Treatment of prolonged tacrolimus toxicity using phenytoin in a haemodialysis patient.

What Is Known And Objective: Treatment of tacrolimus toxicity includes holding tacrolimus and supportive care. The objective is to describe considerations for pharmacologic induction of tacrolimus metabolism.

Case Description: A 52-year-old male with a failed renal transplant on chronic haemodialysis developed tacrolimus toxicity due to a drug-drug interaction with darunavir/ritonavir. Tacrolimus concentrations were >60 ng/mL for 10 days despite holding tacrolimus and darunavir/ritonavir. Development of encephalopathy prompted initiation of phenytoin to induce tacrolimus metabolism. Tacrolimus concentration was <2 ng/mL within 4 days and mental status normalized.

What Is New And Conclusion: Phenytoin metabolic induction is a therapeutic option for prolonged tacrolimus toxicity.