While often the antiviral of choice among high-risk patients, a new study found nearly 15 percent of 62,525 hospitalized COVID-19 patients had a medical contraindication to Paxlovid's antiviral combination of nirmatrelvir and ritonavir.
The study focused on circumstances in which the antiviral is not recommended, such as when patients are on drugs highly dependent on hepatic cytochrome P-450 (CYP3A) metabolism, as ritonavir may elevate the concentrations of these types of drugs to dangerous levels. Drugs highly dependent on CYP3A clearance include some for high blood pressure, some to correct heart rhythm problems as well as some cholesterol-lowering statins.
Researchers used individual contraindications listed by the FDA to evaluate Paxlovid eligibility among 65,505 COVID-19 patients hospitalized across Paris University hospitals from Jan. 24, 2020, to Nov. 30, 2021, according to findings published Nov. 15 in JAMA Network Open.
More than 9,100 patients, or 14.6 percent, had a medical contraindication to Paxlovid. Contraindication rates were higher among men (18 percent) than in women (11.3 percent). Rates in older patients were 26.9 percent.
"The most prevalent contraindications were severe kidney impairment and use of medications dependent on CYP3A for clearance," researchers said.