Comparison of low and high initial tacrolimus dosing in primary heart transplant recipients: a prospective European multicenter study.

Background: The purpose of this prospective, randomized, open-label, phase II, multicenter study was to optimize the initial oral dose of tacrolimus.

Methods: A total of 113 patients were randomly assigned to initial low-dose (0.075 mg/kg/day, n=55) or high-dose (0.15 mg/kg/day, n=58) oral tacrolimus and followed for 3 months. Target whole-blood trough levels were 10 to 20 ng/mL. Prophylactic use of corticosteroids and azathioprine was identical in both groups, and antibody induction was mandatory. The primary endpoint was the time to and incidence of the initial oral tacrolimus dose adjustment because of toxicity or rejection, or withdrawal before initial dose change. Efficacy was assessed by the occurrence of biopsy-proven rejection (International Society for Heart and Lung Transplantation grade > or =1B).

Results: In the primary endpoint, no significant difference was observed between the low- and high-dose groups. After 3 months, there was no difference in freedom from initial oral tacrolimus dose change because of rejection, toxicity, or withdrawal (89.0% vs. 87.6%; not significant [NS]). In both groups, dose adjustments were mainly required to achieve and maintain target blood levels (80.0% vs. 82.8%; NS). Patient survival was 92.7% and 98.3% (NS). There was no significant difference between groups regarding freedom from biopsy-proven acute rejection (57.1% vs. 66.3%; NS). The overall safety profiles indicated a tendency toward better tolerability in the low-dose group.

Conclusions: Although low-dose and high-dose tacrolimus had similar efficacy, low-dose tacrolimus was associated with a more favorable safety profile. Therefore we recommend starting tacrolimus therapy after antibody induction at 0.075 mg/kg and adjust dose according to whole-blood trough levels.