COVID-19 antiviral pills could be our ‘penicillin moment’ – Community News
Covid-19

COVID-19 antiviral pills could be our ‘penicillin moment’

Until now, antiviral drug research has been a place of broken dreams and abandoned endeavors, with few success stories to rival the miracle cures of antibiotics.

But with the creation of pills to kill the COVID-19 virus, the field may be approaching its “penicillin moment.”

Two new oral drugs made by Pfizer and Merck — convenient to take at home, just five days — offer a remarkable 50 to 89% reduction in hospitalizations and deaths in high-risk people when given soon after the infection sets in. occurred, according to the company data.

The use of the Merck pill, known as molnupiravir, will be voted on Nov. 30 by a United States Food and Drug Administration committee, with approval on track for December. Pfizer has not yet applied for FDA approval for its drug, called Paxlovid, but says it plans to submit data “as soon as possible.”

And more antiviral drugs, made by rival companies, are also in the research pipeline.

“Having oral pills that are easy to take — like you would treat strep throat — is a huge advance,” said Dr. Upinder Singh, a professor of medicine at Stanford University, who led a clinical trial of the Pfizer drug this fall.

Vaccines still remain the best way to contain the pandemic, experts say. It is much better to prevent an infection than to treat it. But for Americans who don’t benefit from vaccines, or whose protections are declining, the new drugs will save lives.

And for large parts of the world that still don’t have access to vaccines, they could be a godsend. The goal would be to approve and distribute the drugs in the critical window when vaccines, antibody treatments and other types of drugs are not available.

The antiviral pills may be important for another reason: The drug companies are analyzing whether the pills not only provide treatment for the sick, but also protect vulnerable people who have been accidentally exposed to the virus.

For example, if a nursing home resident develops COVID-19, the pill may be given to other residents to prevent an outbreak.

Unlike existing antivirals such as remdesivir or monoclonal antibodies, the pills do not need to be administered intravenously in a medical setting. They are easy to ship and store as they do not require any special storage conditions.

“You’d just run out and get them” at a pharmacy, said UCSF infectious disease expert Dr. Peter Chin-Hong.

Historically, the development of antivirals has presented far greater technical and financial challenges than antibiotics such as penicillin, which was discovered in 1928 in a neglected petri dish by bacteriologist Alexander Fleming.

Why is it so hard? Antiviral drugs are more complicated than antibiotics. They are to prevent the virus from attaching to or entering the host cell, or by interfering with its replication once inside. And because they have to get into infected cells, the drugs can do damage.

In addition, while an antibiotic can work against many types of bacteria, an antiviral drug has a much more limited attack range and targets a single virus. There are few viral diseases with enough patients, or a market large enough to justify the research and high cost of drug development.

Influenza antivirals, such as Tamiflu, have limited use and commercial value. There is still no antiviral medication that works against cold-causing rhinoviruses.

And while intensive efforts had been made to develop antivirals after the 1997 outbreak of the H5N1 virus and the outbreak of the original SARS virus in 2003, they were short-lived. The number of infections quickly decreased and companies are suspending their programs.

The field took a quantum leap with the emergence of HIV/AIDS, which inspired the development of many drugs targeting different viral enzymes.

“HIV is a really big success story,” says UC San Francisco pharmacologist Tia Tummino. “People have worked for decades to try different things to get us to stop HIV from being a death sentence. We learn from that, in this time of COVID.”

Recent technical breakthroughs – such as the safe cultivation of viruses in the laboratory and accurate detection of viral enzymes – are speeding up research.

But when the first cases of COVID-19 emerged in late 2019, there was no portfolio of antivirals waiting to be used. Companies searched their libraries for something that might work. Merck dusted off a drug that had been developed as a potential therapy for the Venezuelan equine encephalitis virus. Pfizer tinkered with an old compound it had developed after the original SARS epidemic, then combined it with a second antiviral drug called ritonavir.

These efforts have led to today’s success stories. “These two agents really have the potential to really make an impact,” says UCSF infectious disease specialist Dr. Phyllis Tien, who is part of the NIH’s influential COVID-19 Treatment Guidelines Panel, which advises doctors on how to care for patients with the disease.

To be better prepared for next time, the Biden administration is investing more than $3 billion in the discovery, development and production of antiviral drugs.

While more details about the new drugs won’t be known until the FDA’s Nov. 30 meeting, here’s what we know for now:

Q: Who is eligible?

AN: So far, there is only data from patients with mild to moderate COVID-19 who have at least one risk factor for developing serious disease. An analysis on its use in other patients, such as the healthy and newly exposed patients, has not yet been released.

Q: When do you take it?

AN: Trial participants were treated within three or five days of the onset of symptoms. Both drugs are given twice a day for five days.

Q: How do they work?

AN: Pfizer’s drug is part of a class known as protease inhibitors, which are designed to block an enzyme the virus needs to replicate. Merck’s drug is a nucleoside analogue, which introduces errors into the virus’s genetic code.

Q: How effective are they?

AN: Pfizer’s drug reduced hospitalizations and deaths in at-risk patients by 89%. Merck’s drug reduced the risk of hospitalization by about 50%. The results have not yet been peer-reviewed or published in a scientific journal.

Q: Are they safe?

AN: Both drugs were well tolerated by study participants, with only minor side effects. The regulators are waiting for more data.

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