Mirabegron (Oral)

Mirabegron helps to relax muscles in the bladder in order to relieve the symptoms of overactive bladder, including the increased urge to urinate and incontinence.

Overview

Mirabegron is a beta-3 androgenic agonist which works to treat the symptoms of overactive bladder. This condition causes the muscles in the bladder to contract uncontrollably. Symptoms include a frequent and urgent need to urinate, and inability to control urination. Mirabegron helps to relax the bladder muscles in order to reduce these symptoms.

Available only with a doctor's prescription, mirabegron is provided in extended-release capsule form. It is taken orally (by mouth) once each day. In the US, it is available under the brand name Myrbetriq.

Conditions Treated?

Type Of Medicine?

  • Beta-3 androgenic agonist

Side Effects

Mirabegron can cause a variety of unwanted effects as well as its needed effects. While it is unlikely that all of these side effects will occur, some of them are very serious and require urgent medical attention. It is therefore very important that patients familiarize themselves with all potential side effects so that they can recognize those which warrant immediate medical attention.

The following side effects associated with mirabegron should be reported to a doctor immediately:

  • Bladder pain
  • Cloudy or bloody urine
  • Painful, burning, or difficult urination
  • Frequent urge to urinate
  • Decrease in frequency of urination
  • Decrease in urine volume
  • Dribbling urine flow
  • Pain in groin or genitals
  • Pain in lower back or side
  • Pain in lower abdomen or stomach
  • Joint or muscle pain
  • Nausea or vomiting
  • Diarrhea
  • Tearing of eyes
  • Red, irritated eyes
  • Blurred vision
  • Reduced vision
  • Blindness
  • Eye pain
  • Dizziness
  • Headache
  • Nervousness
  • Unusual weakness or tiredness
  • Chills
  • Cough
  • Sore throat
  • Pounding in ears
  • Slow, fast or irregular heartbeat
  • Blistering, peeling, or loosening of skin
  • Itching
  • Red skin lesions, sometimes with purple center
  • Sores, ulcers, or white spots on lips or in mouth

The following side effects are minor and only require medical attention if they become very persistent or severe. You may find that they dissipate as your body adjusts to the medicine. If you are struggling to cope with them or have questions about them, consult your doctor.

  • Back pain
  • Body aches or pain
  • Muscle aches or stiffness
  • Pain or tenderness around cheekbones or eyes
  • Mild abdominal or stomach discomfort
  • Tenderness in stomach area
  • Stomach upset or discomfort
  • Sour or acidic stomach
  • Belching
  • Full or bloating feeling
  • Pressure in the stomach
  • Indigestion
  • Heartburn
  • Burning sensation in chest or stomach
  • Difficulty moving
  • Difficulty breathing
  • Difficulty passing stools
  • Dry mouth
  • Loss of voice
  • Ear congestion
  • Fever
  • Sneezing
  • Runny or stuffy nose
  • Redness of the skin
  • Mild hives or welts
  • Skin rash
  • Swelling of the lips
  • Itching
  • Itching and pain of vagina or genital area
  • Thick white vaginal discharge with mild or no odor

This may not necessarily be an exhaustive list of all side effects that could occur while taking mirabegron. If you notice others not listed here, consult a doctor immediately. You could also report new side effects to the FDA, or your doctor may do this on your behalf.

Dosage

The amount of mirabegron you take will vary depending on your medical history and the severity of your condition. Always follow your doctor's dosage instructions over any other average or recommended dosages. Never take more mirabegron than needed as this could increase the risk of side effects, but taking too little could make the medicine less effective.

Most adults begin with 25 milligrams of mirabegron each day, but this may be adjusted up to 50 milligrams if necessary. Each dose is taken once each day, and it should be taken at around the same time every day. It can be consumed either with or without food. The tablets should be swallowed whole, and should not be crushed, broken, or chewed.

It can take 8 weeks or more before the full effects of mirabegron are noticed and your symptoms of overactive bladder are under control. Once your symptoms have dissipated, do not stop taking the medicine. Mirabegron does not completely cure the condition, but only manages its symptoms. If you stop taking the drug, the symptoms of overactive bladder will return.

If you miss a dose of mirabegron, simply skip the missed dose and continue with your usual dosing schedule. Never double dose on mirabegron to make up for missed doses, as doing so could increase the risk of severe side effects.

Interactions

It is very important to tell your doctor about all the medicines you take so that they can check for harmful interactions with mirabegron. Be sure to mention medicines prescribed to you, those purchased over the counter, and any vitamins or herbal supplements that you take. It is particularly important to mention any blood thinners (anticoagulants), such as warfarin, and other medicines for overactive bladder.

The following medicines should not be taken at the same time as mirabegron. Your doctor will either choose not to prescribe mirabegron, or they will change your existing medicines.

  • Thioridazine (Mellaril)

The following medicines are not recommended to be taken at the same time as mirabegron, but if both medicines are deemed absolutely necessary, they may still be prescribed. Your doctor may give you new dosage instructions for your existing medicines.

  • Propafenone (Rhythmol)
  • Tramadol (ConZip, Ultram)

The following medicines are not recommended for use at the same time as mirabegron because they may increase the risk of certain side effects. However, if both drugs are deemed necessary, your doctor may still prescribe both with dosage adjustments where necessary.

  • Desipramine (Norpramin)
  • Digoxin (Lanoxin, Lanoxicaps, Cardoxin, Digitek)
  • Metoprolol (Lopressor, Toprol-XL)

Warnings

Interactions with other medical conditions

It is very important that your doctor knows about all the conditions you suffer from, and those which you have suffered from in the past. This is because there could be risks associated with mirabegron which are higher if other medical conditions are present.

The following medical conditions may be worsened by mirabegron:

  • Hypertension (high blood pressure)
  • Bladder blockage (difficult urination)

People with kidney disease and liver disease may not be able to take mirabegron. This is because reduced liver and kidney function can result in the drug being processed at a much slower rate than usual. The drug therefore remains in the body for longer, which increases the risk of side effects. Depending on the severity of the liver or kidney disease your doctor may continue to prescribe the drug, perhaps with lower initial dosages.

Blood pressure

Mirabegron can cause blood pressure to increase. Your doctor may want to monitor your blood pressure throughout your treatment with the drug. If you already have high blood pressure, your doctor may want to get it under control before prescribing mirabegron, or they may deem it too risky to prescribe mirabegron at all.

Allergies

Tell your doctor if you have had an allergic reaction to mirabegron in the past, or to drugs like it. You should also make sure your doctor knows about any other allergies you suffer from, including drug, food, dye, chemical, and animal allergies, in case you are allergic to any of the ingredients in mirabegron tablets.

If you notice any of the following signs of an allergic reaction while taking mirabegron, speak to your doctor immediately:

  • Skin rash or hives
  • Swollen lips, tongue, or throat
  • Wheezing
  • Chest tightness

Pediatric use

There have not been any studies into mirabegron to assess the safety and efficacy of the drug in pediatric patients. The drug is therefore not recommended for children.

Geriatric use

There is no evidence to suggest that mirabegron is any less effective in treating overactive bladder in elderly patients than it is in younger adults. However, elderly patients are more likely to have age-related kidney or liver disease, which may make them more sensitive to the drug. Doctors may administer lower doses initially and monitor the patient closely for side effects.

Pregnancy and breastfeeding

Mirabegron should only be taken during pregnancy if the benefits of the drug far outweigh potential risks to the fetus. Although there have been few well-controlled studies in human pregnancy, animal studies have demonstrated that the drug is harmful to the fetus.

It appears that very small amounts of mirabegron are excreted in human breast milk, and it appears that the quantity does not cause harmful effects in nursing infants. However, breastfeeding women should still be cautious when considering this drug and should discuss potential risks with their doctor.

Storage

You should store mirabegron tablets in the container they were provided to you in, and with the lid tightly closed at all times when not in use. Keep the medicine out of sight and reach of children and pets, and never share the tablets with other people.

Mirabegron should be stored at room temperature and away from direct light, heat, or moisture. The tablets should not be allowed to freeze.

If you have leftover or expired mirabegron tablets, ask your healthcare provider how to dispose of them safely. Do not simply flush them down the toilet or throw them in the trash, as they could come to harm other people or the environment. There may be a medicine take-back program provided by a local pharmacy, garbage or recycling center, or your healthcare provider which will ensure the medicine is safely disposed of.

Summary

Mirabegron helps to relieve the symptoms associated with overactive bladder, such as increased need and urgency to urinate, and incontinence. It works by relaxing the muscles of the bladder. It takes around 8 weeks to work and is not a permanent cure for the condition; symptoms will return when patients stop taking the medicine.

Patients may experience indigestion, bloating, mild abdominal discomfort, and muscle and body aches and pains while taking mirabegron. These side effects do not require medical attention unless they become very severe or prolonged. If patients notice reduced urine output, painful or difficult urination, blood in urine, nausea, vomiting, vision problems, or severe skin problems, they should consult their doctor straight away. Mirabegron can also cause blood pressure to increase. This is normal, but it should be monitored regularly by a doctor to ensure that it doesn't become too high.

Most people take one mirabegron tablet each day, with the dose varying between 25 and 50 mg. The medicine can be taken either with or without food, but it should be taken at around the same time each day. Missed doses should simply be skipped and the next dose taken at the usual time.

Patients with hypertension or bladder blockage problems may not be able to take mirabegron because the drug could make these problems worse. People with kidney or liver disease may be more sensitive to the drug's effects and may require smaller doses initially. The drug is not recommended for pregnant women, but it appears safe to take it while breastfeeding. The safety and efficacy of the drug for children have not been established.