosing and effectiveness of this medication. Your doctor should perform regular eye exams while you are taking mirabegron.

Heart conditions: Mirabegron may cause increased blood pressure, or an increased heart rate. If you have a history of high blood pressure or heart disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Kidney function: Kidney disease or decreased kidney function may cause this medication to build up in the body, causing side effects. If you have reduced kidney function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver function: Liver disease or decreased liver function may cause this medication to build up in the body, causing side effects. If you have reduced liver function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if mirabegron passes into breast milk. If you are a breast-feeding mother and are taking mirabegron, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children under the age of 18.

There may be an interaction between mirabegron and any of the following:

• aclidinium
• alfuzosin
• amiodarone
• amphetamines (e.g., dextroamphetamine, lisdexamfetamine)
• antihistamines (e.g., bilastine, cetirizine, doxylamine, diphenhydramine, hydroxyzine, loratadine, rupatadine)
• antipsychotics (e.g., chlorpromazine, clozapine, pimozide, haloperidol, quetiapine, ziprasidone)
• atomoxetine
• atropine
• azelastine
• benztropine
• beta-2 agonists (e.g., formoterol, salbutamol, salmeterol)
• beta-blockers (e.g., carvedilol, propranolol, metoprolol, timolol)
• cyclobenzaprine
• darifenacin
• dextromethorphan
• digoxin
• disopyramide
• dofetilide
• domperidone
• doxepin
• doxorubicin
• dronedarone
• eliglustat
• enzalutamide
• fesoterodine
• flecainide
• glycopyrrolate
• ipratropium
• ketotifen
• lomitapide
• metoclopramide
• mifepristone
• mirtazapine
• monoamine oxidase inhibitors (MAOIs; e.g., moclobemide, phenelzine, tranylcypromine)
• certain opioids (e.g., codeine, hydrocodone, tramadol)
• orphenadrine
• oxybutynin
• paroxetine
• procainamide
• propafenone
• quinidine
• quinine
• rifampin
• scopolamine
• solifenacin
• tacrolimus
• tamoxifen
• tamsulosin
• tetrabenazine
• tiotropium
• tolterodine
• tricyclic antidepressants (e.g., amitriptyline, clomipramine, desipramine, trimipramine)
• trospium
• umeclidinium

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.