Cyclosporine nephrotoxicity is minimized by adjusting dosage on the basis of drug concentration in blood

Lessons to Learn From Low-Dose Cyclosporin-A: A New Approach for Unexpected Clinical Applications

Cyclosporin-A has been known and used for a long time, since its "fast track" approval in the early 80's. This molecule has rapidly demonstrated unexpected immunosuppressive properties, transforming the history of organ transplantation. Cyclosporin's key effect relies on modulation on T-lymphocyte activity, which explains its role in the prevention of graft rejection. However, whether cyclosporin-A exerts other effects on immune system remains to be determined. Until recently, cyclosporin-A was mainly used at a high-dose, but given the drug toxicity and despite the fear of losing its immunosuppressive effects, there is nowadays a tendency to decrease its dose. The literature has been reporting data revealing a paradoxical effect of low dosage of cyclosporin-A. These low-doses appear to have immunomodulatory properties, with different effects from high-doses on CD8+ T lymphocyte activation, auto-immune diseases, graft-vs.-host disease and cancer. The aim of this review is to discuss the role of cyclosporin-A, not only as a consecrated immunosuppressive agent, but also as an immunomodulatory drug when administrated at low-dose. The use of low-dose cyclosporin-A may become a new therapeutic strategy, particularly to treat cancer.

Simultaneous Determination of Tacrolimus and Cyclosporine A in Whole Blood by Ultrafast LC-MS/MS

Numerous methods for the measurement of tacrolimus and cyclosporine A involving traditional liquid chromatography tandem mass spectrometry (LC-MS/MS) have previously been described. The majority of these methods use solid-phase extraction, liquid-liquid extraction, or protein precipitation extraction with instrument run times greater than 15 s per sample. Continued demands in clinical labs for greater efficiency and throughput have put increased stress on traditional technologies such as high-performance liquid chromatography-ultraviolet detection (HPLC-UV) and traditional LC-MS/MS. As an improvement to the existing methods, we describe a sensitive ultrafast LC-MS/MS with run times of less than 15 s per sample.

Immune responses in the aquatic gastropod Lymnaea stagnalis under short-term exposure to pharmaceuticals of concern for immune systems: Diclofenac, cyclophosphamide and cyclosporine A

This is a pioneering study in the ecotoxicological assessment of immunotoxic effects of the three selected drugs of concern to a freshwater gastropod species. Lymnaea stagnalis was exposed in the laboratory for 3 days to three drugs used for immune systems: diclofenac (nonsteroidal anti-inflammatory drug), cyclophosphamide (anti-cancer immunosuppressive drug) or cyclosporine A (anti-xenograft immunosuppressive drug). Exposure ranges included environmental realistic (1-10μgL^-1) and therapeutic concentrations (100-1000μgL^-1). At the end of exposure times, the immune parameters of individual snails were measured: hemocyte density and viability, hemocyte phagocytosis capacity and hemocyte-related oxidative activities (basal and NADPH-oxidase stimulated with zymosan particles). Diclofenac and cyclosporine A induced immune responses, although the effects were not strong. No immunosuppression was observed. Such subtle immunomodulations bring further interrogations regarding their long-term immunotoxicity and possible resulting tradeoffs with life-history traits. On the other hand, the prodrug cyclophosphamide did not induce significant immune responses. Since metabolism pathways differ greatly between vertebrates and invertebrates, this study also suggests that relevant vertebrate metabolites should be included in the immunotoxicity assessment of pharmaceuticals in non-target invertebrate species. Finally, the possible interactive effects of these pharmaceuticals sharing similar modes of action or effects features should also be explored.

Cyclosporin trough levels: is monitoring necessary during short-term treatment in psoriasis? A systematic review and clinical data on trough levels

BACKGROUND

Cyclosporin is an effective treatment for severe plaque psoriasis. Unfortunately, its use may be limited by time- and dose-related nephrotoxicity. Serum trough levels may be useful for monitoring the risk of nephrotoxicity.

OBJECTIVES

To determine whether monitoring of trough levels is necessary in psoriasis patients undergoing short-term treatment with cyclosporin.

METHODS

A computerized and manual literature search identified studies on adults with plaque-type psoriasis treated with cyclosporin < or = 5 mg kg-1 daily, in which trough levels were measured in whole blood. Number of patients, treatment duration, formulation and dosage, renal function tests and trough levels were extracted. The association between renal function and trough levels was investigated. Additionally, in a randomized controlled trial on cyclosporin vs. methotrexate in moderate to severe psoriasis, cyclosporin trough levels were measured frequently in 20 patients during 12 weeks of treatment. The Pearson correlation coefficient between serum creatinine and cyclosporin trough levels was calculated.

RESULTS

Fifty-six articles were found concerning cyclosporin trough level measurements in psoriasis patients, of which eight were analysed. Many studies were excluded due to inappropriate cyclosporin dosages used. As data were heterogeneous and lacked various key parameters, a correlation study and a meta-analysis could not be performed. Instead, a quantitative description of the literature was given. No high mean trough levels or elevations of serum creatinine were described. In our clinical study, all the mean trough levels in 17 patients treated with cyclosporin 3 mg kg-1 daily were within the therapeutic range (< 200 ng mL-1). Elevated trough levels were found in two of three patients treated with cyclosporin 3-5 mg kg-1 daily. No signs of renal dysfunction were seen.

CONCLUSIONS

The literature does not provide a definitive answer on whether monitoring cyclosporin trough levels in patients with psoriasis should be standard practice. Our own data show no need for cyclosporin trough level monitoring during short-term treatment with cyclosporin 3 mg kg-1 daily. However, when cyclosporin doses are > 3 mg kg-1 daily, monitoring may be indicated.

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 randomized, prospective multicenter pharmacoepidemiologic study of cyclosporine microemulsion in stable renal graft recipients. Report of the Canadian Neoral Renal Transplantation Study Group

BACKGROUND

The safety, tolerability, and pharmacokinetics of conventional cyclosporine (ConCsA) and cyclosporine microemulsion (MeCsA) were compared under conditions of normal clinical practice in a prospective, randomized, concentration-controlled, pharmacoepidemiologic study.

METHODS

Between September 1994 and March 1995, 1097 stable renal transplant recipients in 14 Canadian centers were randomized 2:1 to treatment with MeCsA or ConCsA. Patients were commenced on each study drug at a dose equal to their previous therapy with ConCsA, and the dose was adjusted to maintain predose whole blood cyclosporine concentrations within the therapeutic range established for each center. Prednisone and azathioprine were continued unless dose adjustment was required for clinical reasons.

RESULTS

The mean cyclosporine concentration was comparable in both treatment groups at all time points throughout the 6 months of follow-up. The mean dose of cyclosporine was 3.6 mg/kg/day in both treatment groups at entry to the study, and declined by 0.3% and by 2.8% in patients receiving ConCsA and MeCsA, respectively. The nature and severity of adverse events were similar in both treatment groups, but there was a transient increase in neurological and gastrointestinal complications in the group receiving MeCsA within the first month after conversion (P<0.05). Serum creatinine and creatinine clearance did not change in either treatment group throughout the study. Biopsy-proven acute rejection occurred in three patients (0.8%) receiving ConCsA and in seven patients (0.9%) receiving MeCsA, with non-histologically proven acute rejection in an additional three patients (0.8%) receiving ConCsA and five patients (0.6%) receiving MeCsA (P=NS). Serum creatinine rose transiently in 35 patients (9.8%) receiving ConCsA and 138 patients (18.7%) receiving MeCsA (P<0.05) and resolved either spontaneously or after a reduction in the cyclosporine dose. One graft was lost in the MeCsA group due to irreversible rejection, and seven patients died, three in the group receiving ConCsA and four of those receiving MeCsA (P=NS). Absorption of cyclosporine was more rapid and complete from MeCsA than from ConCsA during the first 4 hr of the dosing interval, resulting in almost 40% greater exposure to the drug (P<0.001). There was close correlation between area under the time-concentration curve (AUC) over the first 4 hr of the 12-hr dosage interval and AUC over the entire 12-hr dosage interval for both formulations, making AUC over the first 4 hr a good predictor of total cyclosporine exposure. Using this parameter, patients with low absorption randomized to receive MeCsA showed a marked increase in drug exposure by months 3 and 6, whereas there was no change in those who continued on ConCsA. A limited sampling strategy utilizing samples at the predose and postdose trough levels provided an excellent correlation with drug exposure, particularly for patients receiving MeCsA (r2=0.94 MeCsA vs. r2=0.89 ConCsA).

CONCLUSIONS

MeCsA appears to be a safe and effective therapy in stable renal transplant patients and provides superior and more consistent absorption of cyclosporine when compared with ConCsA. Transient toxicity after conversion to MeCsA occurs in some patients, and may reflect the increased exposure to cyclosporine. Use of a limited sampling approach combining trough and 2-hr postdose concentrations may provide an effective way to monitor this exposure.

The use of therapeutic drug monitoring to optimise immunosuppressive therapy

Most experience of the therapeutic drug monitoring of immunosuppressive agents has been acquired in the field of solid organ transplantation; however, agents such as cyclosporin (cyclosporin A) are being increasingly utilised for the management of autoimmune diseases. Cyclosporin is the most widely studied immunosuppressant, but in spite of this many controversies still exist as to the optimum strategy for monitoring this drug. Owing to its widely variable pharmacokinetics and metabolism, and the absence of a simple method to measure therapeutic effectiveness, many factors should be considered. In most circumstances, measuring whole blood through concentrations of cyclosporin with a specific assay methodology is warranted. In addition, knowledge of other factors that may alter the pharmacokinetics (such as liver function, concomitant food or medications, gastrointestinal status, and time since transplantation) should be taken into account so that therapy can be appropriately adjusted. Other methods of monitoring have been investigated, such as AUC (area under the concentration-time curve) monitoring and immunological monitoring. However, further refinement of these techniques and greater experience with their efficacy must be accumulated before their role in the monitoring of cyclosporin can be defined. Tacrolimus, like cyclosporin, shares many of the difficulties in monitoring for efficacy and toxicity due largely to the variable pharmacokinetics; similarly to cyclosporin, whole blood through concentration monitoring should be utilised in combination with knowledge of the factors that may affect the pharmacokinetics. Muromonab CD3 (OKT3) is a monoclonal antibody used for the treatment and prophylaxis of acute allograft rejection. Several immunological monitoring techniques have been investigated for this agent. Monitoring CD3+ levels can assist clinicians in determining therapeutic efficacy, while measuring antimuromonab CD3 antibody titres can help determine if xenosensitisation has occurred, causing therapeutic ineffectiveness. The clinical monitoring of azathioprine, one of the first immunosuppressive agents used in transplantation, has historically been limited to monitoring complete blood counts for bone marrow suppression. However, newer techniques measuring intracellular DNA nucleotides appear to be promising. The new immunosuppressants on the horizon include mycophenolate mofetil and rapamycin. The clinical experience with therapeutic drug monitoring of these 2 compounds is scant in the literature; however, both agents have demonstrated efficacy in preventing or treating allograft rejection while maintaining a relatively well tolerated toxicity profile in recent clinical trials. Routine monitoring does not appear to be warranted for immunosuppressive therapy in autoimmune diseases.

Optimizing the use of cyclosporine in renal transplantation

OBJECTIVE

To review the existing data on the use of cyclosporine (CsA) in kidney transplantation, particularly with respect to therapeutic drug monitoring.

DATA SOURCES

A literature search was conducted of applicable articles related to therapeutic drug monitoring of cyclosporine in renal transplantation. Previous consensus guidelines were examined. Discussions on issues related to this topic convened in Toronto, ON, on June 15-16, 1994.

DATA SYNTHESIS

The literature was analyzed to examine patient factors and drug interactions affecting CsA concentrations, the effect of CsA concentrations on patient outcome, current methods of analysis, pharmacodynamic monitoring, and new immunosuppressants.

CONCLUSIONS

CsA has improved the success of kidney transplantation, reducing the incidence and severity of acute rejection and improving short-term patient and graft survival. The rate of graft loss after the first year (primarily due to chronic rejection) has remained largely unchanged. Sandimmune Neoral offers promise due to its better bioavailability and limited dependence on bile flow for absorption. Long-term studies are underway to determine its effectiveness and safety. Indications for therapeutic drug monitoring for CsA are provided.

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)

Cyclosporin clinical pharmacokinetics

Cyclosporin is a powerful immunosuppressive drug used in transplantation medicine and to treat autoimmune diseases. It is a lipophilic molecule, with its bioavailability dependent on food, bile and other interacting factors. Cyclosporin is extensively metabolised in the liver by the cytochrome P450 3A system, which is subject to considerable interindividual variation. Distribution of cyclosporin depends not only on physicochemical characteristics, but also on biological carriers such as lipoproteins and erythrocytes in blood. Cyclophilin, a binding protein for cyclosporin, influences distribution of cyclosporin in the body. Despite its lipophilicity, cyclosporin does not appear in the brain. The distribution of metabolites in the body can differ from that of cyclosporin itself. Elimination of the drug is mainly via the bile as metabolites, other routes not being very important. Pharmacokinetic parameters of cyclosporin are highly variable and depend on factors such as age, the physical condition of the patient, type of organ transplant or comedication. Renal side effects of cyclosporin are dose-related, but the influence of the dosage regimen has not been thoroughly investigated. An important factor in the reported variability is the different analytical methods used. Following the recommendations of recent consensus documents to monitor blood concentrations, this source of variability may diminish in the future. Several metabolites are reported as having less immunosuppressive activity than the parent drug. Metabolites with renal side effects have been reported. These and other effects of metabolites have not been clearly defined in the literature, presumably because of the highly variable activity of cyclosporin-metabolising liver enzymes and the paucity of data available on metabolite pharmacokinetics. The therapeutic range and dosage of cyclosporin are therefore highly dependent on many individual parameters in patients. Dosages of less than 5 mg/kg/day, however, rarely cause renal side effects. Further studies to correlate the clinical pharmacokinetics of metabolites with their activity and adverse effects are needed.

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.

Therapeutic monitoring of cyclosporin--an update

The success of organ transplantation is closely related to clinical use of the immunosuppressive drug cyclosporin (CsA). The dosage of CsA is complicated by the large intra- and interindividual variability in its pharmacokinetics, as well as by the narrow concentration range between insufficient immunosuppression and toxicity. Potential sources of error in the sampling procedure and the advantages and disadvantages of the available analytical methods are discussed. Traditionally, 12 or 24 hour trough concentrations of CsA are monitored. Recently, peak concentrations or estimation of AUCs by a limited sampling strategy have been tried to improve the relatively weak concentration-effect and concentration-toxicity relationships found with trough CsA concentration monitoring. Studies of the CsA concentration-effect relationships for various treatment indications are reviewed.

Monitoring of the free concentration of cyclosporine in plasma in man

The free fraction of cyclosporine A (CsA) and its total plasma concentration as determined by HPLC(CsAT) were prospectively monitored in 66 recipients of renal transplants. The free CsA levels (CsAu) were calculated. The variability in free CsA levels was no less than for total CsAT levels. The correlation between CsAu and CsAT was high (r = 0.90). Both CsAT and CsAu covaried with serum triglycerides and apolipoprotein A1. Fourty-four of the 66 patients suffered acute rejection episodes on 69 occasions. CsAT and CSAu both decreased and to a similar extent at the occurrence of acute rejection (42% and 59% decrease, respectively; significant vs baseline. Not significant difference in decrease in CsAT vs CsAu). Acute nephrotoxicity occurred on 11 occasions in 10 patients. Both CsAT and CSAu were approximately twice as high at the time of acute nephrotoxicity as compared to one week previously. Both CsAT and CsAu were higher during the first month after transplantation in patients with than in patients without systemic infection. Thus, plasma CsAu gave no additional clinical information or guidance compared to CsAT in renal transplant recipients. Due to the complexity of its assay, which requires two consecutive analyses, there does not appear to be any need for routine monitoring of CsAu in renal transplant recipients.

Laboratory monitoring of cyclosporine levels: guidelines for the dermatologist

The following guidelines are recommended for laboratory monitoring of circulating levels of cyclosporine in dermatology patients. Measurements should be determined as trough levels in whole blood, not plasma or serum. The measurements should be performed with an assay that is specific for the parent cyclosporine compound (e.g., a high-performance liquid chromatography method or a specific monoclonal immunoassay). The results of nonspecific immunoassays that detect cyclosporine as well as its metabolites are difficult to interpret and cannot readily be compared among different studies or laboratories. In psoriasis patients, the circulating concentration of cyclosporine does not correlate reliably with the therapeutic response. Some patients may achieve an excellent response with blood levels in the range of 50 ng/ml; others may show little or no response despite blood levels as high as 200 ng/ml. In patients with a poor clinical response, monitoring of cyclosporine levels may be useful to confirm that the drug has been taken and may provide an estimate of the degree of absorption and metabolism of the parent compound. Because an upper limit of safety for the circulating concentration of cyclosporine has not been clearly defined, one should attempt to achieve a therapeutic response with the lowest possible dose. Clinicians must carefully monitor patients for signs of cyclosporine toxicity, regardless of the circulating concentration of the drug. Whole blood levels exceeding 250 ng/ml should be avoided.

Assay methods for cyclosporine monitoring following liver transplantation

This article reviews therapeutic drug monitoring for cyclosporine in liver transplantation. Brief descriptions of various immunoassay methods include sample matrix selection, assay reagents, and metabolite cross-reactivity information. Multiple comparisons of the various methods are outlined. Examples of the method-dependent relationship between clinical events and changes in cyclosporine concentration are presented. Other potential predictors of liver allograft function are listed.

Nephrotoxic drugs

The nephrotoxic effects of cyclosporine, aminoglycoside antibiotics, cisplatin, amphotericin B, beta-lactam antibiotics and indomethacin are reviewed. These drugs were chosen because they are among the most frequent causes of renal injury in children. In addition, their nephrotoxicity is caused by different mechanisms. Several generalizations can be made, however. First, agents which cause tubular damage tend to be synergistic in their toxic effects. This synergism is seen when several nephrotoxic drugs are given simultaneously. In addition, the use of a nephrotoxic agent in a patient with pre-existing renal disease can result in severe tubular injury. Second, serum levels of the drug frequently fail to correlate with the degree of nephrotoxicity in individual patients. Third, early signs of renal injury can be subtle (e.g., minor changes in electrolyte excretion) or dramatic (e.g., acute renal failure). The subtle changes are particularly important, since they can be useful predictors of serious nephrotoxicity.