How does this medication work? What will it do for me?

Mepolizumab is a monoclonal antibody that belongs to the class of medications called interleukin-5 inhibitors. It is used in addition to other medications to treat a type of asthma called eosinophilic asthma. This is a type of asthma where there is an increased presence of eosinophils, a type of white blood cells in your blood. Mepolizumab is used when high-dose corticosteroids and other asthma medications are not enough to control the breathing symptoms.

When an allergen enters the lungs, the body produces certain chemicals (interleukins) intended to start the body’s natural defenses by drawing certain types of white blood cells into the area. This causes other chemicals to be produced that cause inflammation and fluid accumulation. The inflammation and fluids contribute to the difficulty breathing that is experienced with asthma. Mepolizumab works by reducing the production of interleukin-5, and therefore reducing the inflammation and fluid production.

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 taking 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.

What form(s) does this medication come in?

Each vial of sterile, preservative-free, lyophilized powder for subcutaneous injection contains 144 mg of mepolizumab. Once reconstituted with 1.2 mL of sterile water for injection USP, each mL of solution provides 100 mg mepolizumab. Nonmedicinal ingredients: sucrose, sodium phosphate dibasic, heptahydrate, and polysorbate 80 with a pH of 7.0.

The vial stopper is latex-free.

How should I use this medication?

The recommended dose of mepolizumab is 100 mg injected subcutaneously (under the skin) once every 4 weeks.

Mepolizumab should be prepared and administered by a qualified health care professional who is experienced in monitoring and treating hypersensitivity reactions that occur after the use of biologic medications. This medication can cause severe, life-threatening allergic reactions. It should be given in your doctor’s office or in a clinic setting where reactions can be treated immediately.

It is important this medication be given exactly as recommended by your doctor. If you miss an appointment to receive mepolizumab, contact your doctor as soon as possible to reschedule your appointment.

If you are providing the medication for injection, store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children. 

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take this medication if you are allergic to mepolizumab or any ingredients of the medication.

What side effects are possible with this medication?

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.

  • back pain
  • headache
  • injection site reactions (e.g., pain, redness, swelling, burning sensation)
  • itchy, red patches on the skin
  • sore throat
  • stomach pain
  • stuffy nose

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:

  • fever
  • symptoms of a lung infection (e.g., chest congestion, cough, general discomfort)
  • 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:

  • signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)

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.

Are there any other precautions or warnings for this medication?

Before you begin using 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 use this medication.

Allergic reactions: Any biologic medication such as mepolizumab can cause severe allergic reactions. If you experience itching, rash, dizziness or fainting, difficulty breathing or swelling of the throat or tongue, seek medical help immediately. These reactions usually occur soon after receiving a dose of the medication, but sometimes occur days after the dose and can occur at any time during your treatment with this medication.

Asthma symptoms: This medication is not intended for use during an asthma attack. Use your reliever medications when you have an episode of wheezing or difficulty breathing.

If your asthma worsens after you start using this medication, let your doctor know.

Other medications: Mepolizumab is not intended to replace other asthma medications. Continue to use your “preventers” (long-acting bronchodilators and corticosteroids) and “relievers” (fast-acting bronchodilators) as prescribed by your doctor.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication or less than 4 months after stopping this medication, contact your doctor immediately.

Breast-feeding: It is not known if mepolizumab passes into breast milk. If you are a breast-feeding mother and are taking this medication, 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 years. 

What other drugs could interact with this medication?

Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that 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. 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.