First known case of rare side effect of Covid-19 drug Paxlovid discovered by experts at Shore Medical Center

A study recently published in SAGE Open Medical Case Reports finds that Paxlovid, a drug used to treat Covid-19, can have a rare side effect of symptomatic bradycardia, commonly known as slow heart rate.

Nirmatrelvir/ritonavir, sold under the brand name Paxlovid, is a co-packaged oral medication developed by Pfizer and used as a treatment for COVID-19 to help high-risk patients from getting so sick that they need hospitalization. It contains the antiviral medications nirmatrelvir and ritonavir. 

This study examined the effect of nirmatrelvir/ritonavir (NMV/r) on a patient who satisfied the following conditions: the patient was not immune-compromised and not taking any other medications while receiving NMV/r, and the patient tested positive for Covid-19 but was asymptomatic. 

Shore Medical Center Critical Care Attending Physician Dr. Farhan Qadeer, MD, published this study along with pharmacists Elizabeth DeMarco, PharmD, BCPS, Matthew Turnipseed, PharmD, and Brian Clarke, PharmD, of Shore Medical Center, all pictured above, left to right.

"The findings of this study are extremely significant because this is the first known case of symptomatic bradycardia caused by administering nirmatrelvir/ritonavir to a patient who was not taking other medications or immune-compromised," said Dr. Qadeer. "This finding is significant for medical professionals and patients, as well as for Shore Medical Center, a community hospital caring for patients in South Jersey.

"Shore has been in contact with Pfizer to add bradycardia as a side effect of Paxlovid," added Dr. Qadeer.

Nirmatrelvir is a newly developed protease (an enzyme that breaks down proteins and peptides) inhibitor. It is combined with a commonly used boosting agent, ritonavir, to help it move throughout the body. In 2021, the US FDA authorized the emergency use of (NMV/r) for treating mild to moderate Covid-19 in adult and pediatric patients at least 12 years old with a positive Covid-19 test who were at risk of progressing to severe Covid-19. 

"Authorized emergency use of NMV/r was necessary, and it is extremely important in our fight against Covid-19," said Dr. Qadeer. "As we learn more about it, we need to share our findings so that all patients have the best possible outcomes."

To read this case report in its entirety, click here.