联苯双酯对他克林引起的肝损伤的保护作用

目的　观察联苯双酯(DDB)对他克林(THA)诱发小鼠肝损伤的保护作用。方法　小鼠一次poTHA(56mg·kg^-1) ,观察12h内动物血清ALT ,肝脏MDA和动物体温的改变;分光光度法测定小鼠脑乙酰胆碱酯酶活性;酶动力法测定小鼠肝微粒体7-乙氧基香豆素脱乙基酶和UDP葡糖醛酸转移酶(UDPGT)的活性;荧光法测定线粒体膜电位的改变。结果　DDB 200 mg·kg^-1 可明显保护THA引起的小鼠体温下降、血清ALT和肝脏MDA的升高。DDB(100 μmol·L^-1 )可减轻THA造成的大鼠线粒体膜电位降低。DDB还可提高小鼠肝微粒体7-乙氧基香豆素脱乙基酶的活性,但对UDPGT无影响。结论　DDB似通过降低肝脏脂质过氧化反应、提高线粒体膜稳定性、调节THA代谢酶活性发挥其肝保护作用     

N-乙酰基-L-谷氨酰基-泼尼松龙肾靶向前体药物研究

目的通过研究N-乙酰基-L-谷氨酰基-泼尼松龙的体内分布，考察该前体药物的肾靶向性。方法小鼠iv后，采用高效液相法，在规定时间段测定各组织脏器的泼尼松龙浓度, 并采用大鼠骨密度的测定仪确证前体药物的副作用。结果小鼠给药后15 min，前体药物组肾脏中泼尼松龙浓度为(86±8) μg·g^-1，泼尼松龙组为(57±4) μg·g^-1，60 min后前体药物组肾脏药物浓度为 (67±5) μg·g^-1；泼尼松龙组(42±4) μg·g^-1。大鼠给药30 d后，股骨的骨密度分别为(0.08±0.03) g·cm^-2 （泼尼松龙）和(0.14±0.06) g·cm^-2(前体药物组)。结论前体药物具有肾靶向性, 并能降低致骨质疏松的副作用。     

克林沙星在大鼠体内的药代动力学和生物利用度

目的　研究克林沙星在大鼠体内的药动学和生物利用度。方法　HPLC法测定大鼠ig和iv克林沙星后的血药浓度,计算药动学参数和生物利用度。色谱柱为C₁₈柱(5μm),流动相为乙腈-0.05mol·L^-1柠檬酸三乙胺液(pH2.5)(20∶80),流速为1.0mL·min^-1,检测波长300nm。结果　克林沙星0.1-20μg·mL^-1呈良好线性关系,在大鼠体内的药动学过程符合一室模型,大鼠ig50和100mg·kg^-1后,C_max和AUC均与剂量呈正比,T_1/2与剂量无关;绝对生物利用度(F)为42%。结论　克林沙星50-100mg·kg^-1的吸收和消除呈一级动力学特征,在大鼠体内的生物利用度低。     

HPLC-MS法测定血浆中克林霉素的浓度

目的 建立快速测定人体血浆中克林霉素浓度的高效液相色谱-质谱测定法。方法 血浆样品以甲醇沉淀蛋白,直接将上清液酸化后进行HPLC-MS分析,色谱柱为Lichrospher C₁₈柱(250 mm×4.6 mm,5μm);流动相为40 mmol·L^-1乙酸铵缓冲液(pH 4.1)-甲醇(30∶70,V/V);内标为林可霉素;检测离子(m/z):425.2(克林霉素[M+H]⁺)、407.3(内标林可霉素[M+H]⁺)。结果 血浆标准曲线线性范围为0.01007 mg·L^-1～10.07 mg·L^-1,高、中、低3种浓度的批内和批间精密度均小于10.0%,提取回收率为87.0%～92.4%。20名健康受试者随机交叉口服受试制剂和参比制剂各300 mg后,用HPLC-MS法测定血浆中克林霉素血药浓度,用面积法估算的受试制剂的相对生物利用度为(100.3±10.5)%。结论 建立的HPLC-MS分析方法快速、灵敏、准确、简便,适用于临床药代动力学研究。     

糖皮质激素前体药在大鼠胃肠道中定位转释的药代动力学

目的探讨以葡聚糖(平均分子量26万)为载体的地塞米松前体药在大鼠胃肠道内的转释特性。方法前体药按5μmol·kg^-1地塞米松(Dex)给大鼠ig,采用HPLC监测前体药在大鼠胃肠道不同部位释放出Dex的动力学过程及血药浓度。结果前体药ig后,Dex集中分布在盲肠和结肠内容物及粘膜中,C_peak为32μg·L^-1;Dexig后,主要分布在胃、小肠近端及远端内容物和粘膜中,C_peak为2120μg·L^-1。结论该前体药可将Dex特异地转运到结肠和盲肠,是一种治疗炎症性肠病的潜在药物。     

间硝苯地平在Beagle犬体内的药代动力学

目的用反相高效液相色谱法研究间硝苯地平(m-nifedipine，m-Nif)在Beagle犬体内的药代动力学特征。方法正交设计优化色谱分离条件，Beagle犬分别iv给予m-Nif 0.288 mg·kg^-1和ig m-Nif 1.152，3.456，10.370 mg·kg^-1。用反相高效液相色谱法分析血浆中原型药物浓度，血浆药物浓度-时间数据用3P97药代动力学软件分析。结果Beagle犬iv m-Nif，其体内过程符合二室模型，T_1/2β为116.8 min；ig给予m-Nif 后在Beagle犬体内的代谢符合一室模型，其中低剂量(1.152 mg·kg^-1)组C_max为20 μg·L^-1， T_1/2(k_e)为147 min；中剂量(3.456 mg·kg^-1)组C_max为36 μg·L^-1，T_1/2(k_e) 为122 min；高剂量(10.37 mg·kg^-1)组C_max为69 μg·L^-1，T_1/2(k_e)为144 min。结论Beagle犬ig和iv m-Nif 后，血浆中药物消除迅速，口服绝对生物利用度较低。     

新一代抗菌药物Dalbavancin的研究进展

目的 综述新一代抗菌药物Dalbavancin的最新研究进展。 方法 通过检索Google Scholar以及Science Direct查阅大量近10年的相关文献,对Dalbavancin抗菌机制、抗菌活性、药动学、药效学以及安全性多角度综述分析。结果 Dalbavancin是一种糖肽类浓度依赖性抗菌药物,其体内外抗耐甲氧西林葡萄球菌(MIC50=0.06 mg·L^-1)的活性明显优于万古霉素(MIC50=1 mg·L^-1)、替考拉宁(MIC50=0.5 mg·L-1);其临床药动学表明具有每周给药1次的潜力,体内有效治疗浓度为20 mg·L^-1。结论 Dalbavancin是一种菌体耐药性突变率低,不良反应温和,药物毒性较小处于临床Ⅲ期研究的最具应用价值的新一代抗菌药物。     

5-单硝酸异山梨酯对兔离体隐动脉交感嘌呤能缩血管反应的影响

采用兔离体隐动脉血管环张力实验及电场刺激诱发交感嘌呤能血管收缩实验，观察5-单硝酸异山梨酯(isosorbide-5-mononitrate，ISMN)对交感嘌呤能缩血管反应的作用，并分析其作用机制。结果表明，电场刺激(电压15 V，波宽1 ms，时程1 s)诱发兔离体隐动脉(去内皮)产生血管收缩反应。该收缩反应呈频率(2～16 Hz)依赖性，可被0.1 μmol·L^-1河豚毒素(tetrodotoxin)完全抑制。α₁受体阻断药哌唑嗪(1 μmol·L^-1)对2～8 Hz电刺激诱发的血管收缩反应无影响。P2X₁受体激动药α,β-亚甲基ATP(3 μmol·L^-1)脱敏P2X₁受体，同时联合应用哌唑嗪(1 μmol·L^-1)完全抑制电刺激诱发的血管收缩反应。采用一个标本一个浓度给药时，ISMN(0.1 mmol·L^-1)显著抑制8 Hz电刺激诱发的血管收缩反应，在0.3及1.0 mmol·L^-1时ISMN显著抑制各频率电刺激诱发的血管收缩反应； 1.0 mmol·L^-1 ISMN对电刺激诱发的血管收缩反应的抑制率分别为46%(2 Hz)、 47%(4 Hz)、 34%(8 Hz)和22%(16 Hz)。ISMN(0.3及1.0 mmol·L^-1)对外源性去甲肾上腺素(0.01～100 μmol·L^-1)或腺苷三磷酸(1 mmol·L^-1)诱发的血管收缩反应无影响。以上结果提示，ISMN显著抑制电场刺激诱发的交感嘌呤能血管收缩反应，其作用机制可能是ISMN作用于交感神经末梢突触前膜抑制嘌呤能神经递质产生的血管收缩反应。     

水溶性帕利哌酮前体药物的合成及其体外透皮研究

目的 合成帕利哌酮（PPD）的水溶性前体药物,使其能通过离子导入技术快速透过皮肤。方法 合成PPD的水溶性前体药物,即PPD的β-丙氨酸酯（PPD-β-Ala）,并对前药进行结构确证;利用高效液相色谱（HPLC）建立PPD及PPD-β-Ala的定量分析方法,并进行方法学验证;测定PPD及PPD-β-Ala的饱和溶解度,并对PPD-β-Ala的脂水分配系数（P_o/w）和pKa进行考察;进行PPD-β-Ala体外透皮实验,包括被动透皮吸收和离子导入透皮研究;在体外离子导入研究中,考察给药池介质[纯水、HEPES溶液（pH 5.5）或HEPES溶液（pH 6.5）]、给药池药物浓度（10、20、30 mmol·L^-1）和电流密度（0.1、0.3、0.5 mA·cm^-2）对PPD-β-Ala透皮递送量的影响。结果 前体药物PPD-β-Ala结构通过核磁共振氢谱得以确证。建立的HPLC法可对PPD及PPD-β-Ala同时检测,方法专属性、精密度和检测限均满足实验要求。PPD-β-Ala在纯水中的饱和溶解度为33.46 mmol·L^-1,远高于PPD的水溶解度;PPD-β-Ala的lg P_o/w小于PPD;PPD-β-Ala可充分质子化,带1个正电荷,PPD不具备易解离或易质子化的基团。PPD-β-Ala不易透皮吸收,但在离子导入条件下可在接收池中检出大量PPD-β-Ala,如在施加电流0.5 mA·cm^-2条件下,当给药池中PPD-β-Ala的浓度为30 mmol·L^-1时,7 h后的累积透皮递送量可达250 nmol·cm^-2。所选给药池介质的变化未对PPD-β-Ala的累积透皮递送量产生明显改变,但给药池药物浓度和电流强度的增加均能提高PPD-β-Ala的累积透皮递送量。在体外离子导入研究各组中均发现大量的PPD和PPD-β-Ala蓄积于皮肤,以0.5 mA·cm^-2电流强度、给药池药物浓度为20 mmol·L^-1（HEPES溶液为介质,pH 5.5）的给药条件为例,蓄积于皮肤中的PPD和PPD-β-Ala的量分别可达（144.21±41.73）、（890.61±106.40） nmol·cm^-2。结论 水溶性离子化的PPD前药PPD-β-Ala可在离子导入过程中通过电迁移作用快速透皮,理论上可利用尺寸适中的离子导入透皮贴片满足PPD的最小日给药剂量。     

蛇床子素在兔体内药物代谢动力学

目的研究蛇床子素在兔体内的药物代谢动力学。方法用高效液相色谱法,以丹皮酚为内标,以甲醇-水(80∶20)为流动相,测定兔血液中蛇床子素(iv,10 mg·kg^-1)的含量。采用3P87程序计算药物代谢动力学参数。结果蛇床子素iv药代动力学符合二房室开放模型,T_1/2α=5.81 min,T_1/2β=42.2 min,K21=0.036 0·min^-1,K₁₂=0.045 0·min^-1,K₁₀=0.054 0·min^-1,AUC=235 mg·min·L^-1,CLs=0.043 0 L·min^-1·kg^-1,V_C=0.780 L·kg^-1。结论蛇床子素在兔体内分布及消除较快     

Synthesis and Characterization of 9-[P-(N,N-dipropyl Sulfamide)] Benzoylamino-1,2,3,4-4H-acridine—A Potential Prodrug for the CNS Delivery of Tacrine

9-[P-(N,N-dipropylsulfamide)]benzoylamino-1,2,3,4-4H-acridine (PTHA) was synthesized as a prodrug to improve the curative effect of tacrine hydrochloride (THA), to prolong the activation time in brain, and to decrease the hepatic toxicity. The prodrug was prepared by attaching carboxyl group of probenecid to 9-amino group of THA. The structure of PTHA was confirmed by IR, ₁HNMR, MS and UV. The physiochemical properties and stabilities of the prodrug under various conditions were investigated. Possibility of the prodrug passing through the blood–brain barrier (BBB) was evaluated in vitro by biopartition micellar chromatography (BMC). The concentrations of THA and PTHA in various tissues were determined by reversed-phase high-performance liquid chromatography after intravenous (i.v.) administration. The results showed PTHA was stable in various pHs and temperatures. It was indicated by partition coefficient in ethyl acetate/water that lipophilicity of the prodrug increased and it was predicted by BMC that the prodrug could improve the infiltration ability across BBB of THA. In-vivo experiment showed the concentrations of THA in brain and liver kept stable for about 4 h, which was beneficial for the treatment of Alzheimer's disease (AD). Compared with THA at the same time, AUC in liver decreases significantly, the overall targeting efficiency (TE) was enhanced from 10.97 to 16.11% and AUC_brain/AUC_liver increased from 1.52 to 2.53, which suggests the possibility to reduce the hepatic toxicity of THA by the way of the prodrug.     

Synthesis and characterization of 9-[P-(N, N-dipropyl sulfamide)] benzoylamino-1,2,3,4-4H-acridine--a potential prodrug for the CNS delivery of tacrine

9-[P-(N,N-dipropylsulfamide)]benzoylamino-1,2,3,4-4H-acridine (PTHA) was synthesized as a prodrug to improve the curative effect of tacrine hydrochloride (THA), to prolong the activation time in brain, and to decrease the hepatic toxicity. The prodrug was prepared by attaching carboxyl group of probenecid to 9-amino group of THA. The structure of PTHA was confirmed by IR, HNMR, MS and UV. The physiochemical properties and stabilities of the prodrug under various conditions were investigated. Possibility of the prodrug passing through the blood-brain barrier (BBB) was evaluated in vitro by biopartition micellar chromatography (BMC). The concentrations of THA and PTHA in various tissues were determined by reversed-phase high-performance liquid chromatography after intravenous (i.v.) administration. The results showed PTHA was stable in various pHs and temperatures. It was indicated by partition coefficient in ethyl acetate/water that lipophilicity of the prodrug increased and it was predicted by BMC that the prodrug could improve the infiltration ability across BBB of THA. In-vivo experiment showed the concentrations of THA in brain and liver kept stable for about 4 h, which was beneficial for the treatment of Alzheimer's disease (AD). Compared with THA at the same time, AUC in liver decreases significantly, the overall targeting efficiency (TE) was enhanced from 10.97 to 16.11% and AUC(brain)/AUC(liver) increased from 1.52 to 2.53, which suggests the possibility to reduce the hepatic toxicity of THA by the way of the prodrug.     

Design, Synthesis and Brain Uptake of LAT1-Targeted Amino Acid Prodrugs of Dopamine

Purpose

Drug delivery to the brain is impeded by the blood-brain barrier (BBB). Here, we attempted to enhance the brain uptake of cationic dopamine by utilizing the large amino acid transporter 1 (LAT1) at the BBB by prodrug approach.

Methods

Three amino acid prodrugs of dopamine were synthesized and their prodrug properties were examined in vitro. Their LAT1-binding and BBB-permeation were studied using the in situ rat brain perfusion technique. The brain uptake after intravenous administration and the dopamine-releasing ability in the rat striatum after intraperitoneal administration were also determined for the most promising prodrug.

Results

All prodrugs underwent adequate cleavage in rat tissue homogenates. The prodrug with phenylalanine derivative as the promoiety had both higher affinity for LAT1 and better brain uptake properties than those with an alkyl amino acid -mimicking promoiety. The phenylalanine prodrug was taken up into the brain after intravenous injection but after intraperitoneal injection the prodrug did not elevate striatal dopamine concentrations above those achieved by corresponding L-dopa treatment.

Conclusions

These results indicate that attachment of phenylalanine to a cationic drug via an amide bond from the meta-position of its aromatic ring could be highly applicable in prodrug design for LAT1-mediated CNS-delivery of not only anionic but also cationic polar drugs.     

Synthesis, pharmacokinetics and anticonvulsant activity of 7-chlorokynurenic acid prodrugs

7-Chlorokynurenic acid 1 is a potent glycine-N-methyl-D-aspartate (NMDA) receptor antagonist, but it shows weak activity after systemic administration. In order to overcome the Blood-brain barrier (BBB), we synthetized three new esters 2-4 of 1 obtained by chemical conjugation with essential nutrients such as glucose and galactose, that are actively transported across the BBB. These compounds were assayed to evaluate their in vitro chemical and enzymatic hydrolysis. In addition the prodrugs 2-4 were tested for their ability to protect mice against NMDA-induced seizures after systemic administration. All the prodrugs 2-4 appeared moderately stable in pH 7.4 buffered solution and were susceptible to in vitro enzymatic hydrolysis. Intraperitoneal administration of either esters 2 or 4 was highly protective against seizures induced by NMDA in mice, with the latter prodrug showing the highest anticonvulsive activity. In addition, ester 4 undergoes a time-dependent extracellular hydrolysis into 1 when applied to mixed cultures of mouse cortical cells, a model that reproduces in vitro the cellular milieu encountered by the prodrugs once they penetrate the brain parenchyma.     

Novel brain targeting prodrugs of naproxen based on dimethylamino group with various linkages

As a preventive and treatment drug for Alzheimer's disease (AD), naproxen's clinical application is hampered by its limited distribution in the brain. To increase the delivery of naproxen across the blood-brain barrier (BBB), 3 prodrugs (P1, P2 and P3) of naproxen were synthesized through either ester bond or amido bond using the dimethylamino moiety as a brain-targeting ligand. The in vitro release of naproxen from the 3 prodrugs was studied in PBS, rat plasma and brain homogenate. P3 with an amido bond appeared to be highly stable in all incubation media, whereas P1 and P2 with ester bonds were partially hydrolyzed in alkaline environment and brain homogenate to yield the parent drug. After i. v. administration to rats, the brain concentration of total naproxen (summation of released and bound naproxen, TN) of P1, P2 and P3 groups were 28.81, 24.51 and 15.54 times greater than that of the control naproxen group at 5 min, respectively, and the brain AUC0-t were 6.94, 10.06 and 6.70 times greater than that of the control naproxen group. In addition, the Cmax of TN in the brain after the administration of prodrugs with ester bonds (P1 and P2) was higher than that of the amide prodrug (P3). The results highlighted the possibility of brain delivery of naproxen using prodrug strategies based on the brain-targeting ligand with dimethylamino moiety, in which the linkage between drug and targeting group might play an important role in modulating the in vivo behaviors of these prodrugs.     

Investigation of the mechanism of enhancement of central nervous system delivery of 2'-beta-fluoro-2',3'-dideoxyinosine via a blood-brain barrier adenosine deaminase-activated prodrug.

Enhanced central nervous system (CNS) delivery of certain poorly penetrating 2',3'-dideoxynucleosides has been achieved by designing prodrugs that are substrates for enzymes, such as adenosine deaminase (ADA), that are present at high activities in brain tissue. In this study, the potential role of adenosine deaminase localized within the endothelial cells of the blood-brain barrier (BBB) in providing enhanced intracellular and CNS delivery of an ADA-activated prodrug is assessed in vitro using cell culture models of the BBB. The kinetics of uptake and bioconversion of 2'-beta-fluoro-2',3'-dideoxyadenosine (F-ddA), a model ADA-activated prodrug of 2'-beta-fluoro-2',3'-dideoxyinosine, were determined in primary cultured bovine brain microvascular endothelial cells. Model-based simulations of CNS availability derived from in vitro estimates of parameters for simple passive diffusion and ADA-catalyzed deamination suggest that ADA that is localized within the BBB plays an important role in the conversion of F-ddA to 2'-beta-fluoro-2',3'-dideoxyinosine during its passage across the BBB. Consistent with in vivo observations, these simulations demonstrate that elevated levels of certain enzymes, such as ADA, in the brain microvascular endothelial cells of the BBB may be exploited in the design of brain-targeted prodrugs or drug-carrier conjugates, which brain tissue selectively converts.     

二氢吡啶载体介导的他克林前体药物合成及靶向性研究

目的:合成以他克林(THA)为原药的化学传输系统,证实其有脑靶向性。方法:将THA与氯乙酰氯连接,再与烟酰胺成季胺盐,最后将其还原成二氢吡啶载体介导的前体药物。结果:用NMR,MS等方法对前药进行结构表征鉴定。前药分子脂溶性比THA大,体内外实验各组织药物浓度监测显示脑组织匀浆浓度高于其他组织匀浆。结论:合成的二氢吡啶载体介导的前体药物脑内药物浓度高于外周,预示着有良好的脑靶向性。     

In vitro and in vivo study of water-soluble prodrugs of dexanabinol

Trialkylammonium acetoxymethyl esters of dexanabinol were synthesized and evaluated as water-soluble prodrugs. Syntheses were performed by conventional methods; solubility in water and stability in buffers and human plasma were determined by HPLC, and in vivo tissue distribution studies were performed in a rat model. Most of the new derivatives were soluble in water (approximately 50 mg/mL). They were relatively stable in water, while rapidly hydrolyzed in human plasma. Distribution studies indicated that peak concentrations of drug both in blood (30 microg/mL) and brain (2 microg/mL) were rapidly (5 min) achieved after iv administration of a selected prodrug to rats. The blood concentration decreased faster than brain levels which were detectable even after 24 h. Some of the examined esters could be further developed as water soluble prodrugs of dexanabinol.     

Prodrugs and endogenous transporters: are they suitable tools for drug targeting into the central nervous system?

Hydrophilic drugs, or neuroactive agents characterized by high molecular weight, do not have the physico-chemical properties required for passive diffusion across the blood brain barrier (BBB). The prodrug approach by lipidization of hydrophilic drugs generally allows to sensibly increase their permeability across BBB, even if this phenomenon is often not associated to an effective entry into the brain of the lipidized drugs. It has been understood that active efflux transporters (AET) can have a very important role in extruding from the brain not only prodrugs obtained by lipidization processes, but also lipophilic drugs. On the other hand, it has been also demonstrated that carrier mediated transporters (CMT), able to transfer essential nutrients and hormones from the bloodstream to the CNS, can be employed for the brain targeting of appropriated designed prodrugs. This approach consists on the chemical modification of a drug into a "pseudonutrient" or, differently, on drug conjugation to essential nutrients transported by CMT systems. This review focuses the molecular aspects that regulate the activity of the CMT and AET systems for the transport of their substrates, taking into account the in vitro and in vivo studies related to these transporters. The studies are described and summarized in the aim to evaluate the molecular keys for the design of prodrugs efficacious in the brain targeting. Among these, the molecular Trojan horses systems are briefly illustrated as carriers for the transport in the brain of large molecular weight neuroactive agents.     

Tools for eradicating HIV in the brain: prodrug dimeric inhibitors of P-gp

Despite positive developments with the use of combination antiretroviral therapy, a major impediment to limiting the neurocognitive effects of HIV and eradicating HIV brain reservoirs is the penetration of these therapies across the blood-brain barrier (BBB). The focus of our work, therefore, has been to develop tools to significantly improve the penetration of antiretroviral agents to sites of HIV reservoirs, with an emphasis on the CNS. To this end, we have developed an innovative chemical approach--dimeric prodrugs of the antiretroviral agents themselves with a traceless tether. These dimeric prodrugs were designed to serve two purposes: inhibition of P-gp, the major drug efflux protein at the BBB, by occupying two substrate binding sites in the transporter; and prodrug dimers that gain entry into the endothelial cells at the BBB would revert to their monomeric forms in the reducing environment of the cytosol due to breakdown of the traceless tether, thus delivering the therapy. We have demonstrated the feasibility of this design by dimerizing the P-gp substrate and antiviral agent abacavir with a traceless tether. Abacavir dimers displayed potent inhibition of P-gp in two different cellular settings and reverted to active abacavir in the reducing environment of HIV-infected T cells, also leading to antiviral activity. Overall, these experiments point to the excellent promise for future use of dimeric prodrug inhibitors of P-gp for brain penetration of a wide range of CNS-active agents that are substrates of P-gp.