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Biomedical subjects

P Glander

Publications and source records attributed to P Glander.

14 recordsLinked to original sources
PubMed2006

[Modern immunosuppression following renal transplantation. Standard or tailor made?].

Renal transplantation is by far the best therapeutic option for end-stage kidney disease with respect to quality of life, psychosocial rehabilitation, and even patient survival. Optimal immunosuppressive therapy should provide effective prophylaxis of both acute rejection and chronic allograft dysfunction. Thus immunosuppressive therapy should help to maintain good renal function and could help to prevent premature death of the recipient. With the introduction of new immunosuppressants over the last decade a dramatic reduction of acute rejection rates from approximately 50% to 15-30% could be achieved. However, the search for novel immunosuppressive drugs continues, drugs which not only lead to effective prevention of acute rejection, but also have an impact on chronic allograft dysfunction and prevent further deterioration of this multifactorial process. Based on a short presentation of the "three signal model" of immunoactivation, the most important mechanisms and characteristics of the presently available immunosuppressants are described. Because the immunosuppressive objectives change over time, a phase-dependent adaptation is necessary. At present, most centers in Germany use an immunosuppressive combination therapy, consisting of a calcineurin inhibitor (CNI; cyclosporine or tacrolimus), a glucocorticoid (prednisolone or methylprednisolone), and mycophenolic acid (MPA), which is eventually combined with an antibody (e.g., IL-2R antibody) for induction. In contrast to the clear situation 10 years ago, highly specialized knowledge is required today with respect to mechanism of action, side effects, and potential interactions. This may enable the physician to adopt patient-oriented optimal immunosuppression. In the near future more individualized treatment options will be employed, which are adapted to the characteristics and side effects of the immunosuppressant, as well as to the characteristics of the donor, the recipient, and the transplanted organ such as immunology and ischemia. Another aspect is the reduction or elimination of some immunosuppressants at the earliest possible time. With new diagnostic and genetic markers the relationship between recipient and transplanted organ will be characterized better in the future and therapy will become more individualized. Altogether, these measures as well as optimized supportive therapy will help to further improve the longevity of the transplanted organ.

Chemotherapy, Adjuvant↗
PubMed2006

Effect of mycophenolate mofetil monotherapy on T-cell functions and inosine monophosphate dehydrogenase activity in patients undergoing a kidney transplantation.

The aim of this study was to assess the effects of 1 g of mycophenolate mofetil (MMF) on T-cell function and inosine monophosphate dehydrogenase (IMPDH) activity among patients undergoing kidney transplantation. Five patients undergoing renal transplantation from a living donor were enrolled in this study. Compared to baseline (before MMF intake), CD25 and CD71 expression were significantly decreased during the first hour following MMF intake. T-cell proliferation and IMPDH activity also decreased dramatically. Thereafter, all biomarker levels increased over time. At 4 hours, CD25 and CD71 levels, as well as IMPDH activity, returned to almost baseline values, whereas T-cell proliferation remained below baseline. Intracytoplasmic IL-2 expression remained unchanged after MMF ingestions. In conclusion, administration of 1 g of MMF was associated with a transient decrease in CD25 expression in addition to a temporary dramatic decrease in both T-cell proliferation and IMPDH activity.

Antigens, CD↗
PubMed2005

Pharmacokinetics of the immunosuppressant everolimus in maintenance renal transplant patients.

The novel macrocyclic immunosuppressant everolimus has been approved for use in renal and heart transplantation. The objective of this randomized, double-blind, placebo-controlled, dose-escalating Phase 1 study was to evaluate the pharmacokinetic profile of different dosing regimens of everolimus. Fifty-four subjects were randomized for 4-weeks treatment with everolimus (n = 44) or placebo (n = 10). Steady state was reached by day 4 of multiple dosing with evidence for dose-proportionality over the dose range tested. Systemic accumulation was 1.6- to 2.2-fold with multiple dosing. Steady-state predose trough concentrations were well correlated with AUC (r = 0.87, p < 0.001). Within-subject coefficients of variation for the tablet formulation ranged from 10-19% and between-subject coefficients from 34-60% for Cmax and AUC. There was no effect of common demographic parameters (age, sex, weight) on variability in steady-state exposure. These results support the clinical use of everolimus in renal transplantation.

Area Under Curve↗
PubMed2005

Problems of cyclosporine absorption profiling using C2-monitoring.

UNLABELLED: The present study sought to validate the concept of C2 monitoring in 41 de-novo transplant patients treated with microemulsion of cyclosporine, mycophenolatesodium, steroids and basiliximab. RESULTS: After 6 months patient and graft survival was 98%, rejection rate was 19%. In the first week only a few patients achieved the suggested C2 levels (19% > 1500, 50% > 1200 ng/ml) despite an increased cyclosporine (CsA) dose. After 14 days 63% of patients reached C2 > 1500 ng/ml (83% C2 > 1200) despite decreased CsA dose. 35% of patients had intermittent high C0 (> 300) and low C2 (< 800), suggesting poor and/or slow absorption. Most of them suffered from CsA toxicity. There was a significant (p < 0.05) change of absorption as measured by C2/C0 leading to an increase of C2/dose. CONCLUSIONS: C2 monitoring may be useful to better estimate the CsA exposure in individual patients; however our results indicate some limitations of the current concept of C2 monitoring. Despite increase of dosage many patients do not reach the proposed levels. A significant proportion of patients are poor and/or slow absorbers. CsA toxicity may not be detected by C2 monitoring alone. With the use of basiliximab and mycophenolatesodium lower target levels seem to be sufficient.

Antibiotics, Antineoplastic↗
PubMed2004

Enteric-coated mycophenolate sodium: safe conversion from mycophenolate mofetil in maintenance renal transplant recipients.

Mycophenolate mofetil (MMF), in combination with cyclosporine and corticosteroids, improves long-term graft function and survival in renal transplant recipients. However, optimal MMF therapy may be limited by gastrointestinal (GI) intolerance, which may result in the need for MMF dose reduction, interruption, or discontinuation, leading to increased risk of acute rejection. Enteric-coated mycophenolate sodium (EC-MPS) is an advanced formulation delivering mycophenolic acid (MPA), developed with the objective of improving MPA-related upper GI adverse events. A pivotal, 12-month, phase III, randomized, multicenter, double-blind, double-dummy, parallel group study investigated whether stable renal transplant patients can be converted from MMF to EC-MPS therapy without compromising tolerability or efficacy. Stable renal transplant recipients received either MMF, 1000 mg b.i.d. (n=159), or EC-MPS, 720 mg b.i.d. (n=163), for 12 months. The incidence of GI adverse events was comparable between both treatment groups at 3 and 6 months, but there was a trend toward reduced severity of GI side effects in the EC-MPS group. There were fewer serious adverse events with EC-MPS and significantly fewer serious infections (P<.05). This comparable safety profile for EC-MPS and MMF also extended to elderly patients and patients with diabetes at baseline. For the composite efficacy variable of biopsy-proven acute rejection, graft loss, death, or loss to follow-up, EC-MPS had a lower 12-month efficacy failure rate (EC-MPS: 7.5% vs MMF: 12.3%; P=ns). These data demonstrate that stable renal transplant recipients receiving MMF can be converted to EC-MPS with no efficacy or tolerability compromise.

Adult↗
PubMed2003

Effect of mycophenolate mofetil on IMP dehydrogenase after the first dose and after long-term treatment in renal transplant recipients.

OBJECTIVE: Mycophenolate mofetil (MMF) is routinely used as an immunosuppressant in a fixed daily dose regimen although it shows marked fluctuations in pharmacokinetics, and despite the fact that in regard to the active metabolite, mycophenolic acid (MPA), there is a well-known association between the pharmacokinetic parameters and clinical outcome. METHOD: In order to determine the time course and the variability in cellular target of MPA after renal transplantation, we investigated the pharmacodynamic response in 8 patients receiving 1 g MMF for the first time prior to renal transplantation and in 8 stable renal transplant patients maintained on long-term MMF therapy (1 g b.i.d.) for more than 1 year. The pharmacodynamic response was measured using inosine 5'-monophosphate dehydrogenase (IMPDH) activity in peripheral mononuclear cells. MPA plasma concentrations were measured in parallel, IMPDH activity in 89 healthy blood donors was used as a control. RESULTS: We observed a high interindividual variability in IMPDH activity in the 89 untreated healthy volunteers (4.0 - 32.9 nmol/h/mg protein), in 8 patients on dialysis (5.3 - 18.9 nmol/h/mg protein) and in 8 renal transplant patients under long-term MMF treatment (2.3 - 14.4 nmol/h/mg protein). The mean AUC0-12h for mycophenolic acid was 2-fold higher in patients receiving long-term treatment with MMF (62.2 +/- 16.6 mg x h/ml) compared to dialysis patients receiving 1 g MMF for the first time (31.5 +/- 15.6 mg x h/ml). Despite this pharmacokinetic difference there were no statistically significant differences in the cellular pharmacodynamic response. Minimal IMPDH activity (1.62 +/- 1.23 vs. 1.77 +/- 1.49 nmol/h/mg protein) and maximal IMPDH inhibition (87.5 +/- 0.08 vs. 77.4 +/- 18.8%) during the dosing interval were similar. CONCLUSIONS: The considerable interindividual variability in the pharmacokinetics of MMF as well as in the drug target support the use of pharmacodynamic drug monitoring to optimize MMF dosing and to reduce the risk of graft rejection and side effects.

Area Under Curve↗
PubMed2003

Cyclosporin C2hour monitoring after renal transplantation.

Therapeutic drug monitoring of cyclosporin A (CsA) is essential because of its variable pharmacokinetics in individual patients and its narrow therapeutic window. In the past, standard trough level (C0) monitoring has been used, and although this method is currently the routine strategy, it has been shown that a single blood concentration measurement 2 hours after CsA administration (C2hour) is a significantly more accurate predictor of drug exposure and clinical events than trough concentrations. The CsA absorption profiling, in particular the measurement of C2hour, is a much more sensitive approach to assessing the pharmacokinetics and predicting the clinical effect in the individual patient. However, there are limited prospective data available examining the risks and benefits of C2hour monitoring in renal transplant recipients. Most studies focus on the early post-transplant phase, but there is little experience with C2hour monitoring in maintenance patients. Our experience in 127 stable long-term renal allograft recipients suggests that the therapeutic window for C2hour levels in patients during maintenance is lower than previously anticipated. Repeat determinations of both C0 and C2hour levels in 46 patients to determine precision of C2hour monitoring showed a high intrapatient variability. We observed only a slightly better coefficient of variation for C2hour than for C0 in repeat determinations. This suggests that drug monitoring using C2hour levels in transplant patients may provide a more accurate and reliable measure of drug exposure in the individual patient. However, CsA absorption showed only a weak correlation with dose during repeated measurements, suggesting high variability in absorption in these stable patients. We conclude that an adequate C2hour level soon after transplantation is associated with a reduced risk of acute rejection in adult renal transplant recipients. It is important to identify slow and poor absorbers in the initial phase after transplantation in order to avoid inappropriate increases in CsA dose. In maintenance patients, C2hour values between 500 and 600 ng/ml are effective and safe for providing effective rejection prophylaxis. Although mean C2hour levels do not seem to identify patients at risk of rejection, they may help to identify excessive immunosuppression and to improve long-term survival by reducing CsA toxicity.

Absorption↗
PubMed2003

Treating type 2 diabetes in renal insufficiency: the role of pioglitazone.

The advent of new antidiabetic drugs is of special importance for diabetic patients with already impaired renal function since renal insufficiency is a relative or absolute contraindication for several of the established hypoglycemic drugs. Pioglitazone is a novel oral hypoglycemic agent that increases insulin responsiveness in target tissues. Pioglitazone and its active metabolites are excreted mainly via the liver. Drug exposure remains almost constant across a wide range of renal function since there is no accumulation of the drug or its active metabolites during repeated dosing in renal insufficiency. The pharmacokinetic properties of pioglitazone are ideally suited for patients with renal insufficiency. Although there are possible side effects (mainly fluid retention and weight gain and--very rarely--hepatotoxicity). Pioglitazone has a good safety profile in diabetic patients with impaired renal function.

Area Under Curve↗
PubMed2001

Non-radioactive determination of inosine 5'-monophosphate dehydro-genase (IMPDH) in peripheral mononuclear cells.

BACKGROUND: The immunosuppressive activity of mycophenolate mofetil (MMF) is based on the reversible inhibition of inosine 5'-monophosphate dehydrogenase (IMPDH) by mycophenolic acid (MPA). It was the aim of this study to develop a nonradioactive method for specific measurement of IMPDH activity in isolated peripheral mononuclear cells (MNC). METHODS: The procedure is based on the incubation of lysed MNC with inosine 5'-monophosphate (IMP) followed by direct chromatographic determination of produced xanthosine 5'-monophosphate (XMP). IMPDH activity was measured in MNC of MMF-treated patients and nontreated volunteers. RESULTS: The within-run (n = 10) and between-run (n = 20) coefficients of variation (CV) for IMPDH activity were < 8% and < 10%, respectively. IMPDH activity in 60 healthy volunteers (19-63 yr) ranged from 4.72 to 32.92 nmol/h/mg protein (mean = 18.39 +/- 6.24). The IC(50) for in vitro inhibition of IMPDH activity was about 2 to 3 microg/L. Application of a single dose of 1 g MMF in dialysis patients resulted in a significant inhibition (by 47-95%; p < 0.05) of IMPDH activity in lysed MNC. CONCLUSIONS: The proposed assay specifically and reliably measures IMPDH activity in MNC. The procedure is applicable to evaluate pharmacodynamic activity in MMF-treated patients. The observed interindividual variability of IMPDH activity may reflect pharmacodynamic differences in MMF-treated patients.

Adult↗
PubMed2000

Pharmacodynamic monitoring of mycophenolate mofetil.

The immunosuppressive activity of Mycophenolate Mofetil (MMF) is based on the reversible inhibition of inosine-5'-monophosphate dehydrogenase (IMPDH) by mycophenolic acid. Pharmacodynamic monitoring by measurement of IMPDH activity reflects directly the biological response to MMF. For measurement of IMPDH activity in peripheral mononuclear cells we established a modified non-radioactive procedure, based on the incubation of cell lysates with inosine-5'-monophosphate and the chromatographic quantification of produced xanthosine-5'-monophosphate by isocratic ion-pair reversed phase HPLC. The between-run precision and within-run precision were 7% and 5%, respectively. We determined the time course of IMPDH activity in five patients after 1 g MMF and in five healthy subjects without administration of MMF. Additionally, IMPDH activity was determined in a population study of 40 healthy volunteers. In healthy volunteers, we observed a wide range of IMPDH activity (4.7-32.9 nmol/h/mg) with only weak diurnal variation. All patients receiving MMF had a significant reduction of IMPDH activity (65-100%) after administration of the drug. Inhibition persisted for up to 6 hours, and after 11 hours IMPDH activity returned to predose activities. The interindividual variability of IMPDH activity may account for pharmacodynamic differences in MMF-treated patients. Based on pharmacodynamic monitoring better dosing strategies for MMF-treated patients may evolve.

Adult↗