Molnupiravir

Usage

• Molnupiravir is an antiviral medication prescribed for the treatment of mild to moderate COVID-19 in non-hospitalized adult patients who are at high risk for progression to severe COVID-19 (e.g., hospitalization, death), or in patients for whom alternative COVID-19 treatment options are not accessible or clinically appropriate. It should be administered within 5 days of symptom onset.
• Pharmacological Classification: Antiviral agent, specifically a nucleoside analogue.
• Mechanism of Action: Molnupiravir introduces errors into the SARS-CoV-2 virus’s RNA during replication. These errors accumulate, ultimately inhibiting viral replication.

Alternate Names

• International Nonproprietary Name (INN): Molnupiravir.
• Brand Name: Lagevrio.

How It Works

• Pharmacodynamics: Molnupiravir is a prodrug that is metabolized to its active form, N4-hydroxycytidine (NHC). NHC acts as a ribonucleoside analogue, resembling cytidine and uridine. During viral RNA replication, NHC can be incorporated in place of either cytidine or uridine. This leads to an accumulation of mutations in the viral genome, impairing viral replication.

• Pharmacokinetics:

  • Absorption: Administered orally; rapidly absorbed.
  • Metabolism: Converted to active NHC triphosphate.
  • Elimination: Primarily renal excretion, with minimal hepatic metabolism.

• Mode of Action: Viral RNA-dependent RNA polymerase incorporation of NHC. Lethal mutagenesis of SARS-CoV-2.

• Receptor Binding/Enzyme Inhibition/Neurotransmitter Modulation: Not applicable to Molnupiravir’s mechanism.

• Elimination Pathways: Primarily renal excretion.

Dosage

Standard Dosage

Adults:

• 800 mg (four 200 mg capsules) every 12 hours for 5 days. Administer orally with or without food. Treatment duration should not exceed 5 days.

Children:

• Not authorized for use in patients under 18 years of age. Safety and efficacy have not been established in pediatric populations. Molnupiravir may affect bone and cartilage growth.

Special Cases:

• Elderly Patients: No dose adjustment necessary.
• Patients with Renal Impairment: No dose adjustment necessary.
• Patients with Hepatic Dysfunction: No dose adjustment necessary.
• Patients with Comorbid Conditions: No specific dose adjustments based on comorbidities are indicated, but clinical judgment should be applied considering the patient’s overall condition.

Clinical Use Cases

Molnupiravir is indicated only for outpatient treatment of mild to moderate COVID-19. It is not indicated for use in hospitalized patients or for pre- or post-exposure prophylaxis.

Dosage Adjustments

• No dose adjustments based on renal or hepatic function, age, or other factors are required.

Side Effects

Common Side Effects:

• Diarrhea
• Nausea
• Dizziness

Rare but Serious Side Effects:

• Hypersensitivity reactions, including anaphylaxis.

Long-Term Effects:

Unknown. Data on long-term use is limited.

Adverse Drug Reactions (ADR):

• Anaphylaxis.

Contraindications

• Hypersensitivity to molnupiravir or any of its components.
• Pregnancy (unless potential benefits outweigh risks).
• Age under 18 years.

Drug Interactions

• No clinically significant drug interactions have been identified based on available data.

Pregnancy and Breastfeeding

• Pregnancy Safety Category: Category D. Not recommended for use in pregnancy unless potential benefits outweigh the risks.
• Fetal Risks: Potential for fetal harm based on animal studies.
• Breastfeeding: Not recommended while breastfeeding and for 4 days after the last dose. Breast milk should be pumped and discarded during treatment and for 4 days after the last dose. Consider interrupting breastfeeding during treatment.

Drug Profile Summary

• Mechanism of Action: Introduces errors into SARS-CoV-2 RNA during replication, inhibiting viral propagation.
• Side Effects: Diarrhea, nausea, dizziness, hypersensitivity reactions.
• Contraindications: Hypersensitivity, pregnancy, age under 18.
• Drug Interactions: None known.
• Pregnancy & Breastfeeding: Contraindicated unless benefit outweighs risk; Not recommended during breastfeeding.
• Dosage: 800 mg PO every 12 hours for 5 days in adults. Not for use in pediatric patients.
• Monitoring Parameters: Monitor for clinical improvement of COVID-19 symptoms and adverse events.

Popular Combinations

• No specific combination therapies are currently established for Molnupiravir.

Precautions

• General Precautions: Assess for hypersensitivity, pregnancy status. Advise patients to use contraception during treatment and after treatment.
• Specific Populations: See Pregnancy and Breastfeeding.
• Lifestyle Considerations: Advise patients against driving or operating machinery if experiencing dizziness.

FAQs (Frequently Asked Questions)

Q1: What is the recommended dosage for Molnupiravir?

A: 800 mg (four 200 mg capsules) orally every 12 hours for 5 days in adults. Not authorized for use in patients under 18 years.

Q2: What is the mechanism of action of Molnupiravir?

A: It introduces errors into the genetic code of the SARS-CoV-2 virus during replication, preventing the virus from reproducing.

Q3: Can Molnupiravir be used in pregnant or breastfeeding women?

A: Molnupiravir is generally contraindicated in pregnancy and breastfeeding unless the potential benefits outweigh the risks. Breastfeeding should be interrupted during treatment and for 4 days after the last dose.

Q4: What are the common side effects of Molnupiravir?

A: Diarrhea, nausea, and dizziness are the most commonly reported side effects.

Q5: Is Molnupiravir effective against all COVID-19 variants?

A: While it has shown efficacy against several variants, the efficacy against emerging variants should be continuously monitored. Consult updated guidelines.

Q6: Can Molnupiravir be used for post-exposure prophylaxis of COVID-19?

A: No, Molnupiravir is not authorized for post-exposure prophylaxis.

Q7: Are there any known drug interactions with Molnupiravir?

A: Currently, no clinically significant drug interactions have been identified.

Q8: How should Molnupiravir be stored?

A: Store at room temperature between 20°C and 25°C (68°F to 77°F).

Q9: How long does it take for Molnupiravir to work?

A: Patients should continue the full 5-day course even if they start to feel better. It should be initiated as soon as possible after diagnosis and within 5 days of symptom onset.

Q10: How is Molnupiravir administered?

A: It is administered orally as capsules, which should be swallowed whole with water.