Understanding the new crown "miracle drug" Namatevir/ritonavir

Recently, everyone is paying attention to the new crown "miracle drug" namatevir/ritonavir. Can this drug prevent infection? What are the indications? How to use it? Can it be crushed for people with dysphagia? Are there any drug interactions? Why does the virus return after taking the drug?

Can infection be prevented?

Namatevir/ritonavir is a small molecule compound that targets the main protease 3CLpro of the new coronavirus, which can prevent the protein from processing polyprotein precursors, thereby inhibiting viral replication. The pharmacological mechanism of this drug is mainly to inhibit the replication of the new coronavirus, and it has not been found to have the potential to prevent the new coronavirus, so it cannot be used to prevent new coronavirus infection.

What are the indications?

On February 11, 2022, the National Medical Products Administration of my country conducted an emergency review and approval for namatevir tablets/ritonavir tablets in accordance with the special drug approval procedures, and conditionally approved the import registration for the treatment of mild to moderate new coronavirus pneumonia in adults with high risk factors for progression to severe illness. The "New Coronavirus Pneumonia Diagnosis and Treatment Plan (Trial Ninth Edition)" states that the drug is indicated for mild and common types within 5 days of onset and adults and adolescents (12-17 years old, weighing ≥40kg) with high risk factors for progression to severe illness.

What are the high-risk factors for severe illness?

According to the "New Coronavirus Pneumonia Diagnosis and Treatment Plan (Trial Ninth Edition)", only those with one of the following diseases or conditions are defined as high-risk groups for severe/critical illness:

(1) Advanced age (≥60 years old);

(2) Those with underlying diseases such as cardiovascular and cerebrovascular diseases (including hypertension), chronic lung diseases, diabetes, chronic liver diseases, kidney diseases, tumors, etc.;

(3) Immune dysfunction (such as AIDS patients, long-term use of glucocorticoids or other immunosuppressive drugs leading to immunodeficiency);

(4) obesity (body mass index ≥ 30);

(5) Women in late pregnancy and perinatal period;

(6) Heavy smokers.

That is, it can only be used by those who meet any of the high-risk groups for severe/critical illness, have had symptoms of infection within 5 days, are ≥12 years old, and weigh ≥40kg.

How to use?

300 mg of namatevir (2 tablets) and 100 mg (1 tablet) of ritonavir were taken simultaneously, twice daily for 5 days.

For moderate renal impairment (eGFR 30-60 mL/min), adjust the dose: 150 mg nematevir (1 tablet) and 100 mg ritonavir (1 tablet) twice daily for 5 days.

It is contraindicated in patients with severe renal impairment (eGFR < 30 mL/min).

It is contraindicated in patients with severe hepatic impairment (Child-Pugh class C).

Can it be crushed for use by people with swallowing difficulties?

Nematevir/ritonavir can be crushed and mixed with applesauce, pudding, or any common food or liquid, including products containing dairy products, based on Phase I studies showing that the suspension has similar pharmacokinetics as the whole tablet. Therefore, the drug can be crushed and mixed with water and administered through a feeding tube.

Are there any drug interactions?

Ritonavir is a strong cytochrome P450 (CYP) 3A4 inhibitor and P-glycoprotein inhibitor. For elderly patients with multiple comorbidities and who are taking many medications, attention should be paid to drug interactions.

Why does reinfection occur after taking medicine?

Many people are curious about why people who were infected with the new coronavirus and treated with namatevir/ritonavir tested positive again? Because the pharmacological mechanism of the drug is mainly to inhibit the replication of the new coronavirus, rather than directly eliminating the pathogenic activity of the virus, the human immune system cannot eliminate the virus in a timely and efficient manner. Then the virus temporarily suppressed by the drug will be detected because the virus becomes active again after the drug concentration is metabolized.