Simultaneous quantification of nirmatrelvir and ritonavir by LC-MS/MS in patients treated for COVID-19

• Published in: Journal of chromatography. B, Analytical technologies in the biomedical and life sciences Analytical technologies in the biomedical and life sciences, 2022-12, Vol.1212, p.123510-123510, Article 123510
• Main Authors: Martens-Lobenhoffer, Jens, Böger, Corinna R., Kielstein, Jan, Bode-Böger, Stefanie M.
• Format: Article
• Language: English
• Subjects: antiviral agents; chemical species; chromatography; Chromatography, High Pressure Liquid - methods; Chromatography, Liquid - methods; COVID-19 - epidemiology; COVID-19 Drug Treatment; COVID-19 infection; disease severity; enzymes; Humans; LC-MS/MS; methanol; Nirmatrelvir; pandemic; proteinase inhibitors; quality control; Ritonavir; Ritonavir - therapeutic use; SARS-CoV-2; Severe acute respiratory syndrome coronavirus 2; tandem mass spectrometry; Tandem Mass Spectrometry - methods; Therapeutic drug monitoring; therapeutics; viruses
• ISSN: 1570-0232; 1873-376X
• DOI: 10.1016/j.jchromb.2022.123510

•First method for therapeutic drug monitoring in Paxlovid-treated COVID-19 patients.•Simultaneous quantification of nirmatrelvir and ritonavir (constituents of Paxlovid)•Sensitive and selective determination by LC-MS/MS.•Plasma sample preparation by simple protein precipitation. Nirmatrelvir is an antiviral agent active against SARS-CoV-2, the virus causing the pandemic disease COVID-19. It is administrated in combination with the protease inhibitor ritonavir, which acts in case of COVID-19 mainly as enzyme blocking agent preventing the premature metabolic elimination of nirmatrelvir. The combination of the two drugs in separate tablets is marketed under the brand name Paxlovid® and shows good effectivity in preventing the progression of COVID-19 to severe disease state. In this work, we described a LC-MS/MS method for the simultaneous quantification of nirmatrelvir and ritonavir in human plasma of patients treated for COVID-19 with Paxlovid®. After addition of D6-ritonavir as internal standard, plasma proteins were precipitated by the addition of methanol. The analytes were separated by gradient elution on a C18-column and were detected by tandem mass spectrometry. Calibration functions were linear in the ranges of 10 – 10000 ng/mL for nirmatrelvir and 2 – 2000 ng/mL for ritonavir. Inter-day and intra-day precision and accuracy was better than 15 % in the quality control samples and better than 20 % at the LLOQ. The method was successfully applied on samples of hospitalized patients treated for COVID-19 and proved to be capable in supporting therapeutic drug monitoring (TDM).