Quercetin pretreatment increases the bioavailability of pioglitazone in rats: involvement of CYP3A inhibition

Herbal antidiabetic preparations are often used as an add-on therapy in diabetes and such herbal preparations often contains quercetin that can inhibit cytochrome P450 (CYP) 3A4. This enzyme is responsible for metabolizing pioglitazone, a commonly used antidiabetic agent. Hence, it was speculated that quercetin may influence the bioavailability of pioglitazone, which could be particularly crucial, as any increment in its plasma levels may raise safety concerns. Thus, we first established the inhibitory influence of quercetin (2, 10 and 20 mg/kg, p.o.) on CYP3A activity by an in vivo method of estimating levels of midazolam in female rats pretreated with dexamethasone. It was further confirmed in vitro using erythromycin-N-demethylase (EMD) assay. These studies indicated potent inhibition of CYP3A activity by quercetin (10 and 20 mg/kg, in vivo; 1 and 10 microM, in vitro). In another experiment, pioglitazone was administered orally (10 mg/kg) and intravenously (5mg/kg) to quercetin (10 mg/kg) pretreated female rats and its plasma levels were determined at various time points (0.5, 1, 2, 4, 8 and 24 h after oral administration; 0.083, 0.5, 1, 2, 8, 12 and 18 h after i.v. administration) by HPLC. Quercetin pretreatment increased AUC(0-infinity) of pioglitazone after oral administration by 75% and AUC(0-infinity) after intravenous administration by 25% suggesting decreased metabolism, which could be due to inhibition of CYP3A by quercetin. In conclusion, add-on preparations containing quercetin may increase the bioavailability of pioglitazone, and hence should be cautiously used.     

β-内酰胺酶抑制剂复方制剂非临床研究技术指南

β-内酰胺酶抑制剂复方制剂在临床上被广泛应用于治疗耐药菌所致感染,由于早期β-内酰胺酶抑制剂的抑酶谱较 窄,抑酶谱更广泛的酶抑制剂在不断研发之中。与一般抗菌药物临床前研究不同,β-内酰胺酶抑制剂复方制剂的临床前研究需 明确β-内酰胺类药物或酶抑制剂本身的抗菌谱与抗菌活性,尤其是明确酶抑制剂是否具有抗菌活性。需要确定合适的β-内酰胺 类药物与酶抑制剂复方制剂,以及适用的不同酶型的目标病原菌。本文主要介绍新型β-内酰胺酶抑制剂复方制剂临床前研究方 法。临床前研究阶段的β-内酰胺酶抑制剂复方制剂研究包括体外研究和体内研究两部分,前者主要为体外药效学研究和体外药 动学/药效学(pharmacokinetic/pharmacodynamic, PK/PD)研究,常用研究方法包括β-内酰胺类药物和β-内酰胺酶抑制剂复方制剂最 低抑菌浓度测定、最低杀菌浓度测定、抗生素后效应测定及时间杀菌曲线。后者主要为动物药动学研究、感染动物药效学研究 和感染动物药动学/药效学研究。在动物药动学/药效学研究中,需考虑β-内酰胺类药物与酶抑制剂的相互影响。这些研究方法的 应用旨在阐明β-内酰胺酶抑制剂复方制剂两组分药效学特点、药动学相似与否、PK/PD指数及其临床前PK/PD靶值,为进入临 床试验阶段目标适应症及剂量选择提供依据。     

LC–MS/MS method for the quantitation of decitabine and venetoclax in rat plasma after SPE: Application to pharmacokinetic study

This study developed a novel, sensitive and selective LC-MS/MS method for the concurrent determination of DCB and VTX in rat plasma using encorafenib as internal standard (IS). To identify DCB, VTX, and IS, the positive multiple reaction monitoring (MRM) mode was used. Chromatographic separation was carried out using a reversed-phase Agilent Eclipse plus C18 column (100 mm × 2.1 mm, 3.5 µm) and an isocratic mobile phase made up of water with 0.1% formic acid and acetonitrile (50:50, v/v, pH 3.2) at a flow rate of 0.30 mL/min for 3.0 min. Prior to analysis, the DCB and VTX with the IS were extracted from plasma using the solid-phase extraction (SPE) method. High recovery rates for DCB, VTX and IS were achieved using the C18 cartridge without interference from plasma endogenous. The developed method was validated as per the FDA guidelines over a linear concentration range in rat plasma from 5–3000 and 5–1000 ng/mL for DCB and VTX, respectively with r² ≥ 0.998. For both drugs, the lower limits of detection (LLOD) were 2.0 ng/mL. After the HLOQ sample was injected, less than 20% of the LLOQ of DCB, VTX, and less than 5% of the IS carry-over in the blank sample was attained. The overall recoveries of DCB and VTX from rat plasma were in the range of 90.68–97.56%, and the mean RSD of accuracy and precision results was ≤6.84%. For the first time, the newly developed approach was effectively used in a pharmacokinetic study on the simultaneous oral administration of DCB and VTX in rats that received 15.0 mg/kg of DCB and 100.0 mg/kg of VTX.     

Novel food drug interaction mechanism involving acyclovir,chitosan and endogenous mucus

Drug absorption from drug products may be affected by pharmaceutical excipients and/or food additives through different mechanisms. Chitosan is a recognized nutraceutical, with potential as an excipient due to its permeability enhancer properties. While chitosan properties have been evaluated in in vitro and pre-clinical models, studies in humans are scarce. Unexpectedly, a controlled clinical trial showed chitosan actually reduced acyclovir bioavailability. The effect seems to be related to an interaction with gastrointestinal mucus that prevents further absorption, although more in depth research is needed to unravel the mechanism. In this paper, we propose a mechanism underlying this excipient effect. The mucus – chitosan interaction was characterized and its effect on acyclovir diffusion, permeation and bioaccessibility was investigated. Further, pharmacokinetic modeling was used to assess the clinical relevance of our findings. Results suggest that in situ coacervation between endogenous mucus and chitosan rapidly entrap 20–30% of acyclovir dissolved dose in the intestinal lumen. This local reduction of acyclovir concentration together with its short absorption window in the small intestine would explain the reduction in acyclovir C_max and AUC. This study highlights the importance of considering mucus in any biorelevant absorption model attempting to anticipate the effect of chitosan on drug absorption.     

Safety evaluation to support First-In-Man investigations I: kinetic and safety pharmacology studies

Kinetic (in vitro, pharmacokinetic, mass balance and toxicokinetic studies) and safety pharmacology data available in 34 Investigator's Brochures used to support First-In-Man clinical trials over a 10 year period have been evaluated to give an insight into the types of study designs used and how these have changed over the period analysed (1997-2006). For kinetic evaluation, study packages often had single dose pharmacokinetic studies in the rodent and non-rodent by oral and intravenous dose routes as well as protein binding measurement accompanied more recently by rodent mass balance studies and an examination of in vitro metabolism across species and/or enzyme activity with hepatocytes, liver microsomes or recombinantly expressed enzymes. Toxicokinetic data were examined from key repeat dose toxicity studies in rodents and non-rodents with the recent inclusion of sampling in control animals to check for drug contamination. For safety pharmacology evaluation, study packages included "core battery" rodent central nervous system as well as anaesthetised non-rodent cardiovascular and respiratory function studies. More recently, cardiovascular assessment occurred in conscious non-rodents, necessitating stand-alone rodent respiratory function studies although conscious models assessing both cardiovascular and respiratory function were also seen in some of the most recent packages. Recent packages also had an in vitro electrophysiology study, usually the hERG assay. Considerations for kinetic and safety pharmacology study designs are discussed.     

Disposition of 4-bromo-2,5-dimethoxyphenethylamine (2C-B) and its metabolite 4-bromo-2-hydroxy-5-methoxyphenethylamine in rats after subcutaneous administration

The psychedelic compound 4-bromo-2,5-dimethoxyphenethylamine (2C-B) has appeared as an agent in drug abuse or overdose cases in humans. The human pharmacokinetics of this drug is unknown and only partial information is available on its metabolites. Our experimental study was focused on the disposition and kinetic profile of 2C-B in rats after subcutaneous administration using a GC-MS validated method. One of the major metabolites 4-bromo-2-hydroxy-5-methoxyphenethylamine (2H5M-BPEA) was confirmed in rat tissues of lung, brain, liver and was quantitatively evaluated as well. The disposition of 2C-B was characterized by its estimated half-life 1.1h and estimated volume of distribution 16L/kg. The lung susceptibility for drug retention and gradual temporal release parallel to the brain were ascertained. The drug penetrating the blood/brain barrier was without significant delay. 2C-B brain to serum ratio attained a maximum value of 13.9 and remained over the value of 6.5 to the end of our observation (6h after the dose). The distribution of the hydroxylated metabolite 2H5M-BPEA into the lipophilic brain tissue was less efficient in relation to the parent compound. The kinetics of the drug partitioning between blood to brain may be important for the subsequent assessment of its psychotropic or toxic effects.     

Pharmacoscintigraphic and pharmacokinetic evaluation on healthy human volunteers of sustained-release floating minitablets containing levodopa and carbidopa

In this study, scintigraphic and pharmacokinetic studies were conducted on 10 healthy, fed volunteers. Two concepts of sustained-release floating minitablets--Levo-Form 1 (matrix) and 2 (coated)--were evaluated and compared to the marketed product Prolopa HBS 125. All the floating forms were radiolabelled with (111)In in order to evaluate their gastric residence time using gamma-scintigraphy. It was shown that the three formulations offered almost the same mean gastric residence time, which was about 240 min. Prolopa HBS 125 and Levo-Form 2 presented intragastric disintegration, which can lead to a more pronounced "peak & valley" effect on the plasma concentration-time profile of levodopa. In contrast, the plasma concentration-time profile of levodopa following the administration of Levo-Form 1 was more evenly distributed. Moreover, Levo-Form 1 provided the lowest variations between men and women in terms of AUC and C(max) values. Finally, when the same amount of inhibitors of extracerebral dopa decarboxylase--carbidopa and benserazide--had been administrated, the mean AUC, C(max) and T(max) values obtained for benserazide were lower than those obtained for carbidopa.     

HPLC-MS/MS法测定比格犬血浆中PA-824的浓度及其药动学研究

摘 要 目的：建立高效液相色谱 质谱连用（HPLC MS/MS）测定比格犬血浆中PA 824的浓度,以及进行PA 824在比格犬体内的药动学研究。方法: 以卡马西平为内标,生物样品预处理采用乙酸乙酯萃取。色谱柱为Eclipse Plus C18柱（100 mm×2.1 mm,3.5 μm）,流动相为甲醇 水（90∶10）,流速为0.6 ml·min^-1,柱温为30℃,进样量为5 μl,样品分析时间为5 min;电喷雾电离源（ESI）,正离子多反应监测扫描分析,PA 824离子对为m/z360.1→m/z 175.0（碰撞能量：35,解簇电压：65）,卡马西平离子对为m/z 237.2→m/z 194.0（碰撞能量：28,解簇电压：83）。比格犬口服给药之后,在不同的时间点取血测定血浆中PA 824的含量,然后再用DAS 2.0软件进行药代动力学参数的计算。结果: 比格犬口服给药之后,PA 824在50～10 000 ng·mL^-1 （r=0.999 1）范围内呈线性关系,回收率为97.7%～105.1%,日内、日间精密度RSD均<5.0%。PA 824 3个不同给药量（100,200,500 mg）的AUC0 t分别为（5 735.18±1 918.76）,（11 548.47±1 838.04）,（21 987.88±4 587.58）ng·min·ml^-1,t^1/2分别为（14.17±5.97）,（11.11±4.39）,（13.13±5.46）h,Cmax分别为（626.66±188.48）,（2 399.13±516.51）,（4 861.33±2 253.61）ng·ml^-1。结论:该方法简单、准确、快速、重复性好,适用于比格犬血浆PA 824的药代动力学研究。     

Chemical-specific adjustment factors (inter-species toxicokinetics) to establish the ADI for steviol glycosides

The acceptable daily intake (ADI) of commercially available steviol glycosides is currently 0–4 mg/kg body weight (bw)/day, based on application of a 100-fold uncertainty factor to a no-observed-adverse-effect-level value from a chronic rat study. Within the 100-fold uncertainty factor is a 10-fold uncertainty factor to account for inter-species differences in toxicokinetics (4-fold) and toxicodynamics (2.5-fold). Single dose pharmacokinetics of stevioside were studied in rats (40 and 1000 mg/kg bw) and in male human subjects (40 mg/kg bw) to generate a chemical-specific, inter-species toxicokinetic adjustment factor. T_max values for steviol were at ∼8 and ∼20 h after administration in rats and humans, respectively. Peak concentrations of steviol were similar in rats and humans, while steviol glucuronide concentrations were significantly higher in humans. Glucuronidation in rats was not saturated over the dose range 40–1000 mg/kg bw. The AUC_0-last for steviol was approximately 2.8-fold greater in humans compared to rats. Chemical-specific adjustment factors for extrapolating toxicokinetics from rat to human of 1 and 2.8 were established based on C_max and AUC_0-last data respectively. Because these factors are lower than the default value of 4.0, a higher ADI for steviol glycosides of between 6 and 16 mg/kg bw/d is justified.     

TU治疗男性性腺功能低下的药代动力学和药效学研究

目的 :本文对长效雄激素注射剂十一酸睾酮 (TU) ,治疗原发性性腺功能低下 (Klinefelter综合征 )的药代动力学以及临床药效学进行观察 ,了解使用该药的最佳间隔时间和最佳剂量。同时为男子性腺功能低下的雄激素替代治疗和男性激素避孕研究与临床实践提供理论依据。　方法 :8例Klinefelter综合征病人接受初次 5 0 0mg或 10 0 0mgTU肌肉注射 ,间隔 3月后交叉剂量 ,5 0 0mg或 10 0 0mgTU注射。观察治疗前后性腺、第二性征变化。同时在不同时相取血 ,以放射免疫法 (RIA)测定有关激素的水平。了解一次注射该药后在体内维持有效浓度的时间 ,并用专用软件分析睾酮 (T)药代动力学。　结果 :注射两种剂量TU后 ,所有病人的性功能和第二性征都有改善。垂体激素FSH和LH均显著抑制 ,对LH作用较FSH更大。血清睾酮 (T)水平在注射后一周迅速升高达到峰值 ,在 5 0 0mg和 10 0 0mg两种剂量分别为 (4 7 8± 10 1)nmol/L和 (5 4 2± 4 8)nmol/L ,维持有效治疗T水平达 5 0～ 6 0d。两种剂量TU的半寿期分别为 (18 3± 2 3)d和 (2 3 7± 2 7)d ,平均滞留时间为 (2 1 7± 1 1)d和 (2 3 0± 0 8)d。第 2次注射5 0 0mgTU较第 1次注射产生更佳的药代动力学。　结论 :对性腺功能低下男子的雄激素替代治疗 ,单一剂量TU可维持 6～ 8