Determination of cyclosporine and its metabolites in blood via HPLC-MS and correlation to clinically important parameters.

The narrow therapeutic window of the immunosuppressive drug cyclosporine (CsA), the interindividual variability of its metabolism, and the immunosuppressive activity/toxicity of some metabolites require investigation to correlate the parent substance and its metabolites and observed clinical parameters. Improved knowledge about these correlations may improve postoperative treatment of transplant patients. To observe such correlation therapeutic drug monitoring was performed by high-performance liquid chromatography-mass spectrometry (HPLC-MS) on 202 blood samples of kidney transplant patients. As CsA and its metabolites are preferably bound to lipoproteins in vivo, sample preparation included protein precipitation, solid phase extraction, and separation on a reversed phase column. Mass-spectrometric detection by an electrospray ionization chamber made the detection and quantification of the sodium adducts of CsA and its metabolites AM1, AM1c, DihydroAM1, AM19, and AM4N possible. With the presented HPLC-MS method, rapid information was achieved about the specific metabolization in a patient. Statistical computations related CsA and its metabolite concentrations to clinically important blood parameters. Significant correlation to the blood level of bilirubin and liver enzymes confirmed the presumed hepatotoxic potential of CsA and some metabolites. Furthermore, a strong correlation of AM19 to CRP and IL6 was observerd. These parameters may influence the prognosis for atherosclerosis, inflammation, and chronic allograft nephropathy.

Differential effects of cyclosporine and tacrolimus on mycophenolate pharmacokinetics in patients with impaired kidney function.

In a single-center prospective randomized controlled study, the impact of calcineurin inhibitor (CNI) reduction or withdrawal on the pharmacokinetics of mycophenolic acid (MPA) was studied in a group of renal transplant recipients with impaired renal function. Mycophenolate mofetil (MMF) was added to a baseline regimen of prednisolone and CNI. Afterwards the patients were randomized into "CNI withdrawal" and "CNI continuation" groups. The dosage of CNIs, cyclosporine or tacrolimus, was gradually reduced and withdrawn within 6 weeks from patients in the withdrawal group. The continuation group was maintained on therapy with CNI, MMF, and steroids. These regimens were maintained until the ninth month. In contrast to the withdrawal of tacrolimus, which has no significant effect on MPA pharmacokinetics, cyclosporine withdrawal was associated with a significant increase in the trough levels and areas under the curve of MPA. Serum creatinine and urine albumine levels stabilized on average after CNI withdrawal in this population. The results are consistent with the hypothesis that cyclosporine attenuates the enterohepatic recirculation of MPA. The withdrawal of CNI has a positive effect on renal function in chronic allograft dysfunction.

Switching immunosuppression from cyclosporine to tacrolimus improves long-term kidney function: a 6-year study.

To improve long-term kidney graft function, acute graft rejection, hyperlipidemia, hypertension, and toxic influences must be avoided because they may contribute to chronic allograft nephropathy. Many studies have demonstrated greater efficacy and tolerability of tacrolimus compared with cyclosporine with regard to these conditions. Our study investigated whether 30 patients with deteriorating renal function benefitted from conversion to tacrolimus based upon a retrospective analysis using data recorded from 3 years before to 3 years after conversion. Renal function (GFR) deteriorated progressively under cyclosporine (creatinine: baseline 1.5 mg/dL; delta(Cyc) = +1.4 mg/dL within 3 years; GFR: delta(Cyc) = -35 mL/min within 3 years). After switching to tacrolimus, kidney function stabilized and even improved (creatinine: baseline after switching 2.9 mg/dL; delta(Tac) = -0.7 mg/dL; GFR: delta(Tac) = 14 mL/min). Conversion from cyclosporine to tacrolimus is recommended for patients with a kidney transplant in which there has been a progressive decrease in renal function. It may lead to stabilization of or even improvement in transplant function.

Cyclosporine and tacrolimus: influence on cardiovascular risk factors.

After allogenic transplantations, a dramatic increase in the development of arteriosclerotic plaques can be observed, which might be due to metabolic alterations, changes in the transplant organ, or the immunosuppression regimen. Many studies have demonstrated beneficial effects of tacrolimus compared with cyclosporine with regard to these conditions. These results have suggested that conversion to tacrolimus from cyclosporine is advantageous. Our study investigated whether patients with deteriorating renal function profit from this conversion. Thirty renal transplant patients were studied retrospectively, using data recorded from 3 years before to 3 years after conversion from cyclosporine to tacrolimus. While renal function (GFR) deteriorated progressively under cyclosporine, it stabilized and even improved under tacrolimus (creatinine: DeltaCyc = +1.4 mg/d; DeltaTac = -0.7 mg/dL; GFR: DeltaCyc = -35 mL/min; DeltaTac = 14 mL/min). In addition, uric acid levels (7.0 mg/dL vs 6.4 mg/dL, P < .05) and cholesterol levels (258 mg/dL vs 225 mg/dL, P < .05) were both significantly lower under tacrolimus. Conversion from cyclosporine to tacrolimus is recommended for kidney transplant patients in whom there has been a progressive fall in renal function. It leads to stabilization or even improvement of transplant function and a reduction in cardiovascular risk factors.

Receptor assay based on surface plasmon resonance for the assessment of the complex formation activity of cyclosporin A and its metabolites.

OBJECTIVE: A new automated receptor assay has been used to determine the complex formation activity of cyclosporin A (CsA) and its metabolites in whole blood. METHODS: CsA in vivo forms a complex with cyclophilin A and calcineurin leading to an inhibition of the calmodulin-dependent phosphatase activity of calcineurin. The equilibrium complex formation gives information about the potential immunosuppressive activity of CsA and its metabolites. To measure the amount of this complex the authors developed an automated receptor assay based on an optical biosensor (Biacore) with surface plasmon resonance (SPR) technology. RESULTS: In the range of 50-300 nM CsA, the intra-day coefficient of variation (CV) was 7.2%, and the inter-day CV was 10.1%. Measuring range of the assay was 10-500 nM with a detection limit of 5 nM and a processing time of 10 min. Recovery rate for sample pretreatment was 74 +/- 5%. 193 blood specimens from heart transplant recipients were analyzed with 3 different methods. The results determined with the receptor assay were correlated with those obtained by fluorescence polarization immunoassay (FPIA; r = 0.599) and high-performance liquid chromatography (HPLC; r = 0.615). CONCLUSION: The receptor assay determines the complex formation activity of CsA and its metabolites with high sensitivity and precision.

Adsorption of sufentanil to epidural filters and catheters.

BACKGROUND AND OBJECTIVE: Stable drug concentrations must be administered to provide adequate patient-controlled epidural analgesia. This study investigated the stability of sufentanil after the epidural delivery system had been flushed with solutions containing the drug. METHODS: Sufentanil citrate, 5 microg mL(-1) was injected through an epidural catheter system into a glass container. The concentrations of the drug leaving the system, in 1 mL aliquots (1-5 mL) were measured using high-performance liquid chromatography. In the same manner, sufentanil samples were analysed after flushing the filter, as well as after priming the filter and catheter. RESULTS: ANOVA for repeated measurements demonstrated that sufentanil concentrations remained constant as long as the catheter had been adequately flushed. However, the concentration of sufentanil in the solution exiting the filter was reduced significantly. Hardly any sufentanil could be detected (0.09 +/- 0.01 microg mL(-1), P < 0.001) in the first 1 mL aliquot (probe) leaving the filter. Altogether, 3 mL sufentanil solution was needed to pass through the filter before the baseline values were restored (P > 0.05). The greatest decrease occurred when the whole epidural delivery apparatus (catheter and filter) was primed; to regain baseline values, as much as 4 mL solution was needed to flush the system. CONCLUSIONS: Sufentanil citrate is adsorbed by the materials used to manufacture systems (catheters, filters) used in epidural anaesthesia. Hence, the epidural catheter system should be primed with sufentanil before connecting it to the patient so as to deliver reliable concentrations.

Effect of parathyroid hormone levels on carotid intima-media thickness after renal transplantation.

BACKGROUND: The present study aimed to investigate the intact parathyroid hormone (iPTH)-dependent evolution of common carotid intima-media thickness (CC IMT) in renal transplant recipients (RTR) within a 12-month follow-up, ie, before (E0) and 3 months (E3), 6 months (E6), and 12 months after renal transplantation (RTX). METHODS: A total of 55 normotensive patients, aged 47 +/- 1.7 years, underwent a RTX. The graft function was stable (clearanceCockroft >60 mL/min and S-creatinine <2.5 mg/dL) in all patients throughout the follow-up. RESULTS: In 67% of the RTR, the iPTH levels were classified as high at E0 (E6: 63%; E6: 49%; E12: 67%). The plasma iPTH levels decreased after RTX (P < .01). The arterial blood pressure remained stable. The CC IMT was positively and independently correlated with age (P < .01), gender (P < .01), and iPTH levels (P < .01). CONCLUSIONS: Normalization of iPTH levels is associated with a significant intima-media thickness (IMT) reduction. The increased IMT in renal transplant recipients may contribute to the high cardiovascular morbidity and mortality in patients with end-stage renal failure.

Influence of age on the prognosis of renal transplant recipients.

With aging, morphologic organ changes due to arteriosclerosis, hypertension, or diabetes increase, and renal transplantation tends to become less successful. We analyzed the outcome of transplantation in 123 recipients who underwent renal transplantation between January 1988 and December 1989. We assessed patient and graft survival after 1, 5, and 6 years as well as mortality and transplant failure and the incidence of rejections. We compared the results of patients aged under 60 years (group 1, n = 60) with the findings of patients aged over 60 years (group 2, n = 63). Immunosuppression was with cyclosporin A and prednisolone without exception. In patients under the age of 60, the overall patient survival at 1, 5, and 6 years was 97, 95, and 90% and was significantly compromised in recipients over the age of 60 (92, 80, and 75%). The 1-, 5- and 6-year graft survival rates were 92, 90, and 90% in recipients aged over 60 years and 88, 82, and 79% in recipients under the age of 60 years. The incidence of rejection was significantly higher in recipients under the age of 60. Patient mortality was mainly due to cardiovascular complications and transplant failure mainly related to transplant thrombosis. In older patients, renal transplantation is thought to be an option of survival rate improvement in comparison with hemodialysis. The incidence of transplant rejection is significantly lower, and this indicates a promising result regarding the long-term prognosis. As cardiovascular complications present as the main mortality factors of both transplant and patient, the prognosis is considered to be highly dependent on screening and treatment of these risk factors.

Long-term outcome after percutaneous transluminal coronary angioplasty in patients with chronic renal failure with and without diabetic nephropathy.

OBJECTIVE: Percutaneous transluminal coronary angioplasty (PTCA) in patients on maintenance hemodialysis leads to high rates of restenosis and postinterventional complications. The additional influence of diabetes mellitus on the results of PTCA in patients with diabetic nephropathy and reduced but sufficient renal function has not been investigated before. METHODS: In a retrospective case-control study, 51 patients with reduced renal function were compared to 71 matched controls. Patients with elevated creatinine values were divided in two subgroups: diabetic nephropathy (diabetes, n = 15) and stable renal insufficiency (renal failure, n = 36). RESULTS: The control group had normal renal function (creatinine: 1.0 +/- 0.01) and a mean survival time of 3.6 +/- 0.8 years. Patients with renal failure showed a mean survival time of 2.7 +/- 0.3 years (p < 0.001), creatinine values of 2.0 +/- 0.2 and elevated fibrinogen values of 401 +/- 28 (p < 0.01). Patients with diabetes (creatinine: 2.2 +/- 0.2) had a significantly higher mortality rate with a reduced mean survival time of 1.25 +/- 0.3 years (p < 0.001), postinterventional acute renal failure (n = 2, p < 0.01) and Re-PTCA (n = 2, p < 0.05). DISCUSSION: Patients with reduced but stable renal function showed a higher mortality than comparable patients from the control group. The group of patients with diabetic nephropathy has a poor prognosis after PTCA even though renal function was only moderately reduced.