Improved Kidney Graft Function After Conversion From Twice Daily Tacrolimus to a Once Daily Prolonged-Release Formulation

Abstract Background Tacrolimus once daily (Tac-QD) formulation has been recently introduced to improve patient adherence to immunosuppressive medications. To evaluate long-term effects of conversion from tacrolimus twice daily (Tac-BID) to Tac-QD on kidney graft excretory function, we retrospectively analyzed kidney graft function after the conversion from Tac-BID to Tac-QD over 24 months. Methods We enrolled 72 kidney transplant recipients, including 19 simultaneous pancreas–kidney cases, who were at least 9 months posttransplantation and showed stable graft function for 6 months. We analyzed kidney graft function (glomerular filtration rate [eGFR] by the Modification of Diet in Renal of Disease equation), tacrolimus daily dose and tacrolimus blood trough level changes over 24 months after conversion. Results All patients completed the 12 months and 56 patients, 24 months observation. At 3 months, the eGFR increased significantly after conversion from 57.1 to 60.0 mL/min/1.73 m2 ( P = .004) and at 24 months to 66.0 mL/min/1.73 m2 ( P < .001). Tacrolimus daily dose diminished over time by almost 10%, a difference that reached statistical significance at 18 months. Tacrolimus blood trough levels did not change significantly until 24 months. There was no correlation between eGFR changes during the first 12 months after conversion and changes in tacrolimus blood trough levels ( r = −0.118; P = .33). Conclusion Conversion from Tac-BID to Tac-QD formulation was followed by a clinically significant improvement in kidney graft function upon long-term observation. The improvement seemed to not be related to changes in tacrolimus blood trough levels.