Objective: To determine the short-term clinical results of conversion of treatment from tacrolimus twice daily (BID TAC) to the extended-release formulation (OD TAC), milligram for milligram, and whether such conversion is safe in stable kidney transplant recipients.
Patients and methods: The study included 38 kidney transplant recipients (median [SD] age, 54.3 [14.4] years) with stable renal function (mean [SD] serum creatinine concentration 1.29 [0.38] mg/dL). Posttransplantation follow-up was 3.4 (3.1) years (range, 4-168 months). All patients had been receiving BID TAC (2.45 [1.52] mg/d) when treatment was converted to OD TAC, milligram for milligram. Follow-up including clinical evaluation and laboratory tests was at 7, 21, and 90 days postconversion.
Results: No significant differences were observed during follow-up in serum creatinine concentration, blood glucose level, hemoglobin level, or proteinuria. There were no episodes of acute rejection. No de novo posttransplantation diabetes mellitus was diagnosed; patients with diabetes required similar dosage of hypoglycemia treatment. Arterial pressure remained stable without changes in antihypertension treatment. Tacrolimus doses were not modified (2.45 [1.52] mg/d at baseline vs 2.45 [1.67] mg/d at 3 months postconversion; however, tacrolimus concentration decreased significantly (7.6 [1.8] ng/mL at baseline vs 6.42 [1.13] ng/mL at 3 months postconversion. Reduction in tacrolimus concentration was more remarkable in patients receiving a dose of less than 0.025 mg/kg/d.
Conclusions: Conversion from BID TAC to OD TAC, milligram for milligram, is clinically safe; however, monitoring of tacrolimus concentration in patients receiving low dosage is mandatory to prevent subtherapeutic levels.