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ABSTRACT: Background
Currently, the applicant has chosen a target plasma trough concentration for nirmatrelvir, which is adjusted to 292 ng/mL based on the drug's molecular weight (499.54 Daltons), its binding to human plasma proteins (69%), and the in vitro antiviral EC90 value (181 nM). However, the current exposure-effect relationships (ER) analysis of viral load in patients enrolled in the EPIC-HR study has not revealed clinically significant trends in the ER. Given that the lungs are the primary site of COVID-19 infection, we aim to further understand this exposure relationship by exploring and analyzing the penetration characteristics of nirmatrelvir in the lungs.Objectives
To explore and understand the target plasma concentration of 292 ng/mL in antiviral activity.Methods
We identified all critically ill patients with coronavirus disease 2019 who received nirmatrelvir/ritonavir treatment in the respiratory intensive care unit of Changhai hospital between January 2023 and October 2023. Samples of plasma and bronchoalveolar lavage fluid were obtained at pre-dose trough concentrations after administration of nirmatrelvir (NMV). The relationship between NMV levels in plasma and the epithelial lining fluid (ELF) was assessed by determining concentrations of NMV.Results
There was a significant relationship between NMV levels in plasma and ELF (ELF = 0.4976*PLASMA- 204; R = 0.96), with a correlation whose slope (0.4976) suggested that the blood-to-ELF ratio of drug penetration was 2:1. A negative value from the equation indicates that NMV requires to reach baseline concentration to penetrate the ELF.Conclusions
The relationship between NMV levels in plasma and ELF with low permeability and a negative baseline value suggests that the target plasma concentration of 292 ng/mL is insufficient for antiviral activity. This study provides a unique perspective to explore and understand no clinically meaningful trend of exposure-response relationships in patients enrolled in EPIC-HR.
SUBMITTER: Zhang W
PROVIDER: S-EPMC11565441 | biostudies-literature | 2024 Nov
REPOSITORIES: biostudies-literature

Immunity, inflammation and disease 20241101 11
<h4>Background</h4>Currently, the applicant has chosen a target plasma trough concentration for nirmatrelvir, which is adjusted to 292 ng/mL based on the drug's molecular weight (499.54 Daltons), its binding to human plasma proteins (69%), and the in vitro antiviral EC<sub>90</sub> value (181 nM). However, the current exposure-effect relationships (ER) analysis of viral load in patients enrolled in the EPIC-HR study has not revealed clinically significant trends in the ER. Given that the lungs a ...[more]