Pharmacokinetic tools for the dose adjustment of ciclosporin in haematopoietic stem cell transplant patients.

AIMS: Ciclosporin A (CsA) is used in the prophylaxis and treatment of acute and chronic graft vs. host disease after haematopoietic stem cell (HSCT) transplantation. Our objective was to build and compare three independent Bayesian estimators of CsA area under the curve (AUC) using a limited sampling strategy (LSS), to assist in dose adjustment. METHODS: The Bayesian estimators were developed using in parallel: two independent parametric modelling approaches (nonmem® and iterative two stage (ITS) Bayesian modelling) and the non-parametric adaptive grid method (Pmetrics®). Seventy-two full pharmacokinetic profiles (at pre-dose and 0.33, 0.66, 1, 2, 3, 4, 6, 8 and 12h after dosing) collected from 40 HSCT patients given CsA were used to build the pharmacokinetic models, while 15 other profiles (n = 7) were kept for validation. For each Bayesian estimator, AUCs estimated using the full profiles were compared with AUCs estimated using three samples. RESULTS: The pharmacokinetic profiles were well fitted using a two compartment model with first order elimination, combined with a gamma function for the absorption phase with ITS and Pmetrics or an Erlang distribution with nonmem. The derived Bayesian estimators based on a C0-C1 h-C4 h sampling schedule (best LSS) accurately estimated CsA AUC(0,12 h) in the validation group (n = 15; nonmem: bias (mean ± SD)/RMSE 2.05% ± 13.31%/13.02%; ITS: 4.61% ± 10.56%/11.20%; Pmetrics: 0.30% ± 10.12%/10.47%). The dose chosen confronting the three results led to a pertinent dose proposal. CONCLUSIONS: The developed Bayesian estimators were all able to predict ciclosporin AUC(0,12 h) in HSCT patients using only three blood with minimal bias and may be combined to increase the reliability of CsA dose adjustment in routine.

Elimination study of intact lipid nanocapsules after intravenous rat administration.

Aim: The present study investigated renal elimination after intravenous administration of four different formulations of lipid nanocapsules (LNCs) containing dyes adapted to Förster resonance energy transfer (FRET-LNCs).Materials & methods: FRET-LNCs of 85 or 50 nm with or without a pegylated surface were injected and collected in the blood or urine of rats at different time points. Quantitative analysis was performed to measure intact FRET-LNCs.Results & conclusion: No intact LNCs were found in urine (0 particles/ml) for all formulations. The 50-nm pegylated LNCs were eliminated faster from the blood, whereas 85-nm pegylated LNCS were eliminated slower than nonpegylated LNCs. Elimination of FRET-LNCs was mainly due to liver tissue interaction and not renal elimination.

This study confirmed that the elimination of FRET LNCs is likely mainly due to liver tissue interaction and not renal elimination. #nanomedicines #lipidnanocapsules #FRET #pharmacokinetic #biodistribution.

Protein corona formation on lipidic nanocapsules: Influence of the interfacial PEG repartition.

The parameters currently used for characterization of nanoparticles, such as size and zeta potential, were not able to reflect the performance of a nanocarrier in the biological environment. Therefore, more thorough in vitro characterization is required to predict their behavior in vivo, where nanoparticles acquire a new biological identity due to interactions with biomolecules. In this present study, we performed in vitro characterization in biological fluids for lipid nanocapsules (LNCs) with varying means sizes (50 nm and 100 nm), different electrical surface charges and different Poly Ethylene Glycol (PEG) compositions. Then, different methods were applied to show the impact of the protein corona formation on LNCs. Even if all formulations attached to plasmatic proteins, a higher thickness of corona and highest protein binding was observed for certain LNC50 formulations. A better knowledge of the phenomenon of protein adsorption over NPs in the plasmatic media is a cornerstone of clinical translation. In fact, after short blood circulation time, it is not the initially designed nanoparticle but the complex nanoparticle bearing its protein corona which circulates to reach its target.

Stability of a high-concentrated aqueous solution of idarubicin stored in a polypropylene syringe for transarterial chemoembolization.

Idarubicin (IDA) is an antineoplasic drug commonly used to treat hematologic diseases. Because of its relative lipophilic properties, this anthracycline is also used in transarterial chemoembolization (TACE) as part of hepatocellular carcinoma (HCC) treatment. But TACE requires injected volume to be reduced to restrict systemic diffusion and side effects. The aim of this study was to determine the stability of a highly concentrated aqueous solution of IDA, stored in polypropylene syringes between 2 °C and 8 °C. Analyses were performed with an HPLC system combined with UV detector and mass spectrometer. Forced degradation was used to investigate potential degradation products. This study demonstrated 7 days of stability after storage in previously mentioned conditions. This conservation is long enough to anticipate drug preparation and facilitates pharmacy organization.

Pharmacokinetics of intact lipid nanocapsules using new quantitative FRET technique.

The present study investigated the pharmacokinetics of intact lipid nanocapsules (LNCs) after intravenous administration in rats. Six different Förster resonance energy transfer LNCs (FRET-LNCs) have been studied with 2 sizes (50 and 85 nm) and 3 coating types (none, DSPE-mPEG 2000 or stearylamine). A FRET-LNCs blood extraction method was developed to retain an accurate FRET signal. Intact FRET-LNCs were specifically quantified through combination of FRET signal and Nano Tracker Analysis. Pharmacokinetic data were first described by non-compartmental analysis, then used to develop a population pharmacokinetic model. The pharmacokinetic elimination of FRET-LNCs was non-linear and dependent on size and surface modification, while the distribution was dependent on size. The LNCs 85 nm volume of distribution was lower than LNCs 50 nm. As expected, LNCs 85 nm with PEG coating displayed a lower clearance than other formulations. Surprisingly, this study highlighted a faster elimination of LNCs 50 nm with PEG compared to other formulations which could be explained by instability in blood. This first pharmacokinetic model of intact LNCs allowed a thorough understanding of the influence of size and coating on pharmacokinetic properties and paves the way for future mechanistic modeling approaches to predict the fate of LNCs in vivo.

Specificity of pharmacokinetic modeling of nanomedicines.

Nanomedicines have been developed for more than four decades to optimize the pharmacokinetics (PK) of drugs, especially absorption, distribution, and stability in vivo. Unfortunately, only a few drug products have reached the market. One reason among others is the lack of proper PK modeling and evaluation, which impedes the optimization of these promising drug delivery systems. In this review, we discuss the specificity of nanomedicines and propose key parameters to take into account for future accurate PK evaluation of nanomedicine. We believe that this could help these innovative drug products to reach to market and change the fate of many diseases.