Background: 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. Methods: 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 . Results: 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. Conclusions: 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.
Objective To develop a simple, rapid, and sensitive LC-MS/MS method for quantifying 23 tyrosine kinase inhibitors (TKIs) in plasma samples, and evaluate the relationship between the trough concentration of anlotinib(ANL) and its toxicities. Methods The method was developed in Agilent 1290–6460 UHPLC-MS/MS system. This study prospectively enrolled 55 cancer patients undergoing ANL treatment. Plasma samples were collected at steady-state trough concentration and subsequently analyzed using the method. Patients were recorded for the occurrence of toxicities. Statistical analysis was performed to assess the association of the toxicities with ANL exposure level and patients’ characteristics. Results The LC-MS/MS method was developed and validated for all items required by pharmacopoeia. The results revealed a positive association between the trough concentration of ANL and the incidence of toxicities. The exposure level 17.655 ng/mL (AUC 0.82, p = 0.010) was identified as a predictive threshold value for grade ≥ 3 overall toxicities. In addition, lower platelet count (PLT count < 179 × 10 9 g/L) was significantly associated with higher occurrence of grade ≥ 3 toxicities (AUC 0.75, p = 0.049). A logistic model incorporating these two factors demonstrated improved diagnostic capacity for predicting ≥ 3 overall toxicities (AUC = 0.90, p = 0.001). Conclusion This study successfully developed and validated a simple, rapid, and sensitive LC-MS/MS method for quantifying 23 TKIs in plasma samples. Besides, this study found that both C trough of ANL and PLT count as independent predictors for ANL-induced ≥ 3 overall toxicities. Moreover, a logistic model including these two factors presents better prediction capacity for ≥ 3 overall toxicities.
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