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Background and Objective: Bodyweight-based dosing of tacrolimus is considered standard care. Currently, at first steady state, a third of pediatric kidney transplant recipients has a tacrolimus pre-dose concentration within the target range. We investigated whether adaptation of the starting dose according to a validated dosing algorithm could increase this proportion., Methods: This was a multi-center, single-arm, prospective trial with a planned interim analysis after 16 patients, in which the tacrolimus starting dose was based on bodyweight, cytochrome P450 3A5 genotype, and donor status (living vs. deceased donor)., Results: At the interim analysis, 31% of children had a tacrolimus pre-dose concentration within the target range. As the original dosing algorithm was poorly predictive of tacrolimus exposure, the clinical trial was terminated prematurely. Next, the original model was improved by including the data of the children included in this trial, thereby doubling the number of children in the model building cohort. Data were best described with a two-compartment model with inter-individual variability, allometric scaling, and inter-occasion variability on clearance. Cytochrome P450 3A5 genotype, hematocrit, and creatinine influenced the tacrolimus clearance. A new starting dose model was developed in which the cytochrome P450 3A5 genotype was incorporated. Both models were successfully internally and externally validated., Conclusions: The weight-normalized starting dose of tacrolimus should be higher in patients with a lower bodyweight and in those who are cytochrome P450 3A5 expressers.

Background: Multiple clinical, demographic, and genetic factors affect the pharmacokinetics of tacrolimus in children, yet in daily practice, a uniform body-weight based starting dose is used. It can take weeks to reach the target tacrolimus pre-dose concentration., Objectives: The objectives of this study were to determine the pharmacokinetics of tacrolimus immediately after kidney transplantation and to find relevant parameters for dose individualization using a population pharmacokinetic analysis., Methods: A total of 722 blood samples were collected from 46 children treated with tacrolimus over the first 6 weeks after renal transplantation. Non-linear mixed-effects modeling (NONMEM ® ) was used to develop a population pharmacokinetic model and perform a covariate analysis. Simulations were performed to determine the optimal starting dose and to develop dosing guidelines., Results: The data were accurately described by a two-compartment model with allometric scaling for bodyweight. Mean tacrolimus apparent clearance was 50.5 L/h, with an inter-patient variability of 25%. Higher bodyweight, lower estimated glomerular filtration rate, and higher hematocrit levels resulted in lower total tacrolimus clearance. Cytochrome P450 3A5 expressers and recipients who received a kidney from a deceased donor had a significantly higher tacrolimus clearance. The model was successfully externally validated. In total, these covariates explained 41% of the variability in clearance. From the significant covariates, the cytochrome P450 3A5 genotype, bodyweight, and donor type were useful to adjust the starting dose to reach the target pre-dose concentration. Dosing guidelines range from 0.27 to 1.33 mg/kg/day., Conclusion: During the first 6 weeks after transplantation, the tacrolimus weight-normalized starting dose should be higher in pediatric kidney transplant recipients with a lower bodyweight, those who express the cytochrome P450 3A5 genotype, and those who receive a kidney from a deceased donor.

Background: The aim of this study was to develop a population pharmacokinetic model of tacrolimus in paediatric patients at least 1 year after renal transplantation and simulate individualised dosage regimens., Patients and Methods: We included 54 children with median age of 11.1 years (range 3.8-18.4 years) with 120 pharmacokinetic profiles performed over 2 to 4 h. The pharmacokinetic analysis was performed using the non-linear mixed-effects modelling software (NONMEM(®)). The impact of covariates including concomitant medications, age, the cytochrome P450 (CYP) CYP3A5*3 gene and the adenosine triphosphate binding cassette protein B1 (ABCB1) 3435 C→T gene polymorphism on tacrolimus pharmacokinetics was analysed. The final model was externally validated on an independent dataset and dosing regimens were simulated., Results: A two-compartment model adequately described tacrolimus pharmacokinetics. Apparent oral clearance (CL/F) was associated with weight (allometric scaling) but not age. Children with lower weight and CYP3A5 expressers required higher weight-normalised tacrolimus doses. CL/F was inversely associated with haematocrit (P < 0.05) and γ-glutamyl transpeptidase (γGT) (P < 0.001) and was increased by 45 % in carriers of the CYP3A5*1 allele (P < 0.001). CL/F was not associated with concomitant medications. Dose simulations show that a daily tacrolimus dose of 0.2 mg/kg generates a pre-dose concentration (C 0) ranging from 5 to 10 µg/L depending on the weight and CYP3A5 polymorphism. The median area under the plasma concentration-time curve (AUC) corresponding with a tacrolimus C 0 of 4-8 µg/L was 97 h·µg/L (interquartile range 80-120)., Conclusions: In patients beyond the first year after transplantation, there is a cumulative effect of CYP3A5*1 polymorphism and weight on the tacrolimus C 0. Children with lower weight and carriers of the CYP3A5*1 allele have higher weight-normalised tacrolimus dose requirements.

Background: The aim of this study was to investigate (a) the extent to which age at first renal replacement therapy, achievement of developmental milestones, satisfaction of psychological needs, and coping were related to subjective well-being and medication adherence among young adult kidney transplant recipients; and (b) the relationship between subjective well-being and immunosuppressive medication adherence., Methods: A cross-sectional, interview study was conducted among renal transplant patients aged 20 to 30 years. In addition to sociodemographic and medical characteristics, concepts measured were: subjective well-being (Positive And Negative Affect Schedule; Satisfaction With Life Scale), medication adherence (Basel Assessment of Adherence to Immunosuppressive Medication Scale), dispositional coping (Brief COPE), achievement of developmental milestones (Course of Life Questionnaire), and satisfaction of psychological needs (Basic Psychological Needs Scale)., Results: Sixty-two patients participated (66% men; mean age, 26 years). Sixty-five percent were classified as nonadherent in the past month. In contrast, subjective self-rated overall adherence was high. None of the variables measured were related to nonadherence. Higher feelings of competence and autonomy, and timely achievement of social and psychosexual developmental milestones were related to higher subjective well-being. Well-being and adherence did not differ according to age at diagnosis or first renal replacement therapy., Conclusions: Two thirds of participants were classified as nonadherent which conflicts with participants' own high rating of medication adherence. This emphasizes the need for continued adherence support among young adult transplant recipients; however, no targets for interventions were found in this study. Potential targets for interventions aimed at improving well-being include competence and autonomy.

Introduction: Starting doses of tacrolimus and ciclosporin are typically chosen on a calculated mg/kg bodyweight basis. After initiation of treatment, doses are adjusted with therapeutic drug monitoring (TDM). This trial-and-error approach has been accepted by most physicians and pharmacists involved in the care of transplanted patients., Areas Covered: Dosing algorithms have only fairly recently been proposed to better individualize the starting dose. This review provides an overview of all the currently available dosing algorithms in adult and children for the starting dose of ciclosporin, tacrolimus and mycophenolic acid. In these algorithms, multiple other covariates influencing the starting dose, such as age, hematocrit, comedication and genotype are taken into account. After selecting the starting dose with an algorithm and after initiation of treatment, TDM will, however, remain necessary. Whether or not implementation of such algorithms will improve clinical outcome remains to be demonstrated., Expert Opinion: First of all an algorithm needs to be validated, against an independent dataset. Second, in a prospective study the algorithm should prove to reduce the time to reach the target concentration, and to reduce the number of patients with drug concentrations (far) outside the therapeutic window. Finally, a clinical trial demonstrating a benefit on clinical outcome will be crucial in achieving broad acceptance of calculating starting dose using individualized dosing algorithms.

Introduction: Since 1995, several immunosuppressive drugs have entered the field of organ transplantation: tacrolimus, mycophenolate and the mTOR-inhibitors. Now treating physicians have a choice., Areas Covered: The authors review the important studies on immunosuppressive drugs used at present after kidney transplantation, published in the last three decades. This review also discusses the available evidence for selecting one of the calcineurin inhibitors, antiproliferative agents and induction therapy. Interesting new drugs are discussed briefly., Expert Opinion: Calcineurin inhibitors (CNIs) are considered, especially in de novo transplantation, to be the most effective maintenance drugs to prevent acute rejection. Combining CNI with mycophenolate or an mTOR-inhibitor has made it possible to reduce CNI dose and diminish nephrotoxicity. Uniform treatment regimes according to guidelines are useful but should leave room for adjustment to the needs of individual patients. Longer follow-up studies are needed to decide on the optimal maintenance treatment.

This study aimed to determine disease activity patterns in juvenile systemic lupus erythematosus (jSLE) and its relation to early treatment. All jSLE patients who visited the outpatient departments of three Dutch university hospitals for at least 6 months were included. Data were retrospectively collected from each patient visit and hospitalization. Patient characteristics, clinical and laboratory findings categorized in organ systems, flare rate, medication use and disease course were analysed. Included were 35 patients (female 77%; White 47%) with a total follow-up of 142 years. Median age at diagnosis was 12.8 years. Flare rate was 0.45/ patient-year. An organ system not earlier involved was affected in 34% of flares. Identifiable disease activity patterns were: chronic active (49%), relapse remitting (14%) and long quiescence (37%), with no significant difference in organ involvement at diagnosis. Positive anti-Sm and non-White ethnicity were significantly associated with a chronic active pattern. In 14 patients with severe symptoms at diagnosis, treatment with intravenous cyclophosphamide and/or biologics and/or intravenous methylprednisone in the first 6 months resulted in a long quiescence pattern in seven patients. In conclusion, distinct disease activity patterns are identifiable in children. Suppression of disease with early aggressive treatment may decrease the rate of progression.

Background: Delayed graft function and acute rejections adversely affect the long-term survival of kidney transplantation. To decrease the incidences of these phenomena, we changed the initial immunosuppressive protocol in pediatric kidney transplantation in The Netherlands., Methods: We compared a cohort (n=123) treated with basiliximab and delayed onset cyclosporine (CsA) with the preceding cohort (n=110) in which CsA was started already preoperatively. Both cohorts were treated with mycophenolate mofetil and corticosteroids as well. All consecutive transplantations were included., Results: The incidence of delayed graft function did not significantly differ between the cohorts (10% and 13%, in basiliximab and control group). Significantly fewer patients in the basiliximab group had acute rejection episodes (20% vs. 36% in control group, P=0.007). The mean estimated glomerular filtration rate at 1 year and graft survival at 2 years posttransplant did not differ between groups (62 vs. 64 mL/min 1.73 m2, and 89% vs. 92%, respectively)., Conclusion: Postponed onset of CsA in triple immunosuppressive therapy (corticosteroids, CsA, and mycophenolate mofetil) with addition of basiliximab did not reduce the incidence of delayed graft function in pediatric kidney transplantation. Yet, fewer acute rejections were noted. Long-term favorable effects could not be detected in this study.

Background: Aiming at reducing cyclosporine toxicity, we investigated safety and efficacy of mycophenolate mofetil (MMF) as an immunosuppressive drug in pediatric kidney transplantation compared with cyclosporine (CsA), both in combination with corticosteroids., Methods: One year after kidney transplantation, children on triple immunosuppression, having experienced no more than one, steroid-sensitive, acute rejection episode, were randomized to withdrawal of either CsA or MMF and were followed for 2 yr., Results: In each group, two patients had an acute rejection episode during withdrawal. Treatment failure occurred in 3 of 21 MMF and 5 of 23 CsA patients. Final analysis was for 18 patients in either group. A larger than 10 mL/min 1.73 m decrease in glomerular filtration rate was observed in more patients on CsA than on MMF (73% vs. 29%, P=0.019). No differences in blood pressure or nightly decrease of blood pressure were noted. Hypercholesterolism improved in the MMF (-16%), but not the CsA group (+5%, P<0.05), over the first, but not over both study years. Differences in triglycerid levels between groups were not shown. At study end, MMF patients tended to have lower hemoglobin levels than patients on CsA. Two MMF patients experienced a first acute rejection episode during the second study year, resulting in chronic transplant glomerulopathy with graft loss in one and deterioration of kidney function in the other., Conclusion: In pediatric kidney transplantation, maintenance immunosuppression with MMF together with corticosteroids has short-term benefits for kidney function and lipid pattern compared with CsA but is not without risk of complications.

Collaboration of the Dutch centers for kidney transplantation in children started in 1997 with a shared immunosuppressive protocol, aimed at improving graft survival by diminishing the incidence of acute rejections. This study compares the results of transplantations in these patients to those in a historical reference group. Ninety-six consecutive patients receiving a first kidney transplant were treated with an immunosuppressive regimen consisting of mycophenolate mofetil, cyclosporine and corticosteroids. The results were compared with those of historic controls (first transplants between 1985 and 1995, n = 207), treated with different combinations of corticosteroids, cyclosporine A and/or azathioprine. Cytomegalovirus (CMV) prophylaxis was prescribed to high-risk patients in the study group, and only a small proportion of the reference group. The graft survival at 1 yr improved significantly: 92% in the study group, vs. 73% in the reference group (p < 0.001). In the study group 63% of patients remained rejection-free during the first year; in the reference group 28% (p < 0.001). After statistical adjustment of differences in baseline data, as cold ischemia time, the proportion of LRD, preemptive transplantation, and young donors, the difference between study and reference group in graft survival (RR 0.33, p = 0.003) and incidence of acute rejection (RR 0.37, p < 0.001), as the only factor, remained statistically significant, indicating the effect of the immunosuppressive therapy. In the first year one case of malignancy occurred in each group. CMV disease occurred less frequently in the study group (11%) than in the reference group (26%, p = 0.02). As a new complication in 4 patients bronchiectasis was diagnosed. A new consensus protocol, including the introduction of mycophenolate mofetil, considerably improved the outcome of pediatric kidney transplantation in the Netherlands, measured as reduction of the incidence of acute rejection and improved graft survival.

More effective immunosuppressive treatment in children following organ transplantation has significantly improved the survival of the grafts. Therefore, quality of life, long-term prognosis and adverse drug reactions have become more important. One of the main complications of immunosuppressive drugs is infections of the respiratory tract, but irreversible damage to the airways has not been described after renal or liver transplantation. Five children following transplantation of kidney or liver were referred to the Paediatric Pulmonology department because of chronic respiratory complaints. Pulmonary function tests and HRCT scan were performed as routine patient care. Four children with a renal transplant and one with a liver transplant showed chronic bronchitis and moderate to severe airways obstruction. HRCT showed bronchiectasis in all of them. We speculate that the immunosuppressive treatment (in)directly contributes to irreversible airway damage. We recommend including follow-up of lung function in the post-transplantation protocol and considering bronchiectasis in case of respiratory symptoms, to try preventing further damage to the lung., (Copyright 2004 Blackwell Munksgaard)