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 (Cmin) 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 Cmin of TAC-BID (pre-conversion Cmin) was determined. Subsequently, TAC-BID was converted to TAC-OD with a similar dose. The Cmin of TAC-OD was first measured at a steady state (immediate post-conversion Cmin) and compared. All enrolled patients received therapeutic monitoring at the first and second months. Main outcome measure Pre-conversion Cmin of TAC-BID and immediate post-conversion Cmin of TAC-OD. Results The immediate post-conversion Cmin was found to be 23% lowered than the pre-conversion Cmin. However, the Cmin of TAC-OD was found to be similar to the pre-conversion Cmin 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 Cmin but comparable Cmin 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.
Keywords: Early conversion; Formulation; Kidney transplant; Tacrolimus; Trough level.