The sub-chronic impact of mPEG2k-PCLx polymeric nanocarriers on cytochrome P450 enzymes after intravenous administration in rats

A topical thermosensitive hydrogel system with cyclosporine A PEG-PCL micelles alleviates ulcerative colitis induced by TNBS in mice

Ulcerative colitis (UC) is an idiopathic, chronic, relapsing disease. In most cases, only the distal colon is affected, and the colonic stasis or fast colonic transit through the inflamed colon usually results in reduced exposure of the distal inflamed colon. Although the immunosuppressant cyclosporine A (CsA) has been used in patients with severe colitis who do not respond to corticosteroids, the clinical application of CsA remains limited due to the systemic toxicities and insufficient accumulation at the site of action for the intravenous and oral routes. In this study, we loaded CsA into the amphipathic poly(ethylene glycol)-poly(ε-caprolactone) (PEG-PCL) micelles and then embedded them in hydrogels consisting of chitosan, poloxamer 188, and poloxamer 407 to construct a thermosensitive and mucoadhesive hydrogel drug delivery system (PLCP). The PLCP presented a high drug-loading capacity and showed a stable and rapid gelation rate after rectal administration into the body. Compared to CsA-loaded micelles and Sandimmun (Neoral®), the developed thermosensitive gel exhibited prolonged retention on the inflamed colon, as seen from in vitro adhesion and in vivo distribution experiments. It also fast mitigated colitis symptoms in TNBS-treated mice by regulating the expression levels of proinflammatory cytokines (TNF-α, IL-1β, COX-2, and iNOS2), anti-inflammatory cytokines (IL-10, Nrf2, NQO1, and HO-1), and other relevant biochemical factors. Our results suggested that CsA-loaded micelle thermal hydrogel system could be a promising strategy by enhancing the retention in the diseased colon and promoting the relief and recovery of UC.

Enteric Polymer-Based Amorphous Solid Dispersions Enhance Oral Absorption of the Weakly Basic Drug Nintedanib via Stabilization of Supersaturation

The pH−induced crystallization of weakly basic drugs in the small intestine limits oral bioavailability. In this study, we investigated the solubilization and inhibitory effects on nintedanib in the presence of enteric polymers (HPMCAS LG, HPMCAS MG, Eudragit L100 55, and Eudragit L100). These polymers provided maintenance of supersaturation by increasing the solubility of nintedanib in PBS 6.8 in a concentration-dependent manner, and the improved ranking was as follows: Eudragit L100 > Eudragit L100 55 > HPMCAS MG > HPMCAS LG. After being formulated into amorphous solid dispersions (ASDs) by a solvent evaporation method, the drug exhibited an amorphous state. The pH shift dissolution results of polymer-ASDs demonstrated that four polymers could effectively maintain the drug supersaturation even at the lowest ratio of nintedanib and polymer (1:1, w/w). Eudragit L100−ASD could provide both acid resistance and the favorable mitigation of crystallization in GIF. In comparison to the coarse drug, the relative bioavailability of Eudragit L100−ASD was 245% after oral administration in rats, and Tmax was markedly delayed from 2.8 ± 0.4 h to 5.3 ± 2.7 h. Our findings indicate that enteric ASDs are an effective strategy to increase the intestinal absorption of nintedanib by improving physiologically generated supersaturation and subsequent crystallization.

The In Vivo Pharmacokinetics of Block Copolymers Containing Polyethylene Glycol Used in Nanocarrier Drug Delivery Systems

Polyethylene glycol (PEG) is one of the most commonly used synthetic macromolecular polymers for modifying small molecule drugs, peptides, proteins, or nanodrug delivery systems to improve their water solubility, biocompatibility, and stability. Block copolymers containing PEG have been widely used in nanodrug delivery systems such as solid lipid nanoparticles, polymeric nanoparticles, polymeric micelles, and liposomes. To date, although numerous PEGylated nanodrug delivery systems have been developed, only a few have been approved for clinical application. Poor safety and effectivity are important reasons for the high failure rate of nanodrug delivery system clinical trials. These factors are not only related to the loaded drugs and released drugs but are also related to the nanocarriers. Therefore, investigating the in vivo spatiotemporal fate of block copolymers containing PEG used in nanodrug delivery systems is necessary and important for evaluating their safety, efficacy, and toxicity. In this article, we will review the information that has been reported about the absorption, distribution, metabolism, and excretion of block copolymers containing PEG. We believe this review is helpful to understand the biologic fate of block copolymers containing PEG.This review describes pharmacokinetic study of block copolymers containing polyethylene glycol. The main focus of this paper is the in vivo fate of these polyethylene glycol-related copolymers after their release from nanocarriers. This review is helpful for understanding of the in vivo fate of block copolymers containing polyethylene glycol used in nanocarrier drug delivery systems.

mPEG2k-PCLx Polymeric Micelles Influence Pharmacokinetics and Hypoglycemic Efficacy of Metformin through Inhibition of Organic Cation Transporters in Rats

Increasing evidence has shown that nanocarriers have effects on several efflux drug transporters. To date, little is known about whether influx transporters are also modulated. Herein, we investigated the impact of amphiphilic polymer micelles on the uptake function of organic cation transporters (OCTs) and the influence on the pharmacokinetics and pharmacodynamics of metformin, a well-characterized substrate of OCTs. Five types of polymeric micelles (mPEG_2k-PCL_2k, mPEG_2k-PCL_3.5k, mPEG_2k-PCL_5k, mPEG_2k-PCL_7.5k, and mPEG_2k-PCL_10k) were prepared to evaluate the inhibition of hOCT1-3-overexpressing Madin-Darby canine kidney cells. The mPEG_2k-PCL_x micelles played an inhibitory role above the critical micelle concentration. The inhibitory potency could be ranked as mPEG_2k-PCL_2k > mPEG_2k-PCL_3.5k > mPEG_2k-PCL_5k > mPEG_2k-PCL_7.5k > mPEG_2k-PCL_10k, which negatively declined with the increase of molecular weight of the hydrophobic segment. The inhibitory effects of polymeric micelles on the hOCT1 isoform were the most pronounced, with the lowest IC₅₀ values ranging from 0.106 to 0.280 mg/mL. The mPEG_2k-PCL_2k micelles distinctly increased the plasma concentration of metformin and significantly decreased V_ss by 35.6% (p < 0.05) after seven consecutive treatments in rats, which was interrelated with the restrained metformin distribution in the liver and kidney. The uptake inhibition of micelles on hepatic and renal rOcts also diminished the glucose-lowering effect of metformin and fasting insulin levels in the oral glucose tolerance test. Consistent with the inhibitory effects, the mRNA and protein levels of rOct1 and rOct2 were decreased in the liver, kidney, and small intestine. The present study demonstrated that mPEG_2k-PCL_x micelles could inhibit the transport function of OCTs, indicating a potential risk of drug-drug interactions during concomitant medication of nanomedicine with organic cationic drugs.