As the omicron surge pummels a pandemic-weary nation, the first antiviral pills for Covid-19 promise desperately needed protection for people at risk of severe disease. U.S. regulators authorized Pfizer’s pill, Paxlovid, and Merck’s molnupiravir last week.
But that convenience comes with a catch: The pills have to be taken as soon as possible once symptoms appear. The challenge, according to the Associated Press, is getting tested, getting a prescription, and starting the pills in a short window. The antiviral pills aren’t authorized for people hospitalized with COVID-19.
Who should take the pills?
The Food and Drug Administration authorized Pfizer’s Paxlovid for mild to moderate Covid in people as young as 12 who have underlying conditions that raise the risk of hospitalization and death from the coronavirus, such as heart disease or diabetes.
Additionally, Pfizer’s pill is not recommended for patients with severe kidney or liver problems. It also may not be the best option for some because it may interact with other prescriptions a patient is taking.
Merck’s molnupiravir is for adults only, and only in scenarios in which other authorized treatments, including monoclonal antibodies, are inaccessible or are not “clinically appropriate.” It also isn’t recommended for pregnant women because of the potential for birth defects.
The treatment window is short
The pills have to be taken within five days of the start of symptoms. Cough, headache, fever, the loss of taste or smell, and muscle and body aches are among the more common signs. The Centers for Disease Control and Prevention (CDC) offers a website to check your symptoms.
Dr. Cameron Wolfe, an infectious disease specialist at Duke University Hospital, advises getting a test as soon as you have symptoms of COVID-19.
“If you wait until you have started to get breathless, you have already to a large extent missed the window where these drugs will be helpful,” Wolfe said.
Additional information
You’ll need a prescription first from a doctor or other authorized health worker. The U.S. government is buying the pills from Merck and Pfizer and providing them for free, but supplies will be limited initially.
The medications will be shipped to states where they will be available at drugstores, community health centers, and other places. Treatment lasts five days.
Pairing Pfizer’s Paxlovid with other medications
One of the two drugs in Pfizer’s Paxlovid antiviral cocktail could cause severe or life-threatening interactions with widely used medications, including statins, blood thinners, and some antidepressants, reports NBC News.
The Pfizer pill regimen consists of two tablets of the antiviral nirmatrelvir and one tablet of ritonavir, a widely used drug that suppresses a key liver enzyme called CYP3A, which metabolizes many medications, including nirmatrelvir.
In the case of Paxlovid treatment, ritonavir slows the body’s breakdown of the active antiviral and helps it remain at a therapeutic level for longer, and this action is all well and good.
However, when Paxlovid is paired with other medications that are also metabolized by the CYP3A enzyme, the chief worry is that the ritonavir component may boost the co-administered drugs to toxic levels.
The medications include but are not limited to: blood thinners; anti-seizure medications; drugs for irregular heart rhythms, high blood pressure, and high cholesterol; antidepressants and anti-anxiety medications; immunosuppressants; steroids (including inhalers); HIV treatments; and erectile dysfunction medications.
“Some of these potential interactions are not trivial, and some pairings have to be avoided altogether,” said Peter Anderson, a professor of pharmaceutical sciences at the University of Colorado Anschutz Medical Campus. “Some are probably easily managed. But some we’re going to have to be very careful about.”
In its fact sheet about Paxlovid, the FDA has published a detailed list of medications that may interact harmfully with ritonavir, including those that should not be paired with the Covid antivirals.
While many drug interactions can be avoided, it is always wise to tell your doctor all of the medications you are taking. There is one alternative that is a safe and effective alternative Covid-19 therapy: GlaxoSmithKline’s sotrovimab is the sole authorized monoclonal antibody treatment that research indicates reliably neutralizes the omicron variant of the virus.
