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•   OFFERS AN ADVANTAGE  A 2021 double-blind randomised trial conducted in 2246 adults with covid-19 who had been symptomatic for 5 days at most, compared a 5-day course of the combination of nirmatrelvir + ritonavir versus placebo. The patients had no signs of severe covid-19, but had at least one risk factor for developing severe disease and had not been vaccinated against covid-19. Most patients were infected with the Sars-CoV-2 Delta variant. In the month following the start of the trial, 0,8% of the patients in the nirmatrelvir group were hospitalised, versus 6% of the patients in the placebo group (p<0.0001). Very little is known about nirmatrelvir's adverse effects. The nirmatrelvir + ritonavir combination is a difficult treatment to use due to the risk of many major drug interactions and the risk of overdose in patients with renal impairment. In practice, as of early 2022, given that the Omicron variant is more prevalent than the Delta variant and less likely to provoke severe covid-19, it is plausible that this combination will only be of value to patients who are unprotected by covid-19 vaccination and have several risk factors for developing severe disease. Even then, its multiple potential drug interactions will need to be carefully managed. 

©Prescrire 1 June 2022

Source: "Nirmatrelvir + ritonavir (Paxlovid°) in covid-19. For certain patients at risk of developing severe disease" Prescrire International 2022; 31 (238): 145-148. Subscribers only.

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