Objectives Nirmatrelvir/ritonavir may cause a clinically relevant drug-drug interaction (DDI) with immunosuppressive drugs, such as tacrolimus, which may condition the use of this antiviral in transplant patients. We aimed to describe the management of this interaction.

Methods Descriptive study in which renal transplant patients in treatment with nirmatrelvir/ritonavir and tacrolimus were included. They suspended tacrolimus the day before starting the antiviral treatment, and the decision to restart it was made based on their tacrolimus blood levels. Main variables studied to measure this DDI were tacrolimus blood concentration, dose adjustment and serum creatinine.

Results Three patients were included. During the study, tacrolimus levels elevation did not have repercussion in the serum creatinine, that remained stable in all patients. No patient required hospitalisation or showed signs of rejection.

Conclusions Our experience provides further evidence that this interaction should not be a contraindication to treatment with nirmatrelvir/ritonavir, and can be managed with close monitoring of tacrolimus levels.