What you need to know about molnupiravir, aka ‘the COVID pill’

CORONAVIRUS UPDATE: As experts learn more about the novel coronavirus, news and information changes. For the latest on the COVID-19 pandemic, please visit the Centers for Disease Control and Prevention (CDC).

What is molnupiravir? | Dose | Side effects | Restrictions | Availability | Where to buy molnupiravir | Cost | Other COVID treatments

A game-changing COVID pill is now available in the United States for certain adults who are at high risk for developing severe symptoms from COVID-19. Molnupiravir is an antiviral medication for COVID-19 co-developed by the pharmaceutical companies Merck & Co and Ridgeback Biotherapeutics. It is also licensed for use in the United Kingdom. It received an emergency use authorization from the CDC on Dec. 23, 2021, and it’s the second authorized oral antiviral treatment for COVID-19. The first was Paxlovid. Experts say that the drug could be a powerful weapon in the world’s battle against the virus. 

What is molnupiravir?

The COVID medication molnupiravir has been studied for many years for its activity against several RNA viruses, including influenza, and studies of its clinical use have been redirected to treat moderate COVID-19. It is a ribonucleoside analog that impairs multiplying of SARS-CoV-2 in your body after infection. It was originally developed by Emory University in Atlanta. Research on molnupiravir suggests the COVID pill is effective against mutations of COVID-19 that the CDC classifies as “variants of concern,” including the Delta, Gamma, and Mu mutations.

“When molnupiravir enters your bloodstream, it inhibits the ability of the SARS-CoV-2 virus to replicate,” says Robert Glatter, MD, an emergency medicine physician at Lenox Hill Hospital in New York. “The virus uses RNA as its genetic material. The structure of molnupiravir resembles the nucleosides, or chemical building blocks, used to make the virus’s RNA. The drug works by incorporating itself into the RNA as it’s being synthesized.” Then, when the virus tries to form viral proteins, there are too many mutations for COVID-19 to optimally function. 

Dosage

The current recommended dosage for molnupiravir is 800 mg taken orally twice a day for five days. 

Molnupiravir is used for non-hospitalized COVID-19 patients within five days of symptom onset. Current research from the MOVe-OUT trial indicates that the treatment is most effective when taken at early symptom onset of the virus. The study showed a reduction in the risk of severe illness requiring hospitalization and/or death from 9.7% in those receiving placebo to 6.8% in those receiving molnupiravir. This equates to a reduction in the absolute risk of hospitalization and/or death by 3%, and the relative risk by 30%.

The clinical trial included patients with at least one factor for increased risk of severe infection, such as those greater than 60 years of age, but “future data will determine whether it may also be used as post exposure prophylaxis (preventive treatment) in relation to SARS-CoV-2,” Dr. Glatter says. The MOVe-AHEAD study, a global, multicenter, randomized, double-blind, placebo-controlled Phase 3 study is ongoing toto evaluate the safety and efficacy of the drug in preventing the spread of COVID-19 within households—a form of post-exposure prophylaxis. 

Side effects

“In the [MOVe-OUT] phase 3 clinical trial with molnupiravir, the incidence of any adverse event was comparable in the molnupiravir and placebo groups [30% and 33%, respectively],” says Javeed Siddiqui, MD, MPH, co-founder and chief medical officer at TeleMed2U in California. 

Though no serious adverse side effects were noted in the study, the following common side effects of molnupiravir were noted:

• Nausea
• Diarrhea
• Headache
• Rashes
• Flu-like symptoms
• Insomnia
• Changes to blood liver tests

“Simple measures to treat nausea and diarrhea using over-the-counter or prescription-based medications can mitigate such effects,” Dr. Glatter says.

Contraindications and restrictions

Merck didn’t test the drug on pregnant women, so it is not yet known whether the drug is safe in pregnant or breastfeeding women. It is recommended that women of childbearing potential be tested for pregnancy prior to initiating treatment as clinically appropriate, and for individuals of childbearing potential to use contraception for the duration of treatment and for four days after the last dose of molnupiravir.

“They not only excluded women who were pregnant, breastfeeding, or anticipating becoming pregnant, but also required men enrolled in the trial not to have unprotected sex with women for a week after they were done with their medication,” Dr. Glatter explains. This is likely due to the fact that animal studies have raised concerns about potential toxicity during gestation. 

In the clinical trial itself, molnupiravir was primarily given to people who were over 60 or other adults at least 18 years of age but had other comorbid conditions or risk factors for adverse outcomes from COVID-19, such as diabetes, heart disease, or obesity. A safe dose in infants and children is unknown, and this medication is not authorized for use in patients less than 18 years of age as it may affect bone and cartilage growth.

When will it be available?

Molnupiravir is currently available in the U.S. to patients over age 18 who are at risk for severe disease. For example, senior citizens, transplant patients, or those with a weakened immune system. It’s approved under emergency use authorization (EUA), the same type of approval initially granted to all COVID vaccines. 

Where to buy molnupiravir

Molnupiravir is only available with a prescription from your local pharmacy. However, there is a limited supply, so it may not be easy to find. The U.S. government created a therapeutic locator to help people determine which stores might have molnupiravir.

How much does molnupiravir cost?

Treatment with molnupiravir costs around $700. However, it is covered by Medicare and other insurance. An Indian drugmaker, Dr. Reddy’s, is launching a generic version, which could help to bring the cost down if it becomes available in the U.S.

RELATED: Get molnupiravir coupons

Other COVID treatment updates

The following treatments for COVID-19 are available and supported by safety and efficacy data:

• Dexamethasone, a commonly available, inexpensive steroid is an FDA-approved therapeutic which is used off-label for management of COVID-19. It is given for patients with hypoxia in the setting of progressive pulmonary symptoms. 
• Remdesivir, a redirected antiviral drug (originally studied for Hepatitis C), gained full FDA approval last year following an EUA that was granted earlier in the pandemic. This medication is used to treat hospitalized patients with severe COVID-19. On Jan. 21, 2022 the FDA expanded the approval indications for Remdesivir to include a three-day outpatient course in adult and pediatric patients (aged 12 years and older, weighing at least 40 kg) with COVID-19 and mild-to-moderate disease but at high risk for progression to severe disease. This expansion was based on the findings of a clinical trial that showed an 87% reduction in hospitalization or death when used early on after a diagnosis of COVID-19. The FDA also modified the EUA to allow use in outpatient pediatric patients who are less than 12 years of age weighing a minimum of 3.5kg and with COVID-19 mild-to-moderate disease but at high risk for progression to severe disease.
• Monoclonal antibodies (MAb) engineered in the lab against the SARS-CoV-2 are another authorized treatment of COVID-19. Three different MAb treatments have been authorized to prevent severe disease in those already infected (bamlanivimab with etesevimab, casirivimab with imdevimab, and sotorovimab); the first two also received authorization for use as post-exposure prophylaxis. Given concerns of efficacy against the Omicron variant, the FDA revised the authorizations on Jan. 24, 2022 for two of the three available MAb treatments—bamlanivimab with etesvimab (administered together) and REGEN-COV (casirivimab with imdevimab)—for use only in patients likely to have been infected or exposed to a variant susceptible to these treatments. Sotrovimab, the third treatment MAb, has maintained efficacy against the prevalent Omicron variant. On Feb. 11, 2022, the FDA issued an EUA for yet another monoclonal antibody for treatment of mild to moderate COVID-19 known as bebtelovimab. The dose is a single 175 mg injection, which can be administered in those at high risk of progressing to severe disease within seven days of symptom onset. This MAb is also believed to maintain viral neutralizing activity against current variants of concern, including Omicron. Data on efficacy of these monoclonal antibodies against circulating variants and subvariants is always evolving. In December, the FDA authorized a new MAb combination Evusheld (tixagevimab and cilgavimab) for a slightly different indication than the others – pre-exposure prophylaxis in certain high risk individuals.
• Paxlovid (nirmatrelvir/ritonavir): “This is a so-called protease inhibitor, in a different class of drugs from remdesivir and molnupiravir,” says  J. Wes Ulm, MD, MPH, a nationally and globally renowned physician-scientist in Washington, D.C. It’s taken as soon as possible (within five days) after you develop symptoms of COVID-19 to prevent severe disease.

Although spoken of often in the media over the past year, ivermectin and hydroxychloroquine have not been proven effective in treating or preventing COVID-19.

There are also many other potential drugs in the pipeline or currently in clinical trials, such as favipiravir, an older antiviral pill used in Japan, with a broadly similar mechanism as molnupiravir, alongside many drug candidates functioning by different mechanisms.