Pfizer’s COVID Pill Is Not Without Risks: Some Blood Thinner, Depressant Drug Interaction Possible

While the Food and Drug Administration has authorized Pfizer’s (PFE) COVID pill Paxlovid for people aged 12 and older with underlying health conditions and mild to moderate virus symptoms, the antiviral drug doesn’t come without risks.

As the FDA authorized the drug, it also said it doesn’t recommend Paxlovid for people who are taking some medications that could cause severe or life-threatening drug interactions, NBC News reported.

These drugs include statins, blood thinners and some antidepressants as well as people who have severe kidney or liver disease, the news outlet said.

As Paxlovid could be a game-changer for some people as a COVID-19 treatment, the concern is it could increase these medications to toxic levels.

Pfizer’s Paxlovid is administered as two tablets of nirmatrelvir and one tablet of ritonavir within five days of COVID symptoms. The latter works by suppressing the liver enzyme CYP3A, which is used to metabolize many medications. While it helps keep nirmatrelvir in the body longer, it slows the metabolizing of other medications that a person may be taking.

It is possible that a drug interaction could occur with medications that include blood thinners, anti-seizure medications, irregular heart rhythm drugs, high blood pressure and high cholesterol medications, antidepressants and anti-anxiety drugs, immunosuppressants, steroids, HIV treatments and erectile dysfunction medications, among others, according to the FDA.

Peter Anderson, a professor of pharmaceutical sciences at the University of Colorado Anschutz Medical Campus, told NBC News, “Some of these potential interactions are not trivial, and some pairings have to be avoided altogether. Some are probably easily managed. But some we’re going to have to be very careful about.”

In a statement to The Hill, a Pfizer spokesperson acknowledged the drug interaction with Paxlovid, saying, “The potential for drug-drug interactions (DDI) for Paxlovid was examined in a series of in vitro studies as well as clinical DDI studies.

“Its effect on drug metabolism may result in drug interactions, and some drugs may be contraindicated. However, in light of the fact that Paxlovid has a short duration of treatment of five days, combined with a low dose of ritonavir of 100 milligrams, we believe that healthcare professionals should find most DDIs to be generally manageable.”

But the spokesperson did note to The Hill that “healthcare providers and patients need to consider the risk-benefit of starting a new treatment.”

Pfizer said that it plans to have as many as 180,000 courses of the Paxlovid treatment available by the end of 2021, with another 80 million packs available by the end of 2022, The Washington Post reported.

As of Monday premarket hours, shares of Pfizer were trading at $58.84, up 13 cents, or 0.22%.