Covid antiviral drugs lose luster as regulatory scrutiny increases


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A Covid drug made by US pharma conglomerate Merck has come under the scrutiny of regulators after a study cast fresh doubt on its usefulness, raising questions over the costly procurement of the antiviral during the peak of the pandemic.

The Medicines and Healthcare products Regulatory Agency, the UK drugs watchdog, is assessing whether the conditional marketing authorization for Merck’s molnupiravir, also known by the trade name Lagevrio, should be renewed.

“We continue to seek advice from the independent scientific advisory body, the Human Medicines Commission,” the Financial Times reported. “Patient safety is our top priority and we are closely assessing the data to ensure that the benefits of Lagevrio outweigh the risks.”

Regulatory scrutiny has focused on the safety and effectiveness of antivirals such as Merck’s molnupiravir and Pfizer’s paxclovid, which were marketed as drugs to treat COVID-19. A study published last month in Nature linked molnupiravir to mutations that may arise when the coronavirus spreads between patients.

“There is no evidence from randomized trials that molnupiravir or paxlovid will cause this [still] be effective, now that most people have either been vaccinated or infected,” said Andy Hill, a senior visiting research fellow in the department of pharmacology and therapeutics at the University of Liverpool.

The original UK approval of molnupiravir in November 2021 was a global first. The MHRA, which said such annual authorizations were subject to “continuous review”, declined to comment on when the review would conclude.

As first reported by the FT in 2022, the European Medicines Agency refused to approve molnupiravir after concerns about its efficacy. Merck dropped an appeal after the regulator insisted that the data submitted was not sufficient to meet EU regulatory requirements. A person familiar with the process said Merck “understood there was no hope. . . [Lagevrio] It’s a little burnt.”

In late 2021 the US Food and Drug Administration granted severely restricted emergency approval, making it a treatment available to people for whom other drugs were not recommended.

Merck said talks are continuing with regulators on reviewing the filing. “We are evaluating our options for how we can generate additional evidence in support of Lagaverio as a treatment for COVID-19.”

The Cyprus government allowed the stock to be used to treat other coronavirus-stricken cats in the Mediterranean country, although the company said it was not approved for veterinary treatment and no such studies were planned.

Whatever the outcome of the round of regulatory reviews, Merck has cashed in on demand for the drug. Its sales of more than $6 billion by 2021 do not include royalties for cheaper versions of the drug. In the second quarter of 2023, sales fell 83 percent to $203 million from the year-ago period, which Merck said was also due to the UK not renewing orders.

Sales of Paxlovid, another oral antiviral that was in heavy demand by China’s elite during a surge in cases in the country late last year, have also declined, falling 98 percent in the second quarter compared with a year earlier. Has been. Yet Pfizer’s $19 billion paxlovid sales were only about a fifth of total sales in 2022.

If Omicron strains, the current dominant strain, continue to demonstrate low virulence and public immunity levels remain strong, there may be minimal demand for both drugs when they are no longer purchased by the US government and become commercially available. Are.

“These drugs can cause overall harm,” Hill said, adding that there is a risk of birth defects if molnupiravir is given to “men or women of reproductive potential who do not use contraception” and if given incorrectly. So paxalovid has a risk of fatal interactions. Medicine.”

He said clinical trials for both drugs included unvaccinated patients infected with more severe variants before Omicron’s surge, but “in 2023, the majority of people will either have been vaccinated or have been infected at least once.” “.

“Merck and Pfizer did not conduct new clinical trials to check that their drugs are still effective,” he said, adding that the original trials showed only a “modest benefit.”

Officials familiar with EMA’s molnupiravir evaluation agree on their limited utility: “The antiviral performed poorly [during the pandemic] “But Paxlovid shows they can be effective if used quickly.”

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