New antiviral drugs mark a major turning point in the Covid-19 pandemic – Community News
Covid-19

New antiviral drugs mark a major turning point in the Covid-19 pandemic

tHE LAST news in the fight against covid-19 is encouraging. Two new antiviral drugs have been found to be so effective that clinical trials were ended early. Data from these trials have not yet been published. However, regulators are moving quickly to consider common use of the drugs. They will fill a major gap in the toolkit doctors are using to fight the virus and could very well help end the global pandemic.

The new drugs are molnupiravir (Lagevrio), developed by Merck, a pharmaceutical company, in collaboration with Ridgeback Biotherapeutics, a biotech company, and Paxlovid, which is developed by Pfizer. All three are US companies. Those most at risk for the serious consequences of Covid are much less likely to be hospitalized or die if they take one of these pills in the five days after symptoms first appear.

Merck said in October that molnupiravir reduced the risk of hospitalization or death by about half when administered to patients with one risk factor for covid, such as obesity or heart disease. Regulators in America, Europe and at the World Health Organization are reviewing the drug. Britain has approved it and will start treatment next month. On Nov. 5, Pfizer said its pill reduced the risk of hospitalization or death by 89% if taken within three days. (In fact, during the trial, no patient died taking Paxlovid within five days of symptoms.)

Molnupiravir is a so-called prodrug, which means that it is converted to its active form when it arrives in the cells. Once there, it gets incorporated into the virus’s genetic material, interfering with its ability to replicate. Errors build up in the virus’s genetic material, a process known as “error catastrophe.” Animal testing has raised concerns that the drug could pose risks to unborn children, so the UK government has advised against its use during pregnancy or while breastfeeding. Other regulators may issue similar warnings.

Paxlovid is basically a combination of two drugs: an existing one called ritonavir, which is given in addition to a new protease inhibitor known asPF-07321332. The protease inhibitor is designed to bind and block the protease enzymes that sars-cov-2 uses to replicate. Ritonavir prevents the protease inhibitor from being broken down too quickly in the body.

Molnupiravir and Paxlovid are also known as ‘small molecule’ medicines. These are molecules that are easy to make. Both companies say the price of the drugs will vary depending on the wealth of the country buying them. That will likely mean rich countries paying $700 for a five-day course of pills, while poorer countries will pay about $20, and perhaps less as production costs fall.

While both companies have said they plan to make these drugs available around the world, Merck is already ahead. It has signed a number of licenses that allow other manufacturers to produce the drug, and it has reserved 3 million doses for low- and middle-income countries. This is to ensure that rich countries do not monopolize the supply of new drugs as they have done for vaccines. Merck expects to make 10 million doses this year and 20 million next year. Generic manufacturers will make many more. Pfizer, which has not yet received regulatory approvals, expects to produce 180,000 packs of pills by the end of this year, and 21 million by the first half of 2022.

These drugs herald a second major turning point in the pandemic (the first being vaccines). Rising numbers of cases across Europe suggest there will be a high demand for such drugs to keep people out of hospital. While patients wait for them to arrive, doctors may also consider taking fluvoxamine, an antidepressant that also appears to lower the risks of Covid.

As the new treatments roll out for use, some scientists and doctors will worry about developing resistance to the virus, especially if patients don’t finish their course. To stay one step ahead of sars-cov-2, planning is required for such an event. That means deducing which antiviral drugs can be given in combination to create a therapy that has a hard time defeating the virus.

This article appeared in the Science & Technology section of the print edition under the heading “Pills with Promise”