Mirikizumab belongs to the class of medications called monoclonal antibodies. Monoclonal antibodies recognize specific proteins in the body and stop them from working.

Specifically, mirikizumab is an interleukin-23 antagonist. It is used for the treatment of adults with moderately to severely active ulcerative colitis or Crohn's disease when there has been a poor response to other treatments, or these treatments are no longer effective or have unacceptable side effects.

Ulcerative colitis is a disease in which the large bowel becomes inflamed, resulting in symptoms such as abdominal pain and cramping, diarrhea, rectal pain, and rectal bleeding. Crohn's disease is a disease where there is chronic inflammation of the gastrointestinal tract, which can be caused by the protein interleukin-23 (IL-23). This medication works to reduce the activity of IL-23.

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.

The usual starting dose, or induction dose, of mirikizumab is 300 mg given by intravenous injection (into a vein) over 30 minutes. The first 3 doses are given with the first on week 0, then 4 weeks after the first dose, then 8 weeks after the first dose. This dose will be prepared and given in a hospital or clinic.

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

After symptoms of ulcerative colitis have been reduced, your doctor may suggest you change to a maintenance dose of mirikizumab. The maintenance dose of this medication is 200 mg injected subcutaneously (under the skin), every 4 weeks. Mirikizumab is available as prefilled pens or syringes containing 100 mg of medication. Each monthly dose involves injecting the contents of 2 prefilled pens or syringes. Vials should not be used for maintenance doses.

Mirikizumab is administered by subcutaneous injection in the thigh, buttocks, or abdomen. It is important to rotate the site of injection in order to minimize the risk of fat wasting at the site of injection.

Do not shake this medication before using it. The solution for injection should be clear, colourless to slightly yellow, and particle-free. If it is discoloured or you can see particles in the solution, do not use it. Allow the medication to warm to room temperature for 30 minutes before you inject it.

If you are using this medication at home, your doctor will ensure that you understand exactly how to use it. Make sure you ask any and all questions necessary to ensure that you use it exactly as prescribed. Please refer to the appropriate package insert for details on proper injection procedures. It is important to visit your doctor regularly during therapy to ensure that the medication is working safely and effectively.

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 taking the medication without consulting your doctor.

Store this medication in the refrigerator, protect it from light, and do not allow it to freeze. Keep this and all medications out of the reach of children. The pre-filled syringe may be kept at room temperature for up to 2 weeks after removing it from the refrigerator.

20 mg/mL Solution for Intravenous Infusion
Each  mL of clear, colourless-to-slightly-yellow, sterile solution, contains 20 mg of mirikizumab. Nonmedicinal ingredients: citric acid anhydrous, polysorbate 80, sodium chloride, sodium citrate dihydrate, and water for injection.

100 mg/mL Pre-filled Syringe or Pen
Each mL of clear, colourless-to-slightly-yellow, sterile solution, contains 100 mg of mirikizumab. Nonmedicinal ingredients: citric acid anhydrous, polysorbate 80, sodium chloride, sodium citrate dihydrate, and water for injection.

Do not take this medication if you:

• are allergic to mirikizumab or any ingredients of the medication
• have a serious, long-term infection, such as active tuberculosis, hepatitis, or HIV/AIDS

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.

• discomfort or swelling at the injection site
• headache
• joint pain
• rash

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:

• increased frequency of cold symptoms (e.g., runny or stuffy nose, sore throat)
• symptoms of infection (e.g., fever, chills, muscle aches, cough, shortness of breath, pain with urination)
• symptoms of liver problems (e.g., tiredness, loss of appetite, pain on the right side of the abdomen, dark urine, yellowing skin and eyes, itchy skin)

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

• serious allergic reactions (e.g., fainting, dizziness, lightheadedness, facial swelling, eyelids, lips, mouth, tongue or throat swelling, trouble breathing, difficulty swallowing)

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 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.

Infections: This medication can increase the risk of developing an infection, including serious infections such as tuberculosis or blood infections. This medication should not be used by people that have clinically important infections, such as hepatitis, HIV/AIDS, or active tuberculosis. If you have had tuberculosis, using this medication may cause symptoms to return. If you notice signs of an infection such as fever, chills, pain, swelling, or coughing, contact your doctor as soon as possible. This medication should also not be started while you have an active infection.

Tell your doctor if you have a history of infections that keep coming back, or other conditions that might increase your risk of infections such as diabetes. While you are taking mirikizumab, your doctor will monitor you for signs of infection.

Vaccines: Before starting this medication, all your immunizations should be up to date. Live vaccines (e.g., BCG, yellow fever) are not recommended for people taking this medication. Talk to your doctor if you need any vaccinations while taking this medication.

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. People who may become pregnant should use effective birth control while using this medication and for at least 12 weeks after the last dose.

Breast-feeding: It is not known if mirikizumab passes into breast milk. If you are breast-feeding and 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.

Seniors: There is limited information about the safety and effectiveness of seniors using this medication. 

For a full list of interactions, use the Drug Interaction Checker available on the Drugs.com website.

If you are taking other 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.

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.