Casirivimab/Imdevimab (Investigational)

Reviewed on 1/6/2022

What Is Casirivimab/Imdevimab (Investigational) and How Does It Work?

Casirivimab/Imdevimab (Investigational) is a prescription medication used to treat COVID-19 (EUA). 

  • Casirivimab/Imdevimab (Investigational) is available under the following different brand names: Regen-Cov

What Are Dosages of Casirivimab/Imdevimab (Investigational)?

Adult and pediatric dosage

Available as:

  • Single vial which contains 2 antibodies co-formulated in a 1:1 ratio, or
  • Individual antibody solution in separate vials (supplied separately or in a dose pack)

Injection, solution

  • Casirivimab/Imdevimab (600mg/600mg) per 10mL vial
  • Casirivimab 1200mg/10mL vial: 300mg/2.5mL vial
  • Imdevimab 1200mg/10mL


Adult and Pediatric Treatment

  • Emergency use authorization (EUA) issued by the FDA for treatment of mild-to-moderate coronavirus disease 2019 (COVID-19) in adults and pediatric patients aged 12 or older weighing 40 kg or more with positive results of direct SARS-CoV-2 viral testing, and who are at high risk for progressing to severe COVID-19 and/or hospitalization
  • IV: Casirivimab 600 mg and Imdevimab 600 mg administered together as a single IV infusion; must dilute before IV infusion
  • SC: Casirivimab 600 mg and Imdevimab 600 mg SC

Dosage Considerations – Should be Given as Follows: 

  • See "Dosages."

What Are Side Effects Associated with Using Casirivimab/Imdevimab (Investigational)?

Common side effects of Casirivimab/Imdevimab (Investigational) include:

  • soreness, irritation or bruising at the injection site

Serious side effects of Casirivimab/Imdevimab (Investigational) include:

  • hives, 
  • itching, 
  • redness, swollen, blistering, or peeling skin with or without fever, 
  • wheezing
  • chest pain or pressure, 
  • difficulty breathing, swallowing, or talking, 
  • unusual hoarseness
  • swelling of the mouth, face, lips, tongue, or throat, 
  • injection site reaction (oozing, heat, swelling, redness, or pain), 
  • confusion, 
  • tiredness, 
  • weakness, 
  • fever, 
  • chills, 
  • fast, slow or abnormal heartbeat, 
  • upset stomach, 
  • shortness of breath, 
  • headache, 
  • dizziness, 
  • fainting
  • sore throat
  • muscle aches, and
  • sweating

Rare side effects of Casirivimab/Imdevimab (Investigational) include:

  • none 
This is not a complete list of side effects and other serious side effects or health problems may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Other Drugs Interact with Casirivimab/Imdevimab (Investigational)?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them.  Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider or pharmacist first

  • Casirivimab/Imdevimab (Investigational) has unknown severe interactions with other drugs.
  • Casirivimab/Imdevimab (Investigational) has unknown serious interactions with other drugs.
  • Casirivimab/Imdevimab (Investigational) has unknown moderate interactions with other drugs.
  • Casirivimab/Imdevimab (Investigational) has unknown minor interactions with other drugs.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drugs interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use.  Keep a list of all your medications with you, and share this information with your doctor and pharmacist.  Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns.

What Are Warnings and Precautions for Casirivimab/Imdevimab (Investigational)?


  • None

Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Casirivimab/Imdevimab (Investigational)?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Casirivimab/Imdevimab (Investigational)?”



  • Potential for serious hypersensitivity reaction, including anaphylaxis
  • If signs and symptoms occur, immediately discontinue IV infusion and initiate appropriate medications and/or supportive care
  • Infusion-related reactions reported, including fever, chills, nausea, headache, bronchospasm, hypotension, angioedema, throat irritation, rash including urticaria, pruritus, myalgia, dizziness

Severe COVID-19

  • Treatment benefit not observed in patients hospitalized due to COVID-19
  • Monoclonal antibodies may be associated with worse clinical outcomes when administered to hospitalized patients with COVID-19 requiring high-flow oxygen or mechanical ventilation
  • Therefore, Casirivimab and Imdevimab are not authorized for use in patients
    • who are hospitalized due to COVID-19, OR
    • who require oxygen therapy due to COVID-19, OR
    • who require an increase in baseline oxygen flow rate due to COVID-19 in those on long-term oxygen therapy due to underlying non-COVID-19-related comorbidity

Viral variants

  • Circulating SARS-CoV-2 viral variants may be associated with resistance to monoclonal antibodies
  • Prescribing clinicians should consider prevalence of Casirivimab/Imdevimab resistant variants in their area
  • Health care providers should review antiviral resistance information provided by state and local health departments
  • Variant proportions circulating in the US can be monitored at the CDC website
  • Fold-reduction in susceptibility August 2021
    • Casirivimab and Imdevimab together retained neutralization activity against pseudovirus expressing all spike protein substitutions tested
    • B.1.1.7 (UK origin): No change
    • B.1.351 (South Africa origin): No change
    • P.1 (Brazil origin): No change
    • B.1.427/B.1.429 (California origin): No change
    • B.1.526 (New York origin): No change
    • B.1.617.1/B.1.617.3 (India): No change
    • B.1.617.2/AY.3 (India): No change
    • AY.1/AY.2g (India): No change
    • B.1.621/B.1.621.1 (Colombia): No change
    • C.37 (Peru): No change

Drug interaction overview

  • Not renally excreted or metabolized by CYP450 enzymes
  • Interactions with concomitant renally excreted drugs or drugs that are CYP450 substrates, inducers, or inhibitors are unlikely

Pregnancy and Lactation

  • Insufficient data to evaluate drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes
  • Use during pregnancy only if the potential benefit outweighs the potential risk for the mother and fetus
  • Data are unknown regarding presence in human or animal milk, effects on breastfed infants, or effects on milk production
  • Maternal IgG is known to be present in human milk
Medscape. Casirivimab/Imdevimab (Investigational).

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