Paxlovid inhibits the multiplication of the virus in the body, is taken orally and is a combined preparation of an active ingredient specially developed against Covid-19 (nirmatrelvir) and an older active ingredient of HIV therapy (ritonavir). The latter is used so that the new active ingredient is not broken down too quickly in the body. Nirmatrelvir prevents the virus from multiplying in the body.
To do this, the substance blocks a virus-specific building block: an enzyme that helps to properly organize the pathogen’s protein molecules. The enzyme is called a protease. The active ingredient Paxlovid is therefore also called a protease inhibitor. Ritonavir itself has no antiviral activity in this context, but protects the active substance nirmatrelvir from hepatic degradation.
Treatment consists of a five-part pack: two 150 mg nirmatrelvir tablets and one 100 mg ritonavir tablet twice daily.