Introduction: It has been suggested that for adequate maintenance of tacrolimus levels, the total daily dosage should be increased when switching from the conventional twice-daily regimen tacrolimus (CT) to once-daily sustained-release tacrolimus (SR-T).
Objective: To evaluate the safety and efficacy of a 25% increase in daily dosage when switching heart transplant (HT) patients from CT to SR-T.
Methods: We switched 75 HT patients including 72% males and an overall mean age of 55.6 years from CT to SR-T using a 25% increase in daily dosage. We screened for adverse events by measurements of lipids, creatinine, glycemia, and tacrolimus in blood samples taken at 1, 3, 7, and 12 weeks after the conversion, as well as by repeated echocardiography and routine clinical examinations.
Results: Just two patients (2.7%) were returned to CT because of failure of SR-T to attain therapeutic levels. In the remainder of subjects, tacrolimus levels remained stable, with trough values of 8.7±3.2, 8.7±2.9, 8.3±2.6, and 7.5±2.0 mg/dL, respectively. Twenty-three patients (31%) required no dosage change in the first 3 months, but 44 (33%) required one or two changes. No departure from therapeutic levels was associated with rejection; there was no case of severe intercurrent infection. We did not observe significant changes in glycemia, creatinine, lipid profile, or blood pressure.
Conclusions: Administration of SR-T at a dosage 25% higher than the daily dosage of CT was safe. It ensured adequate tacrolimus levels in one-third of patients. Nevertheless, strict analytical surveillance is necessary during the initial months to allow dosage adjustments and to detect the minority of patients for whom SR-T does not achieve therapeutic tacrolimus levels.
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