Physiologically Based Pharmacokinetic Modeling to Investigate the Disease‐Drug–Drug Interactions between Voriconazole and Nirmatrelvir/Ritonavir in COVID‐19 Patients with CYP2C19 Phenotypes

Coronavirus disease 2019 (COVID‐19)‐associated pulmonary aspergillosis superinfection with cytokine storm is associated with increased mortality. This study aimed to establish a physiologically‐based pharmacokinetic (PK) model to investigate the disease‐drug–drug interactions between voriconazole and nirmatrelvir/ritonavir in patients with COVID‐19 with elevated interleukin‐6 (IL‐6) levels carrying various CYP2C19 phenotypes. The model was constructed and validated using PK data on voriconazole, ritonavir, and IL‐6, and was subsequently verified against clinical data from 78 patients with COVID‐19. As a result, the model predicted voriconazole, ritonavir, and IL‐6 PK parameters and drug–drug interaction‐related fold changes in healthy subjects and patients with COVID‐19 with acceptable prediction error, demonstrating its predictive capability. Simulations indicated ritonavir could increase voriconazole exposure to CYP2C19 intermediate and poor metabolizers rather than decrease it, in contrast to what is indicated in the drug package insert. However, the predicted ritonavir exposures were comparable across subjects. In patients with COVID‐19, both ritonavir and IL‐6 increased voriconazole trough concentrations, which may lead to CYP2C19 phenotype‐dependent overexposure. In conclusion, COVID‐19‐induced IL‐6 elevation and ritonavir increased voriconazole exposure, and the magnitude of interactions was influenced by CYP2C19 phenotype. Thus, caution is warranted when prescribing voriconazole concomitantly with Paxlovid in patients with COVID‐19.