A UPLC-MS/MS Method for Plasma Biological Monitoring of Nirmatrelvir and Ritonavir in the Context of SARS-CoV-2 Infection and Application to a Case

Abstract

Nirmatrelvir/ritonavir association has been authorized for conditional use in the treatment of COVID-19, especially in solid-organ transplant recipients who did not respond to vaccine and are still at high risk of severe disease. This combination remains at risk of drug interactions with immunosuppressants, so monitoring drug levels seems necessary. After a simple protein precipitation of plasma sample, analytes were analyzed using an ultrahigh performance liquid chromatography system coupled with tandem mass spectrometry in a positive ionization mode. Validation procedures were based on the guidelines on bioanalytical methods issued by the European Medicine Agency. The analysis time was 4 min per run. The calibration curves were linear over the range from 10 to 1000 ng/mL for ritonavir and 40 to 4000 ng/mL for nirmatrelvir, with coefficients of correlation above 0.99 for all analytes. Intra-/interday imprecisions were below 10%. The analytical method also meets criteria of matrix effect, carryover, dilution integrity, and stability. In the context of a SARS-CoV-2 infection in a renal transplant recipient, we present a case of tacrolimus overdose with serious adverse events despite discontinuation of nirmatrelvir and ritonavir. The patient had still effective concentrations of nirmatrelvir and tacrolimus 4 days after drug discontinuation. This method was successfully applied for therapeutic drug monitoring in clinical practice.

Optimizing the use of nirmatrelvir/ritonavir in solid organ transplant recipients with COVID-19: A review of immunosuppressant adjustment strategies

“…In one liver transplant recipient who had recently undergone kidney transplantation, Guyon et al. ( 17 ) discontinued all immunosuppressants. Patients resumed taking tacrolimus either 12 h after the last dose of NR at 100% of the baseline dose ( 17 ), on day 7 (day 1 being the day of NR initiation) at 100% ( 15 ), or 3 days (2–5 days) after the completion of NR at 82% (interquartile range (IQR), 71–100) of their baseline dose ( 13 ).…”

“…( 14 ) reported that three patients experienced supratherapeutic levels (> 20 ng/ml), and Guyon et al. ( 17 ) reported a patient with a tacrolimus trough level of > 111 ng/ml.…”

“…During ISDs adjustment periods, most patients had a stable renal function. Two out of 75 patients (3%) experienced acute kidney injury (AKI), and one case was induced by tacrolimus nephrotoxicity ( 12 , 17 ). No acute rejection or patient death occurred during the follow-up period of approximately 30 days.…”

“…No acute rejection or patient death occurred during the follow-up period of approximately 30 days. Out of the 75 patients, 13.3% (10/75) required hospitalization, with one case of infectious diarrhea, three cases related to COVID-19 symptoms ( 13 ), two cases of acute pyelonephritis ( 15 ), one case of general condition deterioration ( 17 ), and four cases of unknown reasons ( 16 ). Two patients experienced relapses of early SARS-CoV-2 infection, which may have been caused by infection with new variants, but both patients rapidly recovered within a few days of follow-up ( 15 ).…”

“…Along with monitoring whole blood tacrolimus concentrations, qualified institutions can measure nirmatrelvir and ritonavir plasma concentrations to better determine metabolic status and the appropriate timing of tacrolimus administration. A recent study has reported a simple and rapid UPLC-MS/MS method for the quantitative determination of NR in human plasma, which may improve drug guidance ( 17 ).…”