天然乳化剂阿拉伯胶对绿原酸自微乳体内外性能的影响

目的:研究天然乳化剂阿拉伯胶对绿原酸自微乳体内外性能的影响。方法:以阿拉伯胶逐步取代含非离子型乳化剂的绿原酸自微乳(简称"传统绿原酸自微乳")中的聚山梨酯80制成含阿拉伯胶的绿原酸自微乳(简称"新型绿原酸自微乳"),评价两种自微乳的外观、乳滴形态、粒径、电导率、p H值、稳定性、体外释放度和肠吸收动力学指标。结果:新型绿原酸自微乳采用阿拉伯胶取代了聚山梨酯80处方量的50%。传统和新型绿原酸自微乳的微乳液外观澄明,乳滴为近似球形,粒径分别为(24.53±3.03)、(35.51±5.91)nm,电导率分别为(195.6±0.3)、(189.5±0.4)μs/cm,p H分别为3.87±0.02、4.08±0.03(n=3)。与传统绿原酸自微乳比较,新型绿原酸自微乳在十二指肠、空肠、回肠中的吸收速率常数、有效渗透系数和吸收量均略有增加(P>0.05),在结肠中的上述指标均明显降低(P<0.05)。结论:新型绿原酸自微乳可保持传统绿原酸自微乳的性能,并能增加绿原酸在小肠的吸收。     

盐酸齐拉西酮自微乳的制备及其体内外活性

目的制备盐酸齐拉西酮自微乳,提高其体外溶出度及其空腹口服生物利用度。方法选择对盐酸齐拉西酮溶解能力较强的油相,乳化剂和助乳化剂,观察微乳的形成并绘制伪三元相图比较微乳区域大小,通过乳化时间的测定,粒径和Zeta电位测定来确定最佳处方,测定盐酸齐拉西酮自微乳的体外溶出度以及其在Beagle犬体内药物动力学研究。结果以油酸乙酯(油相)-吐温80(乳化剂)-聚乙二醇200(助乳化剂)(质量比为30∶47∶23)时制得的自微乳经水稀释后可形成稳定的微乳,平均粒径为58.4nm,Zeta电位为-31mV。自制盐酸齐拉西酮自微乳和市售胶囊相比,其体外溶出度显著提高,达到93%。Beagle犬体内实验表明,自制盐酸齐拉西酮自微乳的吸收不受食物影响。结论盐酸齐拉西酮自微乳制备简单,微乳粒径小,可显著提高盐酸齐拉西酮的体外溶出度,及其空腹口服生物利用度。     

芒果苷自微乳给药系统的制备及其大鼠体内药动学研究

目的制备芒果苷（mangiferin,MGF）自微乳给药系统（SMEDDS）,并对其进行药动学研究。方法评价系统自微乳化速度,激光散射仪测定乳化后形成微乳粒径的大小及分布情况;以PBS6.8缓冲液为释放介质,考察MGF-SMEDDS的体外释放行为;采用HPLC法测定大鼠血浆药物浓度,考察MGF-SMEDDS的体内吸收情况。结果体系在1min内可乳化完全,乳化后粒径在20nm左右;MGF-SMEDDS在120min的累积释放率可达80%以上;大鼠体内药动学研究结果表明,MGF-SMEDDS达峰时间为0.43h,是MGF的1/7;最大血药浓度为0.93mg/L,是MGF的2.16倍。结论自微乳给药系统可以显著提高MGF的体外释放,改善其药动学性质。     

磷脂对自微乳口服吸收、淋巴转运和体外特征的影响

目的以黄芩素为模型药物制备自微乳(SMEDDS),考察磷脂作为联合乳化剂对SMEDDS乳化、体外释放、体内胃肠吸收以及淋巴转运的影响。方法本研究以油酸乙酯为油相,吐温-80/磷脂为联合乳化剂,Transcutol HP为助乳化剂,构建黄芩素自微乳(BA-PC-SMEDDS),对乳化效率、粒径、Zeta电位、长期储存稳定性、大鼠体内药代动力学和淋巴转运等特征进行考察,并与处方中不含磷脂的传统自微乳(CBA-SMEDDS)进行比较。结果当磷脂作为联合乳化剂时,自微乳的长期储存稳定性提高,药物析出现象得到抑制。BA-PC-SMEDDS口服吸收后的AUC_0～_t为CBA-SMEDDS的1.37倍,淋巴转运程度从56.2%提高到68.6%。结论综上所述,处方中使用磷脂作为联合乳化剂,有利于改善SMEDDS的稳定性,提高难溶性药物的口服吸收,且对淋巴转运有促进作用。     

盐酸小檗碱纳米乳口服给药系统的制备及体外评价

目的 制备盐酸小檗碱纳米乳,优选其处方组成和制备工艺,并对其外观、粒径及体外释放行为等进行评价.方法 采用水滴加法制备盐酸小檗碱纳米乳,绘制纳米乳伪三元相图.选择星点设计-效应面法对纳米乳处方进行优化,确定最优处方组成比例.对制备的盐酸小檗碱纳米乳的粒径、电位、外观形态、体外释药行为等进行表征.结果 确定了盐酸小檗碱纳...     

紫杉醇自乳化微乳的制备及其在大鼠体内的药动学

目的:制备紫杉醇微乳,并对其急性过敏反应和大鼠体内的药动学进行考察。方法:三角相图法探讨了紫杉醇自乳化微乳(以下简称自微乳)的形成条件,采用均匀设计优化组成制备自微乳。以紫杉醇注射液对照,比较自微乳豚鼠的急性过敏反应和大鼠体内的药动学。结果: 以三辛酸甘油酯三丁酸甘油酯(1 ∶1)为油相,无水乙醇作助乳化剂制备的紫杉醇自微乳经生理盐水稀释后形成稳定的微乳,平均粒径为(16±s3)nm。以紫杉醇注射液作对照,自微乳豚鼠的急性过敏反应明显降低。统计矩分析,紫杉醇自微乳与紫杉醇注射液大鼠体内平均滞留时间分别为3. 89h和2. 52h,自微乳延长药物在大鼠体内的滞留时间。结论:通过优化处方制备的紫杉醇自微乳具有较好的稳定性,并可显著降低急性过敏反应。     

氟苯尼考自微乳制剂的研制

目的 制备了氟苯尼考自微乳.方法 通过测定氟苯尼考溶解度及绘制伪三相图,以成乳后的粒径、自乳化时间和色泽为指标,筛选处方中的油相、乳化剂和助乳化剂.结果 结果表明,氟苯尼考、油相Labrafil、乳化剂Cremophor EL、助乳化剂乙醇,四者比例为0.1:4:5:1时可获得较好的自乳化效果.制品平均粒径25nm,自微乳化可在3min内完全,在0.1mol/L盐酸中10～15min完全溶出.     

阿托伐他汀自微乳释药系统的制备和评价

目的制备阿托伐他汀自微乳，为自微乳释药系统的处方设计和体内外评价提供参考。方法采用伪三元相图法研究不同乳化剂、助乳化剂和油相形成微乳的能力和区域，绘制不同处方组成的相图，在此基础上制备阿托伐他汀自微乳，比较温度、介质、稀释等因素对自微乳效率的影响，进行自微乳时间、所成微乳的形态、粒径分布、zeta电位、含量和稳定性等体外评价Beagle犬体内药代动力学研究。结果理想的处方经分散后可得到平均粒径在100 nm以下、呈高斯分布的微乳，稳定性好，自微乳效率高，在Beagle犬体内的吸收明显高于市售片剂。结论本文首次研制阿托伐他汀自微乳，稳定性好，在Beagle犬体内的生物利用度高。     

雷帕霉素自微乳化释药系统的大鼠在体单向灌流肠吸收

目的:考察雷帕霉素自微乳化制剂的大鼠在体单向灌流肠吸收特征。方法:采用大鼠在体小肠单向灌流实验模型,以高效液相色谱法测定灌流液中药物浓度,分别研究不同药物浓度、不同吸收部位、不同灌流速度以及胆管结扎与否对雷帕霉素自微乳化制剂大鼠肠吸收的影响。结果:药物浓度和胆管结扎与否对雷帕霉素微乳的吸收百分率(P%)、吸收速率常数(Ka)以及表观吸收系数(Papp)无显著性影响(P>0.05);灌流速度和大鼠肠段不同吸收部位对P%、Ka以及Papp有显著性影响(P<0.05),其中回肠的P%、Ka和Papp值显著大于其余各肠段(P<0.05),结肠段吸收参数值显著低于十二指肠、空肠、回肠段(P<0.05);同等药物质量浓度下,自微乳化制剂的肠吸收参数值显著高于市售口服液制剂。结论:雷帕霉素自微乳化制剂吸收速率常数不受药物质量浓度的影响而与灌流速度和大鼠肠段不同吸收部位有关(P<0.05)。胆汁排泄和胆汁分泌在本实验条件下不影响药物肠道吸收。药物在大鼠小肠主要通过被动扩散方式吸收,RAPA微乳在整个肠段均有吸收,其中回肠吸收最好,且全肠吸收效果优于市售雷帕霉素口服液。     

水飞蓟素自微乳的制备

制备了水飞蓟素自微乳.通过测定水飞蓟素溶解度及绘制伪三相图,以成乳后的粒径、自乳化时间和色泽为指标,筛选处方中油相、乳化剂、助乳化剂.结果表明,含5%水飞蓟素、油相为MCT、乳化剂为CremophorRH40、助乳化剂为1,2-丙二醇,四者比例为0.5:5:3.6:0.9时可获得较好的自乳化效果.制品平均粒径为68.6nm,自微乳化可在3min内完全,在0.1mol/L盐酸中10～15min完全溶出.     

Interaction of estrone and estradiol with DNA and protein of liver and kidney in rat and hamster in vivo and in vitro

[6,7-³H] Estrone (E) and [6,7-³H]estradiol-17 (E₂) have been synthesized by reduction of 6-dehydroestrone and 6-dehydroestradiol with tritium gas. Tritiated E and E₂ were administered by oral gavage to female rats and to male and female hamsters on a dose level of about 300 g/kg (54 mCi/kg). After 8 h, the liver was excised from the rats; liver and kidneys were taken from the hamsters. DNA was purified either directly from an organ homogenate or via chromatin. The radioactivity in the DNA was expressed in the units of the Covalent Binding Index, CBI = (mol chemical bound per mol DNA-P)/(mmol chemical administered per kg b.w.). Rat liver DNA isolated via chromatin exhibited the very low values of 0.08 and 0.09 for E and E₂, respectively. The respective figures in hamster liver were 0.08 and 0.11 in females and 0.21 and 0.18 in the males. DNA isolated from the kidney revealed a detectable radioactivity only in the female, with values of 0.03 and 0.05 for E and E₂, respectively. The values for male hamster kidney were < 0.01 for both hormones. The minute radioactivity detectable in the DNA samples does not represent covalent binding to DNA, however, as indicated by two sets of control experiments. (A) Analysis by HPLC of the nucleosides prepared by enzyme digest of liver DNA isolated directly or via chromatin did not reveal any consistent peak which could have been attributed to a nucleoside-steroid adduct. (B) All DNA radioactivity could be due to protein contaminations, because the specific activity of chromatin protein was determined to be more than 3,000 times higher than of DNA. The high affinity of the hormone to protein was also demonstrated by in vitro incubations, where it could be shown that the specific activity of DNA and protein was essentially proportional to the concentration of radiolabelled hormone in the organ homogenate, regardless of whether the animal was treated or whether the hormone was added in vitro to the homogenate.Carcinogens acting by covalent DNA binding can be classified according to potency on the basis of the Covalent Binding Index. Values of 10³–10⁴ have been found for potent, 10² for moderate, and 1–10 for weak carcinogens. Since estrone is moderately carcinogenic for the kidney of the male hamster, a CBI of about 100 would be expected. The actually measured limit of detection of 0.01 places covalent DNA binding among the highly unlikely mechanisms of action. Similar considerations can be made for the liver where any true covalent DNA binding must be below a level of 0.01. It is concluded that an observable tumor induction by estrone or estradiol is unlikely to be due to DNA binding.Paper presented at the Satellite Symposium of the European Society of Toxicology, Rome, March 29, 1983     

Arsenic induced changes in growth development and apoptosis in neonatal and adult brain cells in vivo and in tissue culture

Arsenic at a nonlethal level in drinking water consumed over a period of time has been reported to produce chronic toxicity and various types of health problems ranging from skin cancer to disturbance in memory. Neurotoxic effects have been reported in clinical cases with chronic exposure to arsenic. Physiological detoxication of arsenic occurs partially through methylation. Arsenic and its methylated derivatives are distributed in different organs and systems. The present study examined the possible interference in the neuronal development and differentiation due to the exposure to arsenic during gestation. The experiments were carried out to examine short and long term effects of arsenic on brain explants and cells grown and maintained in tissue culture system. The effects of arsenic exposure showed changes in brain cell membrane function indicated by generation and release of reactive oxygen-nitrogen intermediates. On the morphological aspect the explants' growth was reduced, ground matrix was lost and neural networking was inhibited. Cells showed signs of apoptotic changes. Arsenic toxicity may induce damage to brain cells prior to more visible clinical conditions. The deleterious effects also pass from the maternal to fetal tissue across the transplacental barrier.     

Nicotine metabolism and urinary elimination in mouse: in vitro and in vivo

This study aimed at elucidating the in vivo metabolism of nicotine both with and without inhibitors of nicotine metabolism. Second, the role of mouse CYP2A5 in nicotine oxidation in vitro was studied as such information is needed to assess whether the mouse is a suitable model for studying chemical inhibitors of the human CYP2A6. The oxidation of nicotine to cotinine was measured and the ability of various inhibitors to modify this reaction was determined. Nicotine and various inhibitors were co-administered to CD2F1 mice, and nicotine and urinary levels of nicotine and four metabolites were determined. In mouse liver microsomes anti-CYP2A5 antibody and known chemical inhibitors of the CYP2A5 enzyme blocked cotinine formation by 85–100%, depending on the pre-treatment of the mice. The amount of trans-3-hydroxycotine was five times higher than cotinine N-oxide, and ten times higher than nicotine N-1-oxide and cotinine. Methoxsalen, an irreversible inhibitor of CYP2A5, significantly reduced the metabolic elimination of nicotine in vivo, but the reversible inhibitors had no effect. It is concluded that the metabolism of nicotine in mouse is very similar to that in man and, therefore, that the mouse is a suitable model for testing novel chemical inhibitors of human CYP2A6.     

Circulating nucleic acids in plasma and serum: roles in diagnosis and prognosis in diabetes and cancer

The presence of DNA and RNA circulating in human plasma and serum is described. The possible sources of the DNA/RNA in blood, their ability to enter other cells and to express in the recipient cells are discussed and the relationship with metastases considered. The possible role(s) of the DNA/RNA in clinical diagnosis, in monitoring treatment and in prognosis are considered for diabetes and oncology.     

SalB stimulates neurogenesis and angiogenesis in vitro and in vivo

Aims： Previous studies suggested that Salvianolic acid B （SalB） has strong protective effect against cerebral ischemia. Recently, Sal B has been reported to enhance angiogenesis in vitro. Based on the information above, in this study we are interested in the effect of SalB on neurogenesis and angiogenesis. Methods：In vitro study, we used embryonic mouse （El6） primary cortical neural cultures. Neuron was recognized by anti-MAP2 with immunocytochemistry. Neurogenesis was tested with BrdU incorporation by ELSA method. SalB（ 10 -6 -10 -8M） or vehicle was added to the culture medium 24 hrs before BrdU addition. In vivo, middle cerebral artery occlusion （MCAO） rats were used as focal cerebral ischemia model.     

Metabolic interaction between imipramine and carbamazepine in vivo and in vitro in rats

Summary The pharmacokinetic consequences of the combination of carbamazepine with imipramine in male Wistar rats have been investigated. It was found that a 2-week treatment with the combination resulted in the increase of the concentrations of the parent compounds and a simultaneous decrease in their metabolites in blood plasma i.e. carbamazepine inhibited imipramine demethylation in the side chain while imipramine inhibited carbamazepine 10,11-epoxidation. The velocity of imipramine 2-hydroxylation and 10,11-epoxy-carbamazepine hydration did not seem to be changed by the combination. On the basis of studies in vitro it is concluded that the observed metabolic interaction between carbamazepine and imipramine is due to the competition of the drugs for the active centre of cytochrome P 450 and to a certain qualitative alteration of the enzyme by imipramine as can be deducted from the decrease of carbamazepine binding to the cytochrome. Send offprint requests to K. J. Netter     

Nicotine metabolism and urinary elimination in mouse: in vitro and in vivo

This study aimed at elucidating the in vivo metabolism of nicotine both with and without inhibitors of nicotine metabolism. Second, the role of mouse CYP2A5 in nicotine oxidation in vitro was studied as such information is needed to assess whether the mouse is a suitable model for studying chemical inhibitors of the human CYP2A6. The oxidation of nicotine to cotinine was measured and the ability of various inhibitors to modify this reaction was determined. Nicotine and various inhibitors were co-administered to CD2F1 mice, and nicotine and urinary levels of nicotine and four metabolites were determined. In mouse liver microsomes anti-CYP2A5 antibody and known chemical inhibitors of the CYP2A5 enzyme blocked cotinine formation by 85-100%, depending on the pre-treatment of the mice. The amount of trans-3-hydroxycotine was five times higher than cotinine N-oxide, and ten times higher than nicotine N-1-oxide and cotinine. Methoxsalen, an irreversible inhibitor of CYP2A5, significantly reduced the metabolic elimination of nicotine in vivo, but the reversible inhibitors had no effect. It is concluded that the metabolism of nicotine in mouse is very similar to that in man and, therefore, that the mouse is a suitable model for testing novel chemical inhibitors of human CYP2A6.     

Pharmacokinetic and pharmacogenetic determinants and considerations in chemotherapy selection and dosing in infants

INTRODUCTION: There is a lack of high-quality data regarding optimal chemotherapy dosage regimens among infants. Dosing regimens for chemotherapy during the first year of life are commonly based on empiric recommendations extrapolated from older children; however, balancing efficacy and toxicity is critical as severe adverse drug reactions may lead to treatment failure or reduced adherence to needed medications. AREAS COVERED: This review describes pharmacokinetic and pharmacogenetic considerations when administering chemotherapeutic agents to infants. Examples of commonly used agents are provided with practical recommendations for dosing adjustments. EXPERT OPINION: Optimal chemotherapy for children and infants in particular has lagged behind the remarkable progress in cancer treatment and it is clear that far more basic and clinical research are needed with respect to the mechanistic basis of age-dependent differences in pharmacokinetic parameters. More recent studies which have combined pharmacokinetic data with clinical toxicity and outcome data have resulted in a number of more evidence-based guidelines at least for the initial chemotherapy dosing; however, at present, the dosing of chemotherapy drugs in neonates and infants remains largely empiric.     

Consistency in catecholamine and cortisol excretion in males and females

Data from a series of experiments performed on 24 female and 24 male subjects were used to evaluate the consistency in urinary catecholamine and cortisol excretion. Data were available from 8 laboratory situations of varying activity level and content, spaced at intervals of maximum 3 months. Correlational analyses showed that for cortisol, interindividual consistency was higher for measures obtained on the same day than for measures obtained on different days. Interindividual consistency was generally high in catecholamine and cortisol excretion during non-stressful situations in both sexes. During experimental stress, however, consistency was as high as during nonstress for males, while it was lower for females. Analysis of variance components confirmed these results and showed that in males variation due to interindividual differences was high during both baseline and experimental-stress situations, while in females it was high during baseline situations only. During experimental stress, variation for females was due primarily to interaction. It is suggested that the males showed a more generalized stress response over situations than the females.     

Penetration and action of edoxudine in vitro and in vivo

The penetration of 5-ethyl-2'-deoxyuridine (edoxudine, Aedurid) from gel base with and without the addition of urea and other adjuvant has been studied in an in vitro model using guinea pig skin. The formulation of 3% edoxudine gel with 5% urea showed the best results. In vivo experiments on hairless mice infected intracutaneously with herpes simplex virus type 1 also showed this formulation's good efficacy as compared to other formulations.