Casirivimab + Imdevimab

by Douglas Black, Pharm.D. last updated 2021-02-12 05:45:43.078667-05:00 © Antimicrobial Therapy, Inc.
  • Casirivimab and Imdevimab (Regeneron) are two monoclonal antibodies that were designed to specifically block two areas of the 'Spike Protein' of SARS-CoV-2  and, hence, infectivity of the virus. It is a combination product containing both antibodies.
  • The FDA issued an Emergency Use Authorization (EUA) letter on 21 Nov 2020 for treatment of mild to moderate COVID-19 in adults and children (age ≥12 years, wt ≥40 kg) who are at risk of progression to severe disease and/or hospitalization.
  • Combination (Casirivimab 1200 mg + Imdevimab 1200 mg) administered together as a single IV infusion.
  • Administer in 250 mL of normal saline over one hour through an IV line with a 0.2 micron polyethersulfone filter (withdraw 20 mL from the bag, then add each antibody).
  • Administer the diluted infusion solution immediately. If this is not possible, the diluted solution may be stored in the refrigerator (2-8ºC) for up to 36 hours, or at room temperature (25ºC) for up to four hours (including infusion time).
  • Age ≥12 years, weight ≥40 kg: same as adult dose.
  • No adjustment recommended.
  • The effect of hepatic impairment on the pharmacokinetics of casirivimab and imdevimab is unknown.
  • Monitor patients during infusion and for at least one hour after infusion is complete.
  • Infusion-related adverse effects:
    • Fever, chills, nausea, headache, bronchospasm, hypotension, angioedema, throat irritation, rash including urticaria, pruritus, myalgia, dizziness.
  • Serious hypersensitivity reaction, including anaphylaxis.
  Casirivimab Imdevimab
 Class IgG1 mAb IgG1 mAb
PK/PD Index No data No data
Injection Injection
Usual Dose  1200 mg 1200 mg
No human data No human data
Food Effect1 Not applicable Not applicable
Absorption2 (%)
Not applicable Not applicable
Mean Serum Level3
No data No data
Protein Binding
No data No data
Average Serum
No data No data
Biliary Penetration5 (%) No data No data
Penetration6 (%)
No data No data
Therapeutic Levels in CSF7 No data No data
Volume of Distribution8
No data No data
No data No data
CYP450, Transporter
 No known interactions No known interactions
  • Notes:
    • 1 Adult preparations unless otherwise noted.
    • 2 Absorption under optimal conditions.
    • 3 Total drug; adjust for protein binding to determine free drug concentration.
      • SD = after single dose
      • SS = steady state after multiple doses
    • 4 Assumes CrCl > 80 mL/min
    • 5 Peak concentration in bile/peak concentration in serum x 100
    • 6 CSF levels with inflammation
    • 7 Judgment based on drug dose & organism susceptibility. CSF concentration ideally ≥10x above MIC.
    • 8 Volume of Distribution (Vd):
      • V/F = Vd/oral bioavailability
      • Vss = Vd at steady state
  • No clinically significant interactions known.
  • Product availability (both antibodies): 300 mg and 1332 mg vials, 120 mg/mL, preservative free.
  • Storage: refrigerate unopened vials at 2-8ºC, protected from light. Allow to equilibrate to room temperature for 20 minutes before preparation. Do not expose to direct heat.