Mycophenolic acid (MPA) plasma concentrations are highly variable on standard-dose mycophenolate mofetil therapy. At creatinine clearances below 25 mL/min, MPA clearance increases as a result of a higher nonprotein-bound fraction. Patients with delayed graft function (DGF) after renal transplantation are exposed to low total MPA concentrations, when risk of rejection is highest. This study investigated the influence of DGF on MPA exposure and on clinical outcome.
Adult renal transplantation patients treated with mycophenolate mofetil, corticosteroids, and either microemulsified cyclosporine (n = 459) or tacrolimus (n = 371) participated in a randomized controlled trial (the Fixed-Dose Concentration-Controlled [FDCC] Study). Abbreviated MPA areas under the curve (AUCs) were obtained on Day 3, Day 10, Week 4, and Month 3, to calculate MPA AUC₀₋₁₂. Free MPA AUC values were available for a subgroup of patients (n = 269).
The overall incidence of DGF was 187 of 830 (23%) and did not differ between cyclosporine-treated (24%) and tacrolimus- (21%) treated patients. The incidence of biopsy-proven acute rejection at 12 months was significantly higher in patients with DGF (13.8% versus 21.4%). Patients with DGF had significantly lower dose-corrected MPA AUC on Day 3 and Day 10. Free MPA fraction and dose-corrected free MPA AUC were significantly higher in patients with DGF, from Day 3 until Month 3. The total number of patients with at least one opportunistic infection was significantly higher in patients with DGF (33.2%) compared with patients without DGF (25.8%) (P = 0.048). Patients with DGF developing opportunistic infections did not have higher total MPA AUC nor higher free MPA AUC compared with those without opportunistic infections.
Patients with DGF have significantly lower dose-corrected MPA AUC in the first month after renal transplantation, presumably as a result of enhanced MPA clearance on account of the elevated MPA free fraction. Because patients with DGF have a higher rate of acute rejection and lower MPA exposure, higher dosing of mycophenolate mofetil in such patients may improve outcome. However, the already increased incidence of opportunistic infections in patients with DGF is a concern.
[Show abstract][Hide abstract] ABSTRACT: Delayed graft function (DGF) is an important complication in renal transplantation, contributing significantly to decrease in long-term allograft survival. In addition to donor- and recipient-related risk factors such as immunosuppression, altered renal excretion of xenobiotics by membrane transporters may influence DGF. Using DNA samples from recipients and donors, we assessed the impact on DGF of genetic variants in P-glycoprotein (ABCB1), multidrug resistance protein 2 (ABCC2), and the nuclear pregnane X receptor (PXR/NR1I2), which regulates the transcription of enzymes and transporters. In our local cohort of renal transplant recipients (n = 178), DGF occurred in 27.5%. The PXR 8055TT genotype of the donor only (not of the recipient) was significantly associated with an increased risk for DGF. This finding emerged from univariate as well as multivariate logistic regression analysis including 16 nongenetic factors and held true after correction for multiple testing. Our findings provide the first evidence that PXR may be associated with risk of DGF, independent of previously identified risk factors.
[Show abstract][Hide abstract] ABSTRACT: Information is lacking concerning concomitant administration of enteric-coated mycophenolate sodium with tacrolimus (EC-MPS+Tac) in renal transplant recipients (RTxR). In this 6-month, prospective, open-label, multicenter study, de novo RTxR were randomized (1 : 1) to low-dose (LD) or standard-dose (SD) Tac with basiliximab, EC-MPS 720 mg bid, and steroids. Primary objective was to compare renal function at 6-month posttransplantation. Secondary objectives were to compare the incidences of biopsy-proven acute rejection (BPAR), graft loss and death, and new-onset diabetes mellitus (NODM). 292 patients (LD n = 151, SD n = 141) were included. Mean Tac levels were at the low end of the target range in standard-exposure patients (SD, n = 141) and exceeded target range in low-exposure patients (LD = 151) throughout the study. There was no significant difference in mean glomerular filtration rate (GFR) between treatments (ITT-population: 63.6 versus 61.0 mL/min). Incidence of BPAR was similar (10.6% versus 9.9%). NODM was significantly less frequent in LD Tac (17% versus 31%; P = 0.02); other adverse effects (AEs) were comparable. EC-MPS+Tac (LD/SD) was efficacious and well tolerated with well-preserved renal function. No renal function benefits were demonstrated, possibly related to poor adherence to reduced Tac exposure.
Journal of Transplantation 11/2012; 2012:941640. DOI:10.1155/2012/941640
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