Real-world Plasma Exposure of Nirmatrelvir/Ritonavir in Chinese Hospitalized Patients With COVID-19: A Multicenter...

Nirmatrelvir/ritonavir is licensed for the treatment of mild-to-moderate coronavirus disease (COVID-19) in patients at an increased risk of progression to severe disease. However, data on the real-world plasma exposure to nirmatrelvir/ritonavir remain limited, particularly in Chinese patients. This study aimed to assess the nirmatrelvir/ritonavir trough concentration (C trough ) and identify its critical factors in hospitalized Chinese patients treated with nirmatrelvir/ritonavir 300 mg/100 mg twice daily over a 5-day course.

A high-performance liquid chromatography-tandem mass spectrometry assay was developed and validated to measure the nirmatrelvir/ritonavir C trough . Correlation analyses were performed to identify the variables influencing nirmatrelvir/ritonavir C trough .

Among the 110 patients, 100% had plasma concentrations above the antiviral in vitro 90% effective concentration. The median C trough of nirmatrelvir was 4.55 mcg/mL (15.6× 90% effective concentration), ranging from 0.65 to 12.44 mcg/mL. Nirmatrelvir C trough in normal and mild renal impairment cohorts were comparable (4.09 ± 1.97 mcg/mL and 4.57 ± 2.21 mcg/mL) but significantly increased in the moderate renal impairment cohort (6.41 ± 2.31 mcg/mL). Sex, age, and obesity were not significantly associated with nirmatrelvir exposure.

Nirmatrelvir C trough was high in Chinese patients with COVID-19, and therapeutic drug monitoring should not be routinely recommended, except in patients with renal impairment.