A prospective cross-over study comparing the pharmacokinetics of cyclosporine A and its metabolites after oral versus short-time intravenous cyclosporine A administration in pre-heart transplant patients

Dose-adjusted and dose/kg-adjusted concentrations of mycophenolic acid precursors reflect metabolic ratios of their metabolites in contrast with tacrolimus and cyclosporine

Background and purpose: Therapeutic drug monitoring is a valuable tool supporting immunosuppressive therapy. Significant variation of immunosuppressive drug (ISD) concentrations during their use at similar doses is the basis of dose-normalization strategy. The strategy of dose-adjustment is proposed to identify variability in the rate of ISD metabolism. While the parent drug-to-metabolite ratio (metabolic ratio, MR) represents the rate of formation of individual metabolites. The present study was aimed at evaluation of associations between ISDs’ metabolism rate expressed as dose-adjusted concentrations (C/D) and dose/kg-adjusted concentrations (C/D/kg) and MRs of individual metabolites of tacrolimus, cyclosporine A and MPA precursors.

Experimental approach: 506 patients have participated: 284 males (56.13%) and 222 females (43.87%); 318 after kidney (62.85%) and 188 after liver transplantation; median age was 51.34 (39.32-59.95) years and median time after transplantation 78.92 (33.87-138.4) months.

Key results: Generally, we have not observed significant relationships between dose-adjusted and dose/kg-adjusted concentrations and MRs of cyclosporine and tacrolimus. Significant correlations were found for: AM9/CsA and dMC-CsA/CsA in kidney transplant recipients and MIII/Tac, AM1/CsA and AM4N/CsA in liver transplant recipients. In contrast, MRs of mycophenolic acid (MPA) metabolites correlated significantly with MPA C/D and C/D/kg both in kidney and liver transplant recipients.

Conclusion and implications: In conclusion, easily available and easy to use in clinical practice C/D and C/D/kg ratios cannot be considered as parameters directly reflecting the rate of generation of major metabolites of cyclosporine and tacrolimus both in liver and kidney transplant recipients.

Cyclosporine A induces endothelin-converting enzyme-1: Studies in vivo and in vitro

AIM

Cyclosporine A (CsA) induces renal vasoconstriction and hypoxia and enhances the expression of endothelin-1 (ET-1) pro-hormone (pre-pro-ET-1), plausibly leading to a feed-forward loop of renal vasoconstriction, hypoxia and enhanced synthesis of the potent vasoconstrictor ET-1. Endothelin-converting enzyme (ECE)-1 cleaves big endothelin to generate endothelin (ET)-1 and is upregulated by hypoxia via hypoxia-inducible factor (HIF). We hypothesized that in addition to the direct induction of ET-1 synthesis, CsA might also intensify renal ECE-1 expression, thus contributing to enhanced ET-1 synthesis following CsA.

METHODS

CsA was administered to Sprague Dawley rats (120 mg/kg/SC) for 4 days, and renal HIF and ECE-1 expression were assessed with Western blots and immunostaining. Human umbilical vein endothelial cells (HUVEC) and proximal tubular cell line (HK-2) were subjected to CsA, and ECE-1 induction was evaluated using real-time mRNA PCR and Western blots.

RESULTS

Cyclosporine A intensified renal parenchymal ECE-1 expression in the rat kidney, particularly in distal nephron segments, along with renal hypoxia (detected by pimonidazole adducts) and HIF expression, in line with our recent observations showing episodic hypoxia in mice subjected to CsA. Furthermore, in cultured normoxic HUVEC and HK-2 cells, CsA dose-dependently induced both pre-pro-ET-1 and ECE-1 mRNA and protein expression, with enhanced ET-1 generation.

CONCLUSION

CsA induces ECE-1 via both hypoxic and non-hypoxic pathways. ECE-1 may contribute to increased renal ET-1 generation following CsA, participating in a feed-forward loop of renal parenchymal hypoxia and ET synthesis.

Hydroxylated, Hydroxymethylated, Dihydroxylated, and Trihydroxylated Cyclosporine Metabolites Can Be Nephrotoxic in Kidney Transplant Recipients

BACKGROUND

Cyclosporine (CsA) is an immunosuppressive agent whose use is associated with adverse effects, including nephrotoxicity. There are reports indicating that some CsA metabolites may contribute to these effects. This study was aimed at evaluation of CsA metabolites and correlating them with kidney function.

METHODS

In 62 kidney transplant recipients (41.9% women; overall mean age, 48.44 ± 11.75 years), concentrations of CsA and 4 groups of metabolites were assessed: hydroxylated (HCsA), hydroxymethylated (HMCsA), dihydroxylated (DHCsA), and trihydroxylated (THCsA). The results were normalized with the use of the metabolite-to-parent drug ratio, and results were linked with estimated glomerular filtration rate (eGFR) at 3 months before (-3M), point zero (0M), and after 3 (+3M) and 12 (+12M) months.

RESULTS

Multivariate analysis demonstrated the negative influence of eGFR -3M on HMCsA/CsA (β = -0.266; P < .05) and the negative influence of HCsA/CsA, HMCsA/CsA, DHCsA/CsA, and THCsA/CsA on eGFR +3M (β = -0.339, β = 0.396, β = -0.314, and β = -0.321, respectively; P < .005) and eGFR +12M (β = -0.363, β = -0.316, β = -0.267, and β = -0.312, respectively; P < .05). We did not detect such influence of CsA concentrations on eGFR +3M and +12M. The THCsA/CsA receiver operating characteristic cutoff value for prediction of improvement of kidney function at +12M was 0.143.

CONCLUSIONS

Our results suggest that impaired function of the transplanted kidney affects the accumulation of HMCsA. It is possible that the increased metabolite (HCsA, HMCsA, DHCsA, and THCsA) to cyclosporine ratio could influence or could be a marker of cyclosporine nephrotoxicity. In this context, the most promising marker seems to be THCsA/CsA ratio, but its real significance requires further studies to determine.

A cyclosporine derivative is a substrate of the oligopeptide transporter PepT1

Cyclosporine was attached to a thiodipeptide carrier, yielding conjugate 7; this is a substrate for PepT1 with oral bioavailability potential.

Cyclosporine inhibition of hepatic and intestinal CYP3A4, uptake and efflux transporters: application of PBPK modeling in the assessment of drug-drug interaction potential

PURPOSE

To apply physiologically-based pharmacokinetic (PBPK) modeling to investigate the consequences of reduction in activity of hepatic and intestinal uptake and efflux transporters by cyclosporine and its metabolite AM1.

METHODS

Inhibitory potencies of cyclosporine and AM1 against OATP1B1, OATP1B3 and OATP2B1 were investigated in HEK293 cells +/- pre-incubation. Cyclosporine PBPK model implemented in Matlab was used to assess interaction potential (+/- metabolite) against different processes (uptake, efflux and metabolism) in liver and intestine and to predict quantitatively drug-drug interaction with repaglinide.

RESULTS

Cyclosporine and AM1 were potent inhibitors of OATP1B1 and OATP1B3, IC(50) ranging from 0.019-0.093 μM following pre-incubation. Cyclosporine PBPK model predicted the highest interaction potential against liver uptake transporters, with a maximal reduction of >70% in OATP1B1 activity; the effect on hepatic efflux and metabolism was minimal. In contrast, 80-97% of intestinal P-gp and CYP3A4 activity was reduced due to the 50-fold higher cyclosporine enterocytic concentrations relative to unbound hepatic inlet. The inclusion of AM1 resulted in a minor increase in the predicted maximal reduction of OATP1B1/1B3 activity. Good predictability of cyclosporine-repaglinide DDI and the impact of dose staggering are illustrated.

CONCLUSIONS

This study highlights the application of PBPK modeling for quantitative prediction of transporter-mediated DDIs with concomitant consideration of P450 inhibition.

Pharmacokinetics of Cyclosporine A in Chinese heart transplant recipients

AIM

To determine the steady state concentration and the pharmacokinetics of Cyclosporine A (CsA) in heart transplant recipients.

METHODS

A single dose of 100 mg CsA capsules twice daily was given to five heart transplant recipients of steady state. The concentrations of CsA in plasma were determined by streptavidin peroxidase fluorescent polarization immunoassay.

RESULTS

The main pharmacokinetic parameters of CsA were as follows: t(max) (1.60 ± 0.55) h, ρmax(951.60 ± 229.20) μg.L-1, t1/2(6.53 ± 2.40) h, and AUC0 -t(5162.10 ± 1355.01) μg.h.L-1.

CONCLUSION

The study obtained the steady state pharmacokinetic parameters of CsA in Chinese heart transplant recipients.