Casirivimab is generally administered in combination with imdevimab for the treatment and post-exposure prophylaxis of mild to moderate COVID-19 in adults and pediatric patients (12 years of age and older weighing at least 40 kg) who are at high risk for progression to severe COVID-19, including hospitalization or death. It is not authorized for pre-exposure prophylaxis or for use in patients hospitalized due to COVID-19, requiring oxygen support due to COVID-19, or whose oxygen requirements have increased due to COVID-19. (As of February 16, 2025, this information may be subject to change, and consulting the latest medical guidelines is crucial.)
Usage
- Medical Conditions: Mild to moderate COVID-19 in non-hospitalized patients at high risk for disease progression. Post-exposure prophylaxis of COVID-19.
- Pharmacological Classification: Monoclonal antibody, antiviral agent.
- Mechanism of Action: Casirivimab is a recombinant human monoclonal antibody (IgG1) that targets the spike protein of SARS-CoV-2, the virus responsible for COVID-19. It binds to a specific region of the spike protein (receptor-binding domain or RBD), preventing the virus from attaching to and entering human cells, thereby neutralizing the virus.
Alternate Names
- REGN10933
- Brand Names: (in combination with imdevimab) REGEN-COV, Ronapreve
How It Works
- Pharmacodynamics: Casirivimab binds to the RBD of the SARS-CoV-2 spike protein, inhibiting viral entry into host cells and reducing viral replication. This reduces viral load and the risk of severe disease progression.
- Pharmacokinetics: When administered intravenously, casirivimab reaches maximum serum concentrations rapidly. Following subcutaneous administration, peak serum concentrations are achieved in approximately 4 days. The drug is not metabolized by CYP enzymes and is primarily eliminated through non-renal pathways with a half-life ranging from approximately 2 to 4 weeks. It’s unlikely to interact with renally excreted medications or cytochrome P450 substrates, inducers, or inhibitors.
- Mode of Action: Receptor binding inhibition. Casirivimab specifically binds to the RBD of the SARS-CoV-2 spike protein, blocking the interaction with the human ACE2 receptor, which is necessary for viral entry into cells.
- Elimination Pathways: Non-renal pathways. It’s unlikely to interact with renally excreted medications or cytochrome P450 substrates, inducers, or inhibitors.
Dosage
Standard Dosage
Adults: Casirivimab 600 mg and imdevimab 600 mg co-administered as a single intravenous infusion or subcutaneous injection as soon as possible after a positive SARS-CoV-2 test and within 10 days of symptom onset (for treatment) or as soon as possible after exposure (for post-exposure prophylaxis).
Children (12 years and older and weighing at least 40 kg): Same as adult dosage.
Special Cases:
- Elderly Patients: No dosage adjustment is needed.
- Patients with Renal Impairment: No dosage adjustment is needed.
- Patients with Hepatic Dysfunction: The effect of hepatic impairment is unknown.
- Patients with Comorbid Conditions: The presence of comorbidities is a key factor in determining eligibility for Casirivimab/Imdevimab treatment, as it increases the risk of severe COVID-19. No dosage adjustment is required based on specific comorbidities.
Clinical Use Cases
Casirivimab/imdevimab is not indicated for use in hospitalized patients or patients requiring oxygen support, mechanical ventilation, or ICU care due to COVID-19. It is intended for outpatient use.
Dosage Adjustments
No dose adjustments are needed for elderly patients or those with renal impairment.
Side Effects
Common Side Effects
- Pain, redness, or swelling at the injection site
- Nausea
- Hypersensitivity reactions (e.g., rash, itching, hives)
- Infusion-related reactions (e.g., fever, chills, flushing, headache, dizziness)
Rare but Serious Side Effects
- Severe allergic reactions (anaphylaxis)
Long-Term Effects
Data on long-term effects are still limited.
Adverse Drug Reactions (ADR)
Contraindications
- Hypersensitivity to casirivimab, imdevimab, or any component of the formulation.
- Age < 12 years and weight < 40 kg.
- Hospitalized due to COVID-19, requiring oxygen support due to COVID-19, or increased oxygen requirements due to COVID-19.
Drug Interactions
Limited data is available on drug interactions. Clinically significant interactions have not been identified.
Pregnancy and Breastfeeding
- Pregnancy Safety Category: Limited data are available. The benefits of treatment might outweigh the risks in certain situations. The decision to use Casirivimab/imdevimab should be made on a case-by-case basis after careful consultation with a healthcare provider.
- Breastfeeding: Limited information is available. Due to the large molecular weight of casirivimab, breast milk excretion is expected to be low, and oral absorption by the infant is also expected to be low.
Drug Profile Summary
- Mechanism of Action: Binds to the RBD of SARS-CoV-2 spike protein, blocking viral entry into host cells.
- Side Effects: Injection site reactions, nausea, hypersensitivity reactions, infusion-related reactions, anaphylaxis (rare).
- Contraindications: Hypersensitivity, age < 12 years and weight < 40 kg, hospitalized for COVID-19 or requiring oxygen support, increased oxygen requirements.
- Drug Interactions: Limited data; no known clinically significant interactions.
- Pregnancy & Breastfeeding: Limited data; assess benefit vs. risk individually.
- Dosage: 600 mg casirivimab + 600 mg imdevimab IV or SC, single dose.
- Monitoring Parameters: Monitor for signs of hypersensitivity/infusion reactions during and after administration.
Popular Combinations
Casirivimab is most commonly co-administered with imdevimab (REGEN-COV, Ronapreve).
Precautions
- Patients should be monitored during infusion and for at least 1 hour after administration for hypersensitivity reactions.
- The efficacy against emerging SARS-CoV-2 variants should be considered.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Casirivimab?
A: Casirivimab is given in conjunction with imdevimab. The dosage is 600 mg of each, administered together as a single intravenous infusion or subcutaneous injection.
Q2: Can Casirivimab be used in children?
A: Yes, for children aged 12 years and older and weighing at least 40 kg, the dosage is the same as for adults.
Q3: Is Casirivimab safe in pregnancy?
A: Data are limited. The decision to use it should be made after a thorough discussion with a healthcare provider, weighing the potential benefits against the potential risks to the mother and fetus.
Q4: What are the common side effects?
A: Common side effects include reactions at the injection site (pain, redness, swelling), nausea, hypersensitivity reactions (rash, itching), and infusion-related reactions (fever, chills).
Q5: How is Casirivimab administered?
A: It’s administered as a single intravenous infusion or subcutaneous injection, co-administered with imdevimab.
Q6: How does Casirivimab work?
A: It’s a monoclonal antibody that binds to the spike protein of the SARS-CoV-2 virus, preventing the virus from entering human cells.
Q7: Can Casirivimab be used to prevent COVID-19?
A: It can be used for post-exposure prophylaxis after confirmed exposure to SARS-CoV-2, but not for pre-exposure prophylaxis.
Q8: Are there any contraindications to using Casirivimab?
A: Yes. Contraindications include known hypersensitivity to the drug, age under 12 years and weighing less than 40 kg, and patients hospitalized for COVID-19 or requiring oxygen support due to COVID-19.
Q9: Does Casirivimab interact with other medications?
A: Limited interaction data is available. Clinically significant drug interactions have not been identified.
