Impact of absorption profiling on efficacy and safety of cyclosporin therapy in transplant recipients

TRough versus AUC Monitoring of cyclosporine: A randomized comparison of adverse drug reactions in adult allogeneic stem cell recipients (TRAM study)

OBJECTIVE

To investigate the incidence and severity of adverse drug reactions of cyclosporine using AUC-targeted therapeutic drug monitoring (TDM) compared to trough level (C_trough )-targeted TDM in adult allogeneic stem cell recipients.

METHODS

Blind, monocenter, intervention study. Subjects were 1:1 randomized into either an AUC group or a C_trough group. Adverse drug reactions were accessed two and four weeks after start of treatment.

RESULTS

Forty patients were included, resulting in 15 evaluable subjects (AUC group) and 13 evaluable subjects (C_trough group). Grade two/three toxicity was observed in 46% (C_trough group) versus 60% of subjects (AUC group) (P = .463). There was no significant difference between two and four weeks after start of cyclosporine for nausea (P = .142 resp. P = .122), renal dysfunction (P = .464 resp. P = 1.000), and hypomagnesemia (P = 1.000 resp. P = .411). Subjects in the AUC group reached the therapeutic goal earlier (72,7% versus 43,0% at third sampling point, P = .332) and were within the target range more consistently.

CONCLUSION

This study showed no reduction in incidence and severity of cyclosporine-induced toxicity with AUC- versus trough level-targeted TDM. Although modeled dosing based on AUC led to faster optimal target attainment, this did not result in less toxicity in the early days after transplantation.

A new HPLC-MS/MS method for simultaneous determination of Cyclosporine A, Tacrolimus, Sirolimus and Everolimus for routine therapeutic drug monitoring

A rapid, simple and robust HPLC-MS/MS method for simultaneous determination of immunosuppressants Cyclosporine A, Tacrolimus, Sirolimus and Everolimus has been developed and validated. Sample of whole blood with volume of 50 μL was prepared by a protein precipitation with methanol and 0.5 mol. L^-1 ZnSO₄. Chromatographic separation was achieved on a Phenyl-Hexyl column by a gradient elution using 20 mmol.L^-1 ammonium formate/0.1% (v/v) formic acid in water (mobile phase A) and 20 mmol.L^-1 ammonium formate/0.1% (v/v) formic acid in methanol (mobile phase B) with flow rate 1 mL.min^-1. The run time was 3.5 min. Electrospray ionization and multiple reaction monitoring was used. The lower limit of quantification (LLOQ) was set at 0.5 μg.L^-1 for Tacrolimus, Sirolimus and Everolimus and 5 μg.L^-1 for Cyclosporine A. The method demonstrated adequate accuracy and precision with sufficient linearity range.

Pharmacodynamic monitoring using biomarkers to individualize pharmacotherapy

Drug doses are often titrated upon their clinical effects (e.g., blood pressure). Unfortunately, for many drugs there is no direct, clinical read-out to estimate dose adequateness. Alternatively, drug dosing is based on the maximum tolerated dose approach or therapeutic drug monitoring. However, the concentration-response curves may be flattened or bell-shaped as suggested for some ‘biologicals’. Together, these aspects raise the question why drug dosing is not individualized by pharmacodynamic monitoring. Evaluating the effects of drugs at their pharmacological target or meaningful biomarkers might indicate nonresponders, objectively quantify the maximum molecular effect and thus restrict overdose and underdosing. This review outlines the theory and biological or technical prerequisites for biomarker-based pharmacodynamic monitoring, and highlights selected examples from different fields of clinical medicine.

Topical delivery of Cyclosporine A into the skin using SPACE-peptide

Cyclosporine A (CsA) is used for the treatment of psoriasis; however systemic administration of CsA is potentially life threatening and there are long-term side effects. Topical application of CsA has the potential to overcome this hurdle; however, its use is limited by poor water solubility and low permeability. Here, we report the use of a physical mixture of SPACE-peptide and CsA in an aqueous ethanol solution to enhance the dermal absorption of the drug. The aqueous ethanol solution (hydroethanolic solution) containing 5mg/mL CsA and 50mg/mL of free SPACE-peptide (SP50) delivered about 30% of topically applied CsA into the porcine skin in vitro and led to an approximately 9-fold (p<0.01) increase in accumulation in viable epidermis compared to the hydroethanolic solution without SPACE-peptide (control group). In vivo biodistribution and pharmacokinetic studies performed using SKH1 hairless mice also confirmed the efficacy of SP50 in dermal delivery of CsA and also demonstrated its advantages over other routes in terms of minimizing its systemic absorption. Topical application of SP50 significantly increased the localization of CsA in the target skin (113.1±13.6(μg/g)/mg) compared to all other groups (p<0.01). In addition, SP50 led to significantly higher skin/blood ratio (443.4±181.5) and skin/liver ratio (1059.5±110.8) of CsA compared to all other groups (p<0.01). The SP50 formulation reported here offers a promising approach for the dermal delivery of CsA.

Cyclosporin in cell therapy for cardiac regeneration

Stem cell therapy is a promising strategy in promoting cardiac repair in the setting of ischemic heart disease. Clinical and preclinical studies have shown that cell therapy improves cardiac function. Whether autologous or allogeneic cells should be used, and the need for immunosuppression in non-autologous settings, is a matter of debate. Cyclosporin A (CsA) is frequently used in preclinical trials to reduce cell rejection after non-autologous cell therapy. The direct effect of CsA on the function and survival of stem cells is unclear. Furthermore, the appropriate daily dosage of CsA in animal models has not been established. In this review, we discuss the pros and cons of the use of CsA on an array of stem cells both in vitro and in vivo. Furthermore, we present a small collection of data put forth by our group supporting the efficacy and safety of a specific daily CsA dosage in a pig model.

Enteric-coated mycophenolate sodium in combination with full dose or reduced dose cyclosporine, basiliximab and corticosteroids in Australian de novo kidney transplant patients

AIM

Cyclosporine (CsA), dosed to achieve C2 targets, has been shown to provide safe and efficacious immunosuppression when used with a mycophenolate and steroids for de novo kidney transplant recipients. This study examined whether use of enteric-coated mycophenolate sodium (EC-MPS) together with basiliximab and steroids would enable use of CsA dosed to reduced C2 targets in order to achieve improved graft function.

METHODS

Twelve-month, prospective, randomized, open-label trial in de novo kidney transplant recipients in Australia. Seventy-five patients were randomized to receive either usual exposure (n = 33) or reduced exposure (n = 42) CsA, EC-MPS 720 mg twice daily, basiliximab and corticosteroids.

RESULTS

There was no significant difference in mean Cockcroft-Gault CrCl (creatinine clearance) (60.2 ± 17.6 mL/min per 1.73 m(2) vs 63.2 ± 24.3, P = 0.64 for usual versus reduced exposure respectively) at 6 months. There was no significant difference between treatment groups in the incidence of treatment failure defined as biopsy proven acute rejection, graft loss or death (secondary endpoint: 30.3% full exposure vs 35.7% reduced exposure). At 12 months the incidence of overall adverse events was the same in both groups.

CONCLUSION

This exploratory study suggests de novo renal transplant patients can safely receive a treatment regimen of either full or reduced exposure CsA in combination with EC-MPS, corticosteroids and basiliximab, with no apparent difference in efficacy or graft function during the first year after transplant.

Population pharmacokinetics of ciclosporin in haematopoietic allogeneic stem cell transplantation with emphasis on limited sampling strategy

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • The population pharmacokinetics and limited sampling strategies for ciclosporin monitoring have been extensively studied in renal and liver transplant recipients. Little is known about the pharmacokinetics of ciclosporin in patients undergoing haematopoietic allogeneic stem cell transplantation (HSCT). • It is anticipated that there is a difference in pharmacokinetics in patients after kidney or liver transplantation compared with patients undergoing stem cell transplantation, because of mucositis and interacting drugs (e.g. fluconazole). • Data on the pharmacokinetics of ciclosporin and the relationship between its systemic exposure, as reflected by the area under the curve (AUC), and the biological effect as graft vs. host-disease (GVHD) prophylaxis and graft vs. tumour (GVT) response are scarce in patients after HSCT. WHAT THIS STUDY ADDS • A pharmacokinetic model was developed for orally and intravenously administered ciclosporin, enabling an adequate estimate of the systemic exposure of ciclosporin in patients after HSCT. A limited sampling strategy was tested that may serve as a tool to study the optimum systemic exposure (AUC) of ciclosporin in HSCT to prevent GVHD but establish adequate GVT response and to guide therapeutic drug monitoring. AIM To develop a population pharmacokinetic model of ciclosporin (CsA) in haematopoietic allogeneic stem cell transplantation to facilitate a limited sampling strategy to determine systemic exposure (area under the curve [AUC]), in order to optimize CsA therapy in this patient population. METHODS The pharmacokinetics of CsA were investigated prospectively in 20 patients following allogeneic haematopoietic stem cell transplantation (HSCT). CsA was given twice daily, as a 3 h i.v. infusion starting at day 1 of the conditioning scheme, and orally later on, when oral intake was well tolerated. Fluconazole was given as antimycotic prophylaxis. Pharmacokinetic parameter estimation was performed using nonlinear mixed effect modelling as implemented in the NONMEM program. A first order absorption model with lag time was compared with Erlang frequency distribution and Weibull distribution models. The influence of demographic variables on the individual empirical Bayesian estimates of clearance and distribution volume was tested. Subsequently two limited sampling strategies (LSS) were evaluated: posterior Bayesian fitting and limited sampling equations. RESULTS Twenty patients were included and 435 samples were collected after i.v. and oral administration of CsA. A two compartment model with first order absorption best described the data. Clearance (CL) was 21.9 l h(-1) (relative standard deviation [RSD]± 5.2%) with an inter-individual variability of 21%. The central volume of distribution (V(c) ) was 18.3 l (RSD ± 8.7%) with an inter-individual variability of 29%. Bioavailability (F) was 0.71 (RSD ± 9.9%) with and inter-individual variability of 25% and lag time (t(lag) ) was 0.44 h (RSD 5.5%). Weight, body surface area, haematocrit, albumin, ALAT and ASAT had no significant influence on pharmacokinetic parameters. The best multiple point combination for posterior Bayesian fitting, in terms of estimating systemic CsA exposure, appeared to be C0 + C2 + C3. Two selected LSS two time point equations and all selected three and four time point equations predicted de all AUC(0,12 h) within 15% bias and prediction. CONCLUSIONS The i.v. and oralcurves were best described with a two compartment model with first-order absorption with lag time. With the Bayesian estimators from this model, the area under the concentration-time curve in HSCT patients taking fluconazole can be estimated with only three blood samples (0, 2, 3 h) with a bias of 1% and precision of 4%.

Change of Cyclosporine Absorption over the Time after Kidney Transplantation

Background

Although the immunosuppressant cyclosporine (CsA) is widely used after kidney transplantation over the long term, there is still no firm consensus on the best way to monitor of CsA blood levels.

Objectives

Cyclosporine (CsA) assay is critical for the management of renal transplant recipients due to inter– and intra–patient variation in CsA absorption and metabolism. Patients and Methods: In a retrospective cross sectional study, blood levels of CsA (through and 2 hours post dose) measured at least 5 times during 3 years post transplantation, in 7702 kidney transplant recipients from different transplant center of Tehran, IR Iran between 2008 and 2012. Cyclosporine absorption (CA) calculated C2/C0 ratio.

Results

CA had a significant correlation with allograft function (P = 0.000, r =.0.285), this correlation was stronger than its relationship with C0 and C2 blood levels (P = 0.000 and P = 0.000 as well as r = 0.033 and r = 0.090, respectively). In univariate analysis during different times after transplantation, C0 and C2 blood levels significantly decreased over three years follow up (P = 0.000), (P = 0.000); While, CA reversely increases over the time (P = 0.000). In linear regression model overall CA levels had correlation with lower age of recipient (P = 0.02), hypokalemia (P = 0.001), higher level of creatinine (P = 0.02) and triglyceride (P = 0.001).

Conclusions

The present study shows that CsA absorption changes trough the post-transplant time and appears to increases over time in long–term period after kidney transplantation.

Routine Cyclosporine concentration - C2 level Monitoring. Is it helpful during the early post Transplant Period?

BACKGROUND

Pre dose or trough blood cyclosporine (CSA) concentration is routinely monitored and the result is used to alter patient's drug dosing. Patients with identical pre dose blood CSA may have very different systemic exposure to the drug. Recently CSA 2 hour post dose level [C2] has been reported to correlate better with drug exposure. We undertook this study to evaluate the influence of trough and C2, CSA concentration monitoring on short-term renal allograft outcomes.

METHODS

25 patients of renal transplant receiving a triple drug regimen of CSA micro emulsion (Panacea Biotec) 8mg/kg, azathioprine 1mg/kg and prednisolone 0.5mg/kg were analyzed prospectively for graft outcomes. CSA levels were monitored in whole blood by radioimmunoassay using monoclonal antibodies, at 72 hours after the transplant.

RESULTS

The mean age of patients was 37.08 + 9.1 years. There were 20 males and 5 females. The mean age of donors was 40.2 + 8.2 years. There were 11 related donors with at least a haplomatch, 4 spousal and 10 unrelated donors with a nil antigen match. The mean pre dose CSA concentration was 289.22 + 171.9ng/ml; range (98.8 + 783.41ng/ml). The CSA concentration at 2 hours after the CSA administration was 838 + 310.87ng/ml (range, 169 + 1268ng/ml). 3 (12%) patients had acute rejection. In these patients the mean pre dose CSA concentration was 328.67ng/ml and the mean C2, CSA concentration was 1006.26ng/ml. CSA induced hemolytic uraemic syndrome was diagnosed in one patient. The trough and C2, CSA concentration levels were 174 and 870.83ng/ml respectively in this patient.

CONCLUSION

In our study CSA levels, trough and peak showed significant inter patient variability. The trough and C2 concentration levels did not correlate with the episodes of acute rejection. We conclude that in a triple drug regimen with fixed dosing schedules routine trough CSA level monitoring is not helpful in the acute post renal transplant period.

Cyclosporine C2 levels have impact on incidence of rejection in de novo lung but not heart transplant recipients: the NOCTURNE study

BACKGROUND

Cyclosporine (CsA) absorption varies early after transplantation and can be accurately assessed by the area under the absorption curve (AUC). The 2-hour post-dose (C2) level of CsA in whole blood is reported to be a useful surrogate marker of CsA AUC in kidney and liver transplant monitoring, but should be further explored in thoracic organ recipients.

METHODS

In a 12-month study we included de novo lung (n = 95) and heart (n = 96) recipients. All participants received cyclosporine (Sandimmun Neoral) monitored by C0 and blood was collected for analysis of C2 retrospectively. Abbreviated AUC (AUC(0-4)) was measured at 7 days and 3 months. Primary outcome was C2 relation to the frequency of acute cellular rejection (ACR) needing treatment and possible decline in measured glomerular filtration rate (mGFR). Recipients were divided into lower, middle and upper third C2 groups based on 2-week post-operative values (tertiles T1 to T3).

RESULTS

C2 was the most robust substitute for AUC(0-4) in the group of patients studied. For lung, but not heart, recipients there were differences in mean number of ACRs (p = 0.05), incidence of any rejections (p = 0.04), mean number of any rejections (p = 0.001) and time to first rejection (p = 0.03) between T1 and T3. C2 did not predict reduction in mGFR.

CONCLUSIONS

C2 is a sensitive predictor for ACR in lung, but not heart, recipients, C2 was not predictive of a decline in mGFR. This study suggests that management of lung recipients by C2 may diminish the number of ACRs.

Monitoring of blood cyclosporine concentration in steroid-resistant nephrotic syndrome

OBJECTIVE

Cyclosporine has been used for patients with nephrotic syndrome. Because of substantial inter- and intra-patient variability and a narrow therapeutic window, drug monitoring of cyclosporine is mandatory. To confirm the therapeutic effects of a cyclosporine microemulsion (CSAME), the absorption profile of the agent after preprandial administration was determined in steroid-resistant patients with refractory nephrotic syndrome.

METHODS

Fourteen patients were enrolled into the study (mean age, 31.2+/-12; 6 men, 8 women). The patients received 1.5 mg/kg of cyclosporine 30 minutes before breakfast for 6 months. Blood cyclosporine concentration was measured 5 times serially: before administration (C0) and at 1-hour intervals until 4 hours after administration of cyclosporine (C1-C4). In addition, area under the concentration-time curve from 0-4 hours (AUC0-4) was calculated.

RESULTS

After 6 months, CSAME showed marked improvement in proteinuria levels (8.3+/-4.8 g/day vs 0.8+/-0.4 g/day, p<0.001). No changes in serum creatinine and urea nitrogen levels were observed. In 83% of the patients, the CSAME peak concentration appeared within 1 hour after administration (C1). A strong positive correlation was noted between AUC0-4 and C1 (R2=0.90312) and C2 (R2=0.78431). The mean steroid (prednisolone) dose was 40 mg/day when CSAME treatment was started, but a lowering of the dose to 17.5 mg/day (p<0.001) was achieved at 6 months after CSAME therapy.

CONCLUSION

Preprandial administration of CSAME is effective in steroid-resistant patients with refractory nephrotic syndrome. C1 or C2, but not C0, was a good clinical marker for CSAME exposure.

Population pharmacokinetics and bayesian estimator of cyclosporine in pediatric renal transplant patients

Cyclosporine A (CsA) is an immunosuppressive drug widely used in pediatric renal graft recipients. Its large interindividual pharmacokinetic variability and narrow therapeutic index render therapeutic drug monitoring necessary. However, information about CsA pharmacokinetics is scarce and no population pharmacokinetic (popPK) studies in these populations have been reported so far. to the objectives of this study were 1) to develop a PKpop model and identify the individual factors influencing the variability of CsA pharmacokinetics in pediatric kidney recipients; and 2) to build a Bayesian estimator allowing the estimation of the main PK parameters and exposure indices to CsA on the basis of a limited sampling strategy (LSS). The popPK analysis was performed using the NONMEM program. A total of 256 PK profiles of CsA collected in 98 pediatric renal transplant patients (mean age 9.7 +/- 4.5 years old) within the first year posttransplantation were studied. A 2-compartment model with first-order elimination, and Erlang distribution to describe the absorption phase, fitted the data adequately. For Bayesian estimation, the best LSS was determined based on its performance in estimating area under the concentration-time curve (AUC0-12h) and validated in an independent group of 20 patients. The popPK analysis identified body weight and posttransplant delay as individual factors influencing the apparent central volume of distribution and the apparent clearance, respectively. Bayesian estimation allowed accurate prediction of AUC0-12h using predose, C1h, and C3h blood samples with a mean bias between observed and estimated AUC of 0.5% +/- 11% and good precision (root mean square error = 10.9%). This article reports the first popPK study of CsA in pediatric renal transplant patients. It confirms the reliability and feasibility of CsA AUC estimation in this population. The body weight and the posttransplantation delay were identified to influence PK interindividual variability of CsA and were included in the Bayesian estimator developed, which could be helpful in further clinical trials.

The challenge of renal function in heart transplant children

Renal dysfunction may occur after pediatric heart transplantation and impacts on long-term prognosis. This study aims to review the incidence and mechanisms of chronic nephropathy following heart transplantation, and suggest therapeutic directions. The proportion of pediatric heart-transplant recipients with impaired renal function varies from 22 to 57%, and end-stage renal failure from 3 to 10%, depending on the method used for estimating the glomerular filtration rate. The pathophysiology of renal dysfunction is in part due to calcineurin inhibitor-induced renal vasoconstriction, through activation of the intrarenal renin-angiotensin system, TGF-beta1 upregulation and TGF-beta1 gene polymorphisms. Overproduction of angiotensin II, associated with angiotensin-converting-enzyme genotype, might be associated with poor prognosis and pharmacological factor gene polymorphisms, and may contribute to variation of calcineurine inhibitor exposure in the kidney. Strategies to prevent renal dysfunction include reducing calcineurine inhibitor exposure or delaying calcineurine inhibitor administration from the early post-transplant period. Calcium channel blockers and angiotensin-converting-enzyme inhibitors, blockade of angiotensin II, or anti-TGF-beta1 antibodies might limit nephrotoxicity. No accurate marker can predict the potential of renal lesions to develop. Lowering calcineurine inhibitors levels with immunosuppressive agents that are either less nephrotoxic or non-nephrotoxic should be formally studied. Of high interest is the impact of genetic polymorphism on the development of renal dysfunction.

Relationship between acute rejection and cyclosporine or mycophenolic acid levels in Japanese heart transplantation

BACKGROUND

Cyclosporine (CsA), Mycophenolate mofetil (MMF) and prednisolone (PSL) are widely used for the prevention of acute rejection after heart transplantation. Recently, the serum concentration - time curves (AUC) of CsA and MMF have been demonstrated to be precise predictors of acute rejection.

METHODS AND RESULTS

Fourteen heart transplant patients were treated concomitantly with CsA, MMF, and PSL between May 1999 and November 2005 at the National Cardiovascular Center and of them 3 had acute rejection episodes [International Society for Heart & Lung Transplantation grade 3a]. Two patients (man in his 30 s; woman in her 40 s) had acute rejection with a mycophenolic acid (MPA) AUC(0-12 h) <30 microg x h x ml(-1) and low CsA AUC (AUC(0-4 h); 2,408 ng x h x ml-1, 1,735 ng x h x ml-1). However, 1 patient (man in his 30 s) with a high CsA AUC(0-4 h) (4,019 ng x h x ml-1) did not develop cardiac allograft rejection even if the MMF was temporarily stopped. These 3 patients were investigated to evaluate the relationship between acute rejection and pharmacokinetic parameters, including the CsA C0, C2, AUC(0-4 h) and MPA AUC(0-12 h).

CONCLUSIONS

The findings suggest that a high CsA AUC(0-4 h) may prevent rejection of a cardiac allograft, even if MMF is stopped or drastically reduced.

Is C2 Monitoring or Another Limited Sampling Strategy Superior to C0 Monitoring in Improving Clinical Outcomes in Adult Liver Transplant Recipients?

Cyclosporine (CsA) has had a major impact on the process and success of solid organ transplantation. Early in the use of CsA, therapeutic monitoring using the predose (trough, or C0) concentration became the standard of care. However, there are complications with the use of C0 monitoring that have only partly been mitigated with the advent of the micro-emulsion formulation (CsA-ME). More recently, limited sampling strategies (LSSs) for measuring the area under the CsA concentration-time curve (AUC) have been investigated to improve the monitoring of CsA post-transplantation. Many centres now routinely monitor CsA therapy using the concentration at 2 hours postdose (C2). In this paper the strength of the evidence for C2 (or other LSSs) relative to C0 monitoring of CsA-ME for improving clinically important outcomes in liver transplant patients is critically examined. Additionally, gaps in the literature are identified and recommendations are made for clinical research that could be done to provide more definitive evidence for the use of C2 or other LSSs in monitoring liver transplant patients.

An up-date review on individualized dosage adjustment of calcineurin inhibitors in organ transplant patients

Calcineurin inhibitors, tacrolimus (FK506) and cyclosporine (ciclosporin A), are the primary immunosuppressive agents used on recipients of organ transplantations. The hepatic metabolism of these drugs by cytochrome P450 IIIA (CYP3A) subfamilies is considered a major eliminating process. The intestinal efflux-pump P-glycoprotein (Pgp) (multidrug resistance 1 [MDR1], ATP-binding cassette B1 [ABCB1]) and CYP3A4 have been demonstrated as important for the bioavailability of drugs, so called "absorptive barriers". Recently, an important role for CYP3A5 in the intestine for the oral clearance of drugs has been identified. Both tacrolimus and cyclosporine are substrates of Pgp, CYP3A4 and CYP3A5, and therefore, these molecules are potential pharmacokinetic factors with which to establish personalized dosage regimens for these drugs. Although the effect of single nucleotide polymorphisms in the MDR1/ABCB1 and CYP3A5 genes on the pharmacokinetics of immunosuppressant has been widely examined, some contradictions have been emerged. In living-donor liver transplant (LDLT) patients, the intestinal mRNA expression level of MDR1 and CYP3A5 genotyping both in the native intestine and in the grafted liver are suggested to be potential pharmacokinetic factors for adjusting initial dosage and predicting post-operative variation in the pharmacokinetics of tacrolimus. We review the pharmacokinetic and pharmacodynamic characteristics of these drugs including the large pharmacokinetic variation and potential individualized dosage adjustments based on the genomic information of transporters and metabolic enzymes as well as classical pharmacokinetic analyses based on therapeutic drug monitoring (TDM).

Cyclosporine exposure and calcineurin phosphatase activity in living-donor liver transplant patients: twice daily vs. once daily dosing

We have compared the pharmacokinetics and pharmacodynamics of cyclosporine between once- and twice-daily dosing regimens in de novo patients of living-donor liver transplantation (LDLT). A total of 14 patients were enrolled in this study, who had received cyclosporine microemulsion (Neoral) twice a day (BID, n = 5) or once daily in the morning (QD, n = 9) after transplantation. On postoperative day (POD) 6, the QD regimen significantly increased cyclosporine exposure; the blood concentration at 2 hours postdose (C2) and area under the concentration-time curve (AUC) for 4 hours (AUC(0-4)), compared with the BID regimen. Moreover, the area under the calcineurin (CaN) activity in peripheral blood mononuclear cells time-curve (AUA) for 12 hours (AUA(0-12)) and 24 hours (AUA(0-24)) were decreased by approximately 42 and 25% with the QD regimen relative to the BID regimen, respectively. The C2 level was significantly correlated with the AUC(0-4) (r2 = 0.95), which was negatively related to the AUA(0-12) with a large interindividual variability (r(2) = 0.59). However, a significant correlation was found between the AUA(0-12) or AUA(0-24) and CaN activity at trough time points. According to a maximum inhibitory effect attributable to the drug (E(max)) model, the mean estimates of E(max) and the C(b) value that gives a half-maximal effect (EC50) for CaN inhibition were not significantly different between the 2 groups, respectively. These findings suggest that a once daily morning administration of cyclosporine may improve oral absorption and help to provide an effective CaN inhibition early after LDLT. Furthermore, CaN activity at trough time points would be a single surrogate predictor for the overall CaN activity throughout dosing intervals following cyclosporine administration.

Pharmacokinetic Study and Limited Sampling Strategy of Cyclosporine in Japanese Heart Transplant Recipients

BACKGROUND

The purpose of this study was to characterize the pharmacokinetics of cyclosporine (CsA) in Japanese heart transplant patients, and to optimise the monitoring strategy based on measurements of the area under the curve of plasma concentration absorption phase or 2 h post-dose concentrations (C(2)).

METHODS AND RESULTS

At defined time periods during the first year after transplantation, the area under the curve for the CsA serum concentration from 0 to 4 h (AUC(0-4 h)) was evaluated. Pharmacokinetic parameters and renal function at 1 month and 12 months after transplantation were compared in 7 Japanese patients. The highest coefficient of determination between CsA AUC(0-4 h) and a single concentration was observed using C2 (r2 =0.838). For CsA pharmacokinetics, the mean measurement of whole blood trough levels value at 12 months was significantly lower than at 1 month after transplantation (p=0.026). The mean serum creatinine level at 12 months was significantly higher than at 1 month (1.00 mg/dl vs 0.73 p=0.0194).

CONCLUSION

A single-time-point model that includes C2 is useful for predicting CsA AUC(0-4 h) in Japanese heart transplant patients. Mean C2 values >1,000 ng/ml were obtained in patients with no rejection at 1 month and 12 months after transplantation; however, renal impairment may occur.

Association Between Cyclosporine Concentrations at 2 Hours Post-dose and Clinical Outcomes in De Novo Lung Transplant Recipients

BACKGROUND

The objective of this study was to investigate the relationship between cyclosporine (CsA) pharmacokinetic parameters and clinical outcomes after lung transplantation.

METHODS

Data from 48 lung or heart/lung transplant recipients originally recruited to a randomized, prospective clinical trial of Sandimmune vs Neoral and followed for 12 months were included in this study. CsA dosing was based on the trough concentration. CsA concentrations at 0 (C0), 2 (C2), and 6 (C6) hours post-dosing were obtained at 1, 2, 3, 4, 13, 26, 39, and 52 post-operative weeks. Based on their average C2 levels in the first post-transplant month, patients were stratified retrospectively into Low C2 (<1,000 microg/liter, n = 18), Intermediate C2 (1,000-1,500 microg/liter, n = 16) and High C2 (>1,500 microg/liter, n = 14) Groups.

RESULTS

Cyclosporine C2 was the best single-point determinant (r2 = 0.934) for area-under-the-concentration-time curve (AUC(0-6 hours)) compared with C0 (r2 = 0.267) or C6 (r2 = 0.304). The mean +/- SD values of CsA C2 and AUC(0 to 6 hours) in the first year post-transplant were significantly lower in patients with >2 rejection episodes compared with those with < or =2 rejection episodes (C2: 875 +/- 546 microg/liter vs 1,114 +/- 633 microg/liter, p = 0.01; AUC(0-6 hours): 4,036 +/- 1,904 microg x hour/liter vs 4,870 +/- 2,182 microg x hour/liter; p = 0.01) whereas C0 and C6 did not differ. Patients in the Intermediate C2 Group were free from rejection episodes for a significantly longer duration (p < 0.001) and had significantly higher predicted forced expiratory volume in 1 second (%) values (p < 0.001) compared with the Low and High C2 Groups. The percentage of increase in serum creatinine concentration by the end of first month post-transplant was significantly higher in the Intermediate C2 Group (p < 0.003).

CONCLUSIONS

CsA C2 concentrations correlated better with the incidence of multiple rejections after lung transplantation than did C0 or C6. C2 concentrations between 1,000 and 1,500 microg/liter within the first post-operative month may be associated with better graft outcomes and improved pulmonary function and worsened renal function.

Cyclosporine Monitoring With 2-Hour Postdose Levels in Heart Transplant Recipients

Cyclosporine therapeutic drug monitoring based on 2-hour postdose concentration (C2) compared with conventional trough concentration (C0) can improve clinical outcomes for de novo renal and liver transplant patients. However, in heart transplant patients, published studies are limited. To determine the clinical significance of C2 compared with C0 following orthotopic heart transplantation, the authors measured CsA at C0 and C2 and estimated CsA area under the curve (AUC) using Bayesian estimation and 4 sparse sample algorithms in a cross section of 31 adult patients receiving triple-drug immunosuppression with CsA, mycophenolate mofetil (MMF), and prednisone. CsA was measured using a validated HPLC method. Endomyocardial biopsies were graded based on the ISHLT system. Mean +/- SD values for CsA dose, C0, and C2 were 4.8 +/- 1.4 mg/kg/d, 240 +/- 62 microg/L, and 1319 +/- 469 microg/L, respectively. Correlation with AUC, using different estimation algorithms, was better for C2 (r(2) = 0.79-0.99) than for C0 (r(2)= 0.11-0.52). The mean +/- SD values for C0 (microg/L) and C2 (microg/L) for rejectors (n = 3) were 215 +/- 68 and 949 +/- 204 versus 242 +/- 62 and 1359 +/- 474 for the nonrejectors (P = 0.66 and 0.12, respectively). Fisher exact test P values using the median as threshold value for C0 and C2 (234 microg/L and 1251 microg/L, respectively) were 0.6 and 0.1. Analysis of the data revealed that C0 values in rejectors have wider variability than C2. There were no rejectors among the 16 patients exceeding the C2 median value; for C0, however, there was not an easily identifiable threshold value. There is a trend for a significant relationship between C2 and the incidence of rejection, but the number of rejectors was too small to reach statistical significance. A prospective concentration-control de novo study design is recommended as the most appropriate way to fully evaluate the potential utility of C2 monitoring in heart transplant patients.

Early acute rejection does not affect chronic allograft nephropathy and death censored graft failure

BACKGROUND

Even with the development of modern immunosuppression, an acute rejection episode is a major complication after renal transplantation. Acute rejection episodes have been used as clinical indicators for chronic allograft nephropathy and graft loss. We investigated the timing and frequency of acute rejection episodes in relation to long-term graft survival and chronic allograft nephropathy.

METHODS

The Long Term Efficacy and Safety Surveillance study of transplant patients receiving cyclosporin (Neoral) included 1706 adult renal transplants (1995 to 2003) with a functioning graft for at least 1 year. The impact on death-censored long-term graft survival was evaluated for acute rejection episodes (single or multiple) within 3 months, at 3 to 6 months, at 6 to 12 months, or at over 1 year posttransplant. A stepwise binary logistic regression was employed to identify independent risk factors for the time to occurrence of an acute rejection episode.

RESULTS

An acute rejection episode occurring within 3 months posttransplantation had no effect on either death-censored long-term graft failure (P=.2157) or chronic allograft nephropathy (P=.9331). However, an acute rejection episode occurring at 1 year or later posttransplantation was significantly associated with death censored long-term graft failure (P <.0001) and chronic allograft nephropathy (P <.0001). The numbers of HLA-DR mismatches and younger recipient ages were independent risk factors for early acute rejection.

CONCLUSION

Among patients whose graft survives at least 12 months, an early acute rejection episode within 3 months posttransplant was not associated with either death-censored long-term graft survival or chronic allograft nephropathy among adults treated with cyclosporin. However, an acute rejection episode occurring at 1 year or later posttransplantation showed a positive association with death-censored long-term graft survival or chronic allograft nephropathy. Lower numbers of HLA-DR mismatches sum to reduce the occurrence of acute rejection and the hospitalization time.

Outcome of microemulsion cyclosporine C2 concentration monitoring in kidney transplantation

Profiling of absorption of cyclosporine (CsA) microemulsion is a concept in therapeutic drug monitoring (TDM) designed to optimize the clinical benefits of the drug in transplant recipients. A single blood concentration at 2 h (C(2)) after CsA microemulsion administration in kidney transplant recipients accurately predicts graft outcome. An international guidelines has recommended the target C(2) over time-course post-transplantation. We determined whether this recommendation is appropriate for our patients who are Asian ethnic. The clinical data of these C(2) monitoring kidney transplant recipients were compared with the historical cohort of microemulsion CsA trough (C(0)) level monitoring during the first 24-month post-transplantation. The inclusion and exclusion criteria were applied for both C(2) and C(0) cohorts. The mean target C(2) concentrations at 1, 3, 6, and 12-month post-transplantation were achieved in the C(2) cohort as the international guildlines. At 3-month post-transplantation, patients who had C(2) concentrations over 1500 ng/mL had higher serum creatinine as compared with those who had C(2) levels <1300 ng/mL (2.23 +/- 0.8 vs. 1.44 +/- 0.38 mg/dL: p = 0.01). Also, at 6-month post-transplantation, patients who had C(2) concentrations over 1300 ng/mL had higher serum creatinine (1.96 +/- 0.29 vs. 1.37 +/- 0.34 mg/dL: p < 0.01) as compared with those who had C(2) levels <1100 ng/mL. There was no statistical difference of acute rejection episodes between the two cohorts. The international consensus for C(2) concentraion may be too high for Asian ethnic kidney transplant recipients. The data from this study indicated lower than recommended C(2) concentraion as an appropriate C(2) target concentraion.

Bayesian estimation of cyclosporin exposure for routine therapeutic drug monitoring in kidney transplant patients

AIMS

AUC-based monitoring of cyclosporin A (CsA) is useful to optimize dose adaptation in difficult cases. We developed a population pharmacokinetic model to describe dose-exposure relationships for CsA in renal transplant patients and applied it to the Bayesian estimation of AUCs using three blood concentrations.

METHODS

A total of 84 renal graft recipients treated with CsA microemulsion were included in this study. Population pharmacokinetic analysis was conducted using NONMEM. A two-compartment model with zero-order absorption and a lag time best described the data. Bayesian estimation was based on CsA blood concentrations measured before dosing and 1 h and 2 h post dose. Predictive performance was evaluated using a cross-validation approach. Estimated AUCs were compared with AUCs calculated by the trapezoidal method. The Bayesian approach was also applied to an independent group of eight patients exhibiting unusual pharmacokinetic profiles.

RESULTS

Mean population pharmacokinetic parameters were apparent clearance 30 l h(-1), apparent volume of distribution 79.8 l, duration of absorption 52 min, absorption lag time 7 min. No significant relationships were found between any of the pharmacokinetic parameters and individual characteristics. A good correlation was obtained between Bayesian-estimated and experimental AUCs, with a mean prediction error of 2.8% (95% CI [-0.6, 6.2]) and an accuracy of 13.1% (95% CI [7.5, 17.2]). A good correlation was also obtained in the eight patients with unusual pharmacokinetic profiles (r(2) = 0.96, P < 0.01).

CONCLUSIONS

Our Bayesian approach enabled a good estimation of CsA exposure in a population of patients with variable pharmacokinetic profiles, showing its usefulness for routine AUC-based therapeutic drug monitoring.

Cyclosporine A monitoring--how to account for twice and three times daily dosing

Cyclosporine A (CsA) dose-interval pharmacokinetic profiles, performed 1-4 years post-transplantation, were collected from 74 renal transplanted children. Forty patients were on three times daily dosing (t.i.d.) and 34 on twice daily dosing (b.i.d.). Regression models for prediction of area under the curve (AUC) using 1-3 concentration time points as independent variables were developed. With similar weight-adjusted single doses (mg kg(-1)) of CsA, t.i.d. dosing resulted in a trough-concentration (C0) similar to that from b.i.d. dosing, but a 30% lower 2 h post-dose concentration (C2). For b.i.d. dosing the relationship between C0 and AUC was poor (r2=0.23) and the prediction error was large (5.8+/-33.5%). For t.i.d. dosing the relationship was better (r2=0.79), but prediction error was still large (4.5+/-24.9%). For C2 relationships were similar to those for the b.i.d. (r2=0.59) and t.i.d. (r2=0.63) groups, but explained modestly the variations of AUC (prediction error=2.6+/-16.8% b.i.d., 4.8+/-23.2% t.i.d.). Both C0 and C2 are useful monitoring methods when CsA is administered t.i.d. If the aim is similar specified daily drug exposure, the target C2 should be roughly 30% smaller in t.i.d. dosing than in b.i.d. dosing and the target C0 could be similar. The prediction error of AUC can be large in individual patients when using single time-point determinations, however. The use of multiple time points reduces the variation, but is less feasible.

Pharmacokinetic advantages of two-hour post-dose cyclosporin a level for the therapeutic drug monitoring in stable Chinese kidney transplant recipients

BACKGROUND

Recent studies in Caucasian patients show that 2-hour post-dose cyclosporin A level (C2) monitoring has excellent correlation with the actual drug exposure and risk of rejection. However, the reliability of using C2 in stable Chinese renal transplant patients is unknown.

METHODS

Forty-nine stable Chinese renal transplant patients receiving microemulsion cyclosporin A (Neoral) as part of their immunosuppressive therapy were recruited. Area under the time-concentration curve (AUC) was determined from whole blood cyclosporin A level taken at 0, 1, 2, 4 and 6 h post-dose at time 0 month. Cyclosporin A levels were repeated at 0, 1 and 2 h post-dose at 1 and 2 months later to determine the intra-individual variation at these specific time points.

RESULTS

The average duration of transplantation was 77 +/- 42 months, with average daily cyclosporin dosage of 200 +/- 43 mg in two divided doses. AUC has excellent correlations with cyclosporin A level at 1 h (C1) and 2 h (C2) (r = 0.81 and 0.82 respectively, p < 0.001 for both). The correlation between AUC and trough cyclosporin A level (C0) was statistically significant but only modest (r = 0.52, p < 0.001). On the other hand, the intra-individual coefficient of variation (CVw) of C1 was significantly larger than that of C2 (34.4 +/- 24.2 vs. 15.9 +/- 8.3%, p < 0.0001).

CONCLUSION

We conclude that C2 level has favorable pharmacokinetic properties for therapeutic drug monitoring in stable Chinese transplant recipients. Both C1 and C2 have excellent correlation with AUC, but the intra-individual variability of C2 is much lower than that of C1.

Immunosuppressant Drug Monitoring: Is the Laboratory Meeting Clinical Expectations?

OBJECTIVE:

To review the literature relating to immunosuppressant drug measurement as performed in therapeutic drug monitoring laboratories associated with transplantation centers and consider whether the assay methods widely used for patient dosage management achieve acceptable quality criteria in the context of other sources of variability with these drugs.

DATA SOURCES:

Articles used were accessed primarily through MEDLINE, as well as references cited in related publications. Searches were restricted to organ transplantation in humans.

STUDY SELECTION AND DATA EXTRACTION:

Emphasis was placed on the literature relating to the quality of immunosuppressant drug assays, their limitations, and evidence of clinical benefit in dosage individualization.

DATA SYNTHESIS:

There is a dilemma evident between the quality of the analytical services offered by some diagnostic immunoassay manufacturers and the ability of a significant number of clinical laboratories globally to select only appropriate assay methods.

CONCLUSIONS:

In many cases, clinical laboratories fail to meet the reasonable clinical expectations required for interpretation of immunosuppressant drug assay results as an adjunct to optimal dosage individualization and patient care.

More Stable and Reliable Pharmacokinetics with Preprandial Administration of Cyclosporine Compared with Postprandial Administration in Patients with Refractory Nephrotic Syndrome

STUDY OBJECTIVE

To compare the absorption profile of cyclosporine after preprandial administration with that after postprandial administration, and to determine which administration time resulted in a more stable absorption profile and the timing of the drug concentration that was the most reliable marker for monitoring drug absorption.

DESIGN

Prospective analysis.

SETTING

University teaching hospital in Japan.

PATIENTS

Sixteen patients with refractory nephrotic syndrome.

INTERVENTION

Thirteen patients received cyclosporine after breakfast (postprandial group) and eight received the drug 30 minutes before breakfast (preprandial group).

MEASUREMENTS AND MAIN RESULTS

Blood cyclosporine concentration was measured 5 times serially: before administration (C 0 ) and at 1-hour intervals until 4 hours after administration of cyclosporine (C 1 -C 4 ). Also, area under the concentration-time curve from 0-4 hours (AUC 0-4 ) was calculated. Of the 13 patients in the postprandial group, six (46%) showed fair absorption and exhibited a peak concentration at C 1 or C 2 (high-absorption pattern); seven (54%) showed poor absorption and did not reach the peak concentration within the 4-hour period (low-absorption pattern). Five of the seven patients with the low-absorption pattern were switched from postprandial to preprandial administration. All patients in the preprandial administration group showed a high-absorption pattern and reached the peak cyclosporine concentration at C 1 . The C 2 value showed the best correlation with AUC 0-4 in both groups, and the C 0 parameter did not correlate with AUC 0-4 in either group.

CONCLUSION

Preprandial administration provided a more stable absorption profile of cyclosporine compared with postprandial administration. From the correlation with AUC 0-4 , we concluded that C 2 , and not C 0 , is a reliable marker for monitoring cyclosporine exposure.

Cyclosporine C2 monitoring improves renal dysfunction after lung transplantation

BACKGROUND

Cyclosporine (CyA) toxicity is a potential cause of renal dysfunction, which occurs in 38% of lung transplant (LTx) recipients within 5 years. Reducing CyA to "sub-therapeutic" trough (C0) levels increases the risk of rejection. The 2-hour post-dose concentration (C2) is favored as the best single-point surrogate measure of CyA area under the curve (AUC), which reflects drug exposure. In this investigation we assess the effect of conversion to CyA C2 monitoring on renal dysfunction after LTx.

METHODS

Fifteen patients (M:F = 12:3), aged 47 +/- 14 years (range 28 to 62), 3.5 +/- 2.7 (0.2 to 9.0) years post-LTx, with C0 in the therapeutic range (maintenance 100 to 200 microg/liters) (Behring/EMIT immunoassay) and abnormal renal function, were converted from C0 monitoring to C2 monitoring with dose reductions targeting C2 levels of 300 to 600 microg/liter over a 12-month period.

RESULTS

CyA dose was reduced from 6.4 +/- 7.3 (1.2 to 27.9) to 3.1 +/- 2.7 (0.8 to 9.0) mg/kg/day (p = 0.04), with a reduction in C2 levels from 799 +/- 341 (299 to 1,466) to 390 +/- 148 (195 to 675) microg/liter (p < 0.001). Improvements in serum creatinine (0.20 +/- 0.07 [0.12 to 0.35] vs 0.16 +/- 0.04 [0.11 to 0.22] mmol/liter [p = 0.005]) were maintained during the study follow-up period of 1 year. Only 1 patient developed acute rejection and group mean forced expiratory volume in 1 second (FEV(1)) remained stable (2.4 +/- 1.0 [1.1 to 4.0] vs 2.4 +/- 1.2 [1.1 to 4.6] liters).

CONCLUSIONS

C2 monitoring is a practical method of improving renal dysfunction that allows safe dose reductions of CyA when formal AUC monitoring is not feasible. Extended use of this strategy is associated with long-term benefits.

Current immunosuppressive agents in pediatric renal transplantation: efficacy, side-effects and utilization

Advances in immunosuppressive therapy over the past decade have led to dramatic improvements in graft survival. The immunosuppression that is used is center-dependent and is constantly evolving with the development of new medications. The goal remains to find the best combination that will optimize graft survival, while minimizing the adverse effects.

Therapeutic drug monitoring of immunosuppressant drugs in Marmara University Hospital

Immunosuppressive therapy is the most crucial treatment of organ-transplanted patients. Both cyclosporin and tacrolimus have become a part of the standard immunosuppressive therapy for prevention of rejection. However, lower levels of these drugs are associated with insufficient therapy and eventually result in rejection of the organ, and, on the contrary, higher levels are associated with toxicity to certain organs such as liver and kidneys. Therefore, the levels of these drugs in body fluids should be monitored for the prevention of unwanted situations. In this retrospective study, the authors evaluated the 18-month profile of blood drug concentrations of cyclosporin and tacrolimus in patients admitted to the TDM Unit of the Marmara University Hospital (Istanbul, Turkey) between June 2000 and November 2001. A total of 578 blood samples (347 cyclosporin and 231 tacrolimus) from 134 patients (88 for cyclosporin, 46 for tacrolimus) were evaluated in this period. The therapeutic trough ranges were accepted as 100-350 ng/mL for cyclosporin and 5-20 ng/mL for tacrolimus, and levels below or above the identified levels were accepted to be subtherapeutic or toxic. Most of the results were found within the range of therapeutic levels (67.48% for cyclosporin and 82.71% for tacrolimus). Subtherapeutic levels were found in 19.92% of all cyclosporin and 10.53% of all tacrolimus assays, whereas toxic levels were seen in 12.60% and 6.77% of cyclosporin and tacrolimus results, respectively. In conclusion, this study gives information about the TDM practice in institutional clinical laboratory and also indicates the importance of critical information such as sampling time for individual decision making in dosage regiment.

Cyclosporine levels at 2 hours after dose and body mass index in relation to graft function in renal transplant patients treated with azathioprine or mycophenolate mofetil

The aim of this study was to evaluate the effect of C(2) levels on renal graft function in relation to body mass index (BMI). This retrospective study of 95 renal transplant patients included 53 on AZA and 42 on MMF at 3.1 years after transplantation. The cohort was divided into groups according to their C(2) levels, namely <600 ng/mL, 600 to 900 ng/mL, or >900 ng/mL, and according to BMI (>26 kg/m(2)). In every group, we evaluated the percentage of patients with an increase in creatinine by 1 mg/dL or >/=50% from the first year posttransplant. There was no difference in age, gender, graft source, and dose of corticosteroids or CsA between the groups. Patients on AZA with C(2) 600 to 900 ng/mL showed a lower prevalence of renal dysfunction (3.4%) than those with C(2) levels <600 ng/mL (14.3%) or >900 ng/mL (20%). Seventeen percent of the patients on AZA and 11.9% on MMF had BMI >26 kg/m(2) (P = NS). An increased serum creatinine was present in 22.2% of patients with BMI >26 kg/m(2) in the AZA group vs 20% in the cohort MMF (P = NS). These findings suggest that long-standing renal recipients on AZA with C(2) levels of between 600 and 900 ng/mL show better preservation of renal function. We did not identify differences on the basis of C(2) levels in MMF-treated recipients. The influence of BMI on long-term graft function seemed to be independent of AZA or MMF therapy.

Enhanced clinical utility of De Novo cyclosporine C2 monitoring after lung transplantation

BACKGROUND

The 2-hour post-cyclosporine (CyA) dose concentration (C2) is favored as the best single-point correlate of CyA area-under-the-concentration curve. CyA nephrotoxicity is a prominent cause of renal dysfunction that affects 38% of lung transplant (LTx) recipients at 5 years.

METHODS

We assessed the utility of de novo C2 monitoring after LTx by comparing 2 sequential groups of 18 bilateral LTx recipients followed with traditional de novo trough CyA (C0) monitoring and de novo C2 monitoring, respectively. Target C0 levels were 450 microg/liter and 250 microg/liter at 1 week and 3 months (3/12). Target C2 levels were 1,200 microg/liter and 800 microg/liter. Groups were matched for anthropometrics and diagnoses. Baseline serum creatinine (Cr) was lower in the C0 group than in the C2 group (65 +/- 17 vs 81 +/- 21 micromol/liter, p = 0.02).

RESULTS

At 3 months, survival for both groups was 100%, but the C0 group had a greater increase in Cr from baseline (90 +/- 54% vs 33 +/- 23%, p < 0.001) despite similar CyA dosage (6.6 +/- 3.8 vs 6.5 +/- 2.9 mg/kg/day, p = 0.94). There was no difference in forced expiratory volume in 1 second (% predicted) (71 +/- 16 vs 69 +/- 14, p = 0.68), mean acute vascular rejection score per patient (2.61 +/- 2.12 vs 1.44 +/- 1.72, p = 0.079), mean bronchial rejection score per patient (3.72 +/- 1.81 vs 2.83 +/- 1.58, p = 0.126) or rate of infection (1.85 vs 1.79 events per 100 patient-days).

CONCLUSIONS

De novo C2 monitoring, which reduces both the risk of CyA toxicity and the risk of sub-therapeutic dosing, is a safe and effective technique for short-term preservation of renal function after LTx.

Bioequivalence of a new cyclosporine a formulation to Neoral

New cyclosporine A (CsA) formulations must prove their bioequivalence to Neoral, the reference CsA formulation, to allow free prescription for the patients. The aim of this study was to compare the pharmacokinetics (PK) of a new CsA formulation (Zinograf-ME), produced by Strides-Arcolab, to Neoral and to demonstrate their interchangeability in stable renal transplant recipients. Twelve-hour PK studies were obtained from 18 (13 M/5 F) adult patients (mean age 44.7 +/- 12 years). They received their renal allografts from 13 cadaver and 5 living donors. Before enrollment, all patients were receiving a third generic CsA for a mean of 48 months. Nine patients were also under azathioprine and 9 under mycophenolate mofetil; 17 received prednisone. A single oral dose of either Zinograf or Neoral was administered. The first PK study was performed with one formulation, and 1 week later, a second PK was done with the other formulation. During the washout period, patients continued taking the third CsA formulation. The drug substitution was done milligram-for-milligram. The CsA whole-blood level was measured by TDx immunoassay. Mean +/- SD of area under the curve (AUC), maximum concentration (C(max)), and concentration at the second hour (C2) of Zinograf were not statistically different from those with Neoral (4019 +/- 1466 vs 3971 +/- 1325 ng x h/mL, 998 +/- 376 vs 1021 +/- 356 ng/mL, and 707 +/- 254 vs 734 +/- 229 ng/mL, respectively). In the same way, the Zinograf 90% confidence interval for either C(max) (-123, +77 ng/mL) or AUC (-214, +311 ng.mL/h) were within the Neoral bioequivalence interval for the same parameters (+/-204 ng/mL and +/-794 ng x mL/h, respectively). These data demonstrate that the ZinografME CsA formulation is bioequivalent to Neoral.

Population pharmacokinetic modeling of oral cyclosporin using NONMEM: comparison of absorption pharmacokinetic models and design of a Bayesian estimator

There have been very few population pharmacokinetic (PopPK) studies and Bayesian forecasting methods dealing with cyclosporin (CsA) so far, probably because of the difficulty of modeling the particular absorption profiles of CsA. The present study was conducted in stable renal transplant patients treated with Neoral and employed the NONMEM program. Its goals were (1) to develop a population pharmacokinetic model for CsA based on an Erlang frequency distribution (which describes asymmetric S-shaped absorption profiles) combined with a 2-compartment model; (2) to compare this model with models combining a time-lag parameter and either a zero-order or first-order rate constant and with a model based on a Weibull distribution; and (3) to develop a PK Bayesian estimator for full AUC estimation based on that "Erlang model." The PopPK model was developed in an index set of 70 patients, and then individual PK parameters and AUC were estimated in 10 other patients using Bayesian estimation. The "Erlang" model best described the data, with mean absorption time (MAT), apparent clearance (CL/F), and apparent volume of the central compartment (Vc/F) of 0.78 hours, 26.3 L/h, and 76 L, respectively (interindividual variability CV = 33, 30, and 48%). Bayesian estimation allowed accurate prediction of systemic exposure using only 3 samples collected at 0, 1, and 3 hours. Regression analysis found no significant difference between the predicted and observed concentrations (10 per patient), and AUC(0-12) were estimated with a nonsignificant bias (0.6 to 8.7%) and good precision (RMSE = 5.3%). In conclusion, the Erlang distribution best described CsA absorption profiles, and a Bayesian estimator developed using this model and a mixed-effect PK modeling program provided accurate estimates of CsA systemic exposure using only 3 blood samples.

Synergistic penetration enhancement effect of ethanol and phospholipids on the topical delivery of cyclosporin A

In the present study, ethanol was used with a commercially available lipid mixture, NAT 8539, to improve the topical delivery of cyclosporin A (CyA). The vesicles formed from this solution ranged from 56.6 to 100.6 nm in diameter, depending on the amount of ethanol added in the formulation. In-vitro skin penetration studies were carried out with Franz diffusion cell using human abdominal skin. There was a decrease in average size of vesicles, as the amount of ethanol in formulation increased from 0% to 3.3% and a further addition of ethanol resulted in an increase in average diameter of vesicles. CyA vesicles containing 10% and 20% ethanol showed statistically enhanced deposition of CyA into the stratum corneum (SC), as compared to vesicles prepared without ethanol. CyA vesicles prepared with NAT 8539/ethanol (10/3.3) showed a 2.1-fold, CyA vesicles with NAT 8539/ethanol (10/10) showed a 4.4-fold, and CyA vesicles with NAT 8539/ethanol (10/20) showed a 2.2-fold higher deposition of CyA into SC, as compared to vesicles made of NAT 8539 without ethanol [NAT 8539/ethanol (10/0)]. The efficiency of the formulations was sequenced in the order of: NAT 8539/ethanol (10/10)>NAT 8539/ethanol (10/20)>NAT 8539/ethanol (10/3.3)>ethanol>NAT 8539/ethanol (10/0). These results can be considered a step forward for the topical delivery of problematic molecules like CyA using liposomes as a tool for the treatment of inflammatory skin diseases like psoriasis, atopic dermatitis, and diseases of the hair follicle like alopecia areata, etc.

C2 blood concentrations of orally administered cyclosporine in pediatric liver graft recipients with a body weight below 10 kg

Pharmacokinetic studies in adult and pediatric liver transplant recipients have shown that the C(2) monitoring is superior to the traditional determination of CsA trough levels (C(0)) as an estimate of CsA exposure. However, target reference values for C(2) in very small infants have not been established yet. The objective of our study was to assess the distribution of C(2) levels in the first week following Ltx and to analyze enteral absorption of CsA for this group of patients. We documented CsA C(0) and C(2) levels in 25 infants with a body weight below 10 kg (median 6.8 kg; range 3.0-9.8 kg) in the first 7 days after Ltx. The infants had a median age at transplantation of 7 months (range 0.3-20.0 months). The underlying diagnoses were biliary atresia (n = 17), acute liver failure (n = 4), metabolic disease (n = 4). All children received CsA microemulsion (Neoral, initial 10 mg/kg/day), prednisolone, and two single doses of basiliximab as immunosuppressive drugs. The mean C(0) and C(2) levels were as follows: day 1: C(0) 77.0 +/- 39.6, C(2) 340.5 +/- 140.0 ng/mL; day 2: C(0) 135.5 +/- 53.2, C(2) 467.0 +/- 168.2 ng/mL; day 3: C(0) 146.5 +/- 70.8, C(2) 519.0 +/- 219.1 ng/mL; day 4: C(0) 168.5 +/- 55.1, C(2) 570.0 +/- 163.7 ng/mL; day 5: C(0) 156.5 +/- 38.0, C(2) 612.0 +/- 132.4 ng/mL; day 6: C(0) 177.0 +/- 41.1, C(2) 606.0 +/- 149.2 ng/mL; day 7: C(0) 174.0 +/- 27.2, C(2) 622.0 +/- 98.8 ng/mL (r = 0.82, p < 0.05). This analysis demonstrates that there is a good enteral absorption of CsA in very small children post-Ltx in the early post-operative period. Based on the C(2) levels achieved, we conclude that there is a good correlation between C(0) and C(2) levels even in very small infants.

Experience with conversion from sandimmun to neoral cyclosporine and the correlation of c2 levels with renal function

Pharmacologic monitoring of the cyclosporine microemulsion Neoral is an important tool to improve the efficacy and to avoid toxicity of the drug. Recent trials have shown that the absorption profiling tools represented by the area under the time-concentration curve from 0 to 4 hours postdose and concentration 2 hours postdose (C2) levels are the best predictors of acute rejection in the early posttransplant period. Since similar data regarding maintenance immunosuppression are scarce, we report our experience on Neoral C2 monitoring in renal transplant recipients during the late posttransplant period. However, available data on optimal Neoral C2 levels in the late posttransplantation period are scant and have not been correlated with well-defined endpoints such as chronic allograft nephropathy.

Current immunosuppressive agents: efficacy, side effects, and utilization

Advances in immunosuppressive therapy over the past decade have led to dramatic improvements in graft survival. With the development of new agents, the focus of the transplant community is to establish regimens that maintain excellent graft survival rates but with fewer toxicities including infection, nephrotoxicity, malignancy, and cosmetic effects. Examples include the use of steroid-free protocols and calcineurin avoidance regimens, which are currently being studied by NAPRTCS. The ultimate goal of transplant immunosuppressive therapy is the induction of tolerance. As we learn more about immune function from basic and clinical research, tolerance to allografts seems a more reachable goal.

Tacrolimus: a further update of its use in the management of organ transplantation

Extensive clinical use has confirmed that tacrolimus (Prograf) is a key option for immunosuppression after transplantation. In large, prospective, randomised, multicentre trials in adults and children receiving solid organ transplants, tacrolimus was at least as effective or provided better efficacy than cyclosporin microemulsion in terms of patient and graft survival, treatment failure rates and the incidence of biopsy-proven acute and corticosteroid-resistant rejection episodes. Notably, the lower incidence of rejection episodes after renal transplantation in tacrolimus recipients was reflected in improved cost effectiveness. In bone marrow transplant (BMT) recipients, the incidence of tacrolimus grade II-IV graft-versus-host disease was significantly lower with tacrolimus than cyclosporin treatment. Efficacy was maintained in renal and liver transplant recipients after total withdrawal of corticosteroid therapy from tacrolimus-based immunosuppression, with the incidence of acute rejection episodes at up to 2 years' follow-up being similar with or without corticosteroids. Tacrolimus provided effective rescue therapy in transplant recipients with persistent acute or chronic allograft rejection or drug-related toxicity associated with cyclosporin treatment. Typically, conversion to tacrolimus reversed rejection episodes and/or improved the tolerability profile, particularly in terms of reduced hyperlipidaemia. In lung transplant recipients with obliterative bronchiolitis, conversion to tacrolimus reduced the decline in and/or improved lung function in terms of forced expiratory volume in 1 second. Tolerability issues may be a factor when choosing a calcineurin inhibitor. Cyclosporin tends to be associated with a higher incidence of significant hypertension, hyperlipidaemia, hirsutism, gingivitis and gum hyperplasia, whereas the incidence of some types of neurotoxicity, disturbances in glucose metabolism, diarrhoea, pruritus and alopecia may be higher with tacrolimus treatment. Renal function, as assessed by serum creatinine levels and glomerular filtration rates, was better in tacrolimus than cyclosporin recipients at up to 5 years' follow-up.

CONCLUSION

Recent well designed trials have consolidated the place of tacrolimus as an important choice for primary immunosuppression in solid organ transplantation and in BMT. Notably, in adults and children receiving transplants, tacrolimus-based primary immunosuppression was at least as effective or provided better efficacy than cyclosporin microemulsion treatment in terms of patient and graft survival, treatment failure and the incidence of acute and corticosteroid-resistant rejection episodes. The reduced incidence of rejection episodes in renal transplant recipients receiving tacrolimus translated into a better cost effectiveness relative to cyclosporin microemulsion treatment. The optimal immunosuppression regimen is ultimately dependent on balancing such factors as the efficacy of the individual drugs, their tolerability, potential for drug interactions and pharmacoeconomic issues.

Conversion from cyclosporine to azathioprine at three months reduces the incidence of chronic allograft nephropathy

BACKGROUND

Conversion from cyclosporine to azathioprine after renal transplantation has been shown to be beneficial in terms of allograft function, cardiovascular risk factor profile, and the incidence of gout. A higher incidence of acute rejection, however, has also been reported and uncertainty still exists about the long-term outcome after conversion. We report on the extended follow-up of an open-label, randomized trial that examined conversion to azathioprine as early as three months after transplantation.

METHODS

One hundred twenty-eight patients were enrolled in this single-center study. Three months after transplantation they were randomly assigned to continue cyclosporine treatment (N = 68), or they were converted to azathioprine (N = 60). The steroid dose was temporarily increased in the patients who were converted.

RESULTS

Patient survival was not different in the two groups. Graft survival tended to be lower (64.7% vs. 76.5% at 15 years) in the cyclosporine continuation group (P = 0.14) when data were analyzed on an intention to treat basis. The graft survival of the patients that stayed on their assigned treatment was significantly higher in the azathioprine arm, starting at two years' post-transplantation. The glomerular filtration rate was significantly higher in the patients who were converted to azathioprine. More allograft biopsies were taken from patients remaining on cyclosporine for suspicion of cyclosporine-related nephrotoxicity and prompted a high rate of late conversions (19%). The relative risk of chronic allograft nephropathy was significantly higher in the group that continued cyclosporine [relative risk, 4.3 (95% CI, 1.4 to 12.9); P = 0.009]. Conversion to azathioprine reduced the need of blood pressure and lipid-lowering drugs.

CONCLUSION

Conversion to a calcineurin inhibitor-free immunosuppressive regiment three months after renal transplantation improved allograft function, reduced the need of cardiovascular risk factor-controlling medication, and reduced the incidence of chronic allograft nephropathy.

Cyclosporin C(2) and C(0) concentration monitoring in stable, long-term heart transplant recipients receiving metabolic inhibitors

BACKGROUND

Cyclosporin (CsA) dose selection is complicated by significant pharmacokinetic variability between patients. Although therapeutic drug monitoring (TDM) has proven to be a useful tool for dose individualization, the search for an effective and practical measure of clinical effect has uncovered a number of options. Monitoring the CsA concentration in a blood sample taken 2 hours after the dose (C(2)) has been utilized but has not been rigorously evaluated in all clinical situations. The aim of this study was to evaluate C(2) and trough (C(0)) CsA concentrations as surrogate markers of area under the concentration-time curve (AUC) in stable, long-term heart transplant recipients receiving CsA alone or with diltiazem and/or ketoconazole.

METHODS

CsA blood concentration-time data were collected at steady state for 47 stable heart transplant recipients after the morning dose of Neoral. CsA concentration in whole blood was quantitated using the EMIT immunoassay. Patients were stratified into 4 groups, depending on the long-term concomitant administration of drugs known to inhibit CsA metabolism, as part of their routine therapy: Group A (n = 11), CsA alone; Group B (n = 10), CsA with slow-release diltiazem; Group C (n = 13), CsA with ketoconazole; and Group D (n = 12), CsA with a combination of diltiazem and ketoconazole.

RESULTS

In Group A, C(2) correlated poorly with AUC(0-5) (r(2) = 0.197; p = 0.17), whereas C(0) (trough blood sample) showed a stronger correlation (r(2) = 0.710; p = 0.001). Correlations of C(0) and C(2) with AUC(0-5) were the same, but weaker in patients receiving CsA and diltiazem (r(2) = 0.650; p = 0.005); however, C(2) correlated strongly with AUC(0-5) in patients receiving ketoconazole (r(2) = 0.870; p < 0.0001) or ketoconazole with diltiazem (r(2) = 0.898; p < 0.0001). C(0) was a poor predictor of AUC(0-5) in the latter 2 groups.

CONCLUSIONS

C(2) showed a strong correlation with AUC(0-5) in cardiothoracic transplant recipients receiving CsA with ketoconazole, but not with CsA alone or diltiazem. TDM using C(2) as an estimate of AUC requires further evaluation before being applied in long-term, stable cardiac transplant patients, as it may lead to inappropriate dose adjustment of CsA in patients receiving concomitant metabolic inhibitors.