COVID-19 Antiviral Pills: Paxista and Paxzen

  1. How Do the COVID-19 Pills Work?

Paxista and Paxzen are antivirals that work by preventing viral replication. This reduces a person's viral load and makes their symptoms less severe. However, the drugs work in slightly different ways.

Paxzen is a protease inhibitor, which means it stops a part of the virus's life cycle from happening. Protease inhibitors bind to the enzyme that the virus needs to make more copies of itself. This stops the virus from making new viral particles. Paxista is a nucleoside analogue, which means it stops viruses from copying their DNA correctly. This makes new viral particles that can't spread disease.

Both drugs' clinical trials were so successful that they were terminated early. The pills were found to be far more effective than placebos. In a clinical trial done by Pfizer, giving Paxzen within three days of the start of symptoms cut the chance of having to go to the hospital by 89%. In a clinical trial done by Merck, giving Paxista within five days of the start of symptoms cut the number of people who had to go to the hospital or died by 30%.

It is important to note that both of these clinical trials involved a small number of patients, and both of these drugs are still considered experimental. They can be used in an emergency, but they are not FDA-approved, and we don't know all of the risks and benefits.

Both pills require a five-day treatment period. The majority of people who are prescribed Paxzen take three tablets at once, twice a day (there is a dose reduction for people with moderate kidney disease).  Paxista patients must take four capsules twice a day.


  2. Who Is Eligible for the COVID-19 Pills?

Paxista or Paxzen will not be available to everyone who tests positive for COVID-19. According to the FDA, Paxista and Paxzen can only be used on people who have tested positive for COVID-19, have mild to moderate disease, and are at a high risk of getting worse. Paxista is only available to people over the age of 12. Paxzen is only available to people over the age of 18.

Neither pill is made or approved for people with severe COVID-19 who need to stay in the hospital. They are also not intended to prevent COVID-19 in people who have already been exposed to the virus.

If you have tested positive for COVID-19 in the last five days and have questions about your eligibility or risk factors, consult your doctor.


3. How Are COVID-19 Pills Different Than Monoclonal Antibody Therapy?

Monoclonal antibody therapy is an infusion that gives the body antibodies that were made by people to fight COVID-19. While both antiviral pills and monoclonal antibody therapy are effective treatments for COVID-19, the mechanisms by which they do so differ.

Antibodies stick to virus particles and to the virus spike protein or other surface proteins, which keeps the virus from getting into the cells of the body. Paxista and Paxzen work within cells to prevent viral replication.

Both treatments should be given as soon as possible after a positive COVID-19 test, but Paxista pills can only be given five days after the first symptoms appear while Paxzen can be given 10 days after the first symptoms.


  4. Which COVID-19 Treatment Is Right for Me?

Your health care team will decide which COVID-19 treatment is best for you based on your medical history and current medications. This will also be dependent on supply availability, as the Wisconsin Department of Health and Human Services oversees supply distribution and determines how much of each drug is sent to Wisconsin hospitals.

People with severe kidney or liver disease should not take Paxzen medicine.

There are no known drug interactions with Paxista, but based on what we know, it shouldn't be used during pregnancy. Women who are of childbearing age and getting treatment must use birth control during treatment and for four days after the last dose. Men who are sexually active should use contraception both during and after treatment. 

Your medical team will keep track of everything for you and match you with the most appropriate treatment.


  5. Do I Need to Take the COVID-19 Pill if I'm Not Feeling Sick?

Within five days of a positive COVID-19 test, the COVID-19 pills are prescribed. People are only eligible if they have symptoms, but it is possible that you will not feel severely ill during this time period or that your symptoms will be milder. Even though it's your choice whether or not to go through with treatment, it's important to know why your provider suggested it.

“If you're prescribed the COVID-19 pill, you're part of a group of people who are at risk of getting worse,” Oleksia explained. “Consider how this will affect you or your family, and consider the information we have so far about the drug.” “These drugs are quite effective and safe, because they don't make you sick or require hospitalization.”

Current CDC guidelines say that if you are given one of the COVID-19 pills, you must still stay alone while you are being treated.


  6. Are Vaccinations Against COVID-19 Still Necessary With COVID-19 Pills?

The COVID-19 vaccines lower your risk of becoming infected and of spreading the virus. The pills are not a substitute for vaccination because they do not prevent COVID-19; they are a treatment.

“Public health mitigation measures like vaccines, face masks and social distancing are still the best ways to prevent you from getting admitted to the hospital for COVID-19,” Dr. Lodes said. “If you are infected, these new medications could save your life.”