Diurnal cyclosporine dosing optimizes exposure and reduces the risk of acute rejection after kidney transplantation

Pharmacokinetic interaction between levofloxacin and ciclosporin or tacrolimus in kidney transplant recipients: ciclosporin, tacrolimus and levofloxacin in renal transplantation

BACKGROUND AND OBJECTIVE

Bacterial infections are common complications after organ transplantation. Fluoroquinolones are frequently used for treatment because of their broad spectrum of activity; but some of them, such as ciprofloxacin and norfloxacin, are reported to increase blood concentration of ciclosporin because they are metabolised by the liver through the same enzymatic pathway, the cytochrome P450 system. This study was performed to establish whether levofloxacin, a more recent fluoroquinolone that undergoes limited hepatic metabolism, interferes with metabolism and excretion of either ciclosporin microemulsion or tacrolimus.

METHODS

Pharmacokinetic studies were carried out in two groups of renal transplant patients, on either ciclosporin or tacrolimus treatment, before and at the sixth day of treatment with levofloxacin.

RESULTS

Levofloxacin significantly increased the mean area under the blood concentration-time curve (AUC) and the other pharmacokinetic parameters of ciclosporin and tacrolimus by about 25%. The interference of levofloxacin on the hepatic metabolism of these drugs was demonstrated by the concomitant decrease by 5% of polyclonal ciclosporin concentration, which is the expression of parent drug and its metabolites. Both before and during levofloxacin treatment we observed trough concentrations of monoclonal and polyclonal ciclosporin significantly lower in the evening (C(12)) than in the morning (C(0)); this observation suggests a circadian variation in the metabolism of this drug. However, no difference between C(0) and C(12) was observed with tacrolimus, confirming its more predictable bioavailability.

CONCLUSION

Our data demonstrate that levofloxacin partially inhibits the metabolism of both ciclosporin microemulsion and tacrolimus, and therefore close therapeutic monitoring of these two drugs should be recommended during levofloxacin therapy.

A limited sampling strategy for the estimation of 12-hour cyclosporine neoral area under the curve in Chinese cardiac transplant recipients

INTRODUCTION

This study determined the accuracy of a limited sampling strategy to predict the 12-hour cyclosporine neoral (CsA) area-under-the-curve (AUC) to provide a practical method for more accurate therapeutic drug monitoring (TDM) of CsA in Chinese heart transplant recipients.

METHODS

Blood samples were collected at 0 (before the dose), and 0.5, 1, 2, 3, 4, 6, 8, 10, as well as 12 hours after CsA oral administration in 13 de novo heart recipients receiving oral CsA bid after rabbit antithymoglobulin sequential immuno-induction. Pharmacokinetics were analyzed for the first dose (PK-1) and the steady state dose (PK-2, 1 month after transplantation). The limited sampling strategies included single-point, 2-point, and 3-point prediction of AUC using multiple linear regression analyses.

RESULTS

Comparing the AUC/mg dose, PK-1 was much lower than PK-2 (25.2 +/- 11.4 ng x h/mg x mL vs 45.4 +/- 12.9 ng x h/mg x mL; P = .0005 using paired t test). The correlations of each single-point blood level of PK-1 with the AUC were lower than those of the corresponding sampling time in PK-2. In the PK-2 study, C4 had the best correlation (r2 = 0.732; P = .00) as a single-point to predict AUC, but the 2-point C2 + C12 had a higher correlation (r2 = 0.937; P = .00). Among the 3-point combinations, C2 + C4 + C12 showen the best prediction (r2 = 0.982; P = .00) of the AUC in PK-2.

CONCLUSION

The bioavailability of CsA was lower in PK-1 than in PK-2. At steady state, we recommend C2 + C12 to predict AUC because it is accurate and not labor-intensive.

Effect of cyclosporin pharmacokinetics on renal allograft outcome in African-Americans

African-Americans (A-As) experience inferior outcome after transplantation compared with other ethnic groups. Bioavailability of cyclosporin (CsA) has been implicated as a possible contributing factor. This paper describes the outcome of 32 A-A recipients of de novo renal allograft who received CsA-based triple immunotherapy according to individual pharmacokinetic profiles. Patients received CsA-microemulsion q 12 h, dosed initially at 3.5 mg/kg (8 am) and 3.0 mg/kg (8 pm). The am and pm doses were independently adjusted to achieve a 12-h area under the concentration-time curve (AUC0-12) of 6600-7200 nghr/mL and morning trough level (C0) of 250-325 ng/mL, respectively. Mean age was 43 +/- 12 yr, 37% (12) female. Mean AUC0-12 in 1 wk, 1, 3, 6, and 12 months were 7810 +/- 1880 nghr/mL, 9057 +/- 2097 nghr/mL, 7674 +/- 1912 nghr/mL, 7132 +/- 2040 nghr/mL, and 6503 +/- 1410 ngl/h with corresponding C0 of 301 +/- 79 ng/mL, 316 +/- 66 ng/mL, 275 +/- 59 ng/mL, 273 +/- 66 ng/mL, and 224 +/- 49 ng/mL, respectively. Acute rejection occurred in two patients (6%) 1 yr after transplantation. Prospective use of CsA pharmocokinetic profiles improves renal allograft outcome in A-As.

Can a pharmacokinetic approach to immunosuppression eliminate ethnic disparities in renal allograft outcome?

Although renal allograft outcome correlates more closely with area under the concentration time curve (AUC) for cyclosporin (CsA) compared with the 12-h trough level (C0), few studies have prospectively evaluated pharmacokinetic monitoring in kidney transplantation. This paper describes a study designed to evaluate the impact of a novel approach to CsA-based immunosuppression on ethnic differences in renal allograft outcome. Sixty (32 African Americans and 28 Caucasians) renal transplant recipients were treated with cyclosporin-based triple therapy. Morning and evening doses were independently adjusted to reach an AUC0-12 of 6600-7200 ng h/mL and a C0 of 250-325 ng/mL, respectively. AUCs were measured within 48 h of starting CsA, and as often as necessary to maintain target levels. Only two patients experienced significant adverse events related to immunosuppression. One (Caucasian) developed haemolytic uremic syndrome and was converted to tacrolimus, while another (African American) developed acute vascular rejection. One graft was lost (Caucasian) due to death with a functioning graft. An average of 8 AUCs (range 5-13) were measured in the first 3 months. AUCs were significantly higher in African Americans compared with Caucasians only in the first and second month. C0 values were similar in both groups throughout the study period. A pharmacokinetic approach to immunosuppression allows individualization of CsA exposure, and appears to reduce ethnic disparities in renal allograft outcome.