Myrbetriq Uses Explained

Myrbetriq (mirabegron) is a prescription medication developed by Astellas Pharma, approved by the US Food and Drug Administration (FDA) on June 28, 2012. It is the first beta-3 adrenergic receptor agonist introduced for bladder treatment in the US.

Since its approval, Myrbetriq has gained widespread use. In 2020, it ranked among the top 160 most commonly prescribed medications in the US, with over 3 million prescriptions. Its popularity stems from its once-daily dosing and a side effect profile that differs from traditional antimuscarinic treatments.

This article will explore the various approved and potential Myrbetriq uses, providing insights into how it functions and what patients can expect from its use.

What Is Myrbetriq?

Myrbetriq is a medication containing the active ingredient mirabegron. This drug activates beta-3 receptors, helping the bladder muscle relax during the storage phase (when you hold in urine).

The bladder has different types of nerves and receptors that control when you pee. Some are part of the parasympathetic system, which helps you empty your bladder by making it contract. Two receptors called M2 and M3 help with this by making the bladder muscles tighten.

On the other hand, the sympathetic system helps the bladder hold urine. It does this mainly through beta-3 receptors, which relax the bladder muscle.

This effect makes it easier to control urination and helps treat overactive bladder (OAB) symptoms like needing to pee urgently or too often, or leaking urine before you reach the bathroom.

What Is Myrbetriq Used To Treat?

Myrbetriq is used for the following conditions:

1. Overactive Bladder (OAB)

Overactive Bladder (OAB) is a condition where you suddenly feel like you have to pee, even if your bladder isn’t full. People with OAB may:

• • Feel the need to urinate urgently, even if the bladder isn’t full
  • Urinate more frequently than usual (typically 8 or more times in 24 hours)
  • Wake up multiple times at night to urinate (called nocturia)
  • Sometimes leak urine if they can’t reach the bathroom in time (urge incontinence)

This happens because the muscles in your bladder squeeze too early or too often. It’s usually due to how your bladder and nerves are working together. It’s more common as people get older, but it’s not just a normal part of aging.

Myrbetriq is FDA-approved for OAB in adults and can be taken on its own or together with another medicine called solifenacin (Vesicare).

Efficacy

In a recent 12-week study, participants went from urinating 11.71 times a day on average at the start to 7.80 times a day at the end. That’s an average drop of 3.73 times per day, which was statistically significant.

In phase III clinical trials, Myrbetriq in doses of 25 mg, 50 mg, and 100 mg per day helped improve symptoms of OAB such as:

• • Peeing too often
  • Sudden urges to urinate
  • Urine leaks before reaching the toilet

Improvements started as early as week 4 in 50 and 100 mg doses and continued throughout treatment. These benefits were also seen in older adults (age 65+) and in people who had never used bladder medication or had stopped other OAB treatments before.

Side Effects

Researchers analyzed over 14 million safety reports submitted to the FDA’s Adverse Event Reporting System (FAERS) between early 2012 and late 2023. Of those, 18,763 reports were linked to Myrbetriq, and 80 different types of side effects were flagged.

The most common side effects were:

• • High blood pressure
  • Trouble emptying the bladder (urinary retention)
  • Irregular heartbeat (atrial fibrillation)
  • Dry mouth
  • Fast heartbeat (tachycardia)

These matched what’s already known and listed on the product label. However, the study also found some unexpected side effects, including:

• • Palpitations
  • Arrhythmia
  • Dementia
  • Mini-stroke (transient ischemic attack)
  • Parkinson’s disease
  • Rare immune-related issues
  • Lip and tongue swelling

For most people, side effects started within the first 30 days of taking the medicine (55.68% of cases), but some side effects happened even after a year of use.

2. Neurogenic Detrusor Overactivity (NDO)

Neurogenic Detrusor Overactivity (NDO) is a bladder condition caused by nerve problems. In people with NDO, the muscle in the bladder wall that helps push urine out (detrusor muscle) contracts too often or at the wrong times, even when the bladder isn’t full.

This condition is specifically “neurogenic,” meaning it results from damage or dysfunction in the nervous system. It’s most commonly seen in people with:

• • Spinal cord injuries
  • Multiple sclerosis (MS)
  • Spina bifida (a birth defect that affects the spine and spinal cord)
  • Parkinson’s disease
  • Stroke

Myrbetriq is approved to treat NDO in children who are at least 3 years old and weigh 35 kg (about 77 lbs) or more.

Efficacy

In one study of children and teens with NDO who used clean intermittent catheterization (CIC), Myrbetriq was shown to be effective. It helped increase bladder capacity, reduce urine leakage, and improve overall symptoms. On average, bladder capacity (MCC) rose by approximately 87 ml, with noticeable improvements starting as early as week 4.

A separate study focused on adults with NDO due to traumatic spinal cord injury, all of whom were also using CIC to manage bladder emptying. After 6 weeks of treatment with Myrbetriq, the following improvements were observed:

Side Effects

In clinical trials, the most common side effects were:

• • Urinary tract infection (UTI)
  • Nasopharyngitis
  • Constipation
  • Headache
  • Nausea
  • Gastroenteritis
  • Rhinitis
  • Cough

During the study, blood pressure increased slightly in children under 12 years old with NDO. On average, systolic blood pressure increased by 4.3 mm Hg, and diastolic blood pressure increased by 1.7 mm Hg.

The increase was more noticeable in kids under 8, where systolic rose by 5.9 mm Hg and diastolic rose by 2.3 mm Hg.

Among children under 12 who had normal blood pressure at the start of the study, 10 children (24%) had at least one reading that reached the 95th percentile or higher, which is considered high for their age, sex, and height.

Of those 10 kids, 6 (60%) still had high blood pressure by the end of the study, meaning they met the criteria for stage 1 hypertension (high readings on repeated measurements).

Not Sure If Myrbetriq Is Right for You?

Everyone responds differently to treatment. If you’re experiencing side effects or no improvement with Myrbetriq, it may be time to consider other medications. We’ve reviewed the top alternatives of Myrbetriq to help you make an informed decision.

What Are Myrbetriq’s Off-Label Uses?

Myrbetriq or mirabegron is sometimes prescribed for conditions outside of its approved uses, a practice known as off-label prescribing. Here are a few notable examples:

1. Interstitial Cystitis (IC)

Interstitial cystitis, also known as bladder pain syndrome (BPS), is a chronic condition that causes bladder pressure, bladder pain, and sometimes pelvic pain. The pain can range from mild to severe and often worsens as the bladder fills.

IC is not caused by an infection, though its symptoms may resemble those of a urinary tract infection (UTI).

Some studies suggest that mirabegron might help alleviate symptoms of interstitial cystitis, but results are mixed. In one study, researchers used mirabegron as an add-on treatment in people with IC/BPS. Urgency (the strong need to urinate suddenly) improved significantly. However, pain and urinary frequency did not improve.

2. Erectile Dysfunction (ED)

Mirabegron has been explored as a potential treatment for erectile dysfunction (ED) due to its muscle-relaxing properties. ED is defined as the persistent difficulty in achieving or maintaining an erection sufficient for satisfactory sexual activity.

In one 12-week study, 5 out of 13 participants experienced improvement in erectile function, marked by a 4-point increase in their IIEF-5 scores. However, findings from a separate study contradicted this outcome. In that trial, erectile function did not improve. Instead, IIEF-5 scores decreased by 4.9% at Week 4 and declined further by 9.1% at Week 12.

FDA-Approved Medications for ED

The FDA approved several oral medications for the treatment of erectile dysfunction:

• • Sildenafil (Viagra): Typically taken 30 minutes before sexual activity. Its effects last for about 4 hours.

• • Tadalafil (Cialis): Can be taken as needed or daily. Known for its longer duration of action, up to 36 hours.

These medications work by increasing blood flow to the penis and support improved performance when arousal occurs.

3. Cognitive and Mood Disorders

Mirabegron has shown potential in improving anxiety and depression symptoms in some studies, but its impact on memory and cognitive function is still being investigated. Some research suggests that its effect on OAB symptoms may indirectly lead to improvements in anxiety and depression.

Researchers evaluated 112 women with OAB who had not received prior treatment. At the start, 25% had clinical anxiety, while 22.3% showed signs of clinical depression. After taking mirabegron, significant improvements were observed in OAB, anxiety, and depression scores at both 4 and 8 weeks.

Wrap-up

Myrbetriq helps manage overactive bladder (OAB) and neurogenic detrusor overactivity (NDO) by relaxing the bladder muscle, making it easier to hold urine. It’s approved for adults with OAB and for children with NDO who are at least 3 years old and weigh 35 kg or more. Studies show it can reduce urgency, frequency, and leakage in both groups.

Myrbetriq is also being studied for other uses, like interstitial cystitis, erectile dysfunction, and mood symptoms. Results are mixed and not enough to support widespread use for those conditions yet.

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