Paxlovid is an oral antiviral medication that combines nirmatrelvir and ritonavir. It is used to treat mild to moderate COVID-19 in individuals at high risk of developing severe illness. Approved for emergency and standard use during the COVID-19 pandemic, Paxlovid helps reduce hospitalisation and death when taken early in the course of infection. The combination allows for a potent antiviral effect with enhanced duration of action.

Mechanism of Action
Paxlovid contains two key components that work together:

• Nirmatrelvir is the main antiviral agent. It inhibits the SARS-CoV-2 main protease, also known as Mpro or 3CL protease. This enzyme is essential for processing viral proteins required for replication. By blocking this enzyme, nirmatrelvir stops the virus from multiplying in the body.

• Ritonavir does not have direct activity against the coronavirus. Instead, it works by inhibiting the enzymes in the liver that would normally break down nirmatrelvir. This helps maintain higher levels of nirmatrelvir in the blood for a longer period, increasing its effectiveness.

  Uses
  Paxlovid is used in the treatment of COVID-19 in adults and children over a certain age and weight, who:

  • Have mild to moderate symptoms

  • Are at high risk for progression to severe disease, hospitalisation, or death due to age or underlying health conditions

  It is most effective when started within five days of symptom onset. It is not used for prevention or treatment of severe COVID-19 requiring hospitalisation.

  Adverse Effects
  Paxlovid is generally well tolerated, but some people may experience side effects.
  Common side effects include altered or bitter taste in the mouth, diarrhea, high blood pressure, and muscle aches.

  Ritonavir may interact with other medicines by affecting how they are broken down in the liver. This can lead to drug interactions, so a detailed review of current medications is essential before starting Paxlovid.