Pfizer antiviral pill could be risky with other widely used medications

The Food and Drug Administration (FDA) recently authorized two antiviral pills, one from Pfizer and one from Merck, making them the first at-home treatment for COVID-19 that has been touted as a game changer in the fight against the pandemic.

However, experts told NBC News that the pills will require careful monitoring by doctors and pharmacists. 

While Pfizer’s Paxlovid has been authorized for use in children 12 and over with underlying health conditions including heart disease or diabetes, a component of the antiviral cocktail could have serious and life- threatening interactions with drugs including blood thinners, statins and depressants, NBC reported.

“Some of these potential interactions are not trivial, and some pairings have to be avoided altogether,” Peter Anderson, a professor of pharmaceutical sciences at the University of Colorado told NBC News.

“Some are probably easily managed. But some we’re going to have to be very careful about,” he added.

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

The spokesperson further elaborated on the antiviral pill and said that Paxlovid is comprised of the active protease inhibitor Nirmatrelvir, as well as a low-dose of 100 mg of Ritonavir.  

“Its effect on drug metabolism may result in drug interactions, and some drugs may be contra-indicated. 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,” the statement reads.

“The product’s emergency use authorization fact sheets include information on drug interactions and contraindications. Healthcare providers should consider the potential for drug interactions prior to and during PAXLOVID therapy and review concomitant medications during PAXLOVID therapy,” the spokesperson added.

However, the spokesperson noted that “as with many drugs that have the potential for drug interactions, healthcare providers and patients need to consider the risk-benefit of starting a new treatment.”

The Associated Press reported that Merck’s molnupiravir is not authorized for children because it could interfere with bone growth and it isn’t recommended for pregnant women because of the potential for birth defects.

The AP also noted that Pfizer’s pill isn’t recommended for patients with severe kidney or liver problems. It also may not be the best option for some people because it may interact with other prescriptions a patient is taking. The antiviral pills aren’t authorized for people hospitalized with COVID-19 as the treatment options are to be taken as soon as a person feels symptoms and have mild or moderate COVID-19.

The FDA has also issued a list of medications that should not be taken along with Paxlovid.

However, the approval of the Pfizer pill earlier this month was seen as a major step forward in the fight against the virus, with trials showing it reduced the risk of hospitalization or death by 89 percent in high-risk patients.

Pfizer says it expects to have 180,000 courses of the treatment available by the end of 2021, with 30 million available globally in the first half of 2022, rising to 80 million by the end of next year. 

Updated: Dec. 26, 2021, 9:01 p.m.