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Background. Current immunosuppressant regimens need to be improved to prevent acute and chronic graft rejection. The novel macrocyclic immunosuppressant everolimus (Certican TM , RAD) is currently in clinical development to address this issue. Methods. The primary objective of this multicentre, randomized, double-blind, placebo-controlled, doseescalating phase 1 study was to evaluate the safety and tolerability of everolimus at four dose levels (0.75, 2.5, 5 and 10 mg/day) in maintenance renal transplant patients receiving cyclosporin and steroids. The secondary objective was to assess the pharmacokinetic profile of two different formulations (capsule and tablet) of everolimus. Results. Fifty-four subjects were randomized for 4 weeks treatment with everolimus (n ¼ 44) or placebo (n ¼ 10). Dose levels of everolimus between 0.75 and 5 mg daily were well tolerated, permitting dose escalation to the highest everolimus dose of 10 mg daily. At this dose, everolimus was associated with a higher incidence and severity of adverse events, most notably thrombocytopenia. Pharmacodynamic assessment showed a relationship between drug exposure and thrombocytopenia. Notable reversible elevations of cholesterol were also observed at the 10 mg/day dose. Other changes in laboratory evaluations, including triglycerides, were minor, reversible and did not appear to be dose dependent. The bioavailability of the tablet formulation was 2.6-fold higher compared with the capsule, with evidence for dose proportionality over the dose range tested. Within-subject pharmacokinetic variability was low (coefficient of variation: 10–19%); however, between-subject variability ranged from 34 to 60% for AUC and Cmax. Conclusions. These results indicate that up to 5 mg/day everolimus results in a dose-proportional exposure, and is adequately well tolerated in renal transplant recipients receiving cyclosporin and steroids.

Study Objective. To quantify the influence of a high-fat meal on the oral bioavailability of the immunosuppressant everolimus in a single-dose study in healthy subjects and to confirm the results in a small food-effect screening assessment in patients with renal transplants who were receiving multiple-dose everolimus. Design. Randomized, open-label, crossover, single-dose study and confirmatory screening. Setting. Phase 1 unit for the single-dose study and two German hospitals for the patient screening. Subjects. Twenty-four healthy male volunteers; six clinically stable patients with renal transplants who were originally part of a phase I dose-escalation study. Intervention. The 24 healthy men received everolimus 2 mg orally under fasting conditions and after a high-fat meal. The six patients received everolimus 2.5 mg/day orally, in addition to cyclosporine and prednisone. On two occasions, a pharmacokinetic profile was obtained over the dosing interval after drug administration under fasting conditions and after a high-fat meal in a randomized sequence. Measurements and Main Results. In the single-dose study in healthy subjects, a high-fat meal delayed everolimus time to maximum concentration (Tmax) by a median 1.25 hours, reduced peak blood concentration (Cmax) by 60%, and reduced area under the concentration-time curve (AUC) by 16%. In the multiple-dose screening in patients with renal transplants, a high-fat meal delayed (Tmax by a median 1.75 hours and reduced Cmax by 53% and AUC by 21%. Everolimus trough levels showed no food effect, whereas the peak-trough fluctuation was dampened by 52%. Conclusions. A high-fat meal modestly reduced everolimus AUC. To minimize longitudinal variability in exposure, everolimus should be administered consistently either with food or without food.

A concentration-guided study was designed to maintain adequate immunosuppression and avoid excessive drug exposure while determining steady-state relative bioavailability of two cyclosporine G (CyG) oral formulations in stable renal transplant patients. In period I (week 1), 26 patients taking cyclosporine A (CyA)-based immunosuppressive regimens entered the study. Doses were titrated to maintain trough concentrations within a predefined range, as measured by fluorescence polarization immunoassay (FPIA). Patients were given an oral solution of CyG in period II (weeks 2-3), and a microemulsion capsule formulation of CyG in period III (weeks 4-5), with dose titration as necessary to achieve trough concentrations in a predefined range, as measured by FPIA. Full pharmacokinetic profiles were obtained on the last day of each study period. Treatment with CyA was reinitiated in period IV (week 6) at the same doses as at study entry. All blood samples were analyzed at the conclusion of the study using CyG- and CyA-specific high-performance liquid chromatography (HPLC). When changing from oral solution to capsule for CyG, an average 19% dose reduction was necessary to compensate for the elevated trough concentrations resulting from the increased bioavailability of the capsule formulation. The concentration-guided strategy was successful in avoiding over-exposure, and resulted in comparable values for area under the concentration-time curve (AUC) for both formulations of CyG. Dose normalization of the pharmacokinetic parameters subsequently allowed calculation of the relative bioavailability. Specifically, a faster rate and greater extent of CyG absorption from the capsule than the oral solution were manifested as a slightly earlier time to peak concentration (tmax), an average 44% increase in the maximum concentration (Cmax), and an average 29% increase in AUC. This experience demonstrated that a concentration-guided trial design allowed a drug development question for a compound with a narrow therapeutic index to be addressed safely and directly in the target patient population.

The steady-state pharmacokinetics and tolerability of a microemulsion formulation of cyclosporine (Sandimmune Neoral) were compared with Sandimmune in 18 clinically stable renal allograft recipients. In study period I (2 weeks duration), patients entered the study on a stable, individualized twice-daily dosage regimen of Sandimmune. Two approaches were assessed for changing patients over from Sandimmune to Sandimmune Neoral. In period II (2 weeks), doses were converted based on the area under the curve ratio derived from a relative bioavailability study comparing the two formulations in healthy volunteers. In period III (2 weeks), doses were titrated to provide comparable steady-state trough concentrations as at study entry. Sandimmune was reinstituted during period IV (2 weeks). Safety and tolerability were assessed at weekly clinic visits and the steady-state pharmacokinetics of cyclosporine in whole blood were characterized at the end of each study period. Dose conversion in period II based on the AUC ratio derived from healthy volunteers was inadequate for achieving comparable cyclosporine exposure as assessed by steady-state AUC and troughs. The concentration-controlled approach (period III) indicated that maintaining the same cyclosporine dose when changing between formulations yields comparable steady-state trough concentrations. Concomitant with this conversion, steady-state peak concentration and AUC increased on average by 39% and 15%, respectively, due to absorption-related differences between the formulations. These increases were not associated with adverse events or changes in blood pressure or clinical laboratory parameters. Furthermore, they were not detrimental to the transplanted kidney as monitored by ultrasound examination. The pharmacokinetic profiles from Sandimmune Neoral exhibited less variability and yielded a stronger correlation between trough concentration and systemic exposure (AUC) compared with Sandimmune.

To investigate possible interactions of the novel immunosuppressant everolimus with cyclosporine, a multicenter, randomized, double-blind, placebo-controlled, dose-escalating phase I study was performed. Everolimus regimens (0.75-10 mg/d) were administered for 28 days to stable renal allograft recipients receiving the microemulsion form of cyclosporine. Steady-state cyclosporine profiles were assessed at baseline on day 0 (cyclosporine alone) and on day 21 with everolimus on steady state. By day 21, mean dose-normalized cyclosporine AUC 0 - 1 2 increased by 15% in patients receiving placebo. In everolimus-treated patients, mean increases in cyclosporine AUC 0 - 1 2 ranged from 7% to 43%, which were not significantly different across all dosing cohorts including placebo. Linear regression of everolimus AUC on day 21 versus the increase in cyclosporine AUC 0 - 1 2 yielded a slope not significantly different from a horizontal line (P = ns). In conclusion, these results suggest that steady-state everolimus exposure over the wide range assessed in this study did not affect steady-state cyclosporine pharmacokinetics.

The steady-state pharmacokinetics and tolerability of a microemulsion formulation of cyclosporine (Sandimmune Neoral) were compared with the commercial formulation (Sandimmune) in 55 clinically stable renal allograft recipients. In study period I (2 weeks' duration), patients entered the study on a stable, individualized twice-daily dosage regimen of the commercial formulation. In period II (2 weeks), they were changed over to the microemulsion formulation at the same dose as at study entry. In period III (2 weeks), dose titration was subsequently allowed if necessary to provide comparable steady-state trough concentrations as at study entry. The commercial formulation was reinstituted during period IV (2 weeks). Safety and tolerability were assessed at weekly clinic visits, and the steady-state pharmacokinetics of cyclosporine in whole blood were characterized at the end of each study period. A milligram-to-milligram dose conversion was adequate when making the initial change between formulations in order to maintain steady-state trough concentrations in the target therapeutic range. Concomitant with this conversion, the steady-state peak concentration and area under the curve increased on average by 59% and 30%, respectively, due to absorption-related differences between the formulations. These increases were not associated with an increase in adverse experiences or changes in blood pressure or clinical laboratory parameters over the first four weeks after the change-over. Trough concentrations were more stable and were more strongly correlated with systemic exposure (area under the curve) during treatment with the microemulsion formulation. Intraindividual coefficients of variation in steady-state peak concentration, time to attain the peak, area under the curve, and percent peak-trough fluctuation ranged from 18% to 74% from the commercial formulation. Variability from the microemulsion formulation was significantly less, ranging from 10% to 22%.

The analysis of urine obtained from fetuses with hydronephrosis, seen on ultrasound, can give a misleading assessment of residual renal function. Additional parameters for assessment of fetal renal function would be helpful. We have used SDS-polyacrylamide gel electrophoresis to separate urinary proteins from a fetus with obstructive uropathy and severe oligohydramnios, already present at 18 weeks of gestation. The dilated urinary bladder of the fetus was successfully shunted in utero with a double pigtail catheter which worked for 17 weeks, and a boy without renal or pulmonary insufficiency was born at 36 weeks. In this case the prenatal protein analysis by electrophoresis was a better indicator of the ultimate good pregnancy outcome than the evaluation of urinary electrolytes and osmolarity alone. We therefore suggest the addition of this test to the profile of renal function studies performed on fetal urine.