Impact of a Bayesian Individualization of Cyclosporine Dosage Regimen for Children Undergoing Allogeneic Hematopoietic Cell Transplantation: A Cost-Effectiveness Analysis.

BACKGROUND: Cyclosporine A (CsA) is the main drug used to prevent graft-versus-host disease in patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT). CsA therapeutic drug monitoring (TDM) has been performed for ages, with studies revealing clinical benefits, but failing to examine its economic impact. In this article, the main objective was to evaluate the economic impact of the CsA TDM strategy, based on a Bayesian approach, by assessing costs related to its clinical impact. Furthermore, TDM effectiveness was analyzed for pharmacokinetics and clinical outcomes. METHODS: A cost-effective, nonrandomized, retrospective, single-center study compared 2 CsA monitoring and dose adaptation strategies in pediatric patients undergoing HSCT. From 2014 to 2016, CsA TDM was performed using a population pharmacokinetics model-coupled Bayesian approach by a pharmacist ["pharmacist-assisted individualization" (PAI)]. From 2017 to 2018, CsA TDM was performed by the clinician without a Bayesian approach (non-PAI group). HSCT costs were evaluated from the French National Insurance perspective. Economic and clinical outcomes were assessed by measuring incremental cost-effectiveness ratios. RESULTS: The study included 144 patients: 90 and 54 patients in PAI and non-PAI groups, respectively. Both groups were comparable for sociodemographic and clinical characteristics. The mean total cost per patient was significantly lower (P < 0.01) in the PAI group (€85,947) than in the non-PAI group (€100,435). Multivariate analysis revealed that TDM based on the Bayesian approach was a protective factor (odds ratio = 0.86) for severe acute graft-versus-host disease. We noted that pharmacist-based TDM was the dominant strategy. Bayesian method-based TDM allowed an increase in the percentage of target attainment at any period post-HSCT. CONCLUSIONS: CsA TDM with a Bayesian approach is a cost-effective procedure, and highlighted clinical benefits encourage the development of new TDM strategies for HSCT.

A Systematic Literature Review Approach to Estimate the Therapeutic Index of Selected Immunosuppressant Drugs After Renal Transplantation.

BACKGROUND: Drugs that exhibit close margins between therapeutic and toxic blood concentrations are considered to have a narrow therapeutic index (NTI). The Food and Drug Administration has proposed that NTI drugs should have more stringent bioequivalence standards for approval of generic formulations. However, many immunosuppressant drugs do not have a well-defined therapeutic index (TI). METHODS: We sought to determine whether safety, efficacy, and pharmacokinetic data obtained from the medical literature through a comprehensive literature search could be used to estimate the TI of cyclosporine, tacrolimus, and sirolimus. In this analysis, we considered TI ≤2 as a criterion to define a drug as having an NTI. RESULTS: Published literature indicates that cyclosporine has a TI of 2-3, which falls just short of our criteria to be classified as having an NTI. We found sirolimus and tacrolimus to have a therapeutic range of 5-12 ng/mL and of 5-20 ng/mL, respectively, but were unable to calculate the TI. CONCLUSIONS: Although the current literature does not provide a clear indication that these drugs have an NTI, the routine use of therapeutic drug monitoring in clinical practice suggests that more stringent testing of their pharmacokinetic and pharmacodynamic properties should be performed before the approval of generic formulations.

Conversion from Brand-Name Neoral to the Generic Ciqorin in Stable Renal Transplant Recipients.

BACKGROUND/AIMS: Transplant physicians and patients are often reluctant to change to generic versions of immunosuppressive drugs with a narrow therapeutic index, such as ciclosporin (CsA). Thus, in routine follow-up for kidney transplant patients receiving CsA maintenance immunosuppressive therapy in our center, we evaluated the exchangeability of the brand name, Neoral, and the recently approved CsA generic formulation, Ciqorin. METHODS: We assessed the complete 12-h CsA pharmacokinetic profile and direct measurement of glomerular filtration rate (mGFR) of 10 patients receiving stable doses of Neoral (138 ± 43 mg/day), at least 6 months after kidney transplantation (Neoral 1). The same evaluations were repeated 10 days after conversion to Ciqorin on a milligram-to-milligram basis and 10 days after reinstituting Neoral (Neoral 2). RESULTS: The mean CsA area under the concentration-time curve increased slightly after switching from Neoral to Ciqorin (p = 0.03), but did not change significantly after Neoral was reintroduced (Neoral 1: 2,234 ± 783, Ciqorin: 2,452 ± 767, Neoral 2: 2,472 ± 784 ng × h/mL). There were no appreciable differences between the 2 CsA formulations in trough levels, maximum concentrations, or time to reach maximum concentrations. In all patients, renal function remained stable throughout the monitoring period (mGFR, Neoral 1: 52.0 ± 16.2; Ciqorin: 55.0 ± 19.0; Neoral 2: 55.8 ± 18.9 mL/min/1.73 m2), as did urinary and hematochemical parameters. CONCLUSIONS: In stable kidney transplant recipients, switching from Neoral to Ciqorin resulted in similar pharmacokinetic parameters and did not change renal allograft function, reassuring physicians and patients regarding the exchangeability of reference and generic CsA formulations.

Therapeutic monitoring of pediatric renal transplant patients with conversion to generic cyclosporin.

BACKGROUND: Cyclosporin is a calcineurin inhibitor widely used in renal transplant patients to prevent organ rejection. Several position papers have been published but no reports on the practical experience in pediatric patients undergoing conversion between cyclosporin innovator and generic products are available. OBJECTIVE: To evaluate the pharmacokinetics and safety as part of therapeutic monitoring of cyclosporin in renal transplant pediatric patients who switch from the innovator to the generic formulation in Argentina. SETTING: Hospital de Pediatría JP Garrahan, Buenos Aires, Argentina. METHODS: Stable pediatric renal transplant patients (6 months post-transplant) switched from the innovator to the generic formulation of cyclosporin microemulsion capsule. Cyclosporin pharmacokinetic parameters were obtained while taking the innovator and after starting with the generic formulation. Blood samples were drawn before and 1, 2, and 3 h after drug administration and subsequently quantified. Pharmacokinetic parameters were obtained by means of a Bayesian approach. MAIN OUTCOMES MEASURE: Cyclosporin pharmacokinetic parameters (area under the curve, AUC; Blood concentration after 2 h, C2), adverse events and graft rejection. RESULTS: A total of 12 patients were included. Median (range) age and time post-transplant were 10.7 years (6.5-17.7) and 8.3 years (3.4-14.0), respectively. Two patients or their parents did not consent to the switch. Median (range) dose normalized cyclosporin AUC and C2 were 1.15 (mg*h/L)/mg/kg (0.72-3.0) and 265.5 (ng/ml)/mg/kg (120.8-725.7), respectively, on the innovator therapy and 1.05 (mg*h/L)/mg/kg (0.54-2.22) and 317.1 (ng/ml)/mg/kg (116.7-564.7) for the generic drug after the switch. The median (range) percentage of change in the AUC and C2 when switching between formulations were 16.7 % (0.7-56.7) and 13.1 % (3.7-68.6), respectively. No significant changes in serum creatinine levels were registered when comparing before and after substitution of products. Adverse events (number of events) recorded 5 months before and after the switch included hirsutism (2), hypertension (2), and gingival hyperplasia (1). CONCLUSION: Conversion of cyclosporin from innovator brand to generic in pediatric renal transplant patients needs to be closely monitored.

New-onset diabetes after transplantation: assessment of risk factors and clinical outcomes.

BACKGROUND: New-onset diabetes after transplantation (NODAT) is a serious complicatin of kidney transplantation (KT) with adverse impacts on graft and patient survivals. This study aims assess potential risk factors for development of NODAT and compare clinical outcomes of KT recipients with versus without NODAT. METHODS: We retrospectively evaluated 648 patients who underwent KT between 2005 and 2009. From the 83 (12.8%) subjects who developed NODAT, we selected 47 for comparison with controls free of diabetes. RESULTS: The diagnosis of NODAT was made at 4.3 ± 8.5 months after transplantation in 47 patients, including 76.6% males, with an overall mean age of 54.5 ± 10.8 years. Patients with NODAT presented higher pretransplantation fasting plasma glucose levels (P < .001) as well as cyclosporine and tacrolimus trough levels (P = .003 and P < .001, respectively). On multivariate analysis, higher pretransplantation fasting plasma glucose and higher tacrolimus, but not cyclosporine concentrations were independent predictors of NODAT. No differences were found for other potential risk factors. Upon follow-up at 6, 12, 24, 36, 48, and 60 months, renal function (estimated Glomerular Filtration Rate using Modification of Diet in Renal Disease), 24 hour proteinuria and proportions of patients with hypertension were similar between groups. Patients with NODAT showed comparable numbers of hospitalizations and infections, as well as acute rejection episodes and acute cardiovascular events as their counterparts. Event-free survival (loss of graft function/death with functioning graft) was similar between the groups (P = .418; K-M). DISCUSSION: In our population, higher pretransplantation fasting plasma glucose levels and higher tacrolimus concentrations were independent predictors of NODAT. During a mean follow-up of 3 years, NODAT was not associated with worse clinical outcomes.

Bioequivalence and tolerability assessment of a novel intravenous ciclosporin lipid emulsion compared to branded ciclosporin in Cremophor ® EL.

BACKGROUND: Ciclosporin is used as an immunosuppressant in current clinical practice but recent research implies novel indications for the drug, such as neuro- and cardioprotection. The intravenous formulation currently on the market, Sandimmune(®) Injection (Sandimmune(®)), uses Cremophor(®) EL as emulsifying excipient. Cremophor(®) EL is known to cause hypersensitivity reactions in some patients, ranging from skin reactions to potentially fatal anaphylactic shock. OBJECTIVES: The primary objective was to assess if CicloMulsion(®), a Cremophor(®) EL-free lipid emulsion of ciclosporin for intravenous administration, is bioequivalent to Sandimmune(®), and the secondary objective was to compare the tolerability profiles of the two preparations. METHODS: This was a single-centre, open-label, subject-blind, laboratory-blind, single-dose, randomized, two-treatment, two-period, two-sequence crossover study of the pharmacokinetics of two formulations of intravenous ciclosporin. Fifty-two healthy volunteer subjects were administered 5 mg/kg of each of the two formulations of ciclosporin as a 4-h intravenous infusion. The last blood sample was acquired 48 h after the end of the infusion. Bioequivalence assessments according to current guidelines were performed. RESULTS: The geometric mean ratios for CicloMulsion(®)/Sandimmune(®) (90 % confidence interval [CI]) were 0.90 (0.88, 0.92) for AUC(0-last) (area under the blood concentration-time curve from time zero to time of last measurable concentration) and 0.95 (0.92, 0.97) for C(max) (maximum blood concentration). For all additional variables analysed, the 90 % CIs were also within the accepted bioequivalence range of 0.80-1.25. One anaphylactoid and one anaphylactic reaction, both classified as serious adverse events, were reported after treatment with Sandimmune(®). No serious adverse events were recorded after treatment with CicloMulsion(®). CONCLUSION: We have assessed the pharmacokinetics and tolerability of a new Cremophor(®) EL-free lipid emulsion of ciclosporin, CicloMulsion(®), compared to Sandimmune(®). The proportion of adverse events was significantly higher for the Cremophor(®) EL-based product Sandimmune(®). We conclude that CicloMulsion(®) is bioequivalent to Sandimmune(®) and exhibits fewer adverse reactions.

Cyclosporine inhibition of hepatic and intestinal CYP3A4, uptake and efflux transporters: application of PBPK modeling in the assessment of drug-drug interaction potential.

PURPOSE: To apply physiologically-based pharmacokinetic (PBPK) modeling to investigate the consequences of reduction in activity of hepatic and intestinal uptake and efflux transporters by cyclosporine and its metabolite AM1. METHODS: Inhibitory potencies of cyclosporine and AM1 against OATP1B1, OATP1B3 and OATP2B1 were investigated in HEK293 cells +/- pre-incubation. Cyclosporine PBPK model implemented in Matlab was used to assess interaction potential (+/- metabolite) against different processes (uptake, efflux and metabolism) in liver and intestine and to predict quantitatively drug-drug interaction with repaglinide. RESULTS: Cyclosporine and AM1 were potent inhibitors of OATP1B1 and OATP1B3, IC(50) ranging from 0.019-0.093 µM following pre-incubation. Cyclosporine PBPK model predicted the highest interaction potential against liver uptake transporters, with a maximal reduction of >70% in OATP1B1 activity; the effect on hepatic efflux and metabolism was minimal. In contrast, 80-97% of intestinal P-gp and CYP3A4 activity was reduced due to the 50-fold higher cyclosporine enterocytic concentrations relative to unbound hepatic inlet. The inclusion of AM1 resulted in a minor increase in the predicted maximal reduction of OATP1B1/1B3 activity. Good predictability of cyclosporine-repaglinide DDI and the impact of dose staggering are illustrated. CONCLUSIONS: This study highlights the application of PBPK modeling for quantitative prediction of transporter-mediated DDIs with concomitant consideration of P450 inhibition.

Assessment of pharmacokinetic proportionality of levofloxacin and cyclosporine over a 100-fold dose range in healthy human volunteers.

OBJECTIVE: Levofloxacin and cyclosporine show different pharmacokinetic properties, but are known to be dose proportional within the therapeutic range. The authors evaluated the pharmacokinetic proportionality of levofloxacin and cyclosporine over a 100-fold dose range in healthy human volunteers, by liquid chromatography-tandem mass spectrometry (LC-MS/MS). METHODS: Two independent, randomized, crossover studies were performed. For levofloxacin, eight volunteers were randomly assigned in a 1:1 ratio to receive a low dose (7.5 mg) orally or intravenously, followed by a 1-week washout period and administration via the alternate route. After another 1-week washout period, a therapeutic dose (750 mg) was administered to all eight subjects. For cyclosporine, another eight volunteers received a low dose (2 mg) or a therapeutic dose (200 mg) orally with a 1-week washout period. Drug concentrations were determined by LC-MS/MS. RESULTS: For levofloxacin, the mean values for dose-normalized C(max) and AUC(last) with the two doses were as follows: therapeutic dose, 15.2 ± 4.6 ng/ml/mg and 103.6 ± 15.5 ng·h/ml/mg, respectively; low dose, 17.1 ± 6.5 ng/ml/mg and 72.6 ± 8.7 ng·h/ml/mg, respectively. For cyclosporine, the mean values for dose-normalized C(max) and AUC(last) were as follows: therapeutic dose, 4.9 ± 1.5 ng/ml/mg and 15.4 ± 4.9 ng·h/ml/mg, respectively; low dose, 1.6 ± 0.6 ng/ml/mg and 9.3 ± 7.3 ng·h/ml/mg, respectively. CONCLUSION: In this study levofloxacin, which is completely absorbed and primarily eliminated renally without modification, showed better pharmacokinetic proportionality than cyclosporine, which is poorly absorbed and extensively metabolized.

Safety and efficacy of generic cyclosporine arpimune in Filipino low-risk primary kidney transplant recipients.

BACKGROUND: In the Philippines, maintenance of immunosuppression may not always be affordable, leading to acute rejection and graft loss. The availability of the generic cyclosporine Arpimune could be economically beneficial, but its safety and efficacy should be established. METHODS: This prospective cohort study enrolled 30 renal transplant patients who received Arpimune with mycophenolate/prednisone. Their results were compared up to 6 months with 30 matched control patients who received Neoral during the same period. Areas under the receiver operating characteristic curves (AUC) after intake of Arpimune and therapeutic drug monitoring using cyclosporine levels 2 hours after each dose were done. Pearson correlation was performed to determine linearity of relationship between the generic cyclosporine concentrations and AUC 0-4. Chi-square test was used in obtaining cyclosporine Arpimune concentrations. RESULTS: The abbreviated concentration AUC of Arpimune was similar to that of Neoral, and the 2-hour sampling point (r = 0.813; P < .001) showed the best correlation. Calculated creatinine clearance (mL/min) versus Neoral was 71.36 ± 13 versus 68.03 ± 16.6 (P = .61) at 1 month, 70.4 ± 14.8 versus 64.2 ± 11.4 (P = .12) at 3 months, and 74.02 ± 15.8 versus 62.03 ± 12.1 (P = .002) at 6 months. Two Arpimune versus 4 Neoral patients (P = .67) developed biopsy-proven acute rejection. One septic death occurred in the Arpimune group. Graft survival was 100% in both groups. Hyperlipidemia was the most frequent side effect for both. CONCLUSIONS: The AUC of Arpimune was similar to that of Neoral. Use of the generic cyclosporine Arpimune provided effective immunosuppression in the 6 months after transplantation. Renal allograft function was similar to that of Neoral, with minimal rates of acute rejection and adverse events.

Application of a systems approach to the bottom-up assessment of pharmacokinetics in obese patients: expected variations in clearance.

BACKGROUND AND OBJECTIVES: The maintenance dose of a drug is dependent on drug clearance, and thus any biochemical and physiological changes in obesity that affect parameters such as cardiac output, renal function, expression of drug-metabolizing enzymes and protein binding may result in altered clearance compared with that observed in normal-weight subjects (corrected or uncorrected for body weight). Because of the increasing worldwide incidence of obesity, there is a need for more information regarding the optimal dosing of drug therapy to be made available to prescribers. This is usually provided via clinical studies in obese people; however, such studies are not available for all drugs that might be used in obese subjects. Incorporation of the relevant physiological and biochemical changes into predictive bottom-up pharmacokinetic models in order to optimize dosage regimens may offer a logical way forward for the cases where no clinical data exist. The aims of the current report are to apply such a 'systems approach' to identify the likelihood of observing variations in the clearance of drugs in obesity and morbid obesity for a set of compounds for which clinical data, as well as the necessary in vitro information, are available, and to provide a framework for assessing other drugs in the future. METHODS: The population-specific changes in demographic, physiological and biochemical parameters that are known to be relevant to obese and morbidly obese subjects were collated and incorporated into two separate population libraries. These libraries, together with mechanistic in vitro-in vivo extrapolations (IVIVE) within the Simcyp Population-based Simulator™, were used to predict the clearance of oral alprazolam, oral caffeine, oral chlorzoxazone, oral ciclosporin, intravenous and oral midazolam, intravenous phenytoin, oral theophylline and oral triazolam. The design of the simulated studies was matched as closely as possible with that of the clinical studies. Outcome was measured by the predicted ratio of the clearance of the drug in obese and lean subjects ± its 90% confidence interval, compared with observed values. The overall statistical measures of the performance of the model to detect differences in compound clearance between obese and lean populations were investigated by measuring sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). A power calculation was carried out to investigate the impact of the sample size on the overall outcome of clinical studies. RESULTS: The model was successful in predicting clearance in obese subjects, with the degree to which simulations could mimic the outcome of in vivo studies being greater than 60% for six of the eight drugs. A clear difference in the clearance of chlorzoxazone was correctly picked up via simulation. The overall statistical measures of the performance of the Simcyp Simulator were 100% sensitivity, 66% specificity, 60% PPV and 100% NPV. Studies designed on the basis of the ratio of the absolute values required substantial numbers of participants in order to detect a significant difference, except for phenytoin and chlorzoxazone, where the ratios of the weight-normalized clearances generally showed statistically significant differences with a smaller number of subjects. CONCLUSION: Extension of a mechanistic predictive pharmacokinetic model to accommodate physiological and biochemical changes associated with obesity and morbid obesity allowed prediction of changes in drug clearance on the basis of in vitro data, with reasonable accuracy across a range of compounds that are metabolized by different enzymes. Prediction of the effects of obesity on drug clearance, normalized by various body size scalars, is of potential value in the design of clinical studies during drug development and in the introduction of dosage adjustments that are likely to be needed in clinical practice.

Assessment of bioequivalence of a generic cyclosporine (Equoral) by a prospective randomized controlled trial on allogeneic stem cell transplant recipients.

INTRODUCTION: Bioequivalence of Equoral has been suggested by measurements of pharmacokinetic parameters in healthy volunteers and in stable renal transplant recipients, but not study in allogeneic stem cell transplant (ASCT) recipients. The aim of our study was to compare the pharmacokinetics and safety of Equoral to Neoral solution among ASCT recipients. PATIENTS AND METHODS: Our open-label, two-way crossover, randomized controlled trial compared Equoral versus Neoral solutions in ASCT recipients. The 30 enrolled patients from June 2007 to November 2008 had a 7 to 14-day duration of the test period. A 10-point blood sampling from 0 to 12 hours measured Cmax (extent of absorption), tmax (rate of absorption) and AUC(0-12h) (area under the concentration-time curve) calculated by the linear trapezoid rule. The study protocol was approved by the ethics committee. RESULTS: Median age was 26 years (range = 6-47). The mean pharmacokinetic features were: AUC(0-12h): Equoral 4162 ± 1231 ng·mL/h vs Neoral 4370 ± 1059 ng·mL/h (P = .50); Cmax: Equoral 821 ± 244 ng/mL vs Neoral 834 ± 298 ng/mL (P = .86); and tmax: 105 minutes for both formulations. Comparable toxicities and rates of graft-versus-host disease were recorded in both groups. CONCLUSION: We suggest that Equoral and Neoral solution can be considered interchangeable in ASCT recipients.

Healthcare costs in renal transplant recipients using branded versus generic ciclosporin.

BACKGROUND: Generic ciclosporin A modified (CsA) does not have an equivalent pharmacokinetic profile to branded CsA in some transplant populations, potentially leading to negative clinical consequences and increased long-term costs. OBJECTIVE: To assess direct healthcare costs for de novo renal transplant recipients in the US receiving branded versus generic CsA in the first month after transplantation. METHODS: Administrative claims data from eight private US health plans were linked to the Organ Procurement and Transplantation Network data. A total of 227 renal transplant cases between 1996 and 2004 were included: 183 were dispensed branded CsA and 44 received generic CsA. Log transformed multiple linear regression was used to model total first-year healthcare costs after the initial CsA claim, controlling for both patient demographics and clinical characteristics and clustering at the transplant centre level. RESULTS: After controlling for patient factors and pre-CsA costs, total healthcare costs were significantly higher (p = 0.04) for patients receiving generic CsA versus branded CsA. The main driver for the difference was the cost associated with immunosuppressants other than CsA (p = 0.01). CONCLUSION: Despite initial perceived cost savings associated with generic CsA, de novo renal transplant recipients incurred greater total healthcare costs than those treated with branded CsA. Patients receiving generic CsA may need higher doses or other immunosuppressants to maintain the transplanted kidney than patients receiving branded CsA. Providers and payers need to be aware of potential differences in total healthcare costs between formulations of bioequivalent critical-dose drugs to make the best choice for patient care.

[Fish oil supplementation in rheumatoid arthritis]. / La supplementazione dietetica con olio di pesce nell'artrite reumatoide.

The beneficial properties of fish oil are well known and are related to its fatty acid composition rich in omega-3 polyunsaturated fatty acids. In the last years a variety of epidemiological and clinical studies have demonstrated the efficacy of fish oil supplementation in the rheumatic diseases, in particular in rheumatoid arthritis. The anti-inflammatory effects of fish oil are linked to the production of alternative eicosanoids, to the reduction of proinflammatory cytokines, to the inhibition of the activation of T lymphocytes and of catabolic enzymes. Fish oil supplementation could represent a valuable support to the traditional pharmacological treatment of rheumatoid arthritis.

[Therapeutic monitoring of immunosuppressive drugs: interest of calcineurin activity assessment in liver transplantation]. / Place du suivi biologique des traitements immunosuppresseurs : exemple de la mesure de l'activité calcineurine en transplantation hépatique.

Therapeutic monitoring of calcineurin inhibitors (ciclosporin and tacrolimus) consists in pharmacokinetic monitoring. Pharmacodynamics based on calcineurin activity may be particularly interesting in liver transplantation due to the large intra- and interindividual variability of pharmacokinetics of ciclosporin and tacrolimus. A recent investigation on the pharmacokinetic-pharmacodynamic relationship of tacrolimus showed that monitoring of calcineurin activity in PBMC may be particularly relevant within the first three post-transplantation months. Thereafter, the monitoring of trough blood concentrations of tacrolimus remains adequate. Moreover, two clinical investigations carried out within the early and late post-transplantation periods reported a promising result which is a positive correlation between calcineurin activity and incidence of graft rejection, whatever graft type and calcineurin inhibitors. In each study, transplanted recipients with a graft rejection exhibited a greater trough calcineurin activity compared to patients without graft rejection. However, prospective investigations are required because of the small cohorts of patients enrolled in both studies. The aim of these investigations will be to confirm the interest of calcineurin activity monitoring as a marker of cellular immunity and its positive link with pharmacokinetic monitoring.

A randomized, prospective, pharmacoeconomic trial of neoral 2-hour postdose concentration monitoring versus tacrolimus trough concentration monitoring in de novo liver transplant recipients.

Two-hour postdose cyclosporine (C2) monitoring is becoming an accepted method of therapeutic drug monitoring, although it is not known whether C2 monitoring is superior to tacrolimus (FK)-based immunosuppression. The purpose of this trial was to compare the safety, efficacy, and pharmacoeconomics of cyclosporine A (CsA) monitored by C2 levels versus FK monitored by trough levels in de novo liver transplant recipients. After informed consent, 60 de novo liver transplant recipients were randomized in a 1:1 fashion to receive either FK (trough, 6-10 ng/mL) or CsA (C2, 600-1200 ng/mL) and corticosteroids. The 2 groups were similar for gender, race, indication for liver disease, and age. At 1 year, patient survival was similar (93% for FK versus 90% for C2). One patient in the FK arm was retransplanted because of recurrent hepatitis C virus (HCV). Early acute rejection occurred in 27% of FK-treated patients and 23% of CsA-treated recipients [P = not significant (NS)]. Recurrent HCV occurred in 21% of FK-treated patients and 61% of CsA-treated patient (P = 0.04). The incidence of other infections, new onset diabetes mellitus, requirement for antihypertensives, and requirement for cholesterol medications were similar between the groups. Annual calcineurin inhibitor costs were lower in the C2 arm ($5432 +/- 2091 for C2 versus $8291 +/- 3948 for FK, P = 0.001). Annual pretransplant drug costs ($2292 +/- 2331 for C2 versus $2831 +/- 2358 for FK, P = NS) and 1-year posttransplant drug costs ($17,214 +/- 16,600 for C2 versus $15,151 +/- 11,699 for FK, P = NS) were similar. In conclusion, immunosuppression with CsA, monitored by C2 levels, is safe, effective, and economical in liver transplant recipients and provides immunosuppression at least equivalent to that of FK.

Assessment of cyclosporine pharmacokinetic parameters to facilitate conversion from C0 to C2 monitoring in heart transplant recipients.

BACKGROUND: Cyclosporine (CsA) 2-hour postdose (C2) monitoring is recommended to assess CsA exposure and predict clinical outcomes among heart transplant recipients. We correlated pharmacokinetic parameters and clinical outcomes in stable long-term heart transplant recipients monitored with C0 to develop an algorithm to convert patients from C0 to C2 monitoring. METHODS: Paired CsA C0-C2 measurements and serum creatinine levels were obtained from 35 heart transplant recipients more than 2 years posttransplantation (mean 8.8+/-4.7 years). RESULTS: The mean CsA dose and C0, C2, and C0/C2 ratio were 85+/-23 mg/12 hours, 123+/-41 ng/mL, 572+/-274 ng/mL and 4.8+/-2.1, respectively. C0 correlated weakly with C2 (r=.42, P=.011). The CsA dose correlated better with C2 (r=.58; P<.001) than with C0 (r=.37; P=.026). A good correlation was noted between C2 and the C2/C0 ratio (r=.73; P<.001), but none between C0 and the C2/C0 ratio. A borderline significant inverse correlation was noted between C0 and the worst endomyocardial biopsy score (r=-.34; P=.045), whereas none was noted with C2. Serum creatinine level did not correlate with either C2 or C0. Among patients with C0 within our target of 100 to 150 ug/L, six had C2 above 300 to 600 ug/L as suggested by the literature. CONCLUSIONS: In long-term heart transplant recipients, we could not identify a single pharmacokinetic parameter that could be used to develop an algorithm to convert from C0 to C2 monitoring; however, C2 may be better than C0 for identifying patients at risk of overexposure to CsA.

Validation of limited sampling models (LSM) for estimating AUC in therapeutic drug monitoring--is a separate validation group required?

OBJECTIVE: Limited sampling models (LSM) for estimating AUC in therapeutic drug monitoring are usually validated in a separate group of patients, according to published guidelines. The aim of this study is to evaluate the validation of LSM by comparing independent validation with cross-validation using the patient data from the development group. METHODS: The design of the Monte Carlo simulation study was similar to a study described in the literature, i.e. a development group of 20 patients receiving cyclosporine orally every 12 h. Blood samples were taken at 10 fixed time points. In total 20,000 patient data sets were generated by Monte Carlo simulation, taking into account interindividual variability and measurement errors. Accuracy (mean error, ME) and precision (root mean squared error, RMSE) were calculated for evaluation of the validation procedures, varying the time points of the samples used for the estimation of AUC to identify the optimal sampling time points. In addition, the influence of the number of samples and the number of subjects was investigated. RESULTS: Cross-validation resulted in values for ME and RMSE almost identical to values using a separate validation group with the same number of subjects as the development group. CONCLUSION: A separate validation group is not needed. The most efficient method is to use all patient data for the development of the LSM, and to assess the accuracy and precision by cross-validation.

Assessment of converting from intravenous to oral administration of cyclosporin A in pediatric allogeneic hematopoietic stem cell transplant recipients.

We studied the administration method during a transition period from continuous intravenous (i.v.) infusion to oral administration of cyclosporin A (CsA). Thirty-two pediatric hematopoietic stem cell transplant (HSCT) recipients, between the ages of 8 months and 15.6 years (median 7.1 years) participated in this study. The pharmacokinetic properties of CsA was evaluated during the transition period from i.v. to oral CsA. The daily oral dose of CsA was three times higher than the i.v. dose. Oral dosing began immediately after the continuous infusion was discontinued. Whole-blood CsA concentrations were measured by a monoclonal fluorescence polarization immunoassay (FPIA). The mean+/-s.d. value of bioavailability (F), maximum concentration (C(max)), half-life (t(1/2)) of CsA were 43.1+/-14.4%, 1135.3+/-340.6 ng/ml and 3.1+/-1.2 h, respectively. Mean clearance (CL)+/-s.d. was 480.9+/-103.7, 414.9+/-137.1 and 320+/-51.8 ml/h/kg in patients <20, 20-40 and >40 kg of body weight, respectively. The CsA CL of younger children was significantly greater than for older children (P=0.044). CsA trough levels were maintained within the therapeutic range throughout the transition period. Therefore, our findings suggest that the immediate administration of an oral formulation, after discontinuation of the continuous infusion, would be practical and effective for routine clinical use.

Differentiation of innovator versus generic cyclosporine via a drug interaction on sirolimus.

OBJECTIVE: Both sirolimus and cyclosporine are immunosuppressants used in a combined regimen after organ transplantation. When coadministered with the innovator formulation of cyclosporine, sirolimus blood levels increase 3.3-fold due to a pharmacokinetic interaction. We assessed this drug interaction for potential differences when the innovator formulation is replaced by a generic cyclosporine. METHODS: In this randomized single-dose crossover study, 28 healthy subjects received 5 mg sirolimus oral solution with 250 mg cyclosporine soft gelatin capsules given as the innovator formulation (reference treatment) versus a generic formulation (test treatment). Sirolimus peak blood concentration (Cmax) and area under the concentration-time curve (AUC) were compared between test and reference treatments by standard bioequivalence testing. RESULTS: Sirolimus Cmax was significantly lower by 17% in the presence of generic versus innovator cyclosporine (p=0.0003) and failed bioequivalence criteria with a test/reference ratio of 0.83 (90% confidence interval, 0.77-0.90). Nearly half of the subjects (46%) had sirolimus Cmax changes which fell outside the bioequivalence window with individual Cmax decreases up to 52% and increases up to 39%. Sirolimus AUC was significantly lower by 11% in the presence of generic versus innovator cyclosporine (p=0.041) but satisfied average bioequivalence criteria with a test/reference ratio of 0.89 (0.83-0.95). Nonetheless, over a third of the subjects (43%) had sirolimus AUC changes outside the standard bioequivalence window with individual AUC decreases up to 39% and increases up to 42%. CONCLUSIONS: Switching between innovator and generic cyclosporine may have a clinically-relevant impact on coadministered sirolimus pharmacokinetics. If such a switch is initiated by the prescriber, follow-up therapeutic monitoring of both cyclosporine and sirolimus blood levels should be performed to guide dose adjustments as necessary. If the switch is made without consulting the prescriber, potentially significant changes in sirolimus exposure could go unnoticed by the clinician and patient.

Assessment of the bioequivalence of a generic cyclosporine A by a randomized controlled trial in stable renal recipients.

BACKGROUND: The aim of this study was to determine the bioequivalence of Cysporin, a generic cyclosporine A, compared with Neoral in stable renal transplant recipients. METHODS: Study design consisted of an open label, two-way crossover, randomized controlled trial of Cysporin versus Neoral in stable renal transplant recipients. In all, 33 patients were enrolled; 31 were randomized and 28 were evaluable. AUCs(0-12) were done on day 14 and 28; C(0) and C(2) were done on days 0, 7, 21 and 35. Dose conversion was 1:1. Outcome measures for serum cyclosporin A concentrations expressed as the mean+/-SD were AUC(0-12) (microg x hr/L), C(max) (microg/L), C(2) (microg/L), T(max) (hr) and T(1/2) (hr). Mean and 90% CI of the ratio Cysporin/Neoral of log-transformed data were calculated using a general linear model. RESULTS: The main pharmacokinetic features were: AUC(0-12): Cysporin 3495+/-1319, Neoral 3853+/-1378 (P<0.05); C(max): Cysporin 755+/-301, Neoral 881+/-368 (P<0.05); C(2): Cysporin 613+/-235, Neoral 672+/-255 (P>0.05); T(max): Cysporin 1.9+/-0.8, Neoral 1.4+/-0.6 (P<0.005); and T1/2: Cysporin 8.8+/-4.3, Neoral 8.7+/-6.2 (P>0.05). Estimated ratios of Cysporin/Neoral were: AUC 0.93 (90% CI 0.88-0.98; P<0.05); C(max) 0.88 (90% CI 0.80-0.97; P<0.05); and T(max) 1.32 (90% CI 1.14-1.53; P<0.005). CONCLUSIONS: Both the extent and rate of absorption of Cysporin are significantly less than those of Neoral. The 90% CI for the ratios of Cysporin/Neoral for AUC and C(max) lie within 0.80-1.25. Hence in this clinical context Cysporin is pharmacologically bioequivalent with Neoral. This study illustrates the importance of testing bioequivalence of generic cyclosporine A products in transplant recipients not healthy volunteers.