Population pharmacokinetic analysis for dabigatran etexilate in Chinese patients with non-valvular atrial fibrillation.

We aimed to develop a pharmacokinetic (PK) and pharmacodynamic (PD) model from healthy Chinese subjects and real-world non-valvular atrial fibrillation (NVAF) patients. We also investigated meaningful intrinsic and extrinsic factors and related biomarkers for bleeding events. We characterized the integrated PK/PD models based on rich PK/PD data [dabigatran concentration, activated partial thromboplastin time (APTT), prothrombin time (PT), and anti-factor IIa (anti-FIIa) activity] from 118 healthy volunteers and sparse PD data [APTT, PT, and anti-FIIa] from 167 patients with NVAF after verifying the model extrapolation performance. We also documented the correlations between PD biomarkers and clinically relevant bleeding events over one year. Next, we used the final integrated PK/PD model (a two-compartment, linear model with first-order absorption) to evaluate the influence of dosage and individual covariates on PD parameters. The age, high-density liptein cholesterol (HDL-C), and creatinine clearance (CrCL) improved the PK model fit. The linear direct-effects PD model described the correlation between APTT, PT, and anti-FIIa and plasma concentration. CrCL improved the PD model fit. Anti-FIIa was more sensitive to the increase in dabigatran exposure than APTT and PT in the PD model. Therefore, fixed dabigatran doses could be prescribed for patients with NVAF without adjusting for age and HDL-C. We observed an elevated bleeding tendency with higher peak and trough values of APTT, PT, and anti-FIIa. Randomized studies should be performed to evaluate the efficacy and safety of low-dose dabigatran in Chinese patients with NVAF.

Inhibition of Escherichia coli nitroreductase by the constituents in Syzygium aromaticum.

Gut bacterial nitroreductases play an important role in reduction of various nitroaromatic compounds to the corresponding N-nitroso compounds, hydroxylamines or aromatic amines, most of which are carcinogenic and mutagenic agents. Inhibition of gut nitroreductases has been recognized as an attractive approach for reducing mutagen metabolites in the colon, so as to prevent colon diseases. In this study, the inhibitory effects of 55 herbal medicines against Escherichia coli(E. coli) nitroreductase (EcNfsA) were examined. Compared with other herbal extracts, Syzygium aromaticum extract showed superior inhibitory potency toward EcNfsA mediated nitrofurazone reduction. Then, the inhibitory effects of 22 major constituents in Syzygium aromaticum against EcNfsA were evaluted. Compared with other tested natural compounds, ellagic acid, corilagin, betulinic acid, oleanic acid, ursolic acid, urolithin M5 and isorhamnetin were found with strong to moderate inhibitory effect against EcNfsA, with IC50 values ranging from 0.67 to 28.98 mol·L-1. Furthermore, the inhibition kinetic analysis and docking simulation demonstrated that ellagic acid and betulinic acid potently inhibited EcNfsA (Ki < 2 µmol·L -1) in a competitively inhibitory manner, which created strong interactions with the catalytic triad of EcNfsA. In summary, our findings provide new scientific basis for explaining the anti-mutagenic activity of Syzygium aromaticum, where some newly identified EcNfsA inhibitors can be used for developing novel agents to reduce the toxicity induced by bacterial nitroreductase.

[Effect of Açaí oil, alcohol extract and water extract on temperature tendency and metabolic level of mice with deficiency-feat and deficiency-cold].

To investigate the effect of resolution components, such as Açaí oil, alcohol extract and water extract, on the temperature tendency animal behavior and intrinsic biochemical indexes, such ascyclic nucleotides and metabolic level, in mice with deficiency-heat and deficiency-cold syndrome, in order to study the characteristics of the cold and heat properties of each resolution component of Açaí and the material basis of cooling. KM mice were randomly divided into 12 groups, namely blank group, deficiency-heat model group, deficiency-heat+Açaí group, deficiency-heat+Açaí oil group, deficiency-heat+Açaí alcohol extract group, deficiency-heat+Açaí water extract group, deficiency-cold model group, deficiency-cold+Cinnamomi Cortex group, deficiency-cold+Açaí group, deficiency-cold+Açaí oil group, deficiency-cold+Açaí alcohol extract group, deficiency-cold+Açaí water extract group. The mice in deficiency-heat group were given thyroid tablet solution(160 mg·kg~(-1)), the mice in deficiency-cold group were given hydrocortisone solution(25 mg·kg~(-1)) through gastric perfusion every afternoon for 14 days, and each administration group was given the corresponding drug. The temperature tendency, cyclic nucleotides and metabolic level of animals were measured after the experiment. The Açaí alcohol extract was consistent with the Açaí powder, with a regulatory effect on the deficiency-heat model mice; Açaí oil and its water extract were consistent with Cinnamomi Cortex, with a regulatory effect on the deficiency-cold model mice. In this study, based on the parable theory of traditional Chinese medicine's properties and tastes, property of alcohol extract of Açaí was cool, while the property of oil and water extract were warm, the alcohol extract of Açaí was the material basis of Açaí cold medicine by the methods of homogeneous comparison and heterogeneous disproval.