非诺贝特纳米混悬剂溶出度测定与体内吸收的相关性评价

目的考察非诺贝特纳米混悬剂、原料药粉、微粉化原料药粉的体外溶出特性,研究比较三者在大鼠体内的生物利用度,并对其体内外相关性作出评价。方法以紫外分光法测定体外溶出度;以高效液相色谱法测定大鼠灌胃给药后的血药浓度;以Wagner-Nelson法计算体内吸收分数,考察体内吸收与体外溶出的相关性。结果纳米组AUC0-36h和Cmax分别为原料组、微粉组的10倍和2倍,纳米混悬剂组体内吸收分数fa与体外溶出速率ft的关系为：fa=4.407 9ft？303.31,r=0.983 8。结论与原料和微粉组相比,非诺贝特制成纳米混悬剂后,药物的溶出速度和生物利用度均有显著提高,体外溶出与体内吸收相关性良好。     

非诺贝特纳米混悬剂溶出度测定与体内吸收的相关性评价

目的 考察非诺贝特纳米混悬剂、原料药粉、微粉化原料药粉的体外溶出特性,研究比较三者在大鼠体内的生物利用度,并对其体内外相关性作出评价。方法 以紫外分光法测定体外溶出度;以高效液相色谱法测定大鼠灌胃给药后的血药浓度;以Wagner-Nelson法计算体内吸收分数,考察体内吸收与体外溶出的相关性。结果 纳米组AUC0-36h 和Cmax分别为原料组、微粉组的10倍和2倍,纳米混悬剂组体内吸收分数fa与体外溶出速率ft的关系为：fa=4.407 9ft- 303.31,r=0.983 8。结论 与原料和微粉组相比,非诺贝特制成纳米混悬剂后,药物的溶出速度和生物利用度均有显著提高,体外溶出与体内吸收相关性良好。     

熔融乳化法制备非诺贝特纳米混悬剂

采用熔融乳化法制备非诺贝特纳米混悬剂,以粒径和ζ电位为指标,筛选优化处方.体外溶出试验显示,所制纳米混悬剂溶出速率显著高于原药和微粉化原药.大鼠体内药动学试验表明,纳米混悬剂组的AUC和Cmax显著高于原药组和微粉化原药组.     

HPLC测定大鼠血浆中非诺贝特的活性代谢物及其药动学研究

目的采用RP-HPLC测定大鼠血浆中非诺贝特活性代谢物非诺贝特酸的浓度,并研究单次口服不同剂量非诺贝特在大鼠体内的药动学。方法将18只SD大鼠随机分为3组,分别按体重口服低、中、高剂量(10、50、100 mg·kg-1)非诺贝特混悬液后,采用经过验证的RP-HPLC法测定血浆中药物的浓度,绘制血药浓度-时间曲线,以DAS 2.1.1软件拟合药动学参数。结果高、中、低剂量非诺贝特酸的药-时曲线均符合口服吸收的二室模型,主要药动学参数:Cmax分别为18.15±3.02、8.68±1.69、1.68±0.42μg·mL-1;Tmax分别为6.80±0.75、6.33±1.75、6.50±1.38 h;t1/2分别为4.44±1.03、5.38±1.91、4.76±1.12 h;Cl/F分别为0.49±0.08、0.56±0.13、0.50±0.11 L.h-1;AUC0-t分别为209.07±36.25、92.20±23.47、20.17±6.54μg·mL-1·h-1;AUC0-∞分别为210.22±36.29、93.87±23.51、21.27±6.53μg·mL-1·h-1。结论所用RP-HPLC法能够准确地测定非诺贝特酸的血药浓度,满足药动学研究的要求。在给药剂量范围内,非诺贝特酸在大鼠体内的药动学符合线性药动学规律。     

非诺贝特PEG2000-DSPE胶束的制备及在大鼠体内的口服药动学研究

目的:为提高非诺贝特溶解度,将非诺贝特包载于PEG₂₀₀₀-DSPE胶束中,研究其在SD大鼠体内的口服药动学情况。方法:对非诺贝特PEG₂₀₀₀-DSPE胶束进行表征,大鼠单剂量灌胃给予非诺贝特PEG₂₀₀₀-DSPE胶束和非诺贝特混悬液,眼底静脉丛取血,HPLC法测定血浆中非诺贝特酸含量,并用药物与统计（Drug and Statistics,DAS）软件分析处理药动学数据。结果:成功制备了非诺贝特PEG₂₀₀₀-DSPE胶束,平均粒径为（23.40±3.62）nm,包封率和载药量分别为（97.65±3.32）%和（1.33±0.32）%。大鼠体内口服药动学结果表明非诺贝特PEG₂₀₀₀-DSPE胶束和非诺贝特混悬液的药动学行为均符合二室模型,非诺贝特PEG20 00-DSPE胶束和非诺贝特混悬液的AUC_（0-24）分别为（61.41±5.71）μg·h·ml^-1和（8.49±0.66）μg·h·ml^-1,C_max分别为（9.67±1.65）μg·ml^-1和（0.71±0.09）μg·ml^-1。非诺贝特PEG₂₀₀₀-DSPE胶束的AUC_（0-24）和C_max相比于非诺贝特混悬液组分别提高了7倍和14倍。非诺贝特PEG₂₀₀₀-DSPE胶束相对于原料药生物利用度为723.3%。结论:非诺贝特PEG₂₀₀₀-DSPE胶束显著提高了非诺贝特在大鼠体内的口服吸收速度和生物利用度。PEG₂₀₀₀-DSPE胶束作为口服药物载体具有优良的应用前景。     

奈韦拉平纳米混悬液的制备及大鼠体内药动学研究

目的：：制备奈韦拉平纳米混悬剂,考察其在大鼠口服给药后体内的药动学特征。方法：采用高压均质法制备奈韦拉平纳米混悬剂,以纳米混悬剂粒径分布、PdI和Zeta电位为指标,考察了奈韦拉平纳米混悬剂的影响因素,并对制得的纳米粒进行表征;采用高效液相色谱法测定大鼠血浆中的奈韦拉平浓度,使用3P97软件计算相应的药动学参数。结果：奈韦拉平纳米混悬液平均粒径为(456.1±72.1) nm,PdI为(0.441±0.072),Zeta电位为(-24.4±4.7) mV。奈韦拉平混悬液和奈韦拉平纳米混悬剂在大鼠体内的AUC0-12分别为(7.57±0.52)和(11.72±1.83) mg·h·L-1;t1/2分别为(2.45±0.31)和(3.16±0.39) h;Tmax分别为(1.43±0.38)和(1.61±0.32) h;Cmax分别为(1.62±0.42)和(3.15±0.52) mg·L-1。结论：奈韦拉平纳米混悬液能够明显改善大鼠体内奈韦拉平的药动学行为,与奈韦拉平混悬液相比显著提高了药物的生物利用度。     

非诺贝特缓释微球片体内外相关性评价

目的：用脱卷积法进行自制非诺贝特缓释微球片体内外相关性的评价。方法：以市售微粒化非诺贝特胶囊剂的大鼠体内血药浓度数据为权函数，根据自制非诺贝特缓释微球片制剂大鼠体内血药浓度数据，采用脱卷积法，将不同时间点的体内吸收分数与体外累计释放百分数做线性回归，考察体内外相关性。结果：采用脱卷积法计算体外累计释放百分数和体内吸收分数相关系数较好（r=0．9225），相关性方程为Y=0．4642R＋42．044。结论：脱卷积法适用于非诺贝特缓释微球片的体内外相关性研究。     

非洛贝特纳米混悬剂的制备及其体外溶出性考察

目的:制备非洛贝特纳米混悬剂,以促进药物溶出。方法:以非洛贝特为主药,采用熔融乳化法联合高压均质法制备纳米混悬剂;选取处方中表面活性剂泊洛沙姆188(Poloxamer188)与聚乙烯吡咯烷酮(PVP)K30用量比、均质压力、均质次数为考察因素,药物粒径为指标设计正交试验筛选制备工艺,并进行验证试验;同时考察制剂溶出速率和溶出浓度。结果:最佳制备工艺为Poloxamer188:PVPK30用量比2:1、均质压力800bar,均质次数为9。所制纳米粒平均粒径为356nm,多分散系数为0.19,平均Zeta电位为-39mV。制剂5min时溶出浓度可达20.10mg·L-1,4h时达25.46mg·L-1,接近完全溶出。结论:将难溶药物非诺贝特制成纳米混悬剂可以显著改善其溶出作用。     

水飞蓟宾纳米混悬剂的制备及大鼠体内药动学研究

目的:探讨静脉注射用水飞蓟宾纳米混悬剂的制备,并评价其大鼠静注给药后的药动学。方法:通过对水飞蓟宾纳米混悬剂理化性质及稳定性的评价,考察水飞蓟宾纳米混悬剂的制备方法、处方工艺,并以溶液剂为参照考察其在大鼠体内的药动学行为。结果:水飞蓟宾纳米混悬剂的平均粒径是(268.90±9.20)nm,多分散性为0.22±0.12。水飞蓟宾溶液剂及纳米混悬剂的药时曲线下面积分别为(34.92±0.98)μg·h·mL-1和(57.12±3.20)μg·h·mL-1,消除半衰期(t1/2)分别为(3.05±0.06)h和(6.14±0.42)h。结论:制备的水飞蓟宾纳米混悬剂理化性质比较稳定,与溶?液剂相比,延长了药物在体内的驻留时间,具有一定的缓释效果。     

槲皮素纳米乳大鼠在体小肠吸收动力学

目的研究槲皮素纳米乳在大鼠体内各肠段的吸收情况,并考察其形态学及粒径分布.方法采用大鼠在体小肠各段回流实验,紫外分光光度法测定药物浓度,根据药物在小肠各段中的减少量来确定药物的吸收;采用透射电子显微镜观察纳米乳形态.结果槲皮素纳米乳在大鼠十二指肠、空肠、回肠及结肠中的吸收速率常数(ka)依次为0.0675,0.1056,0.1892,0.1615 h-1;透射电镜下槲皮素纳米乳呈球形,大小均匀,平均粒径(16.3±4.6)nm;结论槲皮素纳米乳在小肠下段吸收较好,吸收呈一级动力学过程.     

非诺贝特对衰老大鼠肝脏组织酰基辅酶A合成酶的影响

摘要目的观察非诺贝特对衰老大鼠肝脏组织酰基辅酶A（CoA）合成酶的影响,探讨衰老后出现脂质代谢异常的可能机制及非诺贝特对脂质代谢的调节作用。方法 雄性SD年轻大鼠（4～6周龄）和老年大鼠（24个月龄）各16只,随机分为对照组（常规喂养2周）和实验组（非诺贝特喂养2周）,测定大鼠血清三酰甘油和总胆固醇水平,采用半定量逆转录聚合酶链反应法检测大鼠肝脏组织酰基CoA合成酶水平。结果与年轻对照组比较,老年对照组三酰甘油和总胆固醇水平升高,老年大鼠肝脏组织酰基CoA合成酶水平表达降低。实验组与老年对照组比较三酰甘油和总胆固醇水平均下降;肝脏组织酰基CoA合成酶水平均升高。结论老年大鼠肝脏组织酰基CoA合成酶水平表达减少可能与老年脂质代谢异常有关;非诺贝特对老年脂质代谢异常有调节作用。     

非诺贝特酯防治大鼠非酒精性脂肪肝实验研究

目的观察非诺贝特酯对非酒精性脂肪肝大鼠模型的影响。方法以高脂乳液灌胃制备SD大鼠非酒精性脂肪肝模型,随机分为模型对照组、非诺贝特酯组和阳性对照(易善复)组,预防治疗8周后行血清、肝组织生化检测和病理学检查。结果非诺贝特酯能明显降低非酒精性脂肪肝大鼠模型肝组织中甘油三酯的水平,改善脂肪变性。结论非诺贝特酯对非酒精性脂肪肝大鼠有较好的治疗作用。     

非诺贝特对全脑缺血/再灌注损伤大鼠的保护作用

目的探讨非诺贝特对大鼠全脑缺血/再灌注损伤(I/R)的保护作用及机制。方法采用双侧颈总动脉夹闭合并低血压方法建立全脑缺血/再灌注大鼠模型。药物非诺贝特(fenofibrate,FF;33、100、300mg.kg-1)在缺血前30min灌胃给药,PPARα受体拮抗剂MK886(6mg.kg-1)在给予非诺贝特300mg.kg-1前腹腔注射。Morris水迷宫测定大鼠空间学习能力变化,病理切片HE染色观察海马神经元形态结构变化,免疫组化染色检测海马组织核转录因子NF-κBp65蛋白的表达,生化酶学方法观察超氧歧化酶(SOD)活性、丙二醛(MDA)含量变化,酶联免疫吸附法(ELISA)检测细胞因子IL-1β、IL-6、IL-10、TNF-α含量变化。结果非诺贝特能明显缩短全脑缺血/再灌注大鼠的寻台潜伏期,减轻全脑缺血/再灌注大鼠海马神经元损伤,降低海马神经元NF-κB p65蛋白表达,明显阻遏缺血/再灌注大鼠海马IL-1β、IL-6、TNF-α、MDA含量的升高和IL-10含量及SOD活性的降低;预先给予MK886能取消非诺贝特的作用。结论非诺贝特对缺血/再灌注脑损伤有明显保护作用,其机制与激活PPARα,抑制NF-κB活性,抑制CNS炎症反应和氧化应激有关。     

Fenofibrate-induced decrease of expression of CYP2C11 and CYP2C6 in rat

This short communication is aimed to investigate whether the widely used hypolipidemic drug fenofibrate affects CYP2C11 and CYP2C6 in rats, both counterparts of human CYP2C9, known to metabolise many drugs including S-warfarin and largely used non-steroidal antiinflammatory drugs such as ibuprofen, diclofenac and others. The effects of fenofibrate on the expression of rat liver CYP2C11 and CYP2C6 were studied in both healthy Wistar rats and hereditary hypertriglyceridemic rats. Both strains of rats were fed on diet containing fenofibrate (0.1% w/w) for 20 days. Fenofibrate highly significantly suppressed the expression of mRNA of CYP2C11 and less that of CYP2C6 in liver microsomes of both rat strains; this effect was associated with a corresponding decrease in protein levels. The results indicate that the combination of fenofibrate with drugs metabolised by CYP2C9 in humans should be taken with caution as it may lead, for example, to the potentiation of warfarin effects. This type of drug interaction has been observed previously and the results presented here could contribute to the explanation of their mechanism.     

Absorption and metabolism of glycosidic sweeteners of stevia mixture and their aglycone, steviol, in rats and humans.

Stevia mixture, sweeteners extracted from the leaves of Stevia rebaudiana Bertoni, consists mainly of the glycosides of the diterpene derivative steviol. The aims of this study were to investigate the absorption (in rats) and the hepatic metabolism (in rats and humans) of both stevia mixture and steviol. Absorption was investigated both in vivo and ex vivo. In ex vivo experiments using the rat everted sac method, no absorption of stevia mixture was observed, but significant absorption of steviol was noted (equivalent to approximately 70% of the absorption reference- salicylic acid- value). In the in vivo experiment, rats received a single oral administration of either steviol or stevia mixture; a peak steviol concentration in plasma was observed 15 min after its oral administration, demonstrating rapid absorption. However, after oral administration of stevia mixture, the steviol concentration in plasma increased steadily over 8 h, suggesting that stevia mixture components are first degraded and then absorbed as steviol in the rat intestine. Steviol metabolism in humans and rats was examined by incubating steviol with liver microsomes from the two species. Oxidative (monohydroxy and dihydroxy) metabolites of steviol were observed by LC-ESI/MS after incubation with both human and rat liver microsomes. The intrinsic clearance of steviol in human liver microsomes was 4-times lower than that found in rat liver microsomes. In conclusion, this study suggests that there are no major species differences in steviol hepatic metabolism between rats and humans. Absorption from the human intestine can be predicted to occur in an analogous manner to that from the rat intestine.     

Fenofibrate. A review of its pharmacodynamic and pharmacokinetic properties and therapeutic use in dyslipidaemia

Fenofibrate is a lipid-regulating drug which is structurally related to other fibric acid derivatives, such as clofibrate. At the recommended dosage of 200 to 400 mg daily, it produces substantial reductions in plasma triglyceride levels in hypertriglyceridaemic patients and in plasma total cholesterol levels in hypercholesterolaemic patients. High density lipoprotein (HDL)-cholesterol levels are generally increased in patients with low pretreatment values. Fenofibrate appears to be equally effective in diabetic patients with hyperlipoproteinaemia without adversely affecting glycaemic control. The influence of fenofibrate on the plasma lipid profile is sustained during long term (2 to 7 years) treatment. Comparative studies conducted to date have involved only small groups of patients--in overall terms fenofibrate was at least as effective as other fibrates, but larger comparative studies are needed before valid conclusions on its relative efficacy compared with nonfibrate lipid-lowering drugs can be drawn. The influence of fenofibrate on morbidity and mortality from cardiovascular disease has not been studied. Clinical adverse reactions to fenofibrate have mainly consisted of gastrointestinal disturbances, headache and muscle cramps. Transient elevations in transaminase and creatine phosphokinase levels commonly occur. Isolated cases of hepatitis with substantially elevated transaminase levels have been reported. Fenofibrate induces hepatomegaly, peroxisome proliferation and hepatic carcinomas in rodents, but this type of hepatotoxicity has not been observed in humans. The biliary lithogenic index is increased by fenofibrate, but this has not been shown to have increased the incidence of gallstones in treated patients. Thus, fenofibrate offers an effective and well tolerated alternative to clofibrate or other fibric acid derivatives, but its relative efficacy and tolerability compared with other types of lipid-lowering drugs, and its effect on cardiovascular morbidity and mortality, remain to be clarified.     

Effects of a fenofibrate/losartan combination on the plasma concentration and urinary excretion of purine bases

OBJECTIVE: To assess the effects of a combination of fenofibrate and losartan on the plasma concentrations and urinary excretion of purine bases in healthy male subjects. METHODS: 5 healthy males participated in a fenofibrate plus losartan combination study. The plasma concentrations and urinary excretion of purine bases (hypoxanthine, xanthine, uric acid) were measured before and after administrations of losartan (100 mg o.d.) alone for 2 weeks, losartan and fenofibrate together for 2 weeks and fenofibrate (300 mg o.d.) alone for 2 weeks, which were given consecutively over a 6-week period. RESULTS: Losartan alone significantly reduced the serum uric acid concentration and increased uric acid excretion, whereas the combination of losartan and fenofibrate reduced serum uric acid concentrations further with a concomitant increased uric acid excretion. Fenofibrate alone also reduced plasma uric acid concentration with an increase in urinary excretion, although the effect was weak when compared with the combination treatment. The plasma concentrations and urinary excretion of oxypurines remained unchanged throughout the entire study. CONCLUSION: A combination of fenofibrate and losartan demonstrated an additive urate-lowering effect which may be beneficial in the treatment of patients with gout and hypertriglyceridemia.     

Modulation of lipoprotein production in Hep G2 cells by fenofibrate and clofibrate.

Fenofibrate and other fibrate derivatives are commonly used to treat hyperlipidemia. It is not yet clear how they exert their modulatory effects on plasma lipoproteins. To investigate whether these drugs act on the liver to primarily inhibit very low density lipoprotein production, we utilized the highly differentiated human hepatoma cell line, Hep G2. At concentrations greater than 15 micrograms/mL, fenofibrate caused a 30% decrease in secreted apolipoprotein B (apo B) after 4 days of treatment. Pulse-chase studies demonstrated that this was not due to inhibition of apo B synthesis. Triglyceride synthesis by fenofibrate-treated Hep G2 cells was decreased by 30%, and the amount secreted into the medium was reduced by 50%. At a low concentration of drug (5 micrograms/mL), triglyceride secretion was reduced markedly while apo B secretion remained unchanged. Thus, apo B secretion is less sensitive to fenofibrate than the synthesis and secretion of triglyceride, and may be secondary to changes in the latter. Fenofibrate has also been shown to raise plasma high density lipoprotein concentrations. We found that low concentrations of fenofibrate caused a 20-101% increase in secreted apolipoprotein AI (apo AI), and pulse-chase immunoprecipitation studies showed that this was due to an increase in apo AI synthesis. Fenofibrate was compared to clofibrate to investigate whether their relative effects on lipoprotein production in Hep G2 cells were comparable to their relative effects on plasma lipoproteins. Both fibrates decreased the secretion of apo B to the same extent, but only fenofibrate increased apo AI secretion. Fenofibrate was more effective than clofibrate in inhibiting the secretion of lipids by these cells. Thus, the known effects of fenofibrate on plasma lipoproteins can be attributed to its direct modulation of lipoprotein synthesis in the liver cell. Hep G2 cells may thus be useful in testing the relative efficacy of fibric acid derivatives in vitro.     

Changes in intestinal absorption of 5-fluorouracil-treated rats.

5-Fluorouracil chemotherapy is often accompanied by gastrointestinal toxicity. In this study, we investigated the effect of 5-fluorouracil on the epithelial barrier function of rat small intestine by examining the absorption of a poorly absorbable marker, fluorescein isothiocyanate-labelled dextran (molecular weight 4,400). We further evaluated the intestinal absorption of 5-fluorouracil in rats treated orally with 5-fluorouracil once daily for 4 days. The small intestinal absorption of fluorescein isothiocyanate-labelled dextran and 5-fluorouracil was tested using in situ closed loop intestine technique and in vitro everted intestine technique, respectively. After administration of 5-fluorouracil to rats for 4 days, the body weight of rats decreased significantly and the fluorescein isothiocyanate-labelled dextran concentration in plasma increased significantly, compared with that of control rats to which the saline solution alone was administered. Moreover, the intestinal absorption of 5-fluorouracil in the 5-fluorouracil-treated rats was enhanced significantly, compared with that of control rats. The administration of 5-fluorouracil to rats caused body weight loss and epithelial barrier dysfunction of the small intestine in rats as shown by the increased permeation of the high molecular weight compound, fluorescein isothiocyanate-labelled dextran. The increased absorption of 5-fluorouracil after this treatment suggest that the 5-fluorouracil toxicity might be amplified by its treatment.