Combined immunosuppression with cyclosporine (neoral) and SDZ RAD in non-human primate lung transplantation: systematic pharmacokinetic-based trials to improve efficacy and tolerability

BACKGROUND: We studied the efficacy and tolerability of combined immunosuppressive therapy with cyclosporine A microemulsion (Neoral) plus the macrolide SDZ RAD 40-0 (2-hydroxyethyl) rapamycin (RAD) in a stringent cynomolgus monkey lung graft model in comparison with cyclosporine or SDZ RAD monotherapy. METHODS: Thirty-nine cynomolgus monkeys received mixed lymphocyte reaction (MLR) mismatched unilateral lung transplants. Immunosuppressants were administered orally as single daily doses. The observation period was 28 days and follow-up included serial trough blood drug concentrations measured by high performance liquid chromatography/mass spectrometry, blood analyses, chest radiographs, open lung biopsies, as well as tissue drug concentrations and graft histology at necropsy. RESULTS: Graft biopsies in monkeys treated with vehicle (n=4), Neoral (day 1-7: 150 mg/kg/day; day 8-28: 100 mg/kg/day; n=6; mean +/- SE trough level (MTL): 292+/-17 ng/ml) or SDZ RAD monotherapy (1.5 mg/kg/day; n=6; MTL: 15+/-1 ng/ml) showed severe rejection. Coadministration in two transplant monkeys of Neoral (150/100 mg/kg/day) and SDZ RAD (1.5 mg/kg/day) caused their early death. In both animals, SDZ RAD blood levels were more than 5-fold higher than under monotherapy (MTL: 82+/-18 ng/ml). Simultaneous administration (n=6) of Neoral (150/100 mg/kg/day; MTL: 217+/-16 ng/ml) and SDZ RAD (0.3 mg/kg/day; MTL: 24+/-2 ng/ml) improved graft outcome (mild rejection). Side effects included renal failure (n=2) and seizures (n=1). Three monkeys survived to day 28. In this group the MTL for cyclosporin was 143+/-13 and for RAD 38+/-3.Staggered treatment completely prevented rejection in four of six grafts. However, five of six monkeys had moderate to severe diarrhea. In a concentration-controlled trial of simultaneously administered Neoral and SDZ RAD in transplant monkeys (target SDZ RAD MTL: 20-40 ng/ml; cyclosporine MTL: 100-200 ng/ml) all six monkeys survived with improved drug tolerability and an average biopsy score of mild rejection. CONCLUSION: Combination of orally administered SDZ RAD and Neoral showed excellent immunosuppressive efficacy in a stringent lung transplant model. The drug interaction and the narrow therapeutic index of this drug combination required careful dose adjustments to optimize tolerability and efficacy.     

Oral efficacy of the new immunomodulator FTY720 in cynomolgus monkey kidney allotransplantation,given alone or in combination with cyclosporine or RAD

BACKGROUND: FTY720 is a novel immunomodulator with a unique mechanism of action, i.e. chemokine-dependent lymphocyte homing into secondary lymphoid organs associated with profound lymphocyte depletion in blood. We investigated its efficacy, either FTY720 alone or together with cyclosporine or the rapamycin derivative rapamycin derivative (RAD), in cynomolgus monkey kidney allotransplantation. METHODS: Life-supporting allotransplantation was performed in bilaterally nephrectomized hosts. Compounds were given once daily by oral gavage. Monitoring was done by serum creatinine and urea, and rejection was concluded when values exceeded 500 micromol/L and 50 mmol/L, respectively (5-6 times the upper limit of reference values). Rejection was confirmed by graft histology. The termination point was set to 100 days after transplantation. In addition, animals were monitored for 24 hr drug concentrations and thorough inspection of potential adverse side effects. RESULTS: FTY720 given alone at 3.0 mg/kg per day prolonged rejection-free survival (33-85 days, mean 24 hr concentration between 54 and 66 ng/mL [n=3]), but it was not efficacious at a 0.3 mg/kg per day dose. For cyclosporine alone, 30 mg/kg per day during maintenance was efficacious (average concentration above 100 ng/mL, historical data from our group), and for RAD alone 0.75 mg/kg per day (concentration above 10 ng/mL). Efficacious FTY720-cyclosporine-A (CsA) or FTY720-RAD combinations were established using 0.1-0.3 mg/kg per day FTY720, 10-30 mg/kg per day cyclosporine, and/or 0.25-0.50 mg/kg per day RAD. Compared with single-compound treatment, FTY720 effective doses and 24 hr trough concentrations were at least tenfold lower in combination treatment and those of cyclosporine and RAD about twofold lower, indicative of effective synergy between the compounds. Already at the lowest FTY720 dose tested (0.03 mg/kg per day), there was a profound lymphocyte depletion down to about 30% of pretransplant values, which further increased at the highest dose (3.0 mg/kg per day, to about 14% of pretransplant values). Lymphocyte depletion was reflected by a decrease in T and B subpopulations. CONCLUSION: FTY720 is an effective immunosuppressant in prevention of acute kidney allograft rejection in cynomolgus monkeys and synergizes with cyclosporine and/or RAD in yielding rejection-free allograft survival.     

Toxicology of FK506 in the cynomolgus monkey: a clinical,biochemical, and histopathological study

We investigated clinical, biochemical, and histopathological parameters in FK506-treated cynomolgus monkeys. Eight monkeys given oral FK506, 1 (n = 4) or 10 (n = 4) mg/kg daily, survived the 90 days of treatment apparently in good health and without significant changes in biochemical and histopathological parameters, as did 2 control monkeys except one monkey on 10 mg/kg/day FK506 orally, who was found to have a malignant lymphoma. In contrast, monkeys given intramuscular FK506 1 mg/kg daily (n = 4) had to be sacrificed at day 20, 25, 32, and 47 because of severe illness. They showed abnormal biochemical parameters (increased serum urea and aspartate aminotransferase activity) and major histopathological changes in the kidney (mesangial cell proliferation and acute tubular necrosis), pancreas (depletion of beta cells), liver (steatosis), and heart (cardiomyopathy). Intramuscular administration of 1 mg/kg daily resulted in serum levels ranging from 10 to 15 ng/ml, while oral administration at a dose of 1 or 10 mg/kg daily resulted in equal or even higher serum levels (range 2–70 ng/ml). Thus, the height of the serum trough level of FK506 using the enzyme immunoassay is not related to the toxicity of FK506 in cynomolgus monkeys.     

Optimal serum trough levels of FK506 in renal allotransplantation of the beagle dog

The present study was performed to estimate the optimal serum trough levels of FK506 (FK) for prophylactic use and for the treatment of acute rejection in renal allotransplantation of the beagle dog. The serum trough levels of an immunosuppressive dose of FK 1.0 mg/kg p.o. ranged from 0.1 to 0.4 ng/ml. The data indicate that the effective serum trough level is about 100 times lower than that of cyclosporine, as was already observed in previous in vitro studies. Combining treatment with a nonimmunosuppressive dose of cyclosporine of 2.5 mg/kg could lower the effective trough levels of FK. By the combining treatment, 2 out of 5 renal recipient dogs survived with well-functioning grafts as long as 60 days with the trough levels between 0.04 and 0.07 ng/ml. High-dose 5-day i.m. FK treatment of 0.5 or 1.0 mg/kg was effective in the reversal of acute rejection, with peak serum trough levels during successful rejection therapy ranging between 0.28 and 3.7 ng/ml. Two dogs died of malaise or pneumonia with peak trough levels of 2.25 and 2.78 ng/ml. Among the wide range of the effective trough levels for successful acute rejection therapy, those above 2.0 ng/ml seem to be toxic in some renal-transplanted dogs.     

Effective long-term immunosuppression maintained by low cyclosporine levels in primary cadaveric renal transplant recipients

Nephrotoxicity and cost are the major problems in the use of cyclosporine (CsA) in renal transplantation. Thus, maintenance of CsA levels at the lower limits of the therapeutic range is desirable. The lowest CsA level effective in preventing rejection while avoiding nephrotoxicity has not been defined. We report on 44 primary cadaveric renal transplant recipients treated with a protocol that involved a progressive reduction in the trough CsA levels. CsA was initiated at an oral dose of 15 mg/kg, and this dose was adjusted to achieve serum trough levels, as measured by radioimmunoassay, of 150-200 ng/ml during the first month, 100-150 ng/ml during the second month, 75-100 ng/ml during the third month, and 50-75 ng/ml thereafter. Patient and graft survival at 18 months were 94% and 83.6%, respectively. The mean daily CsA doses were 6.7 +/- 3.1 mg/kg at 6 months, 5.5 +/- 3.2 mg/kg at 12 months, and 4.7 +/- 2.4 mg/kg at 18 months. Corresponding trough serum CsA levels were 94 +/- 59 ng/ml, 64 +/- 22 ng/ml, and 44 +/- 21 ng/ml at 6, 12, and 18 months, respectively. Mean serum creatinine concentrations were 1.8 +/- 0.6 mg/dl at 6 months, 1.7 +/- 0.5 mg/dl at 12 months, and 1.6 +/- 0.5 mg/dl at 18 months. The mean serum creatinine concentration at 18 months was not significantly different from that of 18 conventionally treated primary cadaveric renal transplant recipients (1.6 +/- 0.5 vs. 1.4 +/- 0.4 mg/dl, P = .31). A total of 67% of patients did not have any rejection episodes under this protocol, while 71% of patients never developed CsA nephrotoxicity. No patient was taken off CsA for progressive nephrotoxicity. We conclude that trough serum CsA levels of 50-75 ng/ml, as measured by radioimmunoassay, are sufficient to maintain effective immunosuppression in the long-term management of primary cadaveric renal transplant recipients. These values are much lower than previously recommended, and this approach ameliorates chronic CsA nephrotoxicity.     

Coadministration of neoral and the novel rapamycin analog, SDZ RAD, to rat lung allograft recipients: potentiation of immunosuppressive efficacy and improvement of tolerability of staggered versus simultaneous treatment

BACKGROUND: Neoral and rapamycin derivative (RAD) have complementary mechanisms for inhibition of lymphocyte activation and are substrates for the same pathways of drug metabolism. Therefore, we investigated treatment regimens designed to minimize pharmacokinetic interactions and to potentiate immunosuppressive efficacy in a highly stringent rat lung allograft model. METHODS: Lewis recipients of Brown Norway lungs received the following daily oral doses: (A) RAD at 2.5 mg/kg (n=9); (B) Neoral at 7.5 mg/kg (n=8); (C) RAD at 2.5 mg/kg + Neoral at 7.5 mg/kg simultaneously (n=8); or (D) RAD at 2.5 mg/kg + Neoral at 7.5 mg/kg (n=6) staggered 6 hr apart. Rats were assessed by daily weights, chest radiographs, drug trough levels (high-performance liquid chromatography/mass spectrometry), and blinded scoring of graft histology at death (day 21). RESULTS: Radiographs were completely opacified in all grafts of control and RAD monotherapy groups on days 7 and 14, respectively. Grafts were mildly opacified (Neoral monotherapy) and completely clear (both RAD + Neoral groups) on day 21. Simultaneous or staggered combined treatment dramatically reduced histologic rejection compared with treatment with either drug alone. Simultaneous treatment caused poor tolerability (poor grooming, lethargy) and significantly higher day-14 RAD and cyclosporine (CsA) trough levels (49+/-5 and 638+/-106 ng/ml; P<0.04) than in the staggered group (28+/-3 and 318+/-25 ng/ml) in which all animals were clinically normal. RAD and CsA day-14 trough levels in the staggered group were the same or lower than trough levels in animals treated with either drug alone (RAD 27+/-3/Neoral 815+/-67 ng/ml). CONCLUSIONS: (1) Administration of RAD + Neoral suppressed lung rejection more effectively than treatment with either drug alone. (2) Trough levels did not differ between monotherapy and staggered combination therapy for RAD but were lower for CsA. These results suggested that pharmacological, rather than pharmacokinetic, interactions between the parent drugs were responsible for the potentiation of immunosuppression when these drugs were coadministered. 3) Staggered administration of RAD+Neoral avoided the pharmacokinetic interactions that caused the elevated drug blood levels and poor tolerability caused by simultaneous administration. Thus, we could potentiate efficacy and improve tolerability by staggering administration of RAD and Neoral.     

Efficacies of sirolimus (rapamycin) and cyclosporine in allograft vascular disease in non‐human primates: trough levels of sirolimus correlate with inhibition of progression of arterial intimal thickening

Abstract We investigated the efficacies of sirolimus (rapamycin) and cyclosporine for inhibition of graft vascular disease (GVD) in cynomolgus monkey recipients of aortic allografts. Increases in arterial intimal thickening in the midgraft (six consecutive cross‐sections) after transplantation were quantified by serial intravascular ultrasound (IVUS) from day 21 to day 105. These data enabled correlations between changes in intimal indexes [II = (intimal area/vessel area) × 100] and trough levels of sirolimus and cyclosporine to be determined. Eighteen recipients received no immunosuppression for 6 weeks to allow alloimmune injury to occur. On day 45, monkeys were treated daily with sirolimus (n = 6) or cyclosporine (n = 6); six monkeys remained untreated. II increased significantly from day 63 to day 105 in untreated monkeys and monkeys treated with cyclosporine, whereas monkeys treated with sirolimus did not have a significant increase in II (P = 0.008, P = 0.006, P = NS; paired t‐test). The change in II from days 63 to 105 was significantly greater in untreated monkeys compared to sirolimus‐treated monkeys (P = 0.13; one‐way ANOVA, P = 0.012 Tukey's post hoc test); other post hoc pairwise comparisons were not significant. Mean sirolimus and cyclosporine levels ± SEM were 43 ± 7 ng/ml and 562 ± 20 ng/ml, respectively. Sirolimus trough levels, but not cyclosporine levels, correlated inversely with changes in II from day 42 to 105 (r² = 0.73, P = 0.03). This non‐human primate study shows that inhibition of intimal thickening by sirolimus depends on trough levels and provides the rationale for clinical trials of sirolimus for the control of GVD in organ transplant recipients.     

Prolongation of intraperitoneal segmental pancreatic allografts in primates receiving cyclosporin A

In this study the efficacy of the new immunosuppressive agent, cyclosporin A (CYA), was examined in a model of segmental, intraperitoneal pancreatic allotransplantation with free duct drainage in totally pancreatectomized, outbred Chacma baboons. CYA, in doses of 25 to 50 mg/kg/day administered to recipients of heterotopic segmental (tail) allografts, produced a slight but significant prolongation of graft survival. CYA (25 to 85 mg/kg/day), administered orally after pancreatic transplantation gave daily serum trough levels of CYA that ranged from 300 to 600 ng/ml. Mean serum trough levels on the first postoperative day in recipients of 50 mg/kg/day were 121.1 +/- 61.6 ng/ml. There was a wide variation in daily serum trough levels exhibited between primates on the same daily oral dose, and there was no correlation between absolute serum trough levels of CYA and rejection. It is postulated that adequate serum CYA levels were not achieved by the oral administration of the drug to ensure allograft survival beyond 60 days in pancreatectomized recipients. Adverse effects occurred frequently and included anorexia, diarrhea, and tremors and were in direct proportion to the quantity of CYA required to prolong graft survival. Free duct drainage into the abdominal cavity frequently resulted in pancreatic ascites, which necessitated paracentesis, indicating that this method of duct drainage has limited clinical application. Although heterotopic autotransplantation or allotransplantation of the tail of the pancreas in the baboon was capable of maintaining normoglycemia in pancreatectomized baboons, glucose intolerance, reduced K values, and hypoinsulinemia were consistent findings during glucose tolerance tests, suggesting that an insufficient islet cell mass had been transplanted.     

Plasma Profiles of Ivermectin in Horses following Oral or Intramuscular Administration

A study was undertaken in order to evaluate and compare ivermectin's (IVM) plasma disposition kinetic parameters after oral or intramuscular (IM) administration in horses. Ten clinically healthy adult horses, weighing 380–496 kg body weight (BW), were allocated to two experimental groups of five horses. Group I, was treated with an oral paste formulation of IVM at the manufacturer's recommended dose of 0.2 mg/kg BW. Group II, was treated IM with an injectable 1% formulation of IVM at a dose of 0.2 mg/kg BW. Blood samples were collected by jugular puncture at different times between 0.5 h and 75 days post‐treatment. After plasma extraction and derivatization, samples were analysed by high‐performance liquid chromatography with fluorescence detection. A computerized kinetic analysis was performed, and data were compared using the Wilcoxon signed rank test. The parent molecule was detected in plasma between 30 min and either 20 (oral) or 40 (IM) days post‐treatment. Significant differences were found for the time corresponding to peak plasma concentrations (t_max) and for absorption half‐life. Peak plasma concentrations (C_max) of 51.3 ± 16.1 ng/ml (mean ± SD) were obtained after oral administration and of 31.4 ± 6.0 ng/ml for the IM route. The values for area under concentration–time curve were 137.1 ± 35.9 ng day/ml for the group treated orally, and 303.2 ± 4.3 ng day/ml for the IM treated group. The mean plasma residence times were 4.2 ± 0.4 and 8.9 ± 0.7 days for oral and IM‐treated groups, respectively. The results of this study show that the route of administration considerably affects the disposition of IVM. A significant difference in bioavailabilty and half‐life of elimination of IVM was observed after IM administration compared with oral administration. A close relationship between pharmacokinetic profiles and the clinical efficacy of IVM was established.     

Decreased cyclosporine exposure during the remission of nephrotic syndrome

In this paper, we report the pharmacokinetics changes observed in seven children with steroid-resistant nephrotic syndrome (SRNS). They received cyclosporine A (CsA) microemulsion 6 mg/kg/day and, one week later, they were admitted to perform a 12-h pharmacokinetic profile with eight time sample points. The pharmacokinetic profile was repeated at 24 weeks of treatment, when all patients achieved remission. Blood concentration against time curves were constructed for each patient at weeks 1 and 24 of CsA treatment. Peak concentrations (C _max) and the time needed to reach peak concentrations (t _max) were directly determined from these plots. The area under the curve (AUC) was estimated by the trapezoidal rule. There was a statistically significant difference of the AUC, trough levels, and t _max between weeks 1 and 24, with a decrease of AUC from 5,211 ng*h/ml in week 1 to 3,289 ng*h/ml in week 24, the trough levels decreased from 157 ng/ml to 96 ng/ml, and the t _max decreased from 1.85 h to 1.00 h. The higher CsA bioavailability during the nephrotic state has to be considered when managing patients, since the target AUC cannot be the same throughout the treatment.     

Everolimus (certican) in heart transplantation: optimizing renal function through minimizing cyclosporine exposure

The proliferation signal inhibitor everolimus is efficacious for reducing the incidence of acute rejection and cardiac allograft vasculopathy (CAV) in heart transplantation; and it has the potential to facilitate cyclosporine (CsA) minimization in this setting. Reducing CsA dose in heart transplantation is dependent on everolimus trough blood levels of 3 to 8 ng/mL being achieved. Physicians experienced in the use of everolimus aim for CsA trough blood levels of 175 to 200 ng/mL in everolimus-treated patients during the initial 3 months following heart transplantation. Modeling data from the heart pivotal study suggest that CsA trough blood levels of 100 ng/mL at 6 months posttransplant could be targeted without loss of efficacy, and antibody induction therapy may assist with this approach. Target CsA trough blood levels for maintenance patients could possibly be reduced from the current 80 to 100 ng/mL to 50 to 80 ng/mL. Maintenance patients with renal dysfunction or CAV may benefit from conversion to everolimus and subsequent reduction in CsA trough blood levels (eg, by 50%). Initial experience of everolimus with reduced CsA trough blood levels in heart transplantation is favorable, but there is scope for further study.     

Cyclosporine pharmacokinetics in normal and pancreatectomized dogs

Oral and i.v. cyclosporine (Cs) pharmacokinetics determined from radioimmunoassay (RIA) data were compared in normal and pancreatectomized dogs. An altered pharmacokinetics of Cs was observed in the pancreatectomized dogs that include: a 170% larger central compartment volume; a 34% greater total-body clearance; and lower steady-state average serum concentrations relative to the normals. Even though there were marked intersubject variations, both groups displayed a triexponential decline in Cs serum concentrations and disposition kinetics. Following 7 daily oral doses of commercial cyclosporine (CsA) (20 mg/kg) the Cs serum trough concentrations of the pancreatectomized dogs were consistently below 100 ng/ml, while those of the normal dogs were above 400 ng/ml. No alteration of CsA oral absorption was noted following pancreatectomy. This study suggests that frequent serum Cs concentration monitoring, with appropriate dosage adjustments, even in normals, is necessary to assure adequate drug levels. More significantly, the CsA dosage for pancreatectomized dogs should be several times greater to maintain serum concentrations comparable to normal dogs.     

Paradoxical effects of cyclosporine on concanavalin A-induced blastogenesis

The effects of increasing in vitro cyclosporine concentrations (0, 50 100 or 200 ng./ml.) on lymphocyte blastogenesis, measured by incorporation of tritiated thymidine and induced by varying levels of concanavalin A (0, 0.25, 1.0 or 5.0 ng./ml.), were studied in regard to mean serum level of cyclosporine in 26 renal allograft recipients. Results were compared to similar data obtained in healthy controls. Patients were divided into group 1 (13 patients, mean serum cyclosporine trough level less than 150 ng./ml.) and group 2 (13 patients, cyclosporine level greater than 150 ng./ml.). With no cyclosporine added to the assay proliferation of lymphocytes obtained from all patients inversely correlated to the mean serum trough cyclosporine level at all stimulatory levels of concanavalin A (0.25 ng./ml., p less than 0.01; 1.0 ng./ml., p less than 0.001 and 5.0 ng./ml., p less than 0.001) and was significantly lower than in controls (p less than 0.0002). Whereas increasing in vitro cyclosporine concentrations has produced the expected increase in suppression of blastogenesis in controls and group 1, a paradoxical effect became evident in group 2. Under stronger stimulatory conditions (concanavalin A 1.0 or 5.0 ng./ml.) increasing in vitro cyclosporine concentrations were associated with significantly decreased suppression of blastogenesis (p less than 0.01) compared to group 1. These results confirm previous reports and suggest that the duality of effect of cyclosporine in this in vitro model may be related to its functional relationship to the calcium ion (Ca++)/calmodulin complex and to its cellular concentration/solubility curve. These considerations may be of importance in adjusting cyclosporine dosage based on serum trough levels of cyclosporine.     

Conversion from cyclosporine to tacrolimus in patients at risk for chronic renal allograft failure: 60-month results of the CRAF Study

BACKGROUND: This study compared the long-term effects of switching from cyclosporine to tacrolimus on the incidence, progression, and severity of chronic renal allograft failure in patients with elevated serum creatinine levels. METHODS: Patients were assigned randomly (2:1) to switch to tacrolimus or remain on cyclosporine. Tacrolimus was initiated at 1/50th of the cyclosporine dose or 0.15 mg/kg/day, whichever dose was lower, to maintain trough concentrations between 5 and 15 ng/mL. Cyclosporine doses were adjusted to achieve trough concentrations between 100 and 300 ng/mL. RESULTS: At 60 months, the median change from baseline in serum creatinine was -0.2 mg/dL in the tacrolimus group and 0.3 mg/dL in the cyclosporine group (P=0.003). Median change in estimated creatinine clearance was 1.2 mL/min in the tacrolimus group and -4.1 mL/min in the cyclosporine group (P=0.019). The incidence of new-onset diabetes, hyperglycemia, hypertension, lymphoma, and malignancies was generally low and comparable between groups. Fewer patients in the tacrolimus group than in the cyclosporine group developed new cardiac conditions (11% vs. 28%, P=0.004), had low-density lipoprotein (LDL) cholesterol values more than 130 mg/dL (29% vs. 57%, P=0.002), or developed hyperlipidemia (24% vs. 67%, P=0.046) during the 60-month follow-up period. Despite these changes, patient and graft survival were similar for both groups. CONCLUSION: Switching from cyclosporine to tacrolimus resulted in improved renal function and a reduction in the occurrence of new-onset cardiac conditions and hyperlipidemia, with no increase in the incidence of new-onset diabetes or new-onset hyperglycemia. However, after 5 years there was no impact on patient or graft survival.     

Renal allograft survival in the baboon using a pretreatment protocol with cyclosporine

Cyclosporine extends kidney allograft survival in the chacma baboon, and this study explores various administration protocols to generate optimal serum concentrations of the drug, assessed by radioimmunoassay and by inhibition of lymphocyte transformation by phytohemagglutinin and allogeneic lymphocytes in culture. Serum levels commensurate with concentrations that have been shown to be immunosuppressive in humans (150-400 ng/ml) are reached after 14 days of pretreatment with 10 mg cyclosporine/kg, and after 7 days with 20 and 30 mg cyclosporine/kg. The 10-mg dose prolongs median graft survival from 11 to 21 days, which is the same as that obtained with 20 mg/kg administered after transplantation. Further increases in the pretreatment dose to 20 or 30 mg/kg result in survivals of 27 and 31 days, respectively. All the animals died from rejection during therapy and the T-cell-binding avidity, and absorptive or degradative processes may necessitate doses far in excess of those currently used in transplantation.     

Living related kidney transplantation without calcineurin inhibitors: initial experience in a Mexican center

We performed a prospective randomized trial comparing sirolimus/mycophenolate mofetil (MMF)/prednisone to cyclosporine/MMF/prednisone and selected induction therapy with basiliximab. Twenty patients received sirolimus (10 mg loading dose followed by 3 mg/m body surface area/day, keeping 24-hr trough levels at 10-15 ng/mL for six months and 5-10 ng/mL thereafter. Twenty-one patients began cyclosporine (4 to 8 mg/kg/day, keeping 12-hour trough levels at 150-300 ng/mL for 6 months and 100-200 ng/mL afterwards). Mean follow up was 15.8 months. One-year patient and graft survival was similar in both groups (>90%). Acute rejection rate was 16.6% in the sirolimus group and 5.2% in the cyclosporine group (P=NS). There were no differences in mean serum creatinine between groups. No patients who received basiliximab and had sirolimus target levels suffered acute rejection at one year. The sirolimus group had significantly higher cholesterol and triglycerides. A calcineurin inhibitor-free regimen using sirolimus produces comparable one-year transplant outcomes in living related kidney transplants compared to a calcineurin inhibitor regimen.     

Kidney transplantation without calcineurin inhibitor drugs: a prospective,randomized trial of sirolimus versus cyclosporine

BACKGROUND: Progressive nephrotoxicity caused by calcineurin inhibitor drugs contributes to the long-term decline in renal function in kidney transplant patients. METHODS: We conducted a randomized, prospective trial of calcineurin inhibitor drug avoidance in 61 adult primary kidney transplant recipients. Each patient received induction therapy with 20 mg basiliximab on days 0 and 4, and maintenance therapy with mycophenolate mofetil 1 g two times per day and steroids. Thirty-one patients received sirolimus, 5 mg daily after a 15-mg loading dose. Doses were then concentration-controlled to keep 24-hr trough levels at 10 to 12 ng/mL for 6 months and 5 to 10 ng/mL thereafter. Thirty patients began cyclosporine therapy at 6 to 8 mg/kg per day in divided doses and were then concentration-controlled to keep 12-hr troughs of 200 to 250 ng/mL. RESULTS: Mean follow-up is 18.1 months (range, 12-26 months). The percentages of 1-year patient survival, graft survival, and biopsy-confirmed acute rejection rates were not significantly different between the sirolimus-treated patients (96.7%, 96.7%, and 6.4%, respectively) and the cyclosporine-treated patients (100%, 95.4%, and 16.6%, respectively). At 6 and 12 months, respectively, the sirolimus-treated patients enjoyed significantly better (P=0.008 and P=0.004) mean serum creatinine levels (1.29 and 1.32 mg/dL) and calculated creatinine clearances (77.8 and 81.1 mL/min) than cyclosporine-treated patients (1.74 and 1.78 mg/dL, and 64.1 and 61.1 mL/min, respectively). Sirolimus-treated recipients have significantly (P=0.001) higher 1-year trough levels of mycophenolic acid (4.16 ng/mL) than cyclosporine-treated patients (1.93 ng/mL). Sirolimus also delays the repopulation of basiliximab-depleted CD25 T cells compared with cyclosporine. CONCLUSIONS: Calcineurin inhibitor drug avoidance with basiliximab induction and sirolimus provides comparable 1-year transplant outcomes, with significantly better renal function in primary renal allograft recipients.     

The optimal therapy of calcineurin inhibitors for pregnancy in kidney transplantation

We investigated the effects of pregnancy and delivery on renal function in transplant recipients and the relationship between doses of immunosuppressants and blood drug levels during pregnancy in 75 women with 88 deliveries. Significant serum creatinine elevation (> 0.5 mg/dL) was found in eight deliveries. In the remaining 80 cases, serum creatinine was reduced by an average of 0.14 mg/dL and returned to pre‐pregnant levels after delivery. Tacrolimus was used in 28 deliveries and cyclosporine in others. Tacrolimus blood trough level declined from 5.8 ± 2.8 ng/mL 12 months before delivery to 4.2 ± 1.8 ng/mL at second trimester; therefore, drug dose was increased from 4.1 ± 1.9 mg/d at first trimester to 5.5 ± 2.5 mg/d at delivery. Similarly, cyclosporine levels were 125.1 ± 65.1 ng/mL 12 months before delivery and 75.4 ± 35.0 ng/mL at second trimester resulting in dose elevation from 183.0 ± 71.8 mg/d at first trimester to 225.4 ± 85.1 mg/d at delivery. Renal function in female kidney transplant recipients improved slightly during pregnancy and returned to pre‐pregnant level after delivery. The dose elevation of calcineurin inhibitor by approximately 20–25% should be considered during gestational period to maintain optimal blood drug level.     

Daily renal hypoperfusion induced by cyclosporine in patients with renal transplantation.

A variety of side effects are associated with the use of cyclosporine, the most relevant of which remains the renal toxicity. We did parallel studies on cyclosporine pharmacokinetics and renal function in patients who had a recent kidney transplant and were given cyclosporine as a part of their immunosuppressive therapy. Seven consecutive renal transplant patients were studied at the end of a month of treatment while on different oral cyclosporine doses (5, 3.5, 2.5, or 1.5 mg/kg, twice a day, respectively). Cyclosporine pharmacokinetics profiles and renal function parameters (GFR and renal plasma flow [RPF], as inulin and p-amino hippurate clearances, respectively) were determined before and over a 12-hr period after each single dose of cyclosporine. Plasma levels and urinary excretion rate of endothelin were also studied before and after the highest cyclosporine dose (5 mg/kg). Mean trough levels, area under the curve values, and maximum concentration of blood cyclosporine were comparable after 5 and 3.5 mg/kg cyclosporine and decreased in a dose-dependent manner after the lower doses (2.5 and 1.5 mg/kg). In the same patients GFR declined on average 63%, 53%, 35%, and 18%, 2-4 hr after maximum cyclosporine concentration was reached. As blood levels of cyclosporine returned to trough, GFR progressively increased to baseline. Similar results were found for RPF; 5 mg/kg cyclosporine did not modify endothelin plasma levels. By contrast, urinary excretion of the peptide increased significantly (P less than 0.01) in the 6 hr that followed cyclosporine administration and returned within the normal range in the subsequent 6 hr. Following each oral administration of cyclosporine, 2-4 hr after peak blood concentration was reached, patients showed renal hypoperfusion, transient and rapidly reversible. This was associated with an increased urinary endothelin excretion rate that was also transient. It is speculated that an excessive renal synthesis of endothelin is the cause of the daily renal hypoperfusion observed in patients with renal transplants given cyclosporine.     

Pathologic studies of acute rejection of mismatched feline musculocutaneous flaps. Effect of cyclosporine and prednisolone

The gracilis musculocutaneous flap was developed as an allograft model to study acute rejection and immunosuppression in the cat. Twelve adult cats received a MLC incompatible flap. Six of the cats received cyclosporine oral solution and prednisolone (0.5 mg/kg/24 hr) for 100 days and six cats were not treated. Trough whole-blood levels of cyclosporine in the treatment group were maintained at approximately 750 ng/ml for 70 days, then 500 ng/ml for the remaining 30 days. Three flaps failed due to technical problems; 5 flaps were studied in the treatment group and 4 in the untreated group. All 5 flaps in the treatment group survived the 100 day treatment period and were rejected 30 +/- 26 days following cessation of treatment. Prior to discontinuation of treatment, with the exception of one cat, inflammatory changes associated with rejection were not observed in biopsy specimen. The flaps in the untreated group survived 13 +/- 1.5 days. Histopathologic examination of the flaps revealed little difference in the appearance of acute rejection and rejection after cessation of therapy. The most prominent lesion was a vasculitis with extensive perivascular lymphohistocytic inflammation. The lymphoid infiltrates consisted predominantly of T cells of both major classes (CD4 and CD8). Full-thickness epidermal necrosis and subsequent bacterial invasion followed vascular compromise.