9-硝基喜树碱在大鼠组织中的分布及内酯稳定性

考察9-硝基喜树碱(9-NC)静脉注射后在人鼠组织中的分布及内酯稳定性.建立了HPLC法间时测定组织和血浆中9-NC内酯浓度和总浓度.大鼠静脉注射9-NC溶液后测定各时间点组织中内酯浓度、总浓度和内酯比例.大多数组织中的9-NC内酯比例明显高于血浆;肝中的内酯比例最低,甚至低于血浆;血浆、肾和小肠中的内酯比例随时问延长而下降.9-NC在肝以外的组织中内酯稳定性显著优于血浆.     

Effect of Size on the Biodistribution and Blood Clearance of Etoposide-Loaded PLGA Nanoparticles

Approaches used to avoid uptake of the injected particles by the reticuloendothelial system include modification of the particle properties such as surface charge and particle size. In the present study the effect of mean particle size of etoposide-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) of sizes 105 nm ((99m)Tc-Eto-PLGA NP(105)) and 160 nm ((99m)Tc-Eto-PLGA NP(160)) on biodistribution and blood clearance were studied after intravenous administration of the radiolabeled formulations and compared to that of free drug ((99m)Tc-Eto). It was found that etoposide-loaded PLGA NPs of size 105 nm were present in the blood at higher concentrations up to 24 h and were able to reduce their uptake by the reticuloendothelial system as compared to that of etoposide-loaded PLGA NPs of size 160 nm and pure drug. Moreover, the pure drug ((99m)Tc-Eto) did not cross the blood-brain barrier, whereas (99m)Tc-Eto-PLGA NP(105) showed relatively high concentrations of 0.58% of injected dose in brain in 1 h (8-fold higher), 0.6% in 4 h (20-fold higher) and 0.22% in 24 h (10-fold higher) than the concentration of (99m)Tc-Eto-PLGA NP(160). In bone, concentration of (99m)Tc-Eto-PLGA NP(105) was about 7.2 times higher than the concentration of (99m)Tc-Eto in 24 h. The study concludes that NPs of size ～100 nm can be used for long-term circulation without the need for surface modification. Such NPs could be exploited for use in leukemia therapy for providing sustained release of etoposide by long-term circulation. LAY ABSTRACT: Approaches used to avoid uptake of the injected particles by the reticuloendothelial system include modification of the particle properties such as surface charge and particle size. In the present study the effect of mean particle size of etoposide-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) of sizes 105 nm and 160 nm on biodistribution studies after intravenous administration in mice and blood clearance studies after intravenous administration in rats was studied. It was found that etoposide-loaded PLGA-NPs of size 105 nm were present in the blood at higher concentrations up to 24 h and were able to reduce their uptake by the reticuloendothelial system as compared to that of etoposide-loaded PLGA-NP of size 160 nm and pure drug. Moreover, the NPs of size 105 nm had greater uptake in bone and brain, in which concentration of free drug and NPs of size 160 nm was negligible. The study concludes that NPs of size ～100 nm can be used for long-term circulation without the need for surface modification.     

HPLC法测定人血浆中9-硝基喜树碱内酯型浓度和总浓度

目的:建立以高效液相色谱法测定人血浆中9-硝基喜树碱内酯型浓度和总浓度的方法。方法:血浆样品采用—20℃甲醇快速沉淀蛋白后进行测定,其中色谱柱为shim-packCLS-ODS,流动相为甲醇∶1%三乙胺(冰醋酸调pH6.5)=55∶45,流速为1.0mL·min-1,检测波长370nm,进样量为50μL,柱温为40℃。测定总浓度的样品采用冰醋酸酸化上清液。并以该法测定了不同时间点离体人血浆中9-硝基喜树碱内酯型、羧酸盐型浓度和总浓度的变化。结果:9-硝基喜树碱血药浓度在0.10～10.0μg·mL-1范围内线性关系良好(r=0.9991),定量下限为0.10μg·mL-1,平均方法回收率、酸化回收率各为101.02%、101.46%。结论:本法操作简便、快速,适用于9-硝基喜树碱内酯结构稳定性的研究。     

Effect of injection routes on pharmacokinetics and lactone/carboxylate equilibrium of 9-Nitrocamptothecin in rats

Pharmacokinetics and lactone/carboxylate equilibrium of 9-Nitrocamptothecin (9-NC) were compared after intravenous (i.v.) and intramuscular (i.m.) injection at a dose of 1.5 mg/kg 9-NC solution. The concentrations of three different forms of 9-NC, namely lactone, carboxylate and total 9-NC, were measured by HPLC analysis. Injection routes were demonstrated to have significant effect on pharmacokinetics of 9-NC. Compared with i.v. injection route, mean residence time (MRT) of 9-NC three forms was significantly prolonged following i.m. route (p < 0.05). The AUC_0–∞ ratios of i.m. to i.v. route were calculated to be 102 ± 43%, 273 ± 221% and 150 ± 62% for lactone, carboxylate and total 9-NC, respectively. Compared with i.v. injection route, although AUC_0–∞ was barely changed, MRT of lactone 9-NC was dramatically prolonged 4.5-fold after i.m. injection, which may account for the reported improved antitumor efficacy. However, the results of the present study also demonstrated that i.m. injection route increased both AUC_0–∞ and MRT of carboxylate 9-NC more significantly. Since the carboxylate form of CPT analogs including 9-NC is associated with their unwanted toxicity, i.m. injection route might lead to severe toxicity compared with i.v. route. Lactone/carboxylate equilibrium was also significantly influenced by injection routes. Based on the AUC_0–∞ measurements, the lactone 9-NC constituted 50 ± 8% and 32 ± 7% of circulating total 9-NC after i.v. or i.m. administration, respectively (p < 0.01).     

Pharmacokinetics of lactone, carboxylate and total 9-nitrocamptothecin with different doses and administration routes in rats

9-Nitrocamptothecin (9-NC) is a newly developed poorly soluble derivative of camptothecin and has a wide spectrum of anticancer activity in preclinical evaluation. The effects of the dose and administration route on pharmacokinetics and lactone/carboxylate equilibrium of 9-NC were studied in rats. A single intravenous dose of 1.5, 3 or 6 mg/kg of 9-NC solution was given to male rats (n = 6 per dose level). In another study, a single dose of 6 mg/kg 9-NC solution was given orally to rats (n = 6). Plasma samples were drawn at predetermined intervals and the concentrations of lactone, carboxylate and total 9-NC were determined by a validated HPLC method. Pharmacokinetic analysis was performed using non-compartmental analysis. Analysis of variance showed that the pharmacokinetic characteristics of lactone, carboxylate and total 9-NC were all independent of dose (p > 0.05). Based on the AUC measurements, the lactone 9-NC constituted 52% +/- 4%, 49% +/- 6% and 55% +/- 6% of the circulating total 9-NC in rats after intravenous administration of 1.5, 3, 6 mg/kg 9-NC solution, respectively. After oral administration of 6 mg/kg, the pharmacokinetics parameters were significantly different from those of intravenous administration at the same dose (p < 0.05). The lactone ratio was 60% +/- 14%. The absolute bioavailability of lactone and total 9-NC were calculated to be 23.4% and 22.7%, respectively. In conclusion, the pharmacokinetics of lactone, carboxylate and total 9-NC are not dose-dependent. Lactone, carboxylate and total 9-NC are poorly absorbed following oral administration. Both the dose and the route of administration have little effect on the lactone/carboxylate equilibrium of 9-NC in rats in vivo. But the route of administration plays an important part on the pharmacokinetics of 9-NC.     

不同内酯型比例9-硝基喜树碱对胆汁排泄的影响

目的考察9-硝基喜树碱(9-nitrocamptothecin,9-NC)不同形式(内酯型或羧酸盐型)给药对胆汁排泄的影响。方法建立HPLC测定胆汁中9-NC浓度的方法,比较不同内酯型比例的9-NC溶液以4 mg·kg?1剂量静脉注射后大鼠胆汁中原形药物的排泄量。结果静脉注射100%,75%,50%,25%,0%内酯型比例的9-NC在8 h内的胆汁累积排泄百分数分别为(7.03±2.23)%,(13.36±0.83)%,(22.68±4.83)%,(28.01±6.71)%,(32.65±2.82)%。结论 9-NC羧酸盐型更易经胆汁途径排泄。     

Preparation and characterization of novel polymeric micelles for 9-nitro-20(S)-camptothecin delivery.

9-Nitro-20(S)-camptothecin (9-NC) has achieved remarkable curative effect in anticancer research. However, the clinical application of 9-NC is largely hampered by its poor solubility and stability. In this paper, novel amphiphilic block copolymers derived from d,l-lactide, trimethylene carbonate, and methylated poly(ethylene glycol) (mPEG) (PECA) with different molecular weight were synthesized and characterized. Self-assembly PECA micelles loaded with 9-NC were prepared. The micelles were regular spheres with a diameter ranged from 20 to 120 nm. The critical micelle concentration (CMC) decreased with the increase of the hydrophobic components. The solubility of 9-NC was improved obviously with micelle encapsulation. The stability experiments proved that over 90% of 9-NC could keep its lactone form in micelle solution after incubating in phosphate-buffered saline for 100 min, while the corresponding proportion for free drug solution was 25%. The release of 9-NC was nearly zero-order after the burst release, and the long hydrophobic chain length led to slower release rate. The novel PECA copolymer micelles could be effective carriers to improve the solubility, stability, and release performance of 9-NC.     

Self-assembled nanoparticles of poly(lactide)--Vitamin E TPGS copolymers for oral chemotherapy

Nanoparticles (NPs) of poly(lactide)-Vitamin E TPGS (PLA-TPGS) copolymers were synthesized by a dialysis method in the present study to formulate paclitaxel for oral chemotherapy with Caco-2 cells as an in vitro model of the gastrointestinal (GI) drug barrier. The PLA-TPGS NPs were of size 340nm in diameter with 5.2% drug loading. The drug release kinetics showed a 31% initial burst in the first day, followed by 80% accumulative drug release after 30 days in the PBS buffer at pH 7.4, and the release rate was found lower in simulated gastric and intestinal conditions. The internalization of fluorescent PLA-TPGS NPs by Caco-2 cells was visualized by confocal laser scanning microscopy (CLSM). PLA-TPGS NPs showed significant increase in the cellular uptake by 1.8- and 1.4-fold in comparison with poly(lactide-co-glycolide) (PLGA) NPs cultured with HT-29 and Caco-2 cells, respectively, and the cellular uptake efficiency was found affected by the incubation time and the particle concentration in the culture medium. Investigation on HT-29 and Caco-2 cytotoxicity showed advantages of the PLA-TPGS NP formulation versus Taxol. The IC(50) of the PLA-TPGS NP formulation with HT-29 cells was found 40% lower than of Taxol at the same dose of paclitaxel. The results obtained in this research demonstrated feasibility for the PLA-TPGS NPs to be applied for oral delivery of paclitaxel as well as other anticancer drugs.     

吐温80对9-硝基喜树碱脂质体药物动力学性质的影响

目的:考察吐温80对9-硝基喜树碱(9-NC)脂质体体内药物动力学以及内酯型/羧酸盐型平衡的影响。方法:采用薄膜法制备9-NC脂质体以及吐温80修饰的9-NC脂质体;12只大鼠随机分为两组,按1.5 mg.kg-1剂量分别给予9-NC普通脂质体和吐温80修饰的脂质体,于不同时间点取血,处理后测定9-NC内酯型浓度和总浓度(内酯/羧酸盐)。采用统计矩模型利用3P97程序计算药物动力学参数。结果:采用表面活性剂吐温80进行修饰后,9-NC内酯型和总浓度的AUC分别提高了1.47倍和1.65倍,内酯型和总浓度的清除率CL和表观分布容积Vss显著下降(P<0.01)。此外,总浓度的MRT以及t1/2延长(P<0.05)。结论:吐温80修饰使得9-NC内酯型比例有所下降,但没有显著性差异,9-NC吐温修饰对9-NC脂质体具有一定的长循环效果。     

Characterization, blood profile and biodistribution properties of surface modified PLGA nanoparticles of SN-38

SN-38, the active metabolite of irinotecan, poses a challenge in terms of drug delivery due to its low solubility and labile lactone ring. The aim of this study was to develop a SN-38 nanoparticulate delivery system to evaluate the in vivo blood profile and biodistribution properties of nanoparticles (NPs). Poly lactide-co-glycolide (PLGA) NPs that were covalently bound to polyethylene glycol-folate (PEG-FOL) were prepared, and their in vivo biodistribution in rats was investigated. Either the SN-38 solution or SN-38 NP suspension was administered intravenously into the tail vein at a dose of 2mg SN-38 eq./kg. As expected, SN-38 NPs showed a higher plasma concentration in vivo when compared with free SN-38 during a 24h period. Compared with the SN-38 solution, both folate targeted and non-targeted NPs exhibited superior drug concentration in body organs such as the liver, spleen, and lung at 1 and 8h post-administration.     

Encapsulation of 9-nitrocamptothecin, a novel anticancer drug, in biodegradable nanoparticles: factorial design, characterization and release kinetics.

This study was aimed at developing a polymeric drug delivery system for a new and potent antitumor drug, 9-nitrocamptothecin (9-NC), intended for both intravenous administration and improving the therapeutic index of the drug. To achieve these goals, 9-NC loaded poly(DL-lactide-co-glycolide) (PLGA) nanoparticles were prepared by nanoprecipitation method and characterized. The full factorial experimental design was used to study the influence of four different independent variables on response of nanoparticle drug loading. Analysis of variance (ANOVA) was used to evaluate optimized conditions for the preparation of nanoparticles. The physical characteristics of PLGA nanospheres were evaluated using particle size analyzer, scanning electron microscopy, differential scanning calorimetry and X-ray diffractometry. The results of optimized formulations showed a narrow size distribution with a polydispersity index of 0.01%, an average diameter of 207+/-26 nm, and a drug loading of more than 30%. The in vitro drug release profile showed a sustained 9-NC release up to 160 h indicating the suitability of PLGA nanoparticles in controlled 9-NC release. Thus prepared nanoparticles described here may be of clinical importance in both stabilizing and delivering camptothecins for cancer treatment.     

Role of erythrocytes and serum proteins in the kinetic profile of total 9-amino-20(S)-camptothecin in humans

9-Amino-20(S)-camptothecin (9-AC) is a water-insoluble topoisomerase I inhibitor with evident schedule-dependent antitumor activity in preclinical studies. The pharmacokinetic behavior of 9-AC given as a bolus i.v. infusion (1.0 mg/m2 over 5 min) was recently characterized in 12 patients in a bioavailability study. Remarkable rebound concentrations of 9-AC total drug (i.e. lactone plus carboxylate forms) were observed at about 2-3 h after dosing. In vitro experiments indicated that this phenomenon was associated with a substantial uptake of 9-AC lactone by erythrocytes immediately after dosing and its subsequent release followed by accumulation of 9-AC carboxylate in the plasma compartment mediated by a pH-dependent hydrolysis of the lactone form, which is unable to diffuse across cell membranes. The preferential binding of 9-AC carboxylate to human serum albumin shifts the equilibrium between the lactone and carboxylate forms of 9-AC to the pharmacological inactive carboxylate form.     

In-vitro cytotoxicity, in-vivo biodistribution and anti-tumour effect of PEGylated liposomal topotecan

In attempt to increase the accumulation of topotecan in tumours and improve its anti-cancer activity, PEGylated liposome (H-PEG) containing topotecan was prepared. The in-vitro cytotoxicity, in-vivo biodistribution pattern and anti-tumour effect of H-PEG were studied systemically. Compared with free topotecan or conventional liposome (H-Lip), H-PEG improved the cytotoxic effect of topotecan against human ovarian carcinoma A2780 and human colon carcinoma HCT-8 cells. The IC50 value (concentration leading to 50% cell-killing) of H-PEG decreased 5 fold (P<0.01) and 9 fold (P<0.01) against A2780 and HCT-8 cells compared with H-Lip, respectively. The results of biodistribution studies in sarcoma S(180) tumour-bearing mice showed that liposomal encapsulation increased the concentration of total topotecan and the ratio of lactone form in plasma. H-PEG resulted in a 70-fold and 3.7-fold increase in AUC(0-->24 h) compared with free topotecan and H-Lip, respectively. Moreover, H-PEG increased the accumulation of topotecan in tumours and the relative tumour uptake ratio compared with free topotecan was 5.2, and higher than that of H-Lip. The anti-cancer effect studies in murine heptocarcinoma H(22) tumour-bearing mice showed that H-PEG improved the therapeutic efficiency of topotecan and decreased the toxicity of topotecan to a certain extent compared with H-Lip. These results indicated that PEG-modified liposome might be an efficient carrier of topotecan.     

The in vivo fate of nanoparticles and nanoparticle-loaded microcapsules after oral administration in mice: Evaluation of their potential for colon-specific delivery

Anti-cancer drug loaded-nanoparticles (NPs) or encapsulation of NPs in colon-targeted delivery systems shows potential for increasing the local drug concentration in the colon leading to improved treatment of colorectal cancer. To investigate the potential of the NP-based strategies for colon-specific delivery, two formulations, free Eudragit® NPs and enteric-coated NP-loaded chitosan–hypromellose microcapsules (MCs) were fluorescently-labelled and their tissue distribution in mice after oral administration was monitored by multispectral small animal imaging. The free NPs showed a shorter transit time throughout the mouse digestive tract than the MCs, with extensive excretion of NPs in faeces at 5 h. Conversely, the MCs showed complete NP release in the lower region of the mouse small intestine at 8 h post-administration. Overall, the encapsulation of NPs in MCs resulted in a higher colonic NP intensity from 8 h to 24 h post-administration compared to the free NPs, due to a NP ‘guarding’ effect of MCs during their transit along mouse gastrointestinal tract which decreased NP excretion in faeces. These imaging data revealed that this widely-utilised colon-targeting MC formulation lacked site-precision for releasing its NP load in the colon, but the increased residence time of the NPs in the lower gastrointestinal tract suggests that it is still useful for localised release of chemotherapeutics, compared to NP administration alone. In addition, both formulations resided in the stomach of mice at considerable concentrations over 24 h. Thus, adhesion of NP- or MC-based oral delivery systems to gastric mucosa may be problematic for colon-specific delivery of the cargo to the colon and should be carefully investigated for a full evaluation of particulate delivery systems.     

Chitosan nanoparticles enhance the plasma exposure of (-)-epigallocatechin gallate in mice through an enhancement in intestinal stability

The green tea catechin (-)-epigallocatechin gallate (EGCG) has attracted significant research interest due to its beneficial therapeutic effects, which include anti-oxidant, neuro-protective and anti-cancer effects. However, the therapeutic potential of EGCG following oral consumption is limited by its poor absorption. To address this issue, EGCG has been encapsulated in chitosan-tripolyphosphate nanoparticles (CS NPs) and the oral absorption of EGCG evaluated in Swiss Outbred mice. Administration of the CS NPs enhanced the plasma exposure of total EGCG by a factor of 1.5 relative to an EGCG solution, with plasma AUC((0-5 h)) values of 116.4±4.1 and 179.3±10.8 nM.h (mean±s.d., n=3-5) for the EGCG solution and CS NPs, respectively. Associated with the increased plasma exposure of EGCG was an enhancement in concentrations of EGCG in the stomach and jejunum of mice following CS NP administration. A 2.3-fold increase in the apparent exposure of EGCG to the jejunum (AUC(j)) was observed following CS NP encapsulation, with AUC(j(0-5 h)) values of 5.3±1.1 and 12.3±1.5 μM.h (mean±s.d., n=3-5) for the EGCG solution and CS NPs, respectively. The enhanced exposure of EGCG to the jejunum was likely responsible for the increased plasma concentrations of EGCG. The findings from this study suggest that CS NPs may be a useful approach for enhancing oral delivery, and therapeutic application, of EGCG in a number of disease conditions.     

Prediction of the systemic exposure to oral 9-amino-20(S)-camptothecin using single-sample analysis.

The purpose of this study was to develop and validate limited-sampling strategies for prediction of the area under the plasma-concentration time curves (AUCs) of the lactone and total (i. e., lactone plus carboxylate) forms of the novel topoisomerase-I inhibitor 9-amino-20(S)-camptothecin (9-AC). Complete pharmacokinetic curves for both drug species were obtained from 32 patients who received the drug orally in a clinical phase I setting at dose levels ranging from 0.25 to 1.10 mg/m2. The concentrations of the lactone and carboxylate forms of 9-AC in plasma were measured by HPLC. Using data from 20 randomly selected patients, forward-stepwise multivariate regression analysis was used to generate modeling strategies incorporating data from one, two, or three plasma samples. The simultaneous optimal prediction of both 9-AC lactone and 9-AC total AUCs was obtained with sample time points at 0.33, 3.0, and 11.0 h after drug dosing. Validation of the models on an independent data set comprising data of the remaining 12 patients demonstrated that 9-AC lactone and 9-AC total AUCs could be predicted sufficiently unbiased and precise using one and two time points: [AUC (ng. h/ml) = 7.103*C3 + 4.333] for 9-AC lactone and [AUC (ng. h/ml) = 9.612*C3 + 13.77*C11 - 44.11] for 9-AC total, where C3 and C11 represent the 9-AC plasma concentrations in ng/ml at 3 and 11 h after drug dosing. Application of the proposed models will be valuable in the determination of 9-AC population pharmacokinetics and permits treatment optimization for patients on the basis of individual pharmacokinetic characteristics through restricted drug monitoring in clinical routines.     

Self-microemulsifying drug delivery system (SMEDDS) improves anticancer effect of oral 9-nitrocamptothecin on human cancer xenografts in nude mice.

9-Nitrocamptothecin (9-NC) is an orally administered topoisomerase-I inhibitor for the treatment of pancreatic carcinoma, but its oral absorption and bioavailability are poor. The main objective of this study was to develop optimal 9-nitrocamptothecin (9-NC) microemulsion prepared by self-microemulsifying drug delivery system (SMEDDS). Two SMEDDS formulations of 9-NC prepared from a mixture of ethyl oleate, Tween-80 (T-form) or Cremophor EL (C-form), and PEG-400/ethanol were formed as microemulsions under dilution with aqueous phase. The resulting microemulsions were evaluated in vitro and in vivo, including the kinetics and antitumor effects in SKOV-3 human ovarian cancer xenograft in nude mice. Following 1:10 aqueous dilution of optimal 9-NC SMEDDS, the droplet sizes of resulting microemulsions were (30.8+/-4.6)nm and (39.8+/-8.2)nm for SMEDDS T-form and C-form, respectively, and the zeta potential values were -(4.3+/-0.5)mV and -(5.7+/-0.5)mV, respectively. In SKOV-3 cells, the growth inhibition (IC(50)) of various 9-NC formulations was greatest with SMEDDS T-form (3.5+/-0.7nM) followed by SMEDDS C-form (4.6+/-0.4nM), 9-NC solution (6.6+/-1.4nM) and 9-NC suspension (26.0+/-2.9nM) (P<0.01). It was indicated that the area under the plasma concentration-time curve (AUC(0-->8h)) values of various formulations of 9-NC after oral administration ranked as the following sequence: SMEDDS T-form (360.12+/-19.44ngh/ml) approximately SMEDDS C-form (351.71+/-33.66ngh/ml)>9-NC solution (241.21+/-24.67ngh/ml)>9-NC suspension (161.24+/-24.31ngh/ml). The 9-NC SMEDDS formulations also produced significantly more tumor shrinkage (P<0.01) when compared to 9-NC suspension in nude mice bearing human ovarian cancer xenografts. The results suggest that SMEDDS is a promising drug delivery system to increase the oral bioavailability and antitumor effects of 9-NC and may be applied to other lipophilic drugs. 9-NC SMEDDS represents a novel 9-NC therapy for cancer patients.     

High-performance liquid chromatographic analysis of the investigational anticancer drug 9-aminocamptothecin, as the lactone form and as the total of the lactone and the hydroxycarboxylate forms, in micro-volumes of human plasma

A high performance liquid chromatographic (HPLC) assay is described for the determination of the investigational anticancer drug 9 aminocamptothecin (9-AC) as the lactone form (9AC(lac)) and as the total of the lactone and hydroxycarboxylate forms (9AC-(tot)), in micro volumes of plasma. The analytical methodology reported here involves a protein precipitation step with cold methanol (−30°C) as sample pretreatment procedure. The methanolic extract is used for the determination of 9AC-(tot). The intact (active) lactone form of 9-AC is separated from the hydroxycarboxylate form in the methanolic plasma extract by solid phase extraction within 48 h after sampling and deproteination. After evaporation to dryness (nitrogen, 40°C) the extract can be stored at −70°C for at least 3 weeks. The drug is analysed by reversed-phase liquid chromatography on a Zorbax SB RP-18 column, using methanol–water eluent (pH 2.2) and fluorescence detection. The presented assay is linear over a concentration range 0.2–100 ng·ml⁻¹ with a detection limit and a limit of quantitation of 0.05 and 0.2 ng·ml⁻¹, respectively, for both 9-AC(tot) and 9-AC(lac) using a 100 ml plasma sample. The proposed method has been implemented in a phase I clinical trial for pharmacokinetic evaluation of this potential new drug.     

Brain-targeted delivery of paclitaxel using glutathione-coated nanoparticles for brain cancers

Paclitaxel is not effective for treatment of brain cancers because it cannot cross the blood–brain barrier (BBB) due to efflux by P-glycoprotein (P-gp). In this work, glutathione-coated poly-(lactide-co-glycolide) (PLGA) nanoparticles (NPs) of paclitaxel were developed for brain targeting for treatment of brain cancers. P-gp ATPase assay was used to evaluate the NP as potential substrates. The NP showed a particle size suitable for BBB permeation (particle size around 200?nm) and higher cellular uptake of the NP was demonstrated in RG2 cells. The P-gp ATPase assay suggested that the NP were not substrate for P-gp and would not be effluxed by P-gp present in the BBB. The in vitro release profile of the NP exhibited no initial burst release and showed sustained drug release. The proposed coated NP showed significantly higher cytotoxicity in RG2 cells compared with uncoated NP (p?≤?0.05). Tubulin immunofluorescent study showed higher cell death by the NP due to increased microtubule stabilization. In vivo brain uptake study in mice showed higher brain uptake of the NP containing coumarin-6 compared with solution. The proposed brain-targeted NP delivery of paclitaxel could be an effective treatment for the brain cancers.     

9-硝基喜树碱内酯型在大鼠体内外的稳定性9-硝基喜树碱内酯型在大鼠体内外的稳定性

目的考察9-硝基喜树碱内酯型在大鼠体内和离体大鼠血浆中的稳定性。方法建立利用HPLC法测定大鼠血浆中9-硝基喜树碱内酯型浓度和总浓度的方法；利用此法测定9-硝基喜树碱在离体大鼠血浆、全血及体内血浆中的内酯型比例变化以及大鼠尾静脉注射后不同时间点的内酯浓度和总浓度；并对体内外实验结果进行比较以确定影响血浆中内酯型稳定性的主要因素。结果9-硝基喜树碱内酯型在大鼠体内的稳定性显著优于体外，在体外全血中的稳定性显著优于血浆。结论血细胞具有稳定9-硝基喜树碱内酯型的作用；药物从血浆中的清除是影响体内大鼠血浆中9-硝基喜树碱内酯型比例的主要因素；9-硝基喜树碱内酯型浓度和总浓度在大鼠体内的药代动力学过程符合二室模型，而羧酸盐型浓度符合一室模型。