Casirivimab and Imdevimab Injection

pronounced as (kas ir' iv i mab)(im dev' i mab)

Brand Name(s): REGEN-COV

Why is this medicine prescribed?

Casirivimab and imdevimab injection is used in certain non-hospitalized adults and children 12 years of age and older who weigh at least 88 pounds (40 kg) and who have certain medical conditions that make them at higher risk for developing severe COVID-19 symptoms, including hospitalization or death:

  • to treat mild to moderate symptoms of COVID-19.
  • to prevent COVID-19 in those who are not fully vaccinated against COVID-19 or who are vaccinated, but have a weakened immune system, or are taking a medication that affects the immune system and who have had close contact or are at high risk of close contact to someone who is infected with the SARS-CoV-2 virus (for example, nursing homes, prisons).

Casirivimab and imdevimab are in a class of medications called monoclonal antibodies. They work by blocking the action of a certain natural substance in the body in order to stop the spread of the virus.

Are there other uses for this medicine?

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

How should this medicine be used?

Casirivimab and imdevimab injection comes as a solution (liquid) to be mixed with liquid and infused (injected slowly) into a vein for 20 to 50 minutes or longer by a doctor or nurse. It also may be given subcutaneously (under the skin) as multiple separate injections in your abdomen, upper thighs, or the back of your upper arms around the same time.

For the treatment of COVID-19, it is given as a one-time dose injected into a vein as soon as possible after a positive test for COVID-19 and within 10 days after the start of COVID-19 infection symptoms such as a fever, cough, or shortness of breath. If your doctor decides that you are not able to receive casirivimab and imdevimab injection by infusion into a vein, it may be given subcutaneously (under the skin) to avoid a delay in treatment of COVID-19.

For the prevention of COVID-19 after exposure to someone who is infected with the SARS-CoV-2 virus, you will receive an initial dose, as either as subcutaneous injections or as an infusion into a vein as soon as possible after exposure. Your doctor will let you know if you need to receive additional monthly doses for ongoing protection.

Casirivimab and imdevimab may cause serious reactions during and after the infusion or injection of the medication. A doctor or nurse will monitor you carefully while you are receiving the medication and for at least 1 hour after you receive it. Tell your doctor or nurse immediately if you experience any of the following symptoms during or after the infusion: fever, chills, nausea, headache, changes in your heartbeat, chest pain, weakness or tiredness, confusion, trouble breathing or shortness of breath, wheezing, throat irritation, rash, hives, itching, muscle pain or aches, sweating, dizziness especially when standing up, or swelling of the face, throat, tongue, lips, or eyes. Your doctor may need to slow down your infusion or stop your treatment if you experience these side effects.

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

What special precautions should I follow?

Before receiving casirivimab and imdevimab injection,

  • tell your doctor and pharmacist if you are allergic to casirivimab, imdevimab, any other medications, or any of the ingredients in casirivimab and imdevimab injection. Ask your pharmacist for a list of the ingredients.
  • tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: immunosuppressive medications such as cyclosporine (Gengraf, Neoral, Sandimmune), prednisone, and tacrolimus (Astagraf, Envarsus, Prograf). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
  • tell your doctor if you have received a COVID-19 vaccine or have or have ever had any medical conditions.
  • tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while receiving casirivimab and imdevimab, call your doctor.

What special dietary instructions should I follow?

Unless your doctor tells you otherwise, continue your normal diet.

What side effects can this medicine cause?

Casirivimab and imdevimab may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • pain, bleeding, bruising of the skin, soreness, swelling, or infection at injection site

Some side effects can be serious. If you experience any of these symptoms or those in the HOW section, call your doctor immediately or get emergency medical treatment.

  • fever
  • difficulty breathing
  • changes in heart rate
  • tiredness or weakness
  • confusion

Casirivimab and imdevimab may cause other side effects. Call your doctor if you have any unusual problems while receiving this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online ( ) or by phone (1-800-332-1088).

What other information should I know?

Keep all appointments with your doctor.

Ask your pharmacist any questions you have about casirivimab and imdevimab injection.

You should continue to isolate as directed by your doctor and follow public health practices such as wearing a mask, social distancing, and frequent hand washing.

Treatment with casirivimab and imdevimab injection is not a substitute for receiving a COVID-19 vaccine. Talk to your healthcare provider about receiving a vaccine if you have not already been vaccinated to prevent COVID-19.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

The American Society of Health-System Pharmacists, Inc. represents that this information about casirivimab and imdevimab was formulated with a reasonable standard of care, and in conformity with professional standards in the field. Readers are cautioned that the combination casirivimab and imdevimab is not an approved treatment for coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2, but rather, is being investigated for and is currently available under, an FDA emergency use authorization (EUA) for the treatment of mild to moderate COVID-19 or prevention of COVID-19 in certain outpatients. The American Society of Health-System Pharmacists, Inc. makes no representations or warranties, express or implied, including, but not limited to, any implied warranty of merchantability and/or fitness for a particular purpose, with respect to the information, and specifically disclaims all such warranties. Readers of the information about casirivimab and imdevimab are advised that ASHP is not responsible for the continued currency of the information, for any errors or omissions, and/or for any consequences arising from the use of this information. Readers are advised that decisions regarding drug therapy are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and the information contained in this information is provided for informational purposes only. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. This information about casirivimab and imdevimab is not to be considered individual patient advice. Because of the changing nature of drug information, you are advised to consult with your physician or pharmacist about specific clinical use of any and all medications.
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