A 34-year old man with ESRD nine years post-renal transplant presented with mild SARS-CoV-2 symptoms. Due to the patient’s unvaccinated SARS-CoV-2 status and high risk for progression to severe disease, nirmatrelvir and ritonavir twice daily was started at a renally adjusted dose (baseline sCr 1.2-1.5 mg/dL).

Current medications: amlodipine, calcitriol, cholecalciferol, leflunomide, lisinopril, magnesium oxide, omeprazole, prednisone, tacrolimus

The patient took the morning nirmatrelvir and ritonavir dose on day 3 of treatment then wanted to stop due to N/V. Labs drawn on day 2 but not available until day 3 showed sCr 1.42 mg/dL and tacrolimus level >30 ng/dL (goal range 4-6 ng/dL). Medications were immediately adjusted and the patient’s symptoms began to improve on day 4. However, his sCr continued to climb to 1.62 mg/dL on day 7, and then peaked at 1.79 mg/dL on day 10. Tacrolimus levels were >30 ng/dL on day 7 and 8.8 ng/dL on day 10.

Which drug combo could have caused the patient’s acute renal injury?
amlodipine and nirmatrelvir and ritonavir
omeprazole and nirmatrelvir and ritonavir
leflunomide and nirmatrelvir and ritonavir
tacrolimus and nirmatrelvir and ritonavir
You are correct. Ritonavir (a strong CYP3A4 inhibitor and weak P-gp inhibitor) inhibits the metabolism and P-gp-mediated transport of tacrolimus (a CYP3A4 substrate and P-gp substrate) leading to increased systemic exposure and risk of adverse events including nephrotoxicity, QT prolongation, and cardiac arrhythmias.

More info is available in the free, full-text Transplant Proc article PDF at PubMed Central.

Source article: Prikis M, Cameron A. Paxlovid (Nirmatelvir/Ritonavir) and Tacrolimus Drug-Drug Interaction in a Kidney Transplant Patient with SARS-2-CoV infection: a case report. Transplant Proc. 2022;54:2557. doi:10.1016/j.transproceed.2022.04.015
By rray, 28 February, 2023
By rray, 28 February, 2023
By rray, 28 February, 2023