The safety and tolerability of cyclosporine emulsion versus cyclosporine in a randomized, double-blind comparison in primary renal allograft recipients. The Neoral Study Group

Therapeutic monitoring of calcineurin inhibitors for the nephrologist

The calcineurin inhibitors (CNI) cyclosporine and tacrolimus remain the backbone of immunosuppression for most kidney transplant recipients. Despite many years of experience, protocols that optimize efficacy with minimal toxicity remain a subject of debate. Nevertheless, studies of the pharmacokinetic properties of the CNI, particularly cyclosporine, have led to improved dosing strategies. The purpose of this article is to review the current understanding of CNI pharmacokinetics and its relevance to proper dosing and monitoring of these medications. This article also reviews the trials that have helped to define the optimal dosages and discusses the effect of adjunctive immunosuppressive agents on CNI pharmacokinetics and dosing.

Three generations of cyclosporine a formulations: an in vitro comparison

When the microemulsion formulation of the critical dose drug cyclosporine A (CsA) (Sandimmun Optoral) was introduced in the mid-1990s, it became clear that this new formulation improves the oral bioavailability of CsA and has a positive influence on its pharmacokinetic variability. Previous studies with the original CsA formulation (Sandimmun) showed that the size of the emulsion droplets and concomitant food intake has an effect on the absorption of CsA from the small intestine when orally administered. It was suggested that these effects might have an influence on the drugs' pharmacokinetic parameters. In this study, we focused on the two above-mentioned aspects and compared the first and second generations of CsA products (Sandimmun, Sandimmun Optoral) to generic CsA formulations by analyzing the contents of cyclosporine A gel capsules with respect to their emulsion droplet and micelle sizes using photon correlation spectroscopy (PCS). We tried to discern any differences in droplet size between different generations of CsA formulations, primarily the second and third generation, through simple physical tests. Because a high fat content food may influence the absorption of CsA, we also determined the distribution of CsA between hydrophilic and lipophilic phases using high-performance liquid chromatography analysis. It became clear that when compared under simple physical conditions, established cyclosporine formulations and new generic products show significant differences in droplet size and distribution between an aqueous phase and a high fat content food. Whether these differences are of clinical relevance remains to be investigated.

Impact of cyclosporine on the development of immunosuppressive therapy

With the advent of cyclosporine (CsA) 20 years ago, graft survival increased considerably to more than 80% at 2 years posttransplant. The early formulation of CsA, Sandimmun, is effective in preventing organ rejection, although its absorption profile means it is subject to a high degree of variability. The development of a microemulsion formulation, Neoral, provided a therapy with superior efficacy in kidney, liver, and heart transplantation with an improved pharmacokinetic profile. Calcineurin inhibitors (CNIs), including CsA, have a narrow therapeutic range, so frequent blood measurements to control drug levels are required. Recent research has demonstrated that the measurement of blood CsA concentration at 2 hours postdosing--C2 monitoring--has the potential to optimize efficacy and reduce the side effects associated with CNI use. In heart and de novo kidney transplantation, C2 monitoring may help to further reduce the incidence of acute rejection, while in maintenance renal transplant recipients, C2 monitoring can help to detect overexposure and thus allows safe dose reduction, which may improve blood pressure and renal function. C2 monitoring thus facilitates a better balance between effective Neoral immunosuppression and unwanted side effects. Today, CsA remains the cornerstone of immunosuppression, and ongoing studies aim to further optimize patient management strategies with Neoral. With other trials evaluating the impact of Neoral in combination with newer therapies such as Certican, myfortic, and FTY720, the use of CsA in transplant recipients looks set to continue.

Impact of cyclosporine in the development of immunosuppressive therapy

Cyclosporine has been of great interest to the transplant community during the last 20 years. It has permitted an evolution of knowledge through the changes in its original galenic formulation of Sandimmune to Neoral, and now through the recent application of the knowledge of pharmacodynamics and pharmacokinetics to tailor drug doses to each individual. The achievements of cyclosporine are still valid and possibly will be for the next years.

Therapeutic monitoring of cyclosporine in kidney transplantation: the Halifax experience

Appropriate dosing of an immunosuppressive agent is critical to its efficacy and tolerability. Finding a simple and effective method of monitoring cyclosporine (CsA/CyA) has been formidable despite a long history of widespread usage. Earlier reports linked CsA dosing to trough levels (C0), whereas later more elaborate systems have evaluated efficacy linked to 12-hour area-under-the-curve (AUC(0-12)) as a measure of total drug exposure. Recent work done at our center and elsewhere has shown that the 2-hour postdose concentration (C2) to be simple and more effective than the C0 or the AUC. With C2 monitoring as a guide to CsA dosing, acute rejection (AR) and nephrotoxicity (NT) can be effectively reduced. Furthermore, absorption profile as per C2 levels further emphasizes the importance of achieving the targeted peak concentration in the first week of transplantation. The C2 concentration strategy is discussed in light of newer induction agents and other immunosuppression.

Cardiovascular risk factors and estimated risk for CAD in a randomized trial comparing calcineurin inhibitors in renal transplantation

Cardiovascular morbidity and mortality is high in patients following renal transplantation. The present analysis assessed major cardiovascular risk factors and estimated the risk of coronary artery disease in the largest present-day comparative trial of tacrolimus vs. microemulsified cyclosporine A. In this 6-month study, 557 patients were randomly allocated to therapy with tacrolimus (n = 286) or cyclosporine A (n = 271) concomitantly with azathioprine and corticosteroids. The primary endpoint was the incidence of and time to acute rejection. Blood pressure, serum cholesterol, HDL cholesterol, triglycerides, and blood glucose were measured at baseline, and at months 1, 3, and 6. Ten-year risk of coronary heart disease was estimated according to the Framingham risk algorithm. Tacrolimus resulted in significantly lower summary measures (time-weighted average) of serum cholesterol (p = 0.0004) and mean arterial blood pressure (p = 0.0156), but in a higher summary measure of blood glucose (p = 0.0028) than cyclosporine. The summary measure of serum triglycerides was not different between treatment groups (p = 0.368). The mean 10-year coronary artery disease risk estimate was significantly lowered in men (p = 0.0032) treated with tacrolimus, but was unchanged in women. Tacrolimus and cyclosporine A microemulsion exert a compound-specific impact on cardiovascular risk factors and appear to affect the predicted rate of cardiovascular morbidity in different manners.

Adequate early cyclosporin exposure is critical to prevent renal allograft rejection: patients monitored by absorption profiling

This study used receiver operating characteristic analysis to investigate the properties of area under the concentration-time curve during the first 4h after cyclosporin-microemulsion dosing (AUC0-4) and cyclosporin (CyA) levels immediately before and at 2 and 3h after dosing (C0, C2 and C3) to predict the risk of biopsy-proven acute rejection (AR) at 6 months. Ninety-eight kidney transplant recipients treated with CyA-microemulsion-based triple therapy immunosuppression were studied on post-transplant days 3, 5, and 7, and at increasing intervals thereafter. The most sensitive and specific predictor of AR was AUC0-4. Of the single time-point measurements, the measurement properties of C2 were closest to those of AUC0-4, and superior to those of C3. The relationship between C0 and subsequent AR was weak and did not reach statistical significance. On day 3, CyA AUC0-4 > or = 4,400 ng.h/mL and C2 > or = 1,700 ng/mL were each associated with a 92% negative predictive value for rejection in the first 6months. Pharmacokinetic measurements on or after day 5, and measurements on day 3 in patients with delayed graft function, were not predictive of AR. Adequate exposure within the first 3days post transplantation may be critically important in preventing subsequent rejection.

Cyclosporin: an updated review of the pharmacokinetic properties, clinical efficacy and tolerability of a microemulsion-based formulation (neoral)1 in organ transplantation

Cyclosporin is a lipophilic cyclic polypeptide immunosuppressant that interferes with the activity of T cells chiefly via calcineurin inhibition. The original oil-based oral formulation of this drug (Sandimmun)l was characterised by high intra- and interpatient pharmacokinetic variability, with poor bioavailability in many patients; a novel microemulsion formulation (Neoral)1 was therefore developed to circumvent these problems. Studies show increases, attributable chiefly to improved absorption in patients who absorb the drug only poorly from the original formulation, in mean systemic exposure to cyclosporin with the microemulsion, with no clinically significant differences in tolerability or drug interaction profiles. Cyclosporin microemulsion is at least as effective as the oil-based formulation in renal, liver and heart transplant recipients, with trends towards decreased incidence of acute rejection with the microemulsion formulation in some (statistically significant in a few) trials. Cyclosporin microemulsion and tacrolimus appear to have similar efficacy in preventing acute rejection episodes in most renal, pancreas-kidney, liver and heart transplant recipients. However, there are indications of superior efficacy for tacrolimus in some trials, particularly in the prevention of severe acute rejection and in Black transplant recipients. Current 12-month data also indicate equivalent efficacy of sirolimus in renal transplantation. Conversion from the oil-based to microemulsion formulation in stable renal, liver and heart transplant recipients is achievable with no change in acute rejection rates. The addition of an anti-interleukin-2 receptor monoclonal antibody and/or mycophenolate mofetil to cyclosporin microemulsion plus corticosteroids decreases rates of acute rejection; corticosteroid withdrawal without increased acute rejection rates was also achieved on the addition of these agents in some trials. Pharmacoeconomic analyses have shown savings in direct healthcare costs in kidney or liver transplantation when cyclosporin microemulsion is used in preference to the oil-based formulation, although studies incorporating indirect costs or expressing costs in terms of therapeutic outcomes are currently unavailable.

CONCLUSIONS

The introduction of cyclosporin microemulsion has consolidated the place of the drug as a mainstay of therapy in all types of solid organ transplantation; research into optimisation of outcomes through more effective therapeutic monitoring in patients receiving this formulation is ongoing. Several novel immunosuppressants have been introduced in recent years: further clinical and pharmacoeconomic research will be needed to clarify the relative positioning of these agents, particularly with respect to specific patient groups. Other new drugs (basiliximab/daclizumab and mycophenolate mofetil) offer particular advantages when used in combination with cyclosporin.

Approaching the therapeutic window for cyclosporine in kidney transplantation: a prospective study

Neoral dosing is traditionally based on cyclosporine (CyA) trough levels (C(0)). Four-h area under the curve (AUC(0-4)) for Neoral in the early posttransplantation period was shown previously to have a better correlation to acute rejection (AR) and CyA nephrotoxicity (CyANT), compared with C(0). An AUC(0-4) range of 4400 to 5500 microg/h per L during the first week was associated with the lowest AR and CyANT. This article describes a prospective study to assess the feasibility, safety, and efficacy of dosing Neoral solely by AUC(0-4) monitoring, regardless of C(0), in the first 3 mo after kidney transplantation. Fifty-nine kidney transplant recipients received Neoral-based triple immunosuppression. AUC(0-4) was measured on days 3, 5, 7, 10, and 14 and weeks 3, 4, 6, and 8, then monthly. Target AUC(0-4) was 4400 to 5500 microg/h per L. Dose was adjusted by percentage difference from target AUC(0-4). Ninety-four percent of AUC were performed on the scheduled day or close to it. No patients had CyANT while AUC(0-4) was in target range. Four patients had reversible CyANT with AUC(0-4) > 5500. Only 1 of 33 patients (3%) who achieved and maintained AUC(0-4) > 4400 by day 3 posttransplantation had AR, whereas 10 of 22 (45%) of those with day 3 to 5 AUC(0-4) < 4400 had AR (P: = 0.0002). In logistic regression analysis, higher early AUC(0-4) was the only significant variable associated with lower serum creatinine at 3 mo. Neoral dose monitoring by AUC(0-4) is a potentially valuable tool for optimizing Neoral immunosuppression. Attainment of a target range of 4400 to 5500 microg/h per L for AUC(0-4) early after transplantation has been demonstrated to reduce significantly the risk of AR and CyANT.

Immunosuppressive agents in transplantation: mechanisms of action and current anti-rejection strategies

Over the past century, the concept of interfering with the immune response at various sites by blocking the formation, stimulation, proliferation, and differentiation of lymphocytes has led to relentless development of new immunosuppressive drugs. These agents are associated with reduced risk of short- and long-term toxicity and have dramatically improved allograft and patient survival, especially in recipients of solid organ transplants. Current protocols in such patients are nearly all calcineurin-inhibitor based, using cyclosporine or tacrolimus, as part of dual, triple, or sequential therapy. This review focuses on agents currently in clinical use at transplant centers in United States. The drugs are described in terms of their basic mechanisms of action, therapeutic uses, clinical studies, and adverse effects. In addition, the efficacy and toxicity of a few promising new therapeutic approaches are examined. Finally, important challenges regarding pharmacological immunosuppression as it relates to solid organ and composite tissue allotransplantation are discussed.

Cyclosporine bioavailability of Neoral and Sandimmune in white and black de novo renal transplant recipients. Neoral Study Group

Black renal transplant recipients have inferior graft outcomes when compared to whites. The relative bioavailability of cyclosporine (CsA) with the Sandimmune (SIM) formulation is lower in black recipients when compared to whites. To study relative CsA bioavailability in the Neoral formulation, 18 black and 78 white de novo renal transplant recipients were randomized in a multicenter, double-blind, parallel group study to receive either SIM or Neoral capsules twice a day for 12 weeks. After an overnight fast, CsA whole blood levels (TDx) were collected during 12 hours after the morning dose and 12 hours after the evening dose with a standardized meal. Pharmacokinetic profiles were obtained at the end of weeks 1, 4, 8, and 12. Initial CsA dose was 5 mg/kg twice a day; subsequent doses were titrated to target trough CsA levels. Area under the blood concentration vs. time curve (AUC), peak blood concentration (Cmax) and time to Cmax(Tmax) were obtained from 16 black and 73 white patients. Food conditions (fed and fasting) were averaged, and data was dose-normalized. For black recipients, Neoral was significantly more bioavailable than SIM only during week 1; there was also a consistent trend to higher cyclosporine bioavailability at weeks 4, 8, and 12. For whites, there were significant differences in favor of Neoral at all time periods. No significant differences in relative bioavailability were noted between races for either SIM or Neoral except for a higher Cmax in white patients given Neoral. Neoral is better absorbed than SIM in both blacks and whites. These data suggest that Neoral is the superior CsA preparation for all racial groups.

Comparison of microemulsion and conventional formulations of cyclosporine A in preventing acute rejection in de novo kidney transplant patients. The U.K. Neoral Renal Study Group

BACKGROUND

The microemulsion preconcentrate formulation of cyclosporine A (CsA) (Neoral) exhibits more uniform pharmacokinetics than the conventional formulation (Sandimmun; SIM). This randomized, open-label, U.K. multicenter study compared the efficacy, safety, and tolerability of Neoral and SIM in preventing acute rejection in de novo renal transplant recipients.

METHODS

Adult cadaveric kidney recipients (n=293) received Neoral or SIM twice daily for 12 months. Initially identical Neoral and SIM doses were titrated, maintaining trough CsA levels within locally defined therapeutic limits.

RESULTS

In the year after transplantation, acute rejection occurred in 34% of the Neoral and 47% of the SIM recipients (P=0.037). In the intent-to-treat population, fewer treatment failures (defined as acute rejection, graft loss, withdrawal, or death) occurred in the Neoral (45%) than the SIM recipients (58%) (P=0.015) and therapeutic CsA levels (> or =250 microg/L) were reached faster with Neoral than SIM (P=0.0017). Antibody treatment of refractory rejection was used slightly less in the Neoral group (Neoral: 10%; SIM: 12%). One-year patient and graft survival rates (excluding deaths with functioning grafts) were 95% and 88%, respectively, for Neoral and 96% and 89% for SIM. Both formulations were well tolerated. No differences were observed between therapies in the nature, frequency, or severity of adverse events. Neoral use was not associated with increased nephrotoxicity or excessive immunosuppression.

CONCLUSIONS

Neoral reduced the incidence of acute rejection compared with SIM, without significant increases in adverse events. This was achieved without altering existing SIM protocols and was attributed to improved absorption of CsA from Neoral and less variability in whole blood CsA concentrations.

Safety, tolerability and efficacy of cyclosporine microemulsion in heart transplant recipients: a randomized, multicenter, double-blind comparison with the oil based formulation of cyclosporine--results at six months after transplantation

BACKGROUND

The introduction of cyclosporine has resulted in significant improvement in the survival of cardiac allograft recipients due to decreased mortality from infection and rejection. The original oil-based cyclosporine formulation exhibits variable and unpredictable bioavailability that correlates with an increased incidence of acute and chronic rejection in those patients in whom this is most pronounced. The primary objectives of this prospective, multicenter, randomized, double-blind study in cardiac transplant patients were: to compare the efficacy of cyclosporine microemulsion (CsA-NL) with oil-based cyclosporine (CsA-SM) as measured by cardiac allograft and recipient survival and the incidence and severity of acute rejection episodes; and to assess the safety and tolerability of CsA-NL compared with CsA-SM in this population. This report represents the analysis of results 6 months after transplantation.

METHODS

A total of 380 patients undergoing their first cardiac transplant at 24 centers in the United States, Canada, and Europe were enrolled in this double-blind, randomized trial examining the safety and efficacy of CsA-NL versus CsA-SM. Rejection was diagnosed using endomyocardial biopsy and were graded according to standardized criteria of the International Society of Heart and Lung Transplantation (ISHLT). Clinical parameters were monitored during the study. Survival and freedom from were used for analysis as was Fisher's exact test for comparisons between groups.

RESULTS

At 6 months after transplantation, allograft and patient survival were the same for both groups. The frequency of ISHLT grade 3A or greater episodes in the two groups was identical. Fewer CsA-NL patients (5.9%) required antilymphocyte antibody (ATG or OKT-3) therapy for rejection compared with the CsA-SM-treated patients (14.1%, P=0.01). Females with ISHLT rejection grade > or = 3A treated with CsA-NL had a 46% lower incidence of rejection compared with the CsA-SM-treated group (31.3% vs. 57.6%, P=0.032). Fewer infections were seen in the CsA-NL. With the exception of baseline and 1 week posttransplant creatinines which were higher in the CsA-NL group, the overall creatinine was not significantly different between the two groups.

CONCLUSIONS

This multicenter, randomized study of cardiac transplant recipients documented less severe rejection (in particular those requiring antibody therapy) and a lower incidence of infection in CsA-NL-treated patients. Results from the female subgroup analysis suggest that the improved bioavailability of CsA-NL might reduce the frequency of rejection episodes in female patients. The use of CsA-NL was not associated with an increased risk of adverse events.

Neoral monitoring by simplified sparse sampling area under the concentration-time curve: its relationship to acute rejection and cyclosporine nephrotoxicity early after kidney transplantation

BACKGROUND

Cyclosporine (CsA) dosing is traditionally based on trough blood levels (C0) rather than area under the concentration-time curve (AUC), although AUC correlates better with posttransplantation clinical events. For Neoral, AUC based on limited sampling correlates closely with full 12-hr AUC. The purpose of our study was to correlate C0 with AUC based on CsA levels at 0, 1, 2, 3, and 4 hr after dose (PK0-4) and to compare this AUC with C0 in predicting acute rejection (AR) and acute cyclosporine nephrotoxicity (CsANT) in de novo first kidney transplant patients.

METHODS

PK0-4 was done 2-4 days after starting Neoral for 156 patients. All received CsA-based triple-drug immunosuppression without antibody induction. AUC was calculated as projected 12-hr (AUC0-12) and actual 4-hr (AUC0-4) from the PK0-4 using the parallel trapezoid rule. Neoral dosing was based on C0 not AUC. AUC was retrospectively compared with C0 as a predictor of AR and CsANT during the first 90 days.

RESULTS

C0 correlated poorly with AUC0-12 and AUC0-4 (r=0.61 and r=0.42). C0 (mean+/-SEM) levels were not significantly different in 34 patients with and 109 without AR (293+/-21 vs. 294+/-11 microg/L, P=0.95). AUC0-12 and AUC0-4 were significantly lower in patients with than without AR (AUC0-12 9090+/-598 vs. 10608+/-336 microg x h/L, P=0.01; AUC0-4 3934+/-306 vs. 4802+/-166 microg.h/L, P=0.006). In stepwise regression analysis only AUC0-12 or AUC0-4 (P=0.03/P=0.02) and delayed graft function (P=0.007) predicted AR. AUC0-12, AUC0-4, and C0 were all significantly higher in patients with CsANT than without CsANT (AUC0-12 11746+/-650 vs. 10023+/-301 microg x h/L, P=0.01; AUC0-4 5270+/-358 vs. 4474+/-150 microg x h/L, P=0.01; C0 343+/-18 vs. 287+/-10 microg/L, P=0.01), but in stepwise regression analysis C0 was not an independent predictor of CsANT. Patients with AUC0-12 in the range of 9500 to 11500 microg x h/L or AUC0-4 between 4400 and 5500 microg x h/L had the lowest incidence of AR (13% and 7%, respectively) without significantly higher risk for CsANT.

CONCLUSION

C0 correlates poorly with AUC based on PK0-4. Early AUC based on PK0-4 is more closely associated with AR and CsANT than is C0. Our data suggest that a target AUC0-12 of 9500-11500 or AUC0-4 of 4400-5500 microg x h/L may provide optimal Neoral immunosuppression.

Cyclosporine and tacrolimus (FK506): a comparison of efficacy and safety profiles

Multicenter clinical trials conducted in the United States and Europe to compare the efficacy and safety of cyclosporine with tacrolimus (FK506) have demonstrated comparable long-term patient survival and graft survival in liver and renal transplant recipients. Importantly, treatment with tacrolimus was associated with reductions in the incidence and severity of acute rejection episodes. However, tacrolimus-based therapy was also associated with increased toxicities in comparison to conventional cyclosporine-based therapy. It is becoming increasingly accepted that earlier trials may have employed high or supratherapeutic doses of tacrolimus and may have been unbalanced with respect to study design. In addition, these pivotal comparative trials were performed with the original formulation of cyclosporine, and not the cyclosporine microemulsion preparation. This critical review of the literature focuses on the United States and European tacrolimus multicenter clinical trials and examines the efficacy and safety of the two primary immunosuppressants, cyclosporine and tacrolimus, obtained in these and other studies. The preliminary findings of ongoing studies comparing the efficacy and safety of the improved formulation, cyclosporine microemulsion, with tacrolimus are also discussed. The overall efficacy of the two agents appears to be similar. The safety profile shows differing toxicities of the two medications. The availability of these two immunosuppressants allows the clinician improved options when choosing an immunosuppressive regimen in solid organ transplantation.

Overview of the clinical experience with Neoral in transplantation

The microemulsion preparation of cyclosporine, Neoral, was introduced to improve the limited and sometimes unpredictable absorption of cyclosporine from the gut. Preclinical studies proved a superior bioavailability measured by the AUC and a definitively better predictability of the pharmacokinetic properties. Large-scale randomized and open-labeled studies have been carried out to prove and establish the safety, tolerability, and equal or superior efficacy of NEO if compared with SIM. There is broad evidence that NEO is safe and well tolerated in de novo and stable renal allografts. There are some arguments that NEO has favorable properties in poor absorbers, in patients in need for high dosage per kg body weight. Benefits for some populations such as children, African Americans, and diabetics have been detected. In combined kidney-pancreas transplantation a significant improvement of absorption has been proven. NEO has also been investigated in nonrenal transplants such as heart, lung, and liver transplantation. There are proven dose reduction in heart transplants; significant better absorption in lung transplants, in particular in patients with cystic fibrosis; and no further or even a diminished need for intravenously given CsA in liver transplantation. Studies are now reported for the use of NEO in differing indications of autoimmune disease. No characteristic profile of adverse events has been recognized, nor has an increase of nephrotoxicity if carefully monitoring in the first weeks after conversion was provided.

Improving the therapeutic monitoring of cyclosporin A

The narrow therapeutic window of cyclosporin A (CsA) and the variable pharmacokinetics of the traditional preparation, CsA-SIM (Sandimmune), have made it difficult to establish its optimal use. The introduction of a microemulsion preparation, CsA-ME (Neoral), with less variable pharmacokinetics, has made it possible to attempt to define its use more closely. One hundred and one renal allograft recipients were converted from CsA-SIM to CsA-ME. Absorption was monitored using a standard pharmacokinetic 'profile' measuring 'whole blood' CsA levels at several time points following drug administration. Areas under the resulting time-versus-CsA concentration curve (AUC) were calculated. Surprisingly, many patients showed very little fluctuation in 'whole blood' levels after administration of the conventional preparation: 31% had a difference between trough (to) and maximal levels of < 100 micrograms/L. On microemulsion cyclosporin, there was much better correlation between AUC and several parameters incorporating elements of trough and peak values. The best correlation was with t0 + (t1/4), where t1 represents the concentration at 1 h following administration, (r2 = 0.779 for microemulsion cyclosporin). The use of this parameter is a practical possibility in an out-patient setting. The very common, but under-recognised, pattern of almost flat absorption profiles in patients on conventional CsA suggests that the use of CsA in numerous clinical contexts should be reviewed, since CsA immunosuppression may previously have been inadequately monitored.

Tacrolimus vs Neoral in renal and renal/pancreas transplantation

In a retrospective analysis we compared the outcome of a group of 63 kidney or kidney/pancreas transplant recipients who were transplanted between June 1994 and February 1997 and received either tacrolimus (FK, n = 22) or Neoral (NEO, n = 41) as part of a triple immunosuppressive protocol. Ten patients in the NEO group has recurrent rejection episodes between 1 and 8 months post-transplant and were converted to FK. CellCept was the secondary immunosuppressive agent in about half the FK, three-quarters of the NEO, and in all but one in the conversion (CON) groups. Patients in all groups were on prednisone in equal amounts. Mean duration of follow-up for FK, NEO and CON groups was 32, 19 and 13 months, respectively. One-yr patient and graft survival was 100% in all groups. At 2 yr, graft survival was 95, 96 and 100% in FK, NEO and CON groups, respectively. Acute rejection at 1 yr was twice as high in the NEO group as the FK group. There were no rejection episodes among the FK patients who also received CellCept. The mean current serum creatinines (mg%) were: FK = 1.6, NEO = 1.8, CON = 1.9. Recurrent infection was more common with FK (8/22) than NEO (1/31) (p = 0.023). Our experience suggests there is less rejection but more infection in recipients treated with FK compared to NEO. In patients with recurrent rejection, conversion from NEO to FK stabilizes renal function and minimizes subsequent rejection episodes.

Cyclosporine therapy in patients with steroid resistant autoimmune hepatitis

Autoimmune hepatitis is a form of chronic liver disease characterized by progressive hepatocellular inflammation, which usually responds to treatment with corticosteroids. However, 10% of patients with autoimmune hepatitis are refractory to corticosteroids and develop progressive liver disease and cirrhosis. We describe five patients with autoimmune hepatitis who did not respond to conventional corticosteroids and azathioprine therapy who were then treated with cyclosporine A. Cyclosporine A was started at 2-3 mg/kg/day and induced biochemical remission in four of five patients within 3 months. One of the four responders relapsed within 1 month of discontinuing cyclosporine on two occasions. Each time, liver tests promptly normalized after reinitiation of cyclosporine. Two responders were managed with cyclosporine alone. The single patient who did not respond to cyclosporine developed progressive liver failure, underwent orthotopic liver transplantation, and subsequently died of disseminated cytomegalovirus infection. Cyclosporine was generally well tolerated and none of the patients developed renal insufficiency. These data and review of 11 cases in the literature show that cyclosporine can induce remission of liver disease in patients with autoimmune hepatitis who are refractory to corticosteroids.

Cyclosporine microemulsion increases drug exposure and reduces acute rejection without incremental toxicity in de novo renal transplantation. International Sandimmun Neoral Study Group

BACKGROUND

The new oral microemulsion formulation of cyclosporine (Neoral) possesses superior pharmacokinetics to the conventional formulation, Sandimmun (SIM), providing more complete and predictable absorption, and less pharmacokinetic variability.

METHODS

The safety and tolerability of Neoral, together with the incidence of acute rejection episodes and graft survival, were compared to the conventional cyclosporine formulation, SIM, in a prospective, randomized, double-blind multicenter trial. A total of 167 patients who received a first or second cadaveric renal transplant in 21 participating centers in six countries were randomized equally to two treatment groups and followed for three months after transplantation. Outcomes were analyzed across treatment, center and regional groups. In addition, a nested pharmacokinetic study was performed in four of these centers throughout the period of follow-up.

RESULTS

No difference was detected between the safety or tolerability of the two formulations. Kidney function and other laboratory parameters remained comparable in Neoral- and SIM-treated patients throughout the study. However, the number of patients experiencing acute rejection was significantly reduced for the Neoral group (44.2% vs. 60.5%; P = 0.044), and significantly fewer patients experienced multiple episodes of rejection (12.8% vs. 22.2%, P = 0.028). The proportion of patients free of rejection at three months was significantly higher in patients treated with Neoral than in those receiving SIM (Kaplan-Meier estimated probability of remaining rejection-free at 3 months = 55% for the Neoral group, compared with 39% for the SIM group, P = 0.046, log rank test). Similar results were obtained when acute rejection, graft loss and death were used as a combined endpoint (Kaplan-Meier estimated probability for Neoral group = 54%, compared with 38% for the SIM group, P = 0.047, log rank test). Comparison of results by center or regional groups did not show any significant treatment interaction. A nested pharmacokinetic evaluation (four centers; 28 subjects) showed that the bioavailability of cyclosporine from Neoral was significantly higher than from SIM at all assessment times. Specifically, at weeks 2, 4 to 6, and 12, dose-normalized AUC was 49%, 63% and 32% higher for Neoral. Dose-normalized peak cyclosporine blood concentrations and AUC stabilized by weeks 4 to 6 in patients receiving Neoral, whereas these values increased slowly in SIM-treated patients without reaching the levels achieved in the Neoral group.

CONCLUSIONS

These results suggest that the superior pharmacokinetic characteristics of the microemulsion formulation of cyclosporine lead to more efficient immunosuppression during the first critical months after transplantation, without a deleterious impact on clinical safety.

Safety and tolerability of cyclosporine microemulsion versus cyclosporine: two-year data in primary renal allograft recipients: a report of the Neoral Study Group

BACKGROUND

The new microemulsion formulation of cyclosporine (CsA-ME) is more bioavailable than cyclosporine (CsA) in de novo renal transplant patients. Therefore, it was of interest to compare the safety profile of each formulation in such patients.

METHODS

In a multicenter, double-blind, parallel-group study, 101 renal transplant recipients were randomized after transplantation to receive either CsA (n=50) or CsA-ME (n=51) capsules twice daily for 2 years. Of these patients, 54 (CsA, n=26; CsA-ME, n=28) completed 1 year of the study and entered the second-year, double-blind extension. Initial dose at the time of transplantation was 5 mg/kg b.i.d.; doses were titrated to target trough levels.

METHODS

The mean (+/- SD) doses at the end of 2 years were 4.6 +/- 1.8 and 3.8 +/- 1.1 mg/kg per day for CsA- and CsA-ME-treated patients, respectively. The mean (+/- SD) CsA trough levels at end point were 187 +/- 63 and 210 +/- 95 ng/ml for CsA- and CsA-ME-treated patients, respectively. At least one adverse event was reported by 25/26 (96%) of CsA- and 27/28 (96%) of CsA-ME-treated patients. No patient discontinued the study because of adverse events. No deaths occurred during the study. Renal function, as measured by serum creatinine levels, and blood pressure were comparable over time in both treatment groups.

CONCLUSIONS

There was no significant difference in safety and tolerability between CsA- and CsA-ME-treated kidney recipients for 2 years after transplantation.

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.