Pediatric aspects of therapeutic drug monitoring of mycophenolic acid in renal transplantation
University Children's Hospital Heidelberg, Im Neuenheimer Feld 430, 69120 Heidelberg, Germany. Transplantation reviews (Orlando, Fla.)
(Impact Factor: 3.82).
03/2011; 25(2):78-89. DOI: 10.1016/j.trre.2011.01.001
Mycophenolate mofetil (MMF) is widely used for maintenance immunosuppressive therapy in pediatric renal and heart transplant recipients. Children undergo developmental changes (ontogeny) of drug disposition, which may affect drug metabolism of the active compound mycophenolic acid (MPA). Therefore, a detailed characterization of MPA pharmacokinetics and pharmacodynamics in this patient population is required. In general, the overall efficacy and tolerability of MMF in pediatric patients appear to be comparable with those in adults, except for a higher prevalence of gastrointestinal adverse effects in children younger than 6 years. The currently recommended dose in pediatric patients with concomitant cyclosporine is 1200 mg/m(2) per day in 2 divided doses; the recommended MMF dose with concomitant tacrolimus or without a concurrent calcineurin inhibitor is 900 mg/m(2) per day in 2 divided doses. Recent data suggest that fixed MMF dosing results in MPA underexposure (MPA-area under the concentration-time curve (AUC(0-12)), <30 mg × h/L) early posttransplant in approximately 60% of patients. To achieve adequate MPA exposure in most patients, an initial MMF dose of 1800 mg/m(2) per day with concomitant cyclosporine and 1200 mg/m(2) per day with concomitant tacrolimus for the first 2 to 4 weeks posttransplant has been suggested. As in adults, there is an approximately 10-fold variability in dose-normalized MPA-AUC(0-12) values between pediatric patients after renal transplantation, strengthening the argument for concentration-controlled dosing of the drug. Although the clinical utility of therapeutic drug monitoring of MPA for graft outcome and patient survival is still controversial, potential indications are the avoidance of underimmunosuppression, particularly in patients with high immunologic risk in the initial period posttransplant, in patients who are treated with protocols that explore the possibilities of calcineurin inhibitor minimization, withdrawal or even complete avoidance, and steroid withdrawal or avoidance regimens that might also benefit from intensified therapeutic drug monitoring of MPA. An additional indication especially in adolescent patients is the monitoring of drug adherence. Therapeutic drug monitoring of MPA in pediatric solid organ transplantation using limited sampling strategies is preferable over drug dosing based on trough level monitoring only. Several validated pediatric limited sampling strategies are available. Clearly, more research is required to determine whether pediatric patients will benefit from therapeutic drug monitoring of MPA for long-term maintenance immunosuppression with MMF.
Available from: Stephen D Marks
- "In addition, longer-term follow-up studies are needed to ensure that the improvements are maintained, particularly without an increase in AMR. For patients on MMF, drug monitoring is important to ensure adequately high therapeutic dosages, which may explain the increase in rejection in other studies (76,77). Among patients on the mTOR inhibitors sirolimus and everolimus who exhibit improved renal function, there is a high incidence of side effects, including aphthous ulcers, dyslipidemia, myeloid suppression and proteinuria, necessitating the conversion to alternative medications (78) and counterfoing the benefit of CNI minimization (73,74,79). "
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ABSTRACT: Solid organ transplantation has transformed the lives of many children and adults by providing
treatment for patients with organ failure who would have otherwise succumbed to their disease. The
first successful transplant in 1954 was a kidney transplant between identical twins, which
circumvented the problem of rejection from MHC incompatibility. Further progress in solid organ
transplantation was enabled by the discovery of immunosuppressive agents such as corticosteroids and
azathioprine in the 1950s and ciclosporin in 1970. Today, solid organ transplantation is a
conventional treatment with improved patient and allograft survival rates. However, the challenge
that lies ahead is to extend allograft survival time while simultaneously reducing the side effects
of immunosuppression. This is particularly important for children who have irreversible organ
failure and may require multiple transplants. Pediatric transplant teams also need to improve
patient quality of life at a time of physical, emotional and psychosocial development. This review
will elaborate on the long-term outcomes of children after kidney, liver, heart, lung and intestinal
transplantation. As mortality rates after transplantation have declined, there has emerged an
increased focus on reducing longer-term morbidity with improved outcomes in optimizing
cardiovascular risk, renal impairment, growth and quality of life. Data were obtained from a review
of the literature and particularly from national registries and databases such as the North American
Pediatric Renal Trials and Collaborative Studies for the kidney, SPLIT for liver, International
Society for Heart and Lung Transplantation and UNOS for intestinal transplantation.
Available from: Guido Filler
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ABSTRACT: The management of steroid-dependent nephrotic syndrome, especially in patients who have failed to respond to cytotoxic drugs, such as cyclophosphamide, remains challenging. Rituximab represents a new (off-label) therapeutic option. In a significant portion of patients, it has a short serum half-life following the recovery of CD20-positive cells. The addition of mycophenolate mofetil (MMF) as a maintenance therapy is also an attractive option, but one which requires testing in a prospective randomized clinical trial with therapeutic drug monitoring and mechanistic ancillary studies.
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