Safety and efficacy of conversion from twice-daily tacrolimus (prograf) to once-daily prolonged-release tacrolimus (graceptor) in stable kidney transplant recipients.

BACKGROUND: Graceptor is a new modified-release once-daily formulation of tacrolimus with an efficacy and safety profile similar to twice-daily tacrolimus (Prograf), as identified by clinical trials, offering a more convenient dosing regimen to improve adherence. The aim of this study was to analyze the safety of a 1:1 dose conversion from twice-daily Prograf to once-daily Graceptor in stable kidney transplant recipients. METHODS: We switched 33 Japanese patients who had undergone kidney transplantation ≥1 years before from twice-daily Prograf to once-daily Graceptor. The dose conversion ratio between Prograf and Graceptor was 1:1. We compared the following parameters: minimum tacrolimus concentration (C(min)); concentration dose per weight (CDW); serum creatinine (sCr); blood urea nitrogen (BUN); total cholesterol (TC); high-density lipoprotein cholesterol (HDL-C); uric acid (UA); fasting blood sugar (FBS). Time points for measurements were 1 month before study start and 1 and 2 months afterward. RESULTS: The mean age of the subjects in this study was 46.5 ± 13.1 years. Mean C(min) decreased from 4.55 ± 1.79 to 3.20 ± 1.22 ng/dL. The mean CDW also decreased, from 99.8 ± 69.5 to 75.0 ± 55.1 mg/dL/kg over the 2 months. There were no significant changes in sCR, BUN, UA, and FBS. Mean TC increased from 187.5 ± 51.4 to 194.3 ± 43.4 mg/dL, and mean HDL-C changed from 53.7 ± 12.0 to 56.1 ± 11 mg/dL. There were no episodes of rejection or infection. CONCLUSIONS: We conclude that switching from Prograf to Graceptor is safe and has the advantage of improving adherence. It could also have a beneficial effect in controlling glycemic levels and the adverse effects of tacrolimus. In many cases (25%-30%), the minimum concentration of tacrolimus decreased after changing tablets. With Graceptor, the ratio of area under trough level to area under the curve (AUC) is low compared with Prograf, resulting in low C(min) values of 1-2 ng/mL, and the AUC for Graceptor is very similar to that for Prograf.

Falsely abnormally elevated blood trough concentration of tacrolimus measured by antibody-conjugated magnetic immunoassay in a renal transplant recipient: a case report.

This report presents a falsely abnormally elevated blood trough concentration (C(t)) of tacrolimus measured by antibody-conjugated magnetic immunoassay (ACMIA) methods in a renal transplant recipient. Because the C(t) of tacrolimus was 78.5 ng/mL at day 2 after a 52-year-old man underwent renal transplantation, we stopped the tacrolimus extended-release formulation. However, because the abnormally elevated blood C(t) continued in the range of 41.1-59.1 ng/mL, we then measured the tacrolimus concentration in a stored blood sample before renal transplantation, it was 43 ng/mL. Consequently, the day-7 blood sample was measured with both ACMIA and enzyme-linked immunoassay, showing C(t) values of 42.8 ng/mL and 0.89 ng/mL, respectively. Because the abnormally elevated C(t) was falsely measured by the ACMIA method, we restarted tacrolimus However, the calcineurin inhibitor was subsequently converted to cyclosporine at day 21 after renal transplantation. Although cyclosporine was also measured by ACMIA, there was not an abnormally elevated C(t). Subsequently, the tacrolimus concentration ratio in plasma and whole blood (P/B-tacrolimus concentration ratio) was measured by ACMIA in a posttacrolimus blood sample. The P/B-tacrolimus concentration ratio was 100%. In contrast, the P/B-tacrolimus concentration ratio was <30% in 2 control patients administered tacrolimus. It has been reported recently that there were cases showing falsely slightly elevated C(t) of tacrolimus within the therapeutic range of concentrations. Therefore, we must be careful not to reduce the tacrolimus dose falsely. We consider confirmatory methods for a falsely abnormally elevated C(t) of tacrolimus measured by ACMIA to (1) measure P/B-tacrolimus concentration ratio, (2) compare ACMIA with another measurement, and (3) evaluate a blood sample stored before tacrolimus administration.

Evidence of different pharmacokinetics between cyclosporine and tacrolimus in renal transplant recipients: why cyclosporine is monitored by C2 level and tacrolimus by trough level.

The clinical efficacy of calcineurin inhibitors administered to renal transplant recipients is considered to be a strong function of the area under the concentration time curve (AUC). Monitoring of blood concentrations for two similar calcineurin inhibitors, cyclosporine (CyA) and tacrolimus (TAC) are different. Namely, CyA blood concentration is usually monitored at two hours after administration (C2), a surrogate for peak concentration (Cp), and TAC at trough concentration (Ct). We examined the behavior of blood concentration curves simultaneously for both CyA and TAC in renal transplant recipients with similar clinical backgrounds. Furthermore, we analyzed the correlation of Cp and Ct vs AUC implementing an area under the trough level, or area above the trough level as new pharmacokinetic parameters, so that C2 for CyA and Ct for TAC has validated using controlled clinical data. We observed differences in the pharmacokinetics between.