MOVFOR

Indications

• Mild to moderate COVID-19 in patients with at least one risk factor for severe illness

Dosage

Children: Refer to the BNF for Children for paediatric dosing information.

Adults: 800 mg twice daily for 5 days, starting as soon as possible after diagnosis and within 5 days of symptom onset.

Mechanism of action

Molnupiravir is converted in vivo to N4-hydroxycytidine, which is then phosphorylated to its active triphosphate form. This active form is incorporated into the viral RNA genome, resulting in a phenomenon known as viral error catastrophe, where the accumulation of mutations leads to viral inactivation.

Pharmacodynamics

The pharmacodynamics of molnupiravir involve its ability to cause lethal mutagenesis in RNA viruses, particularly SARS-CoV-2. By integrating into the viral RNA, it disrupts normal viral replication processes and impedes the propagation of the virus, thus reducing viral load and severity of infection.

Pharmacokinetics

Molnupiravir is administered orally and has a relatively rapid absorption profile. Its pharmacokinetic properties include peak plasma concentrations being reached within a few hours of administration. The drug undergoes extensive metabolism and is eliminated primarily through renal pathways, with a half-life that supports twice-daily dosing.

Adverse effects

• Diarrhoea
• Dizziness
• Headache
• Nausea
• Skin reactions
• Vomiting

Precautions

• Use only if potential benefit outweighs risk in pregnancy
• Monitor breast-fed infants for adequate feeding and hypersensitivity reactions

Pregnancy

The safety of molnupiravir during pregnancy has not been established. Use only if potential benefit outweighs risk.

Breast-feeding

Limited excretion into milk suggested, monitor breast-fed infants.

Storage

Store in a refrigerator (2°C–8°C) and protect from light. Consult product literature about storage after dilution.

Formulations

• Oral capsules

Mechanism of action

Molnupiravir is hydrolyzed _in vivo_ to N4-hydroxycytidine, which is phosphorylated in tissue to the active 5’-triphosphate form, and incorporated into the genome of new virions, resulting in the accumulation of inactivating mutations, known as viral error catastrophe. A [remdesivir] resistant mutant mouse hepatitis virus has also been shown to have increased sensitivity to N4-hydroxycytidine.