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Mycophenolate mofetil (MMF) or enteric coated mycophenolate sodium (EC-MPS) and steroids are used for induction and maintenance therapy in severe lupus nephritis (LN). Blood concentrations of mycophenolic acid (MPA), the active metabolite of these drugs varies among LN patients. The objective of this study was to examine whether concentration controlled (CC) dosing (via therapeutic drug monitoring) of EC-MPS result in a higher proportion of participants achieving target exposure of MPA compared to fixed dosing (FD). An additional aim of the study was to evaluate the influence of CC dosing on clinical outcomes. Nineteen participants were randomly assigned either to FD or CC group. All the participants were eligible to have free and total measurements of MPA over a period of 8-12 hours on three different occasions. Area under the concentration-time curve between 0 and 12 hours (AUC0-12) was calculated using non-compartmental method. Dose of EC-MPS was titrated according to AUC0-12 in the CC group. Thirty-two AUC0-12 measurements were obtained from 9 FD and 9 CC participants. Large interpatient variability was observed in both groups but was more pronounced in FD group. There were no significant differences between FD and CC participants in any pharmacokinetic parameters across the study visits except for total C0 (FD 2.0 ± 0.3 mg/L vs. CC 1.1 ± 0.3; p = 0.01) and dose-normalised C0 (FD 2.9 ± 0.2 mg/L/g vs. CC 2.1 ± 0.7 mg/L/g; p = 0.04) at the second visit and total AUC0-12 (FD 66.6 ± 6.0 mg[BULLET OPERATOR]h/L vs. CC 35.2 ± 11.4 mg[BULLET OPERATOR]h/L; p = 0.03) at the third visit. At the first study visit, 33.3% of the FD and 11.1% of the CC participants achieved the target AUC (p = 0.58). From the second visit, none of the FD participants, compared to all the CC participants, achieved target AUC0-12 (p = 0.01). More CC participants achieved remission compared to FD participants (absolute difference of -22.2, 95% confidence interval -0.19-0.55; p = 0.62). The mean free MPA AUC0-12 was significantly lower in those who had complete remission. CC participants reached target AUC0-12 quicker. Larger studies are required to test clinical efficacy.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.

The aim of this study was to characterize the pharmacokinetics of mycophenolic acid (MPA) and MPA glucuronide (MPAG) in Chinese renal transplant patients taking enteric-coated mycophenolate sodium (EC-MPS). Limited sampling strategies (LSSs) were developed to estimate the area under the concentration curve from 0 to 12 hours (AUC0-12h) of total and free MPA. Another objective was to investigate the correlation between high-performance liquid chromatography (HPLC) and enzyme-multiplied immunoassay technology (EMIT) for total MPA determination.Serial blood samples were collected over 12 hours from 15 patients who were administered multiple doses of EC-MPS. LSS was developed by multiple stepwise regression analysis. Measurement by HPLC and EMIT was compared using Passing-Bablok regression and Bland-Altman analysis.Normalized to 720 mg twice daily, the AUC0-12h of total MPA and MPAG was 43.0 ± 17.4 and 653 ± 329 mg·h/L, respectively, whereas the free MPA AUC0-12h was 1.368 ± 0.988 mg·h/L. The free fraction of MPA was 3.01% ± 3.15%. The combination of C2h-C4h-C6h and C2h-C4h-C6h-C8h was found to be superior to estimate total and free MPA simultaneously. The EMIT showed an acceptable correlation with HPLC, with an AUC0-12h overestimation of 11.32% ± 15.77%.The pharmacokinetic profile of total and free MPA and its main metabolite MPAG was examined in Chinese adult renal transplant patients receiving EC-MPS. The use of LSS to estimate individual free and total MPA exposure could be useful in optimizing patient care.

BACKGROUND Enteric-coated mycophenolate sodium is frequently used in renal transplantation. The pharmacokinetic profile of mycophenolic acid (MPA) shows a broad range of time-to-maximum concentration (Tmax) that limits the use of a single MPA concentration to calculate the area under the time-concentration curve (AUC). For both research and clinical MPA monitoring, measuring a complete AUC is troublesome to the center and patients. METHODS We obtained 171 complete MPA-AUC12h (0, 20, 40, 60, 90, 120, 180, 240, 360, 480, 600, and 720 minutes) from 59 adult (54 ± 16 years) patients (29 men and 43 whites) who have been receiving stable doses of tacrolimus/enteric-coated mycophenolate sodium and steroids. We used the 59 curves drawn at 31 ± 4 days after transplantation to develop the abbreviated equations, and the remaining 112 curves drawn at 109 ± 59 days were used to validate them. We used 5 other proposed equations to estimate MPA-AUC (eAUC) (4 with enzyme-multiplied immunoassay technique assay and one with high-performance liquid chromatography [HPLC]) and then used these results to compare with our measured AUC, the bias, and the 10% and 30% accuracy. MPA was measured by ultraperformance liquid chromatography coupled to a tandem mass spectrometry, and AUC was calculated by the trapezoidal rule. RESULTS For both MPA-measuring methods, enzyme-multiplied immunoassay technique and ultraperformance liquid chromatography coupled to a tandem mass spectrometry, the Hospital das Clinicas da Faculdade de Medicina da Universidade de Sao Paulo (HCFMUSP) equations, and others that measure MPA up to 6 hours after the dose had an acceptable low bias with more results in the 10%-30% range than those using data collected until 4 hours. A highly adequate eAUC is obtained using blood collected at 8 hours. CONCLUSIONS This analysis offers blood-sampling alternatives for MPA monitoring depending on the precision needed.

Background: Immunosuppressive agents are still inefficient in preventing biopsy-proven acute rejection (BPAR) after expanded criteria donor (ECD) kidney transplantation. The aim of this study was to investigate the relationships between early immunosuppressive exposure and the development of BPAR. Methods: We performed a retrospective study of 58 recipients of ECD kidney transplantation treated with enteric-coated-mycophenolate sodium, tacrolimus (Tac), and prednisone. The levels of mycophenolic acid-area under the curve (MPA-AUC)0-12h and Tac C0 were measured at the 1st week and the 1st month posttransplant, respectively. The correlation was assessed by multivariate logistic regression. Results: The occurrence rates of BPAR and antibody-mediated rejection were 24.1% and 10.3%, respectively. A low level of MPA-AUC0-12h at the 1st week posttransplant was found in BPAR recipients (38.42 ± 8.37 vs. 50.64 ± 13.22, P < 0.01). In addition, the incidence of BPAR was significantly high (P < 0.05) when the MPA-AUC0-12h level was

Background Mycophenolate mofetil (MMF) or enteric-coated mycophenolate sodium (MPS) is now commonly used in pediatric intestinal transplantation (Tx), but to date, no clear recommendations regarding the dosing regimen have been made in this population. The aim of this study was to determine the MMF/MPS dosage required to achieve an area under the plasma concentration-time curve from 0 to 12 hours (AUC0-12) for mycophenolic acid (MPA) greater than 30 mg·h·L in children after intestinal transplantation. Methods A pharmacokinetic study was conducted in 8 children (median, 9.4 years; range, 0.75-15.8 years) at a median time of 113 months (range, 1.5-160 months) after intestinal transplantation. Results MMF was initially introduced at a low median starting dose of 687 mg·m·d (range, 310-1414 mg·m·d). One of the 3 patients who received MPS and 2 of the 6 patients who received MMF had an MPA AUC0-12 value below 30 mg.h.L. The median MMF dosage had to be increased by 91% (1319 mg·m·d versus 687 mg·m·d) to reach AUC0-12 values above the defined target level of 30 mg·h·L. Conclusions When used in combination with tacrolimus and steroids, an initial MMF dose of 600 mg/m twice a day would be recommended to children after intestinal transplantation to achieve MPA exposure similar to those observed in adults and children after the transplantation of other organs. Further studies are required to recommend a suitable dosage for pediatric intestinal transplant recipients who receive MPA.

Background Considerable interest exists in identifying calcineurin inhibitor (CNI)-free and thus, less-toxic immunosuppressive regimens, with mycophenolic acid (MPA)-based treatments being a suitable approach. Because pharmacokinetic analyses of MPA treatments in stable CNI-free renal transplant recipients are lacking, the authors aimed at comparing the steady-state pharmacokinetic characteristics of MPA in patients on stable treatment with mycophenolate mofetil (MMF) or enteric-coated mycophenolate sodium (EC-MPS) plus prednisone (≤5 mg/d). Methods In the prospective, nonrandomized, open-label study, patients with stable transplant function since ≥6 months received their routine single dose of either MMF (n = 12) or EC-MPS (n = 11). The MPA plasma concentration was recorded over 12 hours. Parameters assessed were predose MPA concentration (C0), postdose minimum and maximum concentration (Cmin and Cmax), time to maximum concentration (Tmax), and area under the concentration-time curve (AUC) for the 12-hours of exposure (AUC0-12). Results Baseline characteristics were comparable between both the groups. Consistent with enteric coating, the mean Tmax was significantly longer after the intake of EC-MPS compared with MMF (2.2 versus 0.8 hours; P = 0.0002). The exposure measures Cmin, Cmax, and AUC0-12 were not significantly different despite the higher mean MPA equivalent dose in patients receiving MMF compared with those receiving EC-MPS (85% versus 64% of the recommended single dose, respectively). Exposures as reflected by the median AUC0-12 values were 50.7 and 58.7 mg·h·L with MMF and EC-MPS, respectively (P = 0.340). All patients achieved a target AUC of >30 mg·h·L, and 61% had an AUC of >50 mg·h·L. Conclusions The study provides first results on the steady-state pharmacokinetics of the 2 MPA drugs in CNI-free immunosuppressant regimens. Pharmacokinetic parameters measured in this study under real-life conditions were comparable in patients receiving MMF or EC-MPS.

Background Mycophenolic acid (MPA), a potent immunosuppressant, is widely used in solid organ transplantations. This study aimed to investigate the pharmacokinetics of enteric-coated mycophenolate sodium (EC-MPS) in Chinese adult renal allograft recipients and to generate optimal model equations for estimation of the MPA area under the concentration-time curve from 0 to 12 hours (AUC0-12 h), using a limited sampling strategy (LSS). Methods Serial blood samples were collected over 12 hours from 38 recipients of a primary living-related donor kidney graft treated with EC-MPS, tacrolimus, and corticosteroid. MPA concentrations were evaluated using an enzyme-multiplied immunoassay technique. The LSSs were developed and validated by multiple regression analysis using a 2-group method (test group, n = 19; validation group, n = 19). Results The best algorithms obtained from the test group were the following: 15.09 + 1.05 × C1.5 + 1.8 × C4 + 4.18 × C6 (for 3 time points, r = 0.902) and 10.44 + 0.7 × C1 + 1.22 × C2 + 1.75 × C4 + 4.36 × C6 (for 4 time points, r = 0.941). When these algorithms were tested in the validation group, there were no significant differences in prediction errors. Conclusions LSSs using time points of 1.5, 4, and 6 hours or 1, 2, 4, and 6 hours after dose provide effective and reliable estimations of the MPA AUC0-12 h in Chinese renal allograft recipients treated concomitantly with EC-MPS and tacrolimus during the early posttransplantation phase.

Background Two oral mycophenolic acid (MPA) formulations, immediate-release mycophenolate mofetil and enteric-coated mycophenolate sodium, have been shown to differ regarding some drug-drug interactions. The aim was to assess whether the effects of cyclosporine (CsA) on steady-state pharmacokinetics (PK) of MPA in renal transplant patients were affected by MPA formulation. Methods A prospective, stratified observational study based on therapeutic drug monitoring of MPA (6 total plasma concentrations over a 12-hour dosing interval, τ) in consecutive stable adult renal transplant recipients (n = 68). Results Patients treated with enteric-coated mycophenolate sodium (n = 45) or mycophenolate mofetil (n = 23) and with either CsA (microemulsion, n = 43) or tacrolimus (Tac) (immediate release, n = 25) were comparable regarding demographics, comorbidity, renal and liver functions, comedication, corticosteroid dose, CsA or Tac dose, and trough concentrations. Based on dose-normalized MPA concentrations and with adjustment for age, sex, body mass index, estimated glomerular filtration rate, and corticosteroid dose, CsA (as compared with Tac) consistently reduced MPA area under the concentration-time curve during the dosing interval at steady state overall [geometric mean ratio (GMR), 0.78; 95% confidence interval, 0.62-0.99] and by MPA formulation (by 22% and 21%, respectively), increased CLT/F,ss overall (1.31; 1.00-1.70) and by formulation (by 25% and 36%, respectively), reduced morning predose MPA concentration overall (0.59; 0.38-0.92) and by formulation (by 34% and 47%, respectively), increased peak-trough fluctuation overall (1.51; 1.06-2.17) and by formulation (by 58% and 45%, respectively), and prolonged tmax,ss overall (adjusted median difference 0.58, 0.04-1.12 hours) and by formulation (by 0.6 and 0.5 hours, respectively). Conclusions Qualitatively and quantitatively, the effect of CsA on steady-state PK of MPA is not conditional on MPA formulation.

Background Substantial research has been conducted to develop limited-sampling strategies (LSS) to estimate the area under the curve (AUC(0-12h)) in patients treated with mycophenolate mofetil. However, no LSS has been validated for enteric-coated mycophenolate sodium (EC-MPS). Our aim was to develop an LSS to measure the AUC(0-12h) of mycophenolic acid in kidney recipients treated with tacrolimus and EC-MPS. Study design Thirteen serial blood samples were collected over 12 hours from 71 patients treated with tacrolimus and EC-MPS. Mycophenolic acid was measured in plasma using the enzyme-multiplied immunoassay. LSSs were developed and validated by multiple regression analysis using a 2-group method (test, n = 47; validation, n = 24). Results The best LSS obtained in the test group were for 3 and 4 time points AUC(0-12h) (mg·h(-1)·L(-1)) = 15.99 + 0.87C1 h + 0.68C2 h + 7.85C4 h and AUC(0-12h) (mg·h(-1)·L(-1)) =11.15 + 0.68C1 h + 0.45C1.5 h + 0.57C2 h + 8.16C4 h, respectively. When these LSS were tested in the validation group, the results were acceptable (adjusted r(2) = 0.71, bias =-0.214 [95% confidence interval (CI): -7.91 to 7.48], precision = 7.48 (95% CI: 3.69-19.39) for 3 time points and adjusted r(2) = 0.76, bias = -1.48 (95% CI: -8.23 to 5.27), precision = 7.68 (95% CI: 4.23-13.50) for 4 time points). Conclusions : An LSS using time points at C(1h)-C(2h)-C(4h) or C(1h)-C(1.5h)-C(2h)-C(4h) provides the most reliable and accurate estimation of the AUC(0-12h) of mycophenolic acid in stable renal transplant recipients treated with EC-MPS and tacrolimus.

Background Approximately half of cyclosporine A-treated renal transplant recipients do not reach sufficient mycophenolic acid (MPA) exposure in the first weeks posttransplantation with standard MPA dosing regimens. Methods Here, we present a prospectively planned meta-analysis of data from two 6-month parallel-run studies that evaluated the effect of an initially intensified versus standard dosing regimen of enteric-coated mycophenolate sodium (EC-MPS). Four hundred forty-one de novo renal transplant recipients were randomized (1:1) to intensified (2 weeks 2880 mg/d; subsequently 4 weeks 2160 mg/d; followed by 1440 mg/d) or standard (1440 mg/d) EC-MPS, with concomitant cyclosporine A treatment and steroids with or without anti-IL-2R induction. Primary endpoint was treatment failure (biopsy-proven acute rejection [BPAR], graft loss, or death) at month 6 posttransplantation. Results Treatment failure rates were 17.4% in intensified and 22.4% in standard groups (P=0.110). The incidence of BPAR was 13.8% (intensified) vs. 19.3% (standard; P=0.034). A total of 80.5% (intensified) versus 39.0% (standard) of patients achieved 12 hr MPA-area under the curve more than 30 μg·hr/mL as early as day 3 posttransplant. Renal function, gastrointestinal symptom rating scores, and safety profiles were comparable between treatment groups. Conclusion The initially intensified EC-MPS dosing regimen was associated with higher MPA exposure, significantly lower rate of BPAR, and comparable safety. However, the intensified regimen did not affect graft function or survival.

The aim of the study is to characterize the pharmacokinetics and the gastrointestinal side effect profiles of enteric-coated mycophenolate sodium (EC-MPS) in de novo kidney transplant patients of Hispanic ethnicity.The pharmacokinetic study of EC-MPS was conducted in 11 de novo kidney transplant patients of Hispanic ethnicity. Eight blood samples were obtained after EC-MPS was given at the steady state. Blood concentrations of mycophenolic acid (MPA) and its glucuronide metabolite (MPAG) were measured.The mean age (± standard deviation) was 39.4 (± 12.3) years. The mean daily dose of EC-MPS at the time of the pharmacokinetic study was 1408 ± 108 mg. For MPA and MPAG, the time to peak concentration was 2.5 ± 1.3 hours and 4.6 ± 3.1 hours, respectively; the peak concentration (Cmax) was 19.3 ± 17.2 mg/L and 109.4 ± 49.2 mg/L; and the area under the curve from 6 to 12 hours (AUC6-12) was 32.2 ± 19.3 mg·hr/L and 373.7 ± 235.8 mg·hr/L, respectively, which represents 41.3% and 43.0% of AUC0-12. The AUC0-12 for MPA measured 77.8 ± 53.1 mg·hr/L and for MPAG 869.2 ± 388.8 mg·hr/L. Seven patients (64%) exhibited a second peak at approximately 8.3 hours after the dose at a mean concentration (± standard deviation) of 10.3 ± 7.6 mg/L. The Cmax or AUC of MPA does not correlate with overall Gastrointestinal Symptom Rating Scale scores or subscale scores, but the Cmax of MPAG correlates with indigestion subscale (P = 0.022), diarrhea (P = 0.032), and overall scores (P = 0.028). The AUC of MPAG also correlates with acid reflux (P = 0.024) and indigestion (P = 0.032).The pharmacokinetics of EC-MPS has a high variability in de novo kidney transplant patients of the Hispanic ethnicity, which was similar to other ethnic groups. The MPA exposure expressed by the AUC appears to be higher in Hispanic patients than those reported in other ethnic groups, which may be the result of various factors such as difference of the uridine diphosphate glucuronosyltransferase enzyme genotypes, but gastrointestinal side effects were acceptable and the Cmax or AUC of MPAG showed correlations with gastrointestinal symptoms.

Background and objectives: The introduction of mycophenolate mofetil has improved graft survival after organ transplantation; however, its use may be limited by important adverse effects. For overcoming these problems, an enteric-coated formulation of mycophenolate sodium has been developed, but pharmacokinetic data of mycophenolic acid release from this formulation are scanty. Design, setting, participants, & measurements: Pharmacokinetic studies in 32 kidney transplant recipients who were given the enteric-coated formulation of mycophenolate sodium (n 12) or mycophenolate mofetil (n 20) were performed. The profiles of mycophenolic acid from the two formulations at months 6, 12, 18, and 24 after transplantation were compared. Subsequently, all patients who were receiving the enteric-coated formulation were shifted to mycophenolate mofetil, and the pharmacokinetic evaluations were repeated. Results: At month 6 after surgery, aberrant and variable pharmacokinetic curves were found in patients who were given the enteric-coated formulation, whereas those who were taking mycophenolate mofetil had regular mycophenolic acid kinetic profiles. Patients who were taking the enteric-coated formulation had mycophenolic acid time of occurrence for maximum drug concentration that ranged from 0 to 480 min and higher dosage-adjusted mycophenolic acid trough levels compared with patients who were given mycophenolate mofetil. Conversion from the enteric-coated formulation of mycophenolate sodium to mycophenolate mofetil resulted in an improvement of the mycophenolic acid kinetics profiles. Conclusions: Given the emerging clinical benefit of mycophenolic acid monitoring in the transplant setting, therapeutic drug monitoring problems with the enteric-coated formulation of mycophenolate sodium should be taken into account. Clin J Am Soc Nephrol 2: 1147–1155, 2007. doi: 10.2215/CJN.02820707

The delayed release of mycophenolic acid (MPA) from enteric-coated mycophenolate sodium (EC-MPS) may lead to different MPA predose (C0) levels compared with mycophenolate mofetil (MMF). A post hoc analysis was performed on MPA morning predose values assessed in 88 maintenance renal transplant patients from three studies converted from MMF (1000 mg twice a day) to equimolar EC-MPS (720 mg twice a day) or vice versa, both in combination with cyclosporine. The median MPA predose level was approximately 30% higher when patients received EC-MPS (2.40 microg/mL; range, 0.49-39.30 microg/mL) compared with MMF (1.83 microg/mL; range

Background Mycophenolic acid (MPA) is an inhibitor of lymphocyte proliferation and is well established as an immunosuppressive agent in solid organ transplantation. The initial formulation of the drug was a prodrug formulation, mycophenolate mofetil (MMF, Cellcept), which is well absorbed and rapidly converted to mycophenolate in plasma. However, the use of MMF is associated with adverse gastrointestinal events, which can lead to withdrawal of therapy. In an effort to reduce the gastrointestinal effects of MMF, an enteric-coated formulation of the drug was developed, based on the sodium salt of MPA (EC-MPS, Myfortic). Methods Although bioequivalence has been demonstrated in an individual study in maintenance kidney transplant patients, this manuscript documents bioequivalence in a much larger data set of 82 patients by a meta-analysis of data from clinical trials. Results The results confirm the bioequivalence of EC-MPS and MMF for both mycophenolate and metabolite exposure, and for maximum plasma mycophenolate concentrations, across three studies. The 90% confidence interval of the ratio of EC-MPS to MMF for mycophenolate plasma AUC in the 82 patients was 101.1 to 114.5% and for Cmax was 83.0% to 112.7%. Conclusion These findings provide reassurance to transplant professionals and patients that, when choosing between EC-MPS and MMF, they are choosing between formulations that give equivalent mycophenolate exposure.

Gastrointestinal (GI) disorders are one of the main adverse events in patients treated by mycophenolic acid (MPA). The aim of this prospective study was to evaluate the effect of conversion from mycophenolate mofetil (MMF) to enteric-coated mycophenolate sodium (EC-MPS) in liver transplant patients presenting GI side-effects Since January 2003, stable liver transplant patients receiving MMF and presenting GI disorders, without evidence of other origin than MMF were enrolled. Conversion was performed without a washout period at an equimolar daily dosage. Thirty-six patients were included after a median delay of 45 months after liver transplantation (LT) (16 women and 20 men, median age of 47 years). Diarrhoea was the main clinical symptom (n = 28, 77.7%). At the time of inclusion, patients were treated with MMF since 18 months (range 3-28) and GI disorders were known for 9 months (range 3-12). After a median follow-up of 12 months after conversion, GI disorders were resolved in 20 patients (55%), improved in 6 patients (17%) and not modified or worsened in 10 patients (28%). Our results strongly suggest that conversion from MMF to EC-MPS in liver transplant patients can improve gastrointestinal disorders in a majority of the patients, and therefore might be considered as the best therapeutic option.

Background. The benefit of converting renal transplant recipients with gastrointestinal (GI) complaints from mycophenolate mofetil (MMF) to enteric-coated mycophenolate sodium (EC-MPS) has not been evaluated using patient-reported outcomes. Methods. A multicenter, open-label, prospective study was undertaken in MMF-treated renal transplant patients. Patients experiencing GI complaints were converted to equimolar EC-MPS (Cohort A). Patients without GI complaints remained on MMF (Cohort B). At baseline and Visit 2 (4-6 weeks postbaseline), patients completed the Gastrointestinal Symptom Rating Scale (GSRS), Gastrointestinal Quality of Life Index (GIQLI) and Psychological General Well-being Index (PGWBI). At Visit 2, patients and physicians completed the Overall Treatment Effect (OTE) scale for GI symptoms. Additionally, patients completed the OTE for health-related quality of life (HRQoL). Minimal important difference (MID) was calculated for GSRS and GIQLI based on patients' and physicians' OTE evaluation. Results. Of 328 patients enrolled (i.e. the intent-to-treat and safety populations), 278 formed the per-protocol population (Cohort A, n= 177; Cohort B, n=101). At baseline, Cohort A had significantly worse scores on all GSRS, GIQLI and PGWBI subscales compared to Cohort B (all P

Background, ERL is the enteric-coated sodium salt of mycophenolic acid, presently in clinical development. The drug substance mycophenolate sodium (MPS) was evaluated in rat transplantation models and compared with mycophenolate mofetil (MMF) for therapeutic window and synergy with cyclosporine (CsA). Methods. Allotransplantation was performed in the Dark Agouti-to-Lewis (DA-to-Lewis; kidney, heart, and aorta) and Brown Norway-to-Lewis (BN-to-Lewis; kidney) strain combinations, and hamster heart xenotransplantation was performed in athymic and euthymic Lewis rats. The compounds were administered daily orally, starting the day of transplantation. Results. In kidney and heart transplantation the minimal efficacious dose of CsA was 5.0 mg/kg/d. For MPS this dose was 10 mg/kg/d in BN-to-Lewis kidney transplantation, 20 mg/kg/d in DA-to-Lewis heart transplantation, and 10 mg/kg/d in hamster-to-athymic rat heart transplantation. At these doses the first signs of adverse effects were evident, indicating a narrow therapeutic window. No window was established for MMF in these models or for MPS in DA-to-Lewis kidney transplantation. There was no potential synergy between CsA and MPS or MMF regarding efficacy, but fewer side effects were noted in efficacious combinations, in particular for MPS. In aorta transplantation, MPS and MMF dose-dependently inhibited intima thickening. The combination of 20 mg/kg/d MPS and 10 mg/kg/d CsA gave long-term survival of hamster-to-rat xenografts. Conclusions. Despite the overall comparable efficacy and narrow therapeutic window of MPS and MMF when given alone, MPS apparently is better tolerated than MMF in some of the transplant models. The combination of these agents with CsA allows fine-tuning between optimal immunosuppression and adverse side effects.

Background. Adding a fixed dose of 1 g b.i.d. of mycophenolate mofetil (MMF) to an immunosuppressive regimen consisting of cyclosporine and prednisone results in a 50% reduction in the incidence of acute rejection after kidney transplantation. This study was designed to investigate the relationship between pharmacokinetic data (mycophenolic acid area under the curve; MPA AUC) and the prevention of rejection after kidney transplantation. Methods. A total of 154 adult recipients of a primary or secondary cadaveric kidney graft were randomly allocated, in this double-blind trial, to receive MMF treatment aimed at three predefined target MPA AUC values (16.1, 32.2, and 60.6 μg-hr/ml). During the first 6 months after transplantation, plasma samples for nine AUCs were collected. After analysis of the samples, a coded dose adjustment advice was generated using a Bayesian algorithm, maintaining the double blinding. Immunosuppressive therapy further consisted of cyclosporine and prednisone. The primary end point of this study was the occurrence of biopsy-proven acute rejection within the 6-month study period. Results. A total of 150 patients were eligible for analysis. Although after day 21, the mean MMF dose was reduced, the mean MPA AUC gradually increased and target MPA AUC values were exceeded in all three groups. The incidences of biopsy-proven acute rejection in the low, intermediate, and high target MPA AUC groups were 14 of 51 (27.5%), 7 of 47 (14.9%), and 6 of 52 (11.5%), respectively. The incidences of premature withdrawal from the study due to adverse events in the three groups were 4 of 51 (7.8%), 11 of 47 (23.4%), and 23 of 52 (44.2%), respectively. Logistic regression analysis showed a highly statistically significant relationship between median ln(MPA AUC) and the occurrence of a biopsy-proven rejection (P