The company hopes to eventually be able to offer a pill given in combination with an older antiviral drug called ritonavir to people who take it home before they get sick enough to go to the hospital.
The so-called interim analysis – performed before the scheduled completion of the trial – showed an 89 percent reduction in the risk of hospitalization or death from Covid-19 if patients were given it quickly enough, the company said.
Pfizer published the results in a press release and did not provide scientists to discuss the data before publication. The data were not peer reviewed or published. The company says it will share more details in a peer-reviewed document and upon submission to the U.S. Food and Drug Administration.
The company is testing the drug in adults with Covid-19, who are considered to be at high risk for progression to a serious illness. Volunteers were randomized to receive a combination of tablets or placebo within three or five days of the onset of symptoms.
The tablet, still known by its experimental name PF-07321332, is what is known as a protease inhibitor. It is designed to prevent the virus from multiplying. Co-administration with ritonavir slows its breakdown in the body, the company said.
Pfizer says 0.8% of patients who received the combination of drugs in three days were hospitalized in four weeks – three out of 389 patients – compared to 7% of patients who received placebo, or 27 of 385. And seven those who received a placebo died, Pfizer said. No one who was treated died within a month.
“A similar reduction in hospitalization or death due to COVID-19 was observed in patients treated within five days of the onset of symptoms; 1% of patients receiving PF-07321332 (z) ritonavir were hospitalized by day 28 after randomization (6 of 607 hospitalized, no deaths) compared to 6.7% of patients who received placebo, ”the company said in a statement.
It said that 19% of the patients receiving the treatment suffered side effects compared to 21% who received the placebo but did not want to disclose what those side effects were.
“These data suggest that our candidate for an oral antiviral drug, if approved by regulators, can save patients’ lives, reduce the severity of COVID-19 infections, and eliminate up to nine out of ten hospitalizations, ”said Albert Bourla, CEO. Pfizer is stated in the statement.
Currently, remdesivir, sold under the Veklury brand, is the only antiviral drug approved by the FDA for the treatment of Covid-19. It is given by intravenous infusion, so it is not as easy to give as a tablet.
People can also be treated with monoclonal antibodies that are injected or infused with therapies that boost the immune system and help fight infection. They are not as easy to take as the pill and must be given by a qualified professional.
Merck is seeking FDA approval for emergency use for molnupiravir, an antiviral capsule that people could take at home. It has been shown to reduce the risk of hospitalization or death by approximately 50%. On Thursday, British drug regulators approved molnupiravir under the Lagevrio brand.