This antiviral is very effective at protecting vulnerable people from Covid, despite the small possibility of rebound symptoms.
Paxlovid became the world’s first oral Covid antiviral when it was authorized for use by the US Food and Drug Administration and the UK Medicines and Healthcare Products Regulatory Agency back in December 2021. With regulators green-lighting the drug less than a year after the first person received it in clinical trials, it has been described as the fastest drug-development project in history.
Since then, Paxlovid has been approved by the European Medicines Agency, and the United Nations struck a deal with manufacturers to produce a generic version of it so that millions of doses can be supplied to low- and middle-income countries, beginning in April 2022.Developed by global pharmaceutical giant Pfizer, Paxlovid is a combination therapy, which means it contains two different drugs: nirmatrelvir and ritonavir.
When SARS-CoV-2 infects a cell, it hijacks the cellular machinery to make the proteins it needs to assemble new copies of itself, which allows it to continue spreading inside the body. Nirmatrelvir is the active antiviral in Paxlovid. It works by targeting an enzyme called Mpro, which is found in many coronaviruses and plays a pivotal role in their ability to reproduce. Nirmatrelvir prevents Mpro from making the active proteins that SARS-CoV-2 needs to replicate. It’s a substance with a bit of history—it was initially developed by Pfizer to combat the original SARS virus back in 2002.
The second drug, ritonavir, is a “boosting agent.” It slows down the rate at which nirmatrelvir is metabolized in the liver, meaning the active antiviral reaches higher concentrations in the body and lasts for longer before being cleared. Ritonavir has previously been used in HIV antiviral therapies to make them more effective.Patients take Paxlovid as three tablets—two 50 mg tablets of nirmatrelvir and one 100 mg tablet of ritonavir—twice daily for five straight days.