Protopic
Time to reach tacrolimus maximum blood concentration,mean residence time, and acute renal allograft rejection: an open-label, prospective, pharmacokinetic study in adult recipients.

Kuypers DR, Vanrenterghem Y.

Department of Nephrology and Renal Transplantation, University Hospitals Leuven, Herestraat 49, B-3000 Leuven, Belgium. Dirk.Kuypers uz.kuleuven.ac.be

OBJECTIVES: The aims of this study were to determine whether disposition-related pharmacokinetic parameters such as T(max) and mean residence time (MRT) could be used as predictors of clinical efficacy of tacrolimus in renal transplant recipients, and to what extent these parameters would be influenced by clinical variables. METHODS: We previously demonstrated, in a prospective pharmacokinetic study in de novo renal allograft recipients, that patients who experienced early acute rejection did not differ from patients free from rejection in terms of tacrolimus pharmacokinetic exposure parameters (dose interval AUC, preadministration trough blood concentration, C(max), dose). However, recipients with acute rejection reached mean (SD) tacrolimus T(max) significantly faster than those who were free from rejection (0.96 [0.56] hour vs 1.77 [1.06] hours; P < 0.001). Taking into account that neither differences in tacrolimus steady-state clearance nor T(1/2) could explain this unusual finding, we used data from the previous study to calculate MRT from the concentration-time curves. RESULTS: As part of the previous study, 100 patients (59 male, 41 female; mean [SD] age, 51.4 [13.8] years;age range, 20-75 years) were enrolled in the study The calculated MRT was significantly shorter in recipients with acute allograft rejection (11.32 [031] hours vs 11.52 [028] hours; P = 0.02), just like T(max) was an independent risk factor for acute rejection in a multivariate logistic regression model (odds ratio, 0.092 [95% CI, 0.014-0.629]; P = 0.01). Analyzing the impact of demographic, transplantation-related, and biochemical variables on MRT, we found that increasing serum albumin and hematocrit concentrations were associated with a prolonged MRT (P < 0.05). Conversely, serum albumin and hematocrit concentrations were significantly lower in recipients with acute rejection (P < (101). CONCLUSIONS: In this selected population of de novo renal allograft recipients, a shorter tacrolimus T(max) and calculated MRT were associated with a higher incidence of early acute graft rejection. These findings suggest that a shorter transit time of tacrolimus in certain tissue compartments, rather than failure to obtain a maximum absolute tacrolimus blood concentration, might lead to inadequate immunosuppression early after transplantation.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15639695&dopt=Abstract tacrolimus Protopic



Protopic
Mycophenolate mofetil pharmacokinetics in transplant patients receiving cyclosporine or tacrolimus in combination therapy.

Vidal E, Cantarell C, Capdevila L, Monforte V, Roman A, Pou L.

Biochemistry Service, University Hospital Vall d'Hebron, Barcelona, Spain. leonor hg.vhebron.es

Mycophenolate mofetil is a highly effective immunosuppressant drug used in the prophylaxis of organ rejection in combination with cyclosporine or tacrolimus and corticosteroids. The present study is a retrospective data analysis of the routinely estimated mycophenolic acid plasma trough levels in 60 transplant patients (kidney, n = 49; lung, n = 11) receiving mycophenolate mofetil in combination with prednisone and cyclosporine (n = 45) or tacrolimus (n = 15). Coadministration of cyclosporine instead of tacrolimus resulted in a significant increase of median (range) of the ratio of dose-to-concentration 0.92 (0.11-8.33) (n=167) versus 0.38 (0.11-14.28) (n = 66); P < 0.0001. No correlation was seen between mycophenolate mofetil dose and mycophenolic acid trough concentrations. The dose-to-concentration in cyclosporine-treated patients increased significantly (P<0.0001) as the cyclosporine level increased, suggesting a possible interaction between mycophenolate mofetil and cyclosporine. No correlation was seen between dose-to-concentration and tacrolimus blood levels (P x 0.215). Further studies are necessary to investigate this issue.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11097273&dopt=Abstract tacrolimus Protopic



Protopic
Clinical outcome after conversion to FK 506 (tacrolimus) therapy for acute graft-versus-host disease resistant to cyclosporine or for cyclosporine-associated toxicities.

Furlong T, Storb R, Anasetti C, Appelbaum FR, Deeg HJ, Doney K, Martin P, Sullivan K, Witherspoon R, Nash RA.

Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109-1024, USA.

This retrospective study describes the outcome in 53 patients who had immunosuppressive treatment changed from cyclosporine (CSP) to tacrolimus for resistant acute GVHD (n = 23), hemolytic uremic syndrome (HUS) (n = 13) or CSP-associated neurotoxicity (n = 17). Tacrolimus was administered at doses of 0.03 mg/kg/day intravenously or 0.12 mg/kg/day orally in divided doses, as tolerated. Median time of conversion to tacrolimus after transplant was day 47. Nineteen patients had treatment changed to tacrolimus for resistant acute GVHD grades III or IV, with the median day of conversion being day 49 after transplant. Two of 20 evaluable patients had a complete resolution of GVHD after changing treatment to tacrolimus, with 18 showing no improvement. Eleven evaluable patients had therapy changed to tacrolimus for CSP-associated neurotoxicity at a median of 36 days after transplant. Eight patients had resolution of neurotoxicity and three had partial improvement. Eleven evaluable patients had therapy changed to tacrolimus for HUS at a median of 46 days after transplant. One patient had complete resolution of HUS and 10 showed no response. Side-effects related to tacrolimus included renal toxicity (34%), neurotoxicity (15%) and HUS (9%). Nine (17%) patients remain alive, including six patients who had therapy changed to tacrolimus for CSP-associated neurotoxicity. While often successful for dealing with neurotoxicity, only a rare patient improved after therapy was changed from CSP to tacrolimus for HUS or resistant acute GVHD.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11100278&dopt=Abstract tacrolimus Protopic



Protopic
Analysis of 100 pregnancy outcomes in women treated systemically with tacrolimus.

Kainz A, Harabacz I, Cowlrick IS, Gadgil S, Hagiwara D.

Fujisawa, Munich, Germany. alexander.kainz fujisawa.de

The aim of this paper is to provide a summary of clinical findings regarding the safety of tacrolimus in pregnancy. From 1992 to 1998 data were collected on 100 pregnancies from 84 mothers who received tacrolimus systemically; 83 cases of solid organ transplantation, and 1 case of Behcet's disease. Maternal mean age at conception was 28 years and pregnancy outcome was live birth in 68%, spontaneous abortion in 12%, induced abortion in 12%, stillbirth/perinatal death in 3%, ongoing pregnancy in 2%, and lost to follow up in 3%. Fifty-nine percent of the neonates were delivered prematurely (< 37 weeks of gestation). Birth weight was appropriate for the gestational age in 90% of the cases. Malformations occurred in 4 neonates: case 1, meningocele and urogenital defects; case 2, alcoholic embryopathy; case 3, ear defect, cleft palate and hypospadia; case 4, multicystic dysplastic kidney. There was no consistent pattern of malformations and 2 mothers subsequently delivered a healthy neonate while on tacrolimus therapy. Nearly 70% of pregnancies following systemic tacrolimus administration resulted in a favourable outcome without any significant effect on intrauterine growth. The incidence of malformations was similar to that reported with other immunosuppressants in transplant recipients.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11112018&dopt=Abstract tacrolimus Protopic



Protopic
Evaluation of microparticle enzyme immunoassay against HPLC-mass spectrometry for the determination of whole-blood tacrolimus in heart- and lung-transplant recipients.

Salm P, Rutherford DM, Taylor PJ, Black MJ, Pillans PI.

The University of Queensland Department of Medicine, Princess Alexandra Hospital, Brisbane, QLD, Australia. psalm medicine.pa.uq.edu.au

OBJECTIVES: Tacrolimus is an immunosuppressant drug with a narrow therapeutic window and thus requires therapeutic drug monitoring. This study evaluates the suitability of the second-generation microparticle enzyme immunoassay (MEIA II) against a specific method, high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS), for the measurement of tacrolimus in both heart- and lung-transplant groups. A secondary objective was to investigate the effect of tacrolimus concentration on MEIA II measurement. METHODS: The HPLC-MS assay was conducted as per our reported method and MEIA II performed according to manufacturer's instructions. Quality-control samples at 5, 11, and 22 microg/L were run in each batch to ensure assay integrity in both methods. Multiple trough samples from 18 heart patients (n = 126) and 17 lung patients (n = 203) were analyzed. RESULTS: The inter-batch imprecision and analytical recovery over the quality-control range by HPLC-MS (n = 12) was <6% and 98.2% to 104%, respectively, and by MEIA II (n = 16) <15% and 92.0% to 99.1%, respectively. The mean overestimation by MEIA II between the two methods for heart- and lung-transplant patient samples was found to be 9.9% (range: -37.4-45.4%) and 13.2% (range: -29.2-64.3%), respectively. Stratification of these data based on the tacrolimus concentration determined by MEIA II, yielded no statistically significant differences in bias between concentration subgroups within the clinically relevant range (p > 0.4). However, a statistically significant difference was detected between the highest concentration subgroup (>20.0 microg/L) and lower concentration subgroups in both transplant populations (p < 0.05). CONCLUSIONS: This study suggests that where HPLC-MS is not available, MEIA II may be suitable for the therapeutic drug monitoring of tacrolimus in heart- and lung-transplant recipients. However, the clinical importance of the observed mean bias, considering the wide range in overestimation in heart- and lung-transplant patient samples, is yet to be determined.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11124341&dopt=Abstract tacrolimus Protopic



Protopic
Tacrolimus in acute renal failure: does L-arginine-infusion prevent changes in renal hemodynamics?

Lopau K, Kleinert D, Erler J, Schramm L, Heidbreder E, Wanner C.

Department of Medicine, Division of Nephrology, University Hospital Wuerzburg, Josef-Schneider-Strasse 2, 97080 Wuerzburg, Germany. k.lopau medizin.uni-wuerzburg.de

Nephrotoxicity is one of the main side effects of calcineurin-inhibitors. The influence of tacrolimus on the renal vasculature has not been well described. We have therefore examined the effects of tacrolimus on renal functional parameters as well as the contribution of the NO-system in a model of ischemic acute renal failure (ARF). Induction of ARF was achieved by clamping both renal arteries of female Sprague-Dawley rats. During the experiment, RBF, GFR, MAP, RVR and FENa were determined during infusion of vehicle, TAC, TAC and the NOS-activator L-arginine, and TAC and NOS-inhibition due to L-NMMA. TAC induced a significant rise in RVR with further decrease of RBF and GFR. Simultaneous L-arginine-infusion could reverse these effects during the infusion without complete restoration to preischemic levels. NOS-inhibition increased MAP and RBF without any effect on GFR. FENa did not differ significantly between the groups. Tacrolimus in the situation of ischemic acute renal failure causes vasoconstriction of pre- and postglomerular vessels with a further deterioration of renal function. L-arginine abolishes the functional deterioration, most likely due to increased NO-liberation.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11140242&dopt=Abstract tacrolimus Protopic



Protopic
Conversion from tacrolimus to neoral for postrenal transplant diabetes.

Butani L, Makker SP.

Section of Pediatric Nephrology, Department of Pediatrics, UC Davis Medical Center, Ticon II Building, 3rd Floor, 2516 Stockton Boulevard, Sacramento, CA 95817, USA.

Diabetes mellitus (DM) is a well-recognized complication of immunosuppressive therapy in the post-transplant (Tx) period. The DM encountered in the setting of tacrolimus therapy has been managed in the past by tacrolimus dose reduction and a rapid corticosteroid taper; frequently insulin therapy is also required to maintain normoglycemia. However, the dose reduction of immunosuppressive agents has often resulted in acute allograft rejection. We are reporting our experience in managing three pediatric renal Tx recipients who developed DM in the post-Tx period while on triple immunosuppressive therapy including tacrolimus and corticosteroids. All of our patients were managed by substitution of tacrolimus with conventional doses of neoral while maintaining their usual corticosteroid dose. All three patients had resolution of hyperglycemia and none experienced acute rejection. Tacrolimus was then successfully reinitiated 4.6 months later; at last follow-up, all of our patients have good allograft function and have maintained a normal blood sugar. In conclusion, we feel that conversion of patients from tacrolimus to neoral should be attempted as a safer alternative to tacrolimus dose reduction, for managing post-Tx DM in tacrolimus treated patients.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11149106&dopt=Abstract tacrolimus Protopic