Establishment of HPLC-ESI-MS method for the determination of eplerenone in human plasma and its pharmacokinetics.

A sensitive high performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) method was established for the determination of eplerenone (EP) in human plasma. The plasma samples of EP were extracted with ethyl acetate and separated by HPLC on a reversed phase C18 column with a mobile phase of 10 mmol x L(-1) ammonium acetate water solution-methanol (30 : 70, v/v). EP was determined with electrospray ionization-mass spectrometry (ESI-MS) in the selected ion monitoring (SIM) mode. The calibration curves were linear over the range of 2-4 000 ng x mL(-1) for EP. The lower limit of quantification was 2 ng x mL(-1). The method has been successfully applied in the pharmacokinetic study of the EP tablets. The main pharmacokinetic parameters of EP after oral administration of 25 mg, 50 mg, 100 mg were as follows, t1/2: (4.9 +/- 2.1), (4.7 +/- 1.5), (5.9 +/- 1.2) h; AUC(0-infinity): (4 402 +/- 1 735), (8 150 +/- 2 509), (13 783 +/- 4 102) microg x h x L(-1); and MRT: (6.2 +/- 2.1), (6.6 +/- 1.3), and (7.2 +/- 1.6) h. Parameters of EP after oral administration of multiple doses of 50 mg were as follows, t1/2: (6.1 +/- 1.7) h; AUC(ss): (10 071 +/- 4220) microg x h x L(-1); MRT: (8.1 +/- 2.3) h; and DF: (3.2 +/- 1.0).

Endoplasmic reticulum stress-mediated apoptosis signal pathway is involved in sepsis-induced liver injury.

Endoplasmic reticulum (ER) stress has been increasingly recognized to have an important role in various liver diseases. Sepsis-induced multi-organ failure remains to have a high mortality rate, and the liver plays a central pathophysiological role. This study aims to explore whether ER stress is involved in liver injury in septic rats. Sepsis was induced via cecal ligation and puncture (CLP). Rats were randomly divided into five groups as follows: sham, CLP 2 h, CLP 6 h, CLP 12 h, and CLP 24 h. They were monitored to record body weight (BW) and liver weight changes for every time point after surgery. The levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were detected via colorimetric activity assays. In addition, the morphological changes of the liver tissue were evaluated by staining the sections with hematoxylin and eosin and observing under light microscopy. The levels of glucose-regulated protein 78 (GRP78), CCAAT/enhancer-binding protein homologous protein (CHOP), and cleaved caspase-12 were detected via Western blot analysis. Apoptosis was detected via terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) method. The results showed that septic rat serums ALT and AST were increased, with the increase being more obvious in the CLP 24 h group. In addition, septic rats appeared to have histopathological abnormalities in the liver. The liver weight and index increased after CLP. No differences were noted in the BW between septic groups. The level of GRP78, CHOP, and cleaved caspase-12 were upregulated after CLP. However, CHOP and caspase-12 were induced later than GRP78. The density of TUNEL-positive apoptotic hepatocytes was significantly increased after 12 h and 24 h CLP. It indicates that the unfolded protein response occurred in the early stage of sepsis-induced liver damage. The ER stress-mediated apoptosis signal pathway is among the mechanisms of septic liver injury and may be a target in clinical prevention and therapy of sepsis-induced liver injury.

Fabricating a sustained releaser of heparin using SBA-15 mesoporous silica.

The sustained release of heparin in sufficient amounts and over long time is a challenge to drive the development of functional materials. In this paper SBA-15 mesoporous silica is selected in the search for a favorable morphology and optimized surface state for the sustained release of heparin. In situ carbonization of the template in the as-synthesized sample enables SBA-15 to possess narrowed channels with rougher surfaces, while modification with (aminopropyl)triethoxysilane (APTES) through a one-pot synthesis offers SBA-15 with positive charges to attract heparin through electro-static interactions. The structure of modified SBA-15 samples is assessed with XRD (powder X-ray diffraction analysis), nitrogen adsorption-desorption and electron microscopy techniques, and their performance is evaluated in adsorption and release of heparin. These modifications improve the heparin adsorption in SBA-15 and thus promote its sustained release, prolonging the release-equilibrium time up to 60 days. Among them, the SBA-15 sample modified with APTES can trap three times as much heparin as the parent SBA-15, and the release ratio is elevated to 80% (that of SBA-15 is 38%), realizing the best performance of controlling heparin release to date.

Multiple functionalization of SBA-15 mesoporous silica in one-pot: fabricating an aluminum-containing plugged composite for sustained heparin release.

To fabricate an efficient releaser of heparin, which is an extensively used anticoagulant, aluminum containing plugged mesoporous silica SBA-15 is prepared using a one-pot synthesis process. A suitable aluminum additive in the starting mixture enables plugs to be formed inside hexagonal channels and Al species to be incorporated into the mesostructure, evidence for which is provided by powder X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), N2 sorption measurements and 27Al MAS NMR tests. Incorporation of aluminum in SBA-15 reduces the negative charge (Zeta-potential) and tailors the surface roughness of the channel through forming plugs, and the former significantly improves heparin adsorption while the latter retards heparin release. As a result, these modified composites adsorb 2-4 times more heparin than parent SBA-15 and release 60-130% more of the drug over several weeks; the sample possessing both an Al-component and plug structure can sustain release of heparin for 6 weeks, demonstrating the increased efficiency of multiply functionalized SBA-15 in the controllable release of heparin and offering a valuable clue for design of novel drug releasers.