Tracking immune-related cell responses to drug delivery microparticles in 3D dense collagen matrix.

Beyond the therapeutic purpose, the impact of drug delivery microparticles on the local tissue and inflammatory responses remains to be further elucidated specifically for reactions mediated by the host immune cells. Such immediate and prolonged reactions may adversely influence the release efficacy and intended therapeutic pathway. The lack of suitable in vitro platforms limits our ability to gain insight into the nature of immune responses at a single cell level.

Long-term distribution of biodegradable microparticles in rat muscle quantified noninvasively by MRI.

Purpose: To demonstrate the feasibility of MRI to monitor longitudinally the fate of PLGA microparticles in muscle tissue after intramuscular injection in rats using standard equipment.

Methods: MRI was performed at different time points and until day 28 after intramuscular administration of microparticles. Image segmentation was used to quantify the MRI signals.

Chitosan/glucose 1-phosphate as new stable in situ forming depot system for controlled drug delivery.

Chitosan (CS)-based thermosensitive solutions that turn into semi-solid hydrogels upon injection at body temperature have increasingly drawn attention over the last decades as an attractive new type of in situ forming depot (ISFD) drug delivery system. Despite the great potential of the standard CS/β-glycerophosphate (β-GP) thermogelling solutions, their lack of stability over time at room temperature as well as at refrigerated conditions renders them unsuitable as ready-to-use drug product. In the present study, we investigated Glucose-1-Phosphate (G1-P) as an alternative gelling agent for improving the stability of CS-based ISFD solutions.

Feasibility of macrophage mediated on-demand drug release from surface eroding poly(ethylene carbonate).

Macrophage induced surface degradation of poly(ethylene carbonate) (PEC) was investigated under in vitro conditions. Degradation of PEC with the MW of 41 kDa (PEC41) was slower than that of PEC with the MW of 200 kDa (PEC200). In terms of macrophage mediated drug release from PEC matrix, in cell-free medium, less than 1% of levofloxacin was released from both PEC samples in 10 days, while more than 60 and 20% of the drug, levofloxacin, can be detected in medium with macrophages from PEC200 and PEC41 films, respectively.

Thermosensitive chitosan/glycerophosphate-based hydrogel and its derivatives in pharmaceutical and biomedical applications.

Introduction: Thermogelling chitosan (CS)/glycerophosphate (GP) solutions have been reported as a new type of parenteral in situ forming depot system. These free-flowing solutions at ambient temperature turn into semi-solid hydrogels after parenteral administration.

Areas Covered: Formulation parameters such as CS physico-chemical characteristics, CS/gelling agent ratio or pH of the system, were acknowledged as key parameters affecting the solution stability, the sol/gel transition behavior and/or the final hydrogel structure.

In situ forming parenteral depot systems based on poly(ethylene carbonate): effect of polymer molecular weight on model protein release.

The objective of this study was to investigate the effect of molecular weight (MW) on the drug release from poly(ethylene carbonate) (PEC) based surface-eroding in situ forming depots (ISFD). In phosphate buffered saline (PBS) pH 7.4, 63.

Enzyme-responsive surface erosion of poly(ethylene carbonate) for controlled drug release.

Cholesterol esterase (CE) induced surface erosion of poly(ethylene carbonate) (PEC) and drug release from PEC under mild physiological environment was investigated. The degradation process was monitored by changes of mass and molecular weight (MW) and surface morphology of polymer films. During the whole period of degradation, MW of PEC was unchanged.

Poly(ethylene carbonate) nanoparticles as carrier system for chemotherapy showing prolonged in vivo circulation and anti-tumor efficacy.

The aim of this study is to investigate the feasibility and efficacy of PEC nanoparticles as delivery system for cancer chemotherapy. Assembly of paclitaxel-loaded nanoparticles with high loading efficiency and narrow-size distribution is successful. For non-invasive in vivo tracing, nanoparticle blends of chelator bearing poly(lactide) with PEC and PLGA are successfully prepared.

Drug eluting stents based on Poly(ethylene carbonate): optimization of the stent coating process.

First generation drug eluting stents (DES) show a fivefold higher risk of late stent thrombosis compared to bare metal stents. Therefore, new biodegradable and biocompatible polymers for stent coating are needed to reduce late stent thrombosis. In this study, a reproducible spray-coating process for stents coated with Poly(ethylene carbonate), PEC, and Paclitaxel was investigated.

Biodegradable poly(ethylene carbonate) nanoparticles as a promising drug delivery system with "stealth" potential.

The goal of this study was to investigate the suitability of poly(ethylene carbonate) (PEC) nanoparticles as a novel drug delivery system, fulfilling the requirements for a long circulation time. Particles were obtained with a narrow size distribution and nearly neutral zeta potential. Adsorption studies with human plasma proteins revealed that PEC nanoparticles bind much less proteins in comparison to polystyrene (PS) nanoparticles.

Poly(ethylene carbonate) as a surface-eroding biomaterial for in situ forming parenteral drug delivery systems: a feasibility study.

To evaluate the technical feasibility of poly(ethylene carbonate), PEC, for injectable in situ forming drug delivery systems, the physical properties of PEC solutions were characterized. The solubility of PEC was investigated in different solvents, and the Hildebrand solubility parameters and Flory-Huggins interaction parameters of PEC were determined. By turbidity titration, the experimental ternary phase diagram of water-NMP/DMSO-PEC was constructed.

Non-invasive assessment of the effect of formulation excipients on stratum corneum barrier function in vivo.

The objective of the present work was to investigate the effect of formulation excipients on human stratum corneum (SC) barrier function in vivo. Two formulations, an ointment and an oil-in-water cream, were applied to the skin of human volunteers under both occlusive and non-occlusive conditions. The effects of each treatment were then evaluated using three non-invasive biophysical techniques: transepidermal water loss (TEWL), impedance spectroscopy (IS) and attenuated-total-reflectance Fourier transform infrared (ATR-FTIR) spectroscopy.

Post-iontophoresis recovery of human skin impedance in vivo.

The objective of this study was to better understand the recovery of human skin impedance following iontophoresis in vivo. Volunteers were subjected to a 15-min period of iontophoresis in the presence of aqueous solutions of either NaCl, KCl, CaCl(2) or MgCl(2) at 133 mM. Subsequently, the low-frequency impedance (at 1 Hz) recovery was followed for a further 30 min.