Myrbetriq: 7 things you should know

Medically reviewed by Carmen Pope, BPharm. Last updated on Aug 29, 2023.

1. How it works

• Myrbetriq is a brand (trade) name for mirabegron which may be used to increase the amount of urine the bladder holds.
• Myrbetriq (mirabegron) works by activating beta-3 AR receptors found in the bladder which causes the detrusor muscle to relax, increasing the amount of urine the bladder can hold, decreasing bladder contractions, and delaying the initial desire to empty the bladder.
• Myrbetriq belongs to the class of medicines known as urinary antispasmodics.

2. Upsides

• May be used to treat the symptoms of overactive bladder (OAB) in adults such as urge urinary incontinence, urgency, and urinary frequency.
• May be used alone or in combination with solifenacin succinate, a muscarinic antagonist, in adults with OAB.
• Myrbetriq granules may be used to treat children aged 3 years and older with neurogenic detrusor overactivity (NDO). Myrbetriq tablets may also be used to treat NDO in children over the age of 3 years weighing 35kg (77 lbs) or more.
• Increases the holding capacity of the bladder and decreases both the urgency and frequency of urination.
• Helps with bladder control in people with an overactive bladder, urinary incontinence, or urinary leakage.
• Available as a 25mg and 50mg tablet and Myrbetriq granules.
• The recommended started dose for Myrbetriq is 25mg once a day, increased after 4 to 8 weeks to 50mg/day if needed. When used in combination with solifenacin succinate Myrbetriq 25mg should be combined with solifenacin succinate 5 mg orally once daily. This may be increased after 4 to 8 weeks if needed.
• Effective at treating symptoms of OAB within 4 to 8 weeks.

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

• High blood pressure, urinary tract infections, nasal congestion, headache, and upper respiratory tract infections are the most common side effects reported. Constipation, joint pain, diarrhea, abdominal pain, and fatigue may also occur. A dry mouth is more common when Myrbetriq is administered with Solifenacin.
• Myrebtriq and Myrebtriq granules can increase blood pressure. Monitor blood pressure regularly, especially in those with preexisting high blood pressure. Avoid giving Myrbetriq and Myrbetriq granules to people with severe uncontrolled high blood pressure (>180/110 mmHg). In trials using Myrbetriq 50mg, the average maximum increase in BP was 3.5/1.5 mmHg more than placebo. Increases in BP have also been reported in children with those aged 3 to < 12 years more likely to be affected than those over the age of 12.
• Urinary retention has been reported in people taking Myrbetriq with bladder outlet obstruction or taking muscarinic antagonists for the treatment of OAB, this includes solifenacin succinate. Be cautious when administering Myrbetriq to these people and monitor for signs and symptoms of urinary retention.
• Do not administer to people with a previous hypersensitivity reaction to Myrbetriq or Myrbetriq granules.
• Myrbetriq and Myrbetriq granules are two different products and they are not able to be substituted on a mg per mg basis. Do not combine them to achieve the desired dose. A recommended dosage of Myrbetriq granules for adults has not been determined.
• Myrbetriq Granules need to be reconstituted immediately before dispensing with 100mL of water and shaken vigorously to dissolve. Once shaken, the reconstituted suspension may be stored at room temperature (20°C to 25°C [68°F to 77°F]) for up to 28 days. After reconstitution with 100 mL water, the suspension contains 8 mg/mL of mirabegron.
• Angioedema of the face, lips, tongue, and/or throat that may be life-threatening has been reported with Myrbetriq/Myrbetriq Granules. May occur soon after the first dose, hours after the first dose, or after multiple doses. Provide treatment as necessary and discontinue Myrbetriq/Myrbetriq Granules.
• The dosage of Myrbetriq may need to be reduced in people with moderate kidney or liver disease.
• May interact with several other drugs including antidepressants and warfarin.
• Not recommended during pregnancy or breastfeeding unless the benefits outweigh the risks. There is a lack of data about the effects Myrbetriq has on a developing fetus and during breastfeeding.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

4. Bottom Line

Myrbetriq may be used to relieve symptoms of overactive bladder in adults such as urinary incontinence and urinary frequency. It may also be used to treat the symptoms of neurogenic detrusor overactivity (NDO) in children aged 3 years and older. Side effects include a headache, nasal congestion, and infection, and it is unknown what effects Myrbetriq has during pregnancy or breastfeeding.

5. Tips

• Myrbetriq tablets should be swallowed whole with water and taken at the same time as food by children and with or without food by adults. The tablets should not be chewed, divided, or crushed.
• Take exactly as directed by your doctor. Do not take more or less than recommended.
• Myrbetriq Granules should be mixed with 100mL of water by your pharmacist before dispensing. Vigorous shaking may be required to get the granules to dissolve. Once shaken, the reconstituted suspension may be stored at room temperature (20°C to 25°C [68°F to 77°F]) for up to 28 days. They are recommended for children only because a recommended dosage for adults has not been determined, and they should be taken with food. Use an appropriate measuring device to administer Myrbetriq. Before drawing up a dose of Myrbetriq suspension for your child, shake the bottle vigorously for 1 minute then let it stand until the foam on the top has gone (approximately 1 to 2 minutes). After using wash the oral dosing device with water and mild detergent and leave to air dry.
• if you miss a dose of Myrbetriq or Mebetriq granules, take it as soon as you remember unless it has been more than 12 hours since your missed dose, then skip that dose and go back to your regular dosing schedule.
• Myrbetriq granules, t mirabegron for extended-release oral suspension) is calculated based on the weight of the patient. Prepare oral suspension at the time of dispensing.
• Tell your doctor if you are pregnant or intend to become pregnant before taking Myrbetriq. It is not known what effects Myrbetriq has on the developing fetus or the newborn when breastfeeding.
• Talk to your doctor about any side effects that you may experience such as a headache, fatigue, difficulty urinating, or constipation. Myrbetriq and Myrbetriq Granules can cause high blood pressure, and the blood pressure of the person taking Mybentriq should be monitored regularly. Seek urgent medical attention if you develop signs of an allergic reaction such as difficulty breathing, or facial or neck swelling.
• Do not take any other medications, including herbals and dietary supplements, without talking to your doctor first because Myrbetriq may interact with these.

6. Response and effectiveness

• Research has shown the number of incontinence episodes in 24 hours decreased by an average of 1.36 to 1.57 in people taking Myrbetriq 25-50mg after 12 weeks. In addition, the number of micturitions per 24 hours (episodes of urinating) decreased on average by 1.60 to 1.93, and the volume voided per micturition increased on average by 12.8mL to 24.4mL from placebo.
• Myrbentriq 25mg was effective at treating symptoms of OAB within 8 weeks and the 50mg dose was effective within 4 weeks.
• The addition of solifenacin succinate 5mg improved symptoms further, with the number of incontinence episodes in 24 hours decreasing by an average of 1.98 to 2.04 in people taking Myrbetriq 25-50mg after 12 weeks, and the number of micturitions per 24 hours (episodes of urinating) decreased on average by 2.49 to 2.59. Improvements were maintained throughout a 1-year follow-up period.
• For children with NDO, the maximum bladder capacity changed by 72mL in those aged 3 to 12 years and by 113 in those aged 12 to 17 years after 24 weeks of treatment with Myrbetriq/Myrbetriq Granules.

7. Interactions

Medicines that interact with Myrbetriq may either decrease its effect, affect how long it works, increase side effects, or have less of an effect when taken with Myrbetriq. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with Myrbetriq include:

• antidepressants, such as amitriptyline, or clomipramine
• antipsychotics, such as aripiprazole, brexpiprazole, chlorpromazine, or clozapine
• atomoxetine
• berotralstat
• antihistamines such as chlorpheniramine, diphenhydramine, or doxylamine
• heart medications, such as carvedilol, flecainide, or metoprolol
• dextromethorphan
• digoxin
• echinacea
• erdafitinib
• fostamatinib
• metoclopramide
• oxybutynin
• pimozide
• propafenone
• ritonavir
• solifenacin
• tamoxifen
• timolol
• venetoclax
• warfarin.

Myrbetriq/Myrbetriq granules moderately inhibit CYP2D6 enzymes, therefore, they may potentially interact with any CYP2D6 substrate, such as amitriptyline, clomipramine, duloxetine, fluoxetine, fluvoxamine, imipramine, mirtazapine, nortriptyline, paroxetine, sertraline, and venlafaxine.

Note that this list is not all-inclusive and includes only common medications that may interact with Myrbetriq. You should refer to the prescribing information for Myrbetriq for a complete list of interactions

References

• Myrbetriq (mirabegron). Updated 07/2022. Astellas Pharma US, Inc. https://www.drugs.com/pro/myrbetriq.html

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Myrbetriq only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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