Bottom-Up and Top-Down Approaches to Explore Sodium Dodecyl Sulfate and Soluplus on the Crystallization Inhibition and Dissolution of Felodipine Extrudates

The objectives of this study were to explore sodium dodecyl sulfate (SDS) and Soluplus on the crystallization inhibition and dissolution of felodipine (FLDP) extrudates by bottom-up and top-down approaches. FLDP extrudates with Soluplus and SDS were prepared by hot melt extrusion, and characterized by polarized light microscopy, differential scanning calorimetry, and fourier transform infrared spectroscopy. Results indicated that Soluplus inhibited FLDP crystallization, and the whole amorphous solid dispersions (ASDs) were binary FLDP-Soluplus (1:3) and ternary FLDP-Soluplus-SDS (1:2:0.15～0.3 and 1:3:0.2～0.4) extrudates. Internal SDS (5%-10%) decreased glass transition temperatures of FLDP-Soluplus-SDS ternary ASDs without presenting molecular interactions with FLDP or Soluplus. The enhanced dissolution rate of binary or ternary Soluplus-rich ASDs in the nonsink condition of 0.05% SDS was achieved. Bottom-up approach indicated that Soluplus was a much stronger crystal inhibitor to the supersaturated FLDP in solutions than SDS. Top-down approach demonstrated that SDS enhanced the dissolution of Soluplus-rich ASDs via wettability and complexation with Soluplus to accelerate the medium uptake and erosion kinetics of extrudates, but induced FLDP recrystallization and resulted in incomplete dissolution of FLDP-rich extrudates. In conclusion, top-down approach is a promising strategy to explore the mechanisms of ASDs' dissolution, and small amount of SDS enhances the dissolution rate of polymer-rich ASDs in the nonsink condition.     

Characterization of CYP2C Induction in Cryopreserved Human Hepatocytes and Its Application in the Prediction of the Clinical Consequences of the Induction

CYP2C enzymes play key roles in drug metabolism, and clinical drug-drug interactions caused by CYP2C induction have been reported. The aim of this study was to establish a method to predict the potency of CYP2C inductions considering the mechanism. We first investigated the relations of CYP2C induction with CYP3A4 or CYP2B6 induction in human hepatocytes after 48-h exposure with 19 inducers. The fold-induction values of CYP2C8 and CYP2C9 were well correlated with those of CYP3A4, whereas the inducers were separated into 2 groups showing different correlations with CYP2B6 induction for CYP2C8 and CYP2C9 induction. In the regression models established, the fold-induction values of CYP2C8 and CYP2C9 were well expressed as the functions of those of CYP3A4 and CYP2B6, while no such obvious correlation was observed for CYP2C19 induction. These results suggest that CYP2Cs are not simply coinduced with CYP3A4 and that CYP2C8 and CYP2C9 inductions are regulated by both pregnane X receptor and constitutive androstane receptor with different contributions. Finally, simple correlations were proposed using the experimental E_max values obtained and plasma concentrations of CYP2C9 substrates from the literature, and positive correlations were observed. These data provide methods to estimate the clinical impact of CYP2C9 induction from in vitro data.     

Prediction of drug‐drug interactions using physiologically‐based pharmacokinetic models of CYP450 modulators included in Simcyp software

In recent years, physiologically based PharmacoKinetic (PBPK) modeling has received growing interest as a useful tool for the assessment of drug pharmacokinetics. It has been demonstrated to be informative and helpful to quantify the modification in drug exposure due to specific physio‐pathological conditions, age, genetic polymorphisms, ethnicity and particularly drug–drug interactions (DDIs). In this paper, the prediction success of DDIs involving various cytochrome P450 isoenzyme (CYP) modulators namely ketoconazole (a competitive inhibitor of CYP3A), itraconazole (a competitive inhibitor of CYP3A), clarithromycin (a mechanism‐based inhibitor of CYP3A), quinidine (a competitive inhibitor of CYP2D6), paroxetine (a mechanism‐based inhibitor of CYP2D6), ciprofloxacin (a competitive inhibitor of CYP1A2), fluconazole (a competitive inhibitor of CYP2C9/2C19) and rifampicin (an inducer of CYP3A) were assessed using Simcyp^® software. The aim of this report was to establish confidence in each CYP‐specific modulator file so they can be used in the future for the prediction of DDIs involving new victim compounds. Our evaluation of these PBPK models suggested that they can be successfully used to evaluate DDIs in untested scenarios. The only noticeable exception concerned a quinidine inhibitor model that requires further improvement. Additionally, other important aspects such as model validation criteria were discussed.     

Indirect activation of pregnane X receptor in the induction of hepatic CYP3A11 by high-dose rifampicin in mice

Rifampicin (RIF), a typical ligand of human pregnane X receptor (PXR), powerfully induces the expression of cytochrome P450 3A4 (CYP3A4) in humans. Although it is thought that RIF is not a ligand of rodent PXR, treatment with high-dose RIF (e.g. more than 20?mg/kg) increases the expression of CYP3A in the mouse liver. In this study, we investigated whether the induction of CYP3A by high-dose RIF in the mouse liver is mediated via indirect activation of mouse PXR (mPXR). The results showed that high-dose RIF increased the expression of CYP3A11 and other PXR-target genes in the liver of wild-type mice but not PXR-knockout mice. However, the results of reporter gene and ligand-dependent assembly assays showed that RIF does not activate mPXR in a ligand-dependent manner. In addition, high-dose RIF stimulated nuclear accumulation of mPXR in the mouse liver, and geldanamycin and okadaic acid attenuated the induction of Cyp3a11 and other PXR-target genes in primary hepatocytes, suggesting that high-dose RIF triggers nuclear translocation of mPXR. In conclusion, the present study suggests that high-dose RIF stimulates nuclear translocation of mPXR in the liver of mice by indirect activation, resulting in the transactivation of Cyp3a11 and other PXR-target genes.     

Exploring the feasibility of the use of biopolymers as a carrier in the formulation of amorphous solid dispersions – Part I: Gelatin

Biopolymers have rarely been used so far as carriers in the formulation of amorphous solid dispersions (ASD) to overcome poor solubility of active pharmaceutical ingredients (APIs). In an attempt to enlarge our knowledge on this topic, gelatin, type 50PS was selected. A screening study was initiated in which twelve structurally different poorly soluble biopharmaceutical classification system (BCS) Class II drugs (carbamazepine, cinnarizine, diazepam, itraconazole, nifedipine, indomethacin, darunavir (ethanolate), ritonavir, fenofibrate, griseofulvin, ketoconazole and naproxen) were selected for evaluation. Solid dispersions of five different drug loadings of these twelve compounds were prepared by lyophilization and evaluated for their solid state properties by mDSC and XR(P)D, and in vitro dissolution performance. Even without any process optimization it was possible to form either fully amorphous or partially amorphous systems, depending on the API and API to carrier ratio. Hence in this respect, gelatin 50PS behaves as any other carrier. Dissolution of the API from the solid dispersions significantly exceeded that of their crystalline counterparts. This study shows the potential of gelatin as a carrier to formulate amorphous solid dispersions.     

Penta-block copolymer microspheres: Impact of polymer characteristics and process parameters on protein release

Here, we aimed to develop protein loaded microspheres (MSs) using penta-block PLGA-based copolymers to obtain sustained and complete protein release. We varied MS morphology and studied the control of protein release. Lysozyme was used as a model protein and MSs were prepared using the solid-in-oil-in-water emulsion solvent extraction method. We synthesized and studied various penta-block PLGA-based copolymers. Copolymer characteristics (LA/GA ratio and molecular weight of PLGA blocks) influenced MS morphology. MS porosity was influenced by process parameters (such as solvent type, polymer concentration, emulsifying speed), whereas the aqueous volume for extraction and stabilizer did not have a significant effect. MSs of the same size, but different morphologies, exhibited different protein release behavior, with porous structures being essential for the continuous and complete release of encapsulated protein. These findings suggest strategies to engineer the morphology of MSs produced from PLGA-based multi-block copolymers to achieve appropriate release rates for a protein delivery system.     

Cytochrome P450 genotype‐guided drug therapies: An update on current states

Over the past 2 decades, knowledge of the role and clinical value of pharmacogenetic markers has expanded so that individualized pre‐emptive therapy based on genetic background of patients could be within reach for clinical implementation. This is evidenced from the frequent updating of drug labels that incorporates pharmacogenetic information (where compelling data become available) by the regulatory agencies (such as the US FDA), and the periodical publication of guidelines of specific therapeutic recommendations based on the results of pharmacogenetic tests by the pharmacogenetics working groups or consortiums of professional bodies. Clinical relevance of the cytochrome P450 (CYP) polymorphism related to dose, effectiveness and/or toxicity of key drugs are presented in this review, including that of warfarin, clopidogrel, tricyclic antidepressants, and proton pump inhibitors. Prospect for routine clinical application of CYP genotyping before prescribing drugs is still currently unclear due to challenges and barriers associated with availability of well‐defined and validated pharmacogenetic studies, the interpretation, result reporting and potential error of genotype testing, involvement of non‐genetic factors, and other patient's demographic and disease conditions. Further studies to provide additional supporting clinical data and acceleration of pharmacogenetic testing standards and techniques should help improve the evidence base needed for clinical utility and hence move the implementation of genotype‐guided therapy in clinical practice a step closer to reality.     

细胞色素P4503A5~*3基因多态性与环孢素所致肝损伤相关性的评价

目的系统评价细胞色素P450 3A5*3(CYP3A5*3)基因多态性与环孢素所致的肝损伤的相关性。方法系统检索Pub Med、MedLine、EMbase、Cochrane图书馆、维普数据库、中国知网和万方数据库,查找CYP3A5*3基因多态性与环孢素致患者肝损伤相关性的研究,检索时间自各数据库建库至2016年3月。试验组为环孢素致肝损伤患者,对照组为无肝损伤患者或其他原因致肝损伤患者。用Rev Man 5. 2. 0软件进行Meta分析。结果共纳入病例对照研究3篇(包括英文1篇和中文2篇),患者807名。患者的基因型分布均符合Hardy-Weinberg平衡定律。试验组和对照组CYP3A5*3AA型的分布率分别为21. 70%(87例/401例)和22. 36%(91例/407例),差异有统计学意义(P <0. 01)。试验组和对照组中携带等位基因A的分布率分别为21. 20%和32. 89%,携带等位基因G的分布率分别为78. 80%和67. 11%,差异均无统计学意义(均P> 0. 05)。结论 CYP3A5*3基因多态性与环孢素致患者肝损伤相关,其中携带CYP3A5*3AA基因型的患者服用环孢素所致肝损伤的发生率较低,而此发生率与等位基因A和G的分布无关。     

熊果酸对K562/ADR细胞多药耐药基因1 mRNA和P-糖蛋白表达影响及机制研究

目的研究熊果酸对多药耐药基因1 (MDR1) mRNA和P-糖蛋白(P-gp)表达的影响及机制。方法空白组给予0. 5%二甲基亚砜(DMSO),核因子-κB(NF-κB)激动剂组给予5μmol·L^-1阿霉素,NF-κB抑制剂组给予25μmol·L^-1吡咯烷二硫代氨基甲酸盐(PDTC),实验组单独或联合激动剂或抑制剂给予5,10,25,50μmol·L^-1熊果酸。培养48 h后,用逆转录聚合酶链式反应(RT-PCR)检测MDR1 mRNA水平,用Western blot法测定P-糖蛋白和核蛋白P65的表达水平。结果与空白组比较,5,10,25,50μmol·L^-1熊果酸分别使MDR1 mRNA的表达下调了7. 41%,15. 58%,28. 75%和44. 21%(IC50=66. 04μmol·L^-1),P-糖蛋白的表达下调了23. 36%,37. 23%,43. 07%和64. 23%(IC50=26. 27μmol·L^-1)。与空白组相比,5,10,25,50μmol·L^-1熊果酸分别使P65的表达下调了13. 73%,28. 92%,44. 07%和56. 77%(IC50=34. 07μmol·L^-1),且熊果酸和PDTC在5～50μmol·L^-1均能明显抑制阿霉素诱导的P65的表达,差异均有统计学意义(均P <0. 05)。结论熊果酸可显著抑制K562/ADR细胞MDR1 mRNA和P-糖蛋白的表达,且对抗阿霉素的诱导作用;其机制可能是通过抑制MDR1 mRNA和P-糖蛋白的上游调控信号通路NF-κB位点核蛋白P65的表达;减少NF-κB的核转位,从而抑制NF-κB活性并干扰MDR1基因转录,最终导致MDR1 mRNA及P-糖蛋白表达量的下调。     

红酒多酚对细胞色素P4503A4介导的硝苯地平代谢的影响

目的体外研究红酒多酚成分对细胞色素P4503A4(CYP3A4)介导的硝苯地平代谢的影响。方法将红酒多酚、人肝微粒体及探针底物睾酮孵育后,用高效液相色谱法测定代谢产物6β-羟基睾酮的生成量,用来考察红酒多酚对CYP3A4抑制的浓度依赖性。将不同浓度红酒多酚、人肝微粒体与硝苯地平孵育,测定硝苯地平的减少率并计算IC₅₀值。在不同浓度硝苯地平存在下,绘制米氏曲线,得到红酒多酚存在时硝苯地平的代谢清除率CL_红酒(K_m-红酒/V_max-红酒),对比空白组,考察红酒多酚对硝苯地平代谢的影响。结果红酒多酚对CYP3A4存在明显的浓度依赖抑制效应(IC₅₀=18.29%)。在以硝苯地平为底物时,IC₅₀为25.04%。红酒多酚对硝苯地平的代谢清除率CL_红酒为14μL·min^-1·mg^-1,显著低于空白组(640μL·min^-1·mg^-1)。结论红酒多酚可通过抑制CYP3A4的活性,减少其对硝苯地平的代谢,具有诱导食物-药物不良反应的风险。