by Editorial Board last updated 2021-11-22 10:42:16.847040-05:00
  • Molnupiravir is a new antiviral agent for treatment of COVID-19.
  • The drug is a 5'-isobutyrate prodrug that is hydrolyzed to the ribonucleoside analog N-hydroxycytidine (NHC) prior to reaching the systemic circulation. Intracellular triphosphorylation of NHC produces NHC-TP, which competes with natural CTP for incorporation into nascent viral RNA by RNA polymerase. This results in viral error catastrophe.
  • On November 4, 2021, the Medicines and Healthcare Products Regulatory Agency (MHRA) in the UK authorized the use of molnupiravir for use in people who have:
    • Been symptomatic for no more than 3-5 days
    • Have mild to moderate COVID-19 and
    • Have at least one risk factor for developing severe illness. Such risk factors include obesity, older age (>60 years), diabetes mellitus, and  heart disease.
  • 800 mg (four 200 mg capsules) po q12h for five days, with or without food.
  • Capsules should not be open, crushed, or chewed.
  • Safety and efficacy in patients under 18 years of age not established.
  • No dosage adjustment in renal impairment required.
  • No dosage adjustment in hepatic impairment required.
  • Diarrhea (3%)
  • Nausea (2%)
  • Dizziness (1%)
  • Headache (1%)
  • Rash, urticaria
Class  Ribonucleoside analog
PK/PD Index  No data
 200 mg capsules
Usual Adult Dose  800 mg q12h x5 days
 Not recommended during pregnancy
Food Effect1  Take with or without food
Absorption2 (%)
 No data
Tmax (hr)  1.5
Peak Serum Level3
Protein Binding
Average Serum
Half-life4 (hr)
3.3 (NHC)
Biliary Penetration5 (%)  No data
Penetration6 (%)
 No data
Therapeutic Levels in CSF7  No data
Volume of Distribution8
 No data
 8.26 (AUC12)
CYP450, Transporter
None known
  • 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
      • Vss/F = Vd at steady state/oral bioavailability
    • 9 Area under the plasma concentration versus time curve
  • No data