Mycophenolate-Induced Hepatotoxicity Precipitates Tacrolimus Nephrotoxicity in a Kidney Transplant Recipient: A Case...

Mycophenolate (mycophenolate mofetil [MMF]; mycophenolate sodium [MPS]) and tacrolimus (FK-506) are commonly and concomitantly used to prevent rejection in organ transplant. Mycophenolate-induced hepatotoxicity causing the reduced FK-506 metabolism with nephrotoxicity may be less appreciated, leading to inappropriate management. We describe a new living donor kidney recipient receiving pretransplant and post-transplant immunosuppressants including oral mycophenolate (MMF 1 g daily) and tacrolimus (FK-506 4-8 mg daily) who developed progressive liver dysfunction (up to 10-fold increase) despite the reduced FK-506 dosage (6 mg daily). A thorough investigation including infection, inflammation, and autoimmune hepatitis were unremarkable. With a withdrawal of MMF, his liver function improved, but persistently higher trough serum FK-506 level (12-15 ng/mL) and increased serum creatinine were notable. Moreover, the reintroduction of MPS with the reduced FK-506 dosage (4 mg daily) worsened liver function along with FK-506 nephrotoxicity (serum creatinine from 1.4-2.4 mg/dL). The replacement of MPS with mammalian target of rapamycin inhibitor not only resolved liver injury but also normalized serum FK-506 level and kidney function. Mycophenolate should be kept in mind as a cause of drug-induced hepatotoxicity that can reduce tacrolimus metabolism, leading to FK-506 nephrotoxicity and acute kidney injury in organ transplant.