Trough level from twice daily to once daily tacrolimus in early conversion kidney transplant recipients: a prospective study

Background Early conversion from twice-daily tacrolimus (TAC-BID) to once-daily tacrolimus (TAC-OD) provides a greater benefit of reducing under-exposure of TAC-OD during the first period after transplantation. Information regarding the conversion dose among Asian kidney transplant recipients is still limited. Objective This study aimed to compare the trough levels (C_min) of TAC-BID (Prograf^®) and TAC-OD (Advagraf^®). The values were obtained from early conversion intervention by 1:1 milligram per-milligram. Setting A university-based hospital. Method This study employed a single-center, open-label, prospective and single-armed design. Fifteen de novo standard risk kidney transplant recipients were enrolled. Fourteen days after transplantation, the C_min of TAC-BID (pre-conversion C_min) was determined. Subsequently, TAC-BID was converted to TAC-OD with a similar dose. The C_min of TAC-OD was first measured at a steady state (immediate post-conversion C_min) and compared. All enrolled patients received therapeutic monitoring at the first and second months. Main outcome measure Pre-conversion C_min of TAC-BID and immediate post-conversion C_min of TAC-OD. Results The immediate post-conversion C_min was found to be 23% lowered than the pre-conversion C_min. However, the C_min of TAC-OD was found to be similar to the pre-conversion C_min compared during the follow-up period. Renal function was found to be stable in all patients over 2 months. Conclusion Early conversion therapy was associated with a significantly lower immediate post-conversion C_min but comparable C_min throughout the follow-up period. The “one to one conversion ratio” from TAC-BID to TAC-OD could be performed among Asian de novo kidney transplant recipients at an early period after transplantation.