Cyclosporine pharmacokinetics in liver transplant recipients: evaluation of results using both polyclonal radioimmunoassay and liquid chromatographic analysis

A simple and accurate LC‑MS/MS method for monitoring cyclosporin A that is suitable for high throughput analysis

With time, the number of samples in clinical laboratories from therapeutic drug monitoring has increased. Existing analytical methods for blood cyclosporin A (CSA) monitoring, such as high-performance liquid chromatography (HPLC) and immunoassays, have limitations including cross-reactivity, time consumption, and the complicated procedures involved. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) has long been considered the reference standard owing to its high accuracy, specificity, and sensitivity. However, large numbers of blood samples, multi-step preparation procedures, and longer analytical times (2.5-20 min) are required as a consequence of the different technical strategies, to ensure good analytical performance and routine quality assurance. A stable, reliable, and high throughput detection method will save personnel time and reduce laboratory costs. Therefore, a high throughput and simple LC-MS/MS method was developed and validated for the detection of whole-blood CSA with CSA-d12 as the internal standard in the present study. Whole blood samples were prepared through a modified one-step protein precipitation method. A C18 column (50x2.1 mm, 2.7 µm) with a mobile phase flow rate of 0.5 ml/min was used for chromatographic separation with a total running time of 4.3 min to avoid the matrix effect. To protect the mass spectrometer, only part of the sample after LC separation was allowed to enter the mass spectrum, using two HPLC systems coupled to one mass spectrometry. In this way, throughput was improved with detection of two samples possible within 4.3 min using a shorter analytical time for each sample of 2.15 min. This modified LC-MS/MS method showed excellent analytical performance and demonstrated less matrix effect and a wide linear range. The design of multi-LC systems coupled with one mass spectrometry may play a notable role in the improvement of daily detection throughput, speeding up LC-MS/MS, and allowing it to be an integral part of continuous diagnostics in the near future.

Application of Machine Learning to Sleep Stage Classification

Sleep studies are imperative to recapitulate phenotypes associated with sleep loss and uncover mechanisms contributing to psychopathology. Most often, investigators manually classify the polysomnography into vigilance states, which is time-consuming, requires extensive training, and is prone to inter-scorer variability. While many works have successfully developed automated vigilance state classifiers based on multiple EEG channels, we aim to produce an automated and openaccess classifier that can reliably predict vigilance state based on a single cortical electroencephalogram (EEG) from rodents to minimize the disadvantages that accompany tethering small animals via wires to computer programs. Approximately 427 hours of continuously monitored EEG, electromyogram (EMG), and activity were labeled by a domain expert out of 571 hours of total data. Here we evaluate the performance of various machine learning techniques on classifying 10-second epochs into one of three discrete classes: paradoxical, slow-wave, or wake. Our investigations include Decision Trees, Random Forests, Naive Bayes Classifiers, Logistic Regression Classifiers, and Artificial Neural Networks. These methodologies have achieved accuracies ranging from approximately 74% to approximately 96%. Most notably, the Random Forest and the ANN achieved remarkable accuracies of 95.78% and 93.31%, respectively. Here we have shown the potential of various machine learning classifiers to automatically, accurately, and reliably classify vigilance states based on a single EEG reading and a single EMG reading.

Nephro and neurotoxicity of calcineurin inhibitors and mechanisms of rejections: A review on tacrolimus and cyclosporin in organ transplantation

CONTEXT

In the meadow of medical sciences substituting a diseased organ with a healthy one from another individual, dead or alive, to allow a human to stay alive could be consider as the most string event. In this article we review the history of transplantation, mechanisms of rejection, nephro-neurotoxicity of tacrolimus and cyclosporin in organ transplantations.

EVIDENCE ACQUISITIONS

Directory of Open Access Journals (DOAJ), Google Scholar, Pubmed (NLM), LISTA (EBSCO) and Web of Science have been searched.

RESULTS

The first reference to the concept of organ transplantation and replacement for therapeutic purposes appears to be to Hua-To (136 to 208 A.D), who replaced diseased organs with healthy ones in patients under analgesia induced with a mixture of Indian hemp. In 1936, the first human renal transplant performed by Voronoy in Russia. The first liver transplant in humans was performed on March 1, 1963 by Starzl in Denver, USA. Medawar was the first to assert that rejection was an immunological response, with the inflammatory reaction due to lymphocyte infiltration. Consequently, rational immunosuppressive therapies could inhibit deleterious T-cell responses in an antigen specific manner.

CONCLUSIONS

Searching related to the history of organ transplantation from mythic to modern times suggests that, to prevent graft rejection, minimize nephro and neuro toxicity monitoring of immunosupressive concentrations could provide an invaluable and essential aid in adjusting dosage to ensure adequate immunosuppression.

Learning and new discovery with cyclosporine in the cambridge-king's programme: a personal view

Immunosuppressive regimens in the early precyclosporine days of liver transplantation for the Cambridge-King's Programme from 1968 until the early 1980s were inadequate in the control of rejection. The consequent use of high-dose steroids led to many infections, which seriously affected outcome. Nevertheless, occasional patients did well but a consistent increase in survival was not seen until after the introduction of cyclosporine and experience was gained with its proper usage in terms of toxicity. The development of Neoral with its greater oral bioavailability marked a major step forward in the development of the drug. Whether 2-hour postdose monitoring with reduction in rejection frequency and toxicity as described recently better match results with tacrolimus in comparison-controlled trials remains to be determined.

Evaluation of a No-Pretreatment Cyclosporin A Assay on the Dade Behring Dimension RxL Clinical Chemistry Analyzer

Background: Monitoring whole-blood concentrations of cyclosporin A (CsA) is common practice in the management of solid organ and bone marrow transplant recipients. In a multicenter study we evaluated a new, direct (no pretreatment) CsA assay on the Dade Behring Dimension RxLTM system and compared results with those from the Abbott TDx CsA immunoassay and a HPLC method.

Methods: Whole-blood samples from heart (n = 111; 35 patients), liver (n = 201; 44 patients), kidney (n = 279; 65 patients), and miscellaneous organ (n = 77; 12 lung, 12 bone marrow, 5 kidney/pancreas, and 1 pancreas patient) recipients were obtained from patient populations of the participating institutions. Routine clinical monitoring of CsA was performed using either the TDx method or HPLC.

Results: The minimum detectable concentration of CsA averaged 9.4 μg/L, and the lower limit of quantification was 30 μg/L. The method was linear from 30 to 500 μg/L. Cross-reactivity with seven different CsA metabolites ranged from 0.0% to 5.7% for the Dimension RxL assay compared with 0.4–15.9% for the TDx assay. Total imprecision (CV) averaged 6.2%, and within-run imprecision averaged 4.9%. Passing–Bablok linear regression analyses of all samples from two sites yielded the following: RxL = 0.81 × TDx − 16.8; and RxL = 1.12 × HPLC − 1.7.

Conclusions: The Dade Behring CsA assay for the random-access Dimension platform offers adequate performance characteristics for routine clinical use, does not require a manual pretreatment step, and demonstrates less cross-reactivity with CsA metabolites than another commonly used immunoassay.

A population pharmacokinetic model of cyclosporine in the early postoperative phase in patients with liver transplants, and its predictive performance with Bayesian fitting

The availability of personal computer programs to individualize drug regimens has stimulated interest in modeling population pharmacokinetics. This study used the NPEM2 software to determine cyclosporine population pharmacokinetic parameter values and distributions in a first group of 25 recipients of liver transplants during their first postoperative week. On a second group of 25 patients, the authors used these values to evaluate Bayesian predictive performance of cyclosporine blood concentrations with the USC*PACK PC program. During the study period, all the patients have been treated by continuous intravenous infusion. The one-compartment model pharmacokinetic parameter-the slope of volume to body weight (Vs) and the elimination rate constant (Kel) values found (mean values: Vs = 2.177 l/kg, Kel = 0.235 h(-1); median values: Vs = 1.559 l/kg, Kel = 0.163 h(-1); the percent coefficient of variation (Vs = 92%, Kel = 79%) appear reasonable and show the ability of NPEM2 to deal with sparse data. When the predictions were studied with day 1, day 2, or day 3 concentrations, predictive bias was respectively -0.030, -0.013, and 0.013 microg/ml, suggesting a greater clearance of cyclosporine immediately after surgery, the clearance decreasing in the days after. With the first three blood levels and the Bayesian fitting procedure, it was possible to predict at least half the subsequent measured blood levels of each patient accurately (within 20%) in more than three-quarters (76%) of the second group of recipients of transplants, and for 40% of patients the authors obtained accurate predictions in 100% of the subsequent blood levels. For a few patients (12%) they found quite poor predictions. The reason for this is unclear. The results suggest that this population model and the Bayesian fitting procedure using two or three blood levels can be reasonably and carefully used to control, in real time, cyclosporine blood levels in a majority of new patients with liver transplants.

Effect of the transition from intravenous to oral dosing on cyclosporin-A trough concentrations in liver transplant patients

Cyclosporin A (CsA) absorption is low and variable after liver transplantation, and during the intravenous-oral transition period CsA concentrations may not be maintained within the therapeutic range. Trough whole blood CsA concentrations were measured by high-performance liquid chromatography before and after the transition period in 27 liver transplant patients. Mean (SD) CsA concentrations decreased from 291 (92) to 198 (96) ng/ml (p < 0.001). When analyzed on individual charts, a decrease was observed in 15 of 27 patients and it was associated with a duration of 2 days or less (p < 0.01) and a total bilirubin value below 3.5 mg/dl (p < 0.05). Our results show that, despite therapeutic drug monitoring, CsA blood concentrations may decrease during the intravenous-oral transition period.

Importance of cytochrome P-450IIIA activity in determining dosage and blood levels of FK 506 and cyclosporine in liver transplant recipients

We have investigated the importance of cytochrome P-450IIIA enzyme activity in influencing dosage of the immunosuppressive drugs FK 506 and cyclosporine after liver transplantation. Cytochrome P-450IIIA enzyme activity in vivo was measured 1 yr postoperatively in 37 stable orthotopic liver graft recipients (21 receiving FK 506 and 16 given cyclosporine) by the erythromycin breath test and the production of monoethylglycinexylidide from lignocaine. A strong correlation existed between FK 506 dose and erythromycin breath test results (r = 0.583, p < 0.007), but no corresponding relationship with monoethylglycinexylidide production was observed. The FK 506 dose (14 to 196 micrograms/kg/day) also correlated closely with circulating predose levels of the drug in both plasma and blood (r = 0.538 and 0.731, p = 0.015 and < 0.001, respectively). Although no correlation existed between cyclosporine dose (0.254 to 0.494 mg/kg/day) and trough blood levels, a relationship was demonstrated when erythromycin breath test results were included in the derived equation: Drug dose/cytochrome P-450IIIA activity alpha drug level (p = 0.011 vs. 0.175 without erythromycin breath test). A corresponding enhancement was demonstrated with erythromycin breath test results to relate FK 506 dose and plasma levels (p = 0.006 versus 0.015 without erythromycin breath test results), although breath test results and FK 506 levels were highly discordant (p > 0.8). The use of monoethylglycinexylidide test results as an alternative measure of cytochrome P-450IIIA activity provided no comparable increase in correlation for FK 506 or cyclosporine.(ABSTRACT TRUNCATED AT 250 WORDS)

Variable effect of ursodeoxycholic acid on cyclosporin absorption after orthotopic liver transplantation

The acute effects of administering a single dose of ursodeoxycholic acid (UDCA) on cyclosporin pharmacokinetics were recorded during paired studies in twelve liver transplant recipients, six of whom were cholestatic. Cyclosporin was measured using monoclonal selective antibodies (for parent drug) and non-selective antibodies (for cyclosporin plus metabolites). UDCA resulted in more rapid absorption of cyclosporin in 8 of 12 cases (67%) but had no effect in two patients with and two patients without cholestasis. Median tmax did not change significantly after UDCA (3.0 vs 4.0 h without UDCA) and only 7 of 12 patients (58%) showed a rise in the amount of cyclosporin absorbed over 24 h with the AUC not having changed significantly (median 4527 vs 4979 micrograms.h.l-1 without UDCA). Median Cmax and C24 also increased only marginally following UDCA administration (616 vs 587 micrograms.l-1 and 87 vs 58 micrograms.l-1 without UDCA, respectively). In the cholestatic patients, median AUC was 50% smaller (3223 vs 6439 micrograms.h.l-1) and median t1/2 a was 100% longer (1.58 vs 0.8 h) than in patients without cholestasis. There was no consistent improvement in cyclosporin pharmacokinetics in the cholestatic patients following UDCA, although the significantly elevated ratio of non-selective:selective AUC measurements (median 4.8 vs 2.7) fell markedly in the two most severely affected, possibly as a result of an increased clearance of cyclosporin metabolites by choleresis.

A review of assay methods for cyclosporin. Clinical implications

Cyclosporin is a unique immunosuppressive agent with a narrow therapeutic range. The pharmacokinetics of the drug present substantial within- and between-patient variability and drug interactions can significantly alter blood cyclosporin concentrations. Monitoring of cyclosporin concentrations in blood is an invaluable and essential aid in adjusting dosage to ensure adequate immunosuppression while minimising toxicity. The principal rationale behind therapeutic monitoring of cyclosporin is the fact that the incidence of rejection is higher at low cyclosporin concentrations and toxicity occurs more often at high concentrations. In renal transplant recipients, cyclosporin concentrations help to discriminate between insufficient immunosuppression and cyclosporin-induced nephrotoxicity. There are several methods available, both specific and nonspecific, for the routine measurement of cyclosporin. Radioimmunoassay and fluorescence polarisation immunoassay are most widely employed, while high performance liquid chromatography remains the reference procedure. The allegedly specific immunoassays tend to slightly overestimate the actual blood cyclosporin concentrations. There is a need for assay systems capable of measuring the biological activity of cyclosporin. Cyclosporin concentrations should be determined by a specific method, using whole blood as the sample matrix. The routine monitoring of individual cyclosporin metabolites is not warranted, but characterising the metabolite pattern of cyclosporin by concomitant use of a nonspecific and a specific assay can be clinically useful in patients with cyclosporin-associated toxicity or impaired liver function. In organ transplantation, measurement of blood cyclosporin concentration should be continued periodically as long as the therapy continues, whereas monitoring is only indicated in special circumstances in patients with autoimmune and other nontransplant diseases. The assessment of a 'therapeutic window' for cyclosporin is complicated for several reasons and definite target ranges cannot be given. Cyclosporin concentrations should always be interpreted in conjunction with the recent blood concentration history and other relevant clinical and laboratory data.

Cyclosporin metabolism by human gastrointestinal mucosal microsomes

The in vitro metabolism of the immunosuppressant cyclosporin (CsA) by human gastrointestinal mucosal microsomes has been studied. Macroscopically normal intestinal (n = 4) and liver (n = 2) tissue was obtained from kidney transplant donors, and microsomes prepared. Intestinal metabolism was most extensive with duodenal protein (15% conversion to metabolites M1/M17 after 2 h incubation at 37 degrees C; metabolite measurement by h.p.l.c). Western blotting confirmed the presence of P-4503A (enzyme subfamily responsible for CsA metabolism) in duodenum and ileum tissue, but not in colon tissue. The results of this study indicate that the gut wall may play a role in the first-pass metabolism of CsA, and could therefore be a contributory factor to the highly variable oral bioavailability of CsA.