联合包载Combretastatin A-4和阿霉素的长循环脂质体的体外体内初步研究

目的制备一种具有程序释药功能的联合包载抗肿瘤药物阿霉素(doxorubicin,DOX)和新生血管抑制剂(combretastatin A-4,CA-4)的新型长循环脂质体并进行体内药动学评价。方法以卵磷脂、胆固醇和聚乙二醇磷脂衍生物(1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-polyethylene gly-col,DSPE-PEG)为载体材料,采用薄膜分散法和硫酸铵梯度法分步包载CA-4和DOX制备得到脂质体。通过单因素考察,筛选最佳处方和制备工艺,并评价其体外释放情况。采用正常大鼠考察该制剂在静脉注射后的药动学行为。结果 m(卵磷脂)∶m(胆固醇)∶m(DSPE-PEG)为85∶10∶5、m(药)∶m(脂材)为1∶20、水化脂材浓度为50 mmol.L-1时,CA-4的包封率最高(>85%),DOX的包封率也在95%以上,平均粒径小于80 nm。体外释放结果表明联合包载DOX和CA-4的脂质体在pH7.4磷酸盐介质中可以快速释放CA-4,而DOX释放相对较慢。体内药动学实验结果表明,脂质体包载可明显增加CA-4的体内循环时间,但CA-4的联用并未对DOX体内药动学行为产生明显干扰。结论联合包载CA-4和DOX的脂质体可有效地实现程序释药,并延长药物体内循环时间,将可能成为肿瘤治疗的新策略。     

Enhanced solubility and stability of PEGylated liposomal paclitaxel: in vitro and in vivo evaluation

An improved PEGylated liposomal formulation of paclitaxel has been developed with the purpose of improving the solubility of paclitaxel as well as the physicochemical stability of liposome in comparison to the current Taxol formulation. The use of 3% (v/v) Tween 80 in the hydration media was able to increase the solubility of drug. The addition of sucrose as a lyoprotectant in the freeze-drying process increased the stability of the liposome particles. There was no significant difference in the entrapment efficiency of paclitaxel between the conventional non-PEGylated liposomes and our PEGylated liposomes. Cytotoxicity in human breast cancer cell lines (MDA-MB-231 and SK-BR-3) of our paclitaxel formulation was less potent compared to Taxol after 24h incubation, but was equipotent after 72 h due to the slower release of drug from the liposome. Our PEGylated liposomes increased the biological half-life of paclitaxel from 5.05 (+/-1.52)h to 17.8 (+/-2.35)h compared to the conventional liposomes in rats. Biodistribution studies in breast cancer xenografted nude mouse model showed that our liposomes significantly decreased the uptake in reticuloendothelial system (RES)-containing organs (liver, spleen and lung) while increasing the uptake in tumor tissues after injection compared to Taxol or the conventional liposomal formulation. Moreover, the PEGylated liposome showed greater tumor growth inhibition effect in in vivo studies. Therefore, our PEGylated liposomal formulation of paclitaxel could serve as a better alternative for the passive targeting of human breast tumors.     

In vitro and in vivo efficacy of PEGylated diisopropyl fluorophosphatase (DFPase)

Highly toxic organophosphorus compounds that irreversibly inhibit the enzyme acetycholinesterase (AChE), including nerve agents like tabun, sarin, or soman, still pose a credible threat to civilian populations and military personnel. New therapeutics that can be used as a pretreatment or after poisoning with these compounds, complementing existing treatment schemes such as the use of atropine and AChE reactivating oximes, are currently the subject of intense research. A prominent role among potential candidates is taken by enzymes that can detoxify nerve agents by hydrolysis. Diisopropyl fluorophosphatase (DFPase) from the squid Loligo vulgaris is known to effectively hydrolyze DFP and the range of G-type nerve agents including sarin and soman. In the present work, DFPase was PEGylated to increase biological half-life, and to lower or avoid an immunogenic reaction and proteolytic digest. Addition of linear polyethylene glycol (PEG) chains was achieved using mPEG-NHS esters and conjugates were characterized by electrospray ionization--time of flight--mass specrometry (ESI-ToF-MS). PEGylated wildtype DFPase and a mutant selective for the more toxic stereoisomers of the agents were tested in vivo with rats that were challenged with a subcutaneous 3x LD(50) dose of soman. While wildtype DFPase prevented death only at extremely high doses, the mutant was able keep the animals alive and to minimize or totally avoid symptoms of poisoning. The results serve as a proof of principle that engineered variants of DFPase are potential candidates for in vivo use if substrate affinity can be improved or the turnover rate enhanced to lower the required enzyme dose.     

阿霉素的不同盐型对其脂质体体外药物泄漏和体内长循环的影响

目的探讨阿霉素不同盐型对脂质体体内外稳定性的影响。方法以薄膜分散-挤压法制备含有不同缓冲对的空白脂质体，用pH梯度和化学梯度法包载阿霉素，对其在脂质体内状态进行观察，测定了阿霉素脂质体理化性质；用透析法检测阿霉素脂质体在不同介质中的药物泄漏；用HPLC法研究不同盐型阿霉素脂质体在大鼠体内药代动力学行为。结果甘氨酸盐缓冲液、柠檬酸盐缓冲液和硫酸铵溶液作内水相制得的空白脂质体的平均粒径分别为(103±8)，(102±12)和(97±8) nm，zeta电位分别为(-21.3±0.5)，(-21.7±0.4)和(-20.9±0.7) mV，对阿霉素的包封率分别为47.8%，96.7%和98.6%。甘氨酸盐制得的脂质体体外泄漏最快，硫酸铵制得的脂质体泄漏最慢；甘氨酸盐缓冲液、柠檬酸盐缓冲液和硫酸铵溶液作内水相制得的阿霉素脂质体大鼠体内平均滞留时间分别为12.13，23.31和29.79 h。结论阿霉素在脂质体内水相中不同盐型影响其脂质体的体内外稳定性，以硫酸铵为内水相制得的阿霉素脂质体最稳定，其稳定次序与内水相中酸的强度有关，酸性越弱其脂质体稳定性越高。     

In vitro cellular accumulation and cytotoxicity of liposomal and conventional formulations of daunorubicin and doxorubicin in resistant K562 cells

Previous investigations have indicated the possibility to circumvent multidrug resistance (MDR) by incorporation of an anthracycline into liposomes. We examined the in vitro cytotoxicity and cellular drug accumulation of the anthracyclines daunorubicin and doxorubicin compared with the commercially available liposomal formulations DaunoXome and Caelyx in human myelogenous leukemia K562 cells. The drug-sensitive parental K562/K line was compared with the P-glykoprotein (P-gp)-expressing cell lines K562/Dnr and K562/Vcr. Two cell lines with reduced levels of topoisomerase II (K562/Nov and K562/Ida) were also included. The cytotoxicity was determined by fluorometric microculture cytotoxicity assay and the cellular drug levels were determined by high performance liquid chromatograghy. There was a strong inverse correlation between P-gp levels and cellular drug accumulation (rho = -0.83, p = 0.04) and cytotoxicity (rho = -0.95, p = 0.01) of daunorubicin. Also the cytotoxicity of DaunoXome and doxorubicin was related to P-gp levels (rho = -0.96, p = 0.01 and rho = -0.90, p = 0.07, respectively). Caelyx did not show any cytotoxic effect due to impaired cellular uptake of the pegylated liposome. Regardless of the P-gp levels of the treated cells, DaunoXome showed the same cytotoxic effect despite lower intracellular accumulation (range 22-47%), compared with conventional daunorubicin.     

PEG-蛋白质类药物的体内代谢与安全性评价

聚乙二醇化蛋白质（pegylated protein,PEG-蛋白质）是延长蛋白质类药物半衰期的最有效的途径之一,通过延缓蛋白的排泄,提高其抗酶解的能力,增加其溶解性与稳定性,以及降低其免疫原性,可显著延长蛋白质类药物体内的生物活性,从而改善蛋白质类药物的药代动力学和药效学性质。由于方法学上的限制,PEG-蛋白质类药物的代谢、组织分布和排泄研究极具挑战,但众多的文献资料表明,聚乙二醇（polyethyleneglycol,PEG）分子的体内代谢与安全性已经确立,无需过度担心PEG-蛋白质类药物的安全性。将从PEG-蛋白质体内组织分布与排泄研究方法、PEG的代谢与安全性和PEG-蛋白质类药物动物和临床应用的安全性3方面介绍和评述PEG-蛋白药物的体内代谢与安全性评价问题。     

乳酸-羟基乙酸共聚物微球的研究进展

特殊注射剂是一类复杂的载药系统,如脂质体、微球和注射混悬剂等,尽管上市的产品不多,但经济价值巨大,部分产品的市场表现甚至超过了新分子实体。分别对全球范围内已上市的注射脂质体、注射微球和注射混悬剂作简要介绍,从技术特征、市场效应和临床需求3个方面,介绍这3种特殊注射剂的发展现状和发展潜力。

     

In vivo and in vitro anti-cancer activities and enhanced cellular uptakes of EGF fragment decorated doxorubicin nano-aggregates

Doxorubicin nano-aggregate was prepared for the purpose of epidermal growth factor receptor targeted anti-cancer therapy. An epidermal growth factor fragment composed of 11 amino acids was conjugated to an amino terminal of bi-functional poly(ethylene glycol) and doxorubicin was subsequently conjugated to the other carboxyl terminal of the conjugate. A mixture of the conjugate, free doxorubicin, and triethylamine spontaneously formed nano-sized aggregates in aqueous phase, which was confirmed by transmission electron microscopy and dynamic light scattering. A549 cells incubated with doxorubicin nano-aggregates with the epidermal growth factor fragment showed increased endocytic uptakes of the aggregates compared to unmodified aggregates. Pre-blocking of the epidermal growth factor receptor on the cell significantly decreased a degree of the cellular uptakes. Cytotoxicity of the nano-aggregates was significantly increased when epidermal growth factor fragments were decorated on the surface of doxorubicin nano-aggregates, which was confirmed by a live/dead cell assay and a MTT-based cytotoxicity assay. When doxorubicin nano-aggregates were administered to model animals bearing human lung carcinoma, the epidermal growth factor fragment significantly strengthened in vivo anti-cancer effects of doxorubicin nano-aggregates compared to native doxorubicin or unmodified nano-aggregates. Thus, doxorubicin nano-aggregates decorated with an epidermal growth factor fragment is expected to be a potent anti-cancer agent aiming to tumor tissue over-expressing epidermal growth factor receptors.     

In vivo pharmacokinetics, immunogenicity and mechanism of PEGylated antitumor polypeptide

HM-3, An RGD (Arg-Gly-Asp)-modified polypeptide derived from endostatin, is a potent angiogenesis inhibitor. Its robust inhibitory effects on endothelial cell migration and tumor growth have been demonstrated by activity assay both in vitro and in vivo. However, HM-3 has relatively short half-life in vivo. In order to prolong its half-life and retain its safety and efficacy, previous studies modified HM-3 with four types of PEG (site-specific N-terminal modification), and the results showed that mPEG-SC20k-HM-3 was the most ideal modification product via activity evaluation in vivo. In the present study, we determined the pharmacokinetic properties, immunogenicity and binding targets of mPEG-SC20k-HM-3. The results showed that mPEG-SC20k-HM-3 had good linear pharmacokinetic properties in SD rats. The half-life of mPEG-SC20k-HM-3 was 43.76-fold longer than that of unmodified HM-3 after intravenous injection in SD rats. The administration frequency of the modified product (mPEG-SC20k-HM-3) was reduced from twice a day to once every 2 days, while the safety and efficacy were retained. The immunogenicity of mPEG-SC20k-HM-3 was significantly lower than that of HM-3 in BALB/c mice. Histochemical and immunohistochemical results showed that mPEG-SC20k-HM-3 could significantly inhibit angiogenesis and tumor growth, induce continuous necrosis, and reduce vessel density within tumor tissues. Furthermore, mPEG-SC20k-HM-3 could bind multi-target αvβ3 and α5β1 of integrin, and the major binding target was integrin αvβ3. All of these results indicated that PEGylated HM-3 had a good application prospect.     

脂质体纳米银凝胶剂的体外释放及其含量测定

目的建立脂质体纳米银凝胶剂的含量测定方法。方法采用火焰原子吸收分光光度法(FLAA)对脂质体纳米银凝胶剂中的银元素进行含量测定。结果纳米银在0.25～8.0μg/ml范围内呈现良好的线性关系(r=0.9999),检测限1.2×10-3μg/ml,平均加样回收率为99.1%,相对标准偏差(RSD)为1.70%。体外释放试验数据表明,本制剂中纳米银体外释放行为较为符合零级方程和Higuchi方程,12h累积释放率为40.92%。结论本含量测定方法操作简便准确,专属性强,可用于该制剂的含量测定。对于纳米银的进一步深入研究具有一定的实际应用价值。     

阿霉素脂质体对克服肿瘤多药耐药的细胞学体外评价

目的:评价市售阿霉素脂质体体外逆转肿瘤多药耐药(MDR)的作用。方法:MTT法比较阿霉素和阿霉素脂质体体外对敏感和耐药细胞的细胞毒作用;荧光显微镜观察2组药物对敏感和耐药细胞的影响;流式细胞仪检测2组分别在细胞内的积累和外排情况。结果:细胞毒性试验结果显示,尽管在敏感细胞中,阿霉素脂质体IC50远高于阿霉素溶液组,对于耐药细胞株,阿霉素脂质体的IC50与游离阿霉素无显著性差异(P>0.05);细胞荧光染色显示,阿霉素脂质体较溶液在耐药细胞核中有更强的红染;细胞摄取试验显示,相同浓度下,阿霉素脂质体较溶液组在耐药细胞中积累量差异无显著性(P>0.05),但外排试验显示,在耐药细胞KBv200中,相同浓度下的脂质体较溶液具有更强的细胞滞留能力(P<0.05)。结论:阿霉素脂质体较阿霉素溶液在体外能更多进入耐药细胞核,并表现出更强的药物滞留能力,可部分克服多药耐药。     

Preparation,characterization and evaluation of liposomal doxorubicin and harmine that show synergistic activity in vitro

A combinatory therapeutic system that simultaneously targets several independent pathways is preferred for the treatment of cancer. In our study, a combinatory liposomal delivery system containing doxorubicin (Dox) and harmine (HM) was constructed by thin film dispersing method together with pH gradient method. A simple, precise and accurate spectrophotometric method for the determination of Dox and HM in liposomal formulation was established and validated. A drug HSPC ratio of 1: 20, loading time of 30 min and loading temperature of 50 °C were the optimal conditions for the preparation of drug loaded liposomes, which exhibited excellent physicochemical properties such as average particle size of ~100 nm, low polydispersity index below 0.2 and high entrapment efficiency above 93%. Sustained release of drug from liposomes at pH 7.4 showed good biological safety. The synergetic cytotoxic effect for these two drugs was evaluated in MCF-7 cells. The in vitro antitumor studies demonstrated the superior anti-proliferation activity of the liposomal Dox and HM with a combination index of 0.81, which indicated great synergistic effect and increased anti-proliferation efficiency. The experimental data suggested that combinational liposome therapy could be an effective way to develop efficient treatment of cancers.     

In vitro mechanistic study of cell death and in vivo performance evaluation of RGD grafted PEGylated docetaxel liposomes in breast cancer

Objectives of the investigations were to prepare RGD grafted docetaxel liposomes (RGD-PEG-LP-DC) using supercritical fluid technology and evaluate it in vitro for cytotoxicity, DNA content analysis, mechanism of cell death, and in vivo for pharmacokinetic and biodistribution studies in BALB/c mice. The RGD-PEG-LP-DCs were found to be most cytotoxic in BT-20 and MDA-MB-231 cell lines. The flowcytometry results shows at 48 hours, 96% G2 phase arrest for RGD-PEG-LP-DC at 5 nM drug concentration. The mode of cell death was found to be mainly by necrosis at low drug equivalent concentration (1 nM) and by apoptosis at high drug equivalent concentration (10 nM). With increase in time and concentration the mode of cell death by apoptosis was found to be increasing. Biodistribution demonstrated that site specific drug distribution, t(1/2), and MRT improved significantly for RGD-PEG-LP-DC. From the studies site specific and sustained intracellular drug delivery from RGD-PEG-LP-DCs may provide promising strategy in enhancing embattled against breast cancer treatment. FROM     

Pegylated liposomal doxorubicin: tolerability and toxicity

We evaluated the tolerability and toxicity attributed to pegylated liposomal doxorubicin (PL-DOX) in women with recurrent or refractory ovarian cancer, and reviewed procedures to prevent or treat toxicity induced by the agent. Medical records of 13 women who received PL-DOX between October 1997 and December 2000 were reviewed. Patients 1-8 received PL-DOX once it was added to the hospital formulary in 1997. Patients 9-13 received it after medical staff education. Data on premedications, number of cycles, dosage, length of infusion, tolerability, side effects, and indicators for response were collected. The median number of cycles and cumulative dose/patient of PL-DOX were higher (6 and 420 mg) in the second group than in the first group (2 and 240 mg). Patient factors such as duration of disease and number of chemotherapy cycles influenced tolerability. One patient experienced a life-threatening adverse reaction within minutes of receiving the first dose. Treatment was discontinued, and she was resuscitated successfully. Other dose- or treatment-limiting complications (neutropenia, stomatitis, plantar-palmar erythrodysesthesia) were documented. Toxicity management consisted of dosage reduction or treatment delay; treatment often was discontinued. Patients with recent disease tolerated more cycles of PL-DOX when given early in recurrence compared with heavily pretreated women with long-standing disease. Tolerability was not necessarily indicative of response. The agent is simple to administer, but its tolerability and lack of uniform toxicity management remain concerns.     

In vivo monitoring of liposomal release in tumours following ultrasound stimulation

Dioeleoylphosphatidylethanolamine (DOPE)-based liposomes were recently reported as a new class of liposomes for ultrasound (US)-mediated drug delivery. The liposomes showed both high stability and in vitro US-mediated drug release (sonosensitivity). In the current study, in vivo proof-of-principle of US triggered release in tumoured mice was demonstrated using optical imaging. Confocal non-thermal US was used to deliver cavitation to tumours in a well-controlled manner. To detect in vivo release, the near infrared fluorochrome Al (III) Phthalocyanine Chloride Tetrasulphonic acid (AlPcS₄) was encapsulated into both DOPE-based liposomes and control liposomes based on hydrogenated soy phosphatidylcholine (HSPC). Encapsulation causes concentration dependent quenching of fluorescence that is recovered upon AlPcS₄ release from the liposomes. Exposure of tumours to US resulted in a significant increase in fluorescence in mice administered with DOPE-based liposomes, but no change in the mice treated with HSPC-based liposomes. Thus, DOPE-based liposomes showed superior sonosensitivity compared to HSPC-based liposomes in vivo.     

In vitro and in vivo pharmacokinetic characterizations of AMG 900, an orally bioavailable small molecule inhibitor of aurora kinases

1. AMG 900 is a small molecule being developed as an orally administered, highly potent, and selective pan-aurora kinase inhibitor. The aim of the investigations was to characterize in vitro and in vivo pharmacokinetic (PK) properties of AMG 900 in preclinical species.

2. AMG 900 was rapidly metabolized in liver microsomes and highly bound to plasma proteins in the species tested. It was a weak Pgp substrate with good passive permeability.

3. AMG 900 exhibited a low-to-moderate clearance and a small volume of distribution. Its terminal elimination half-life ranged from 0.6 to 2.4?h. AMG 900 was well-absorbed in fasted animals with an oral bioavailability of 31% to 107%. Food intake had an effect on rate (rats) or extent (dogs) of AMG 900 oral absorption.

4. The clearance and volume of distribution at steady state in humans were predicted to be 27.3?mL/h/kg and 93.9?mL/kg, respectively.

5. AMG 900 exhibited acceptable PK properties in preclinical species and was predicted to have low clearance in humans. AMG 900 is currently in Phase I clinical testing as a treatment for solid tumours. Preliminary human PK results appear to be consistent with the predictions.

     

In vitro and in vivo pharmacokinetic characterizations of AMG 900, an orally bioavailable small molecule inhibitor of aurora kinases

AMG 900 is a small molecule being developed as an orally administered, highly potent, and selective pan-aurora kinase inhibitor. The aim of the investigations was to characterize in vitro and in vivo pharmacokinetic (PK) properties of AMG 900 in preclinical species. AMG 900 was rapidly metabolized in liver microsomes and highly bound to plasma proteins in the species tested. It was a weak Pgp substrate with good passive permeability. AMG 900 exhibited a low-to-moderate clearance and a small volume of distribution. Its terminal elimination half-life ranged from 0.6 to 2.4 h. AMG 900 was well-absorbed in fasted animals with an oral bioavailability of 31% to 107%. Food intake had an effect on rate (rats) or extent (dogs) of AMG 900 oral absorption. The clearance and volume of distribution at steady state in humans were predicted to be 27.3 mL/h/kg and 93.9 mL/kg, respectively. AMG 900 exhibited acceptable PK properties in preclinical species and was predicted to have low clearance in humans. AMG 900 is currently in Phase I clinical testing as a treatment for solid tumours. Preliminary human PK results appear to be consistent with the predictions.     

In vitro and ex vivo methods predict the enhanced lung residence time of liposomal ciprofloxacin formulations for nebulisation

Liposomal ciprofloxacin formulations have been developed with the aim of enhancing lung residence time, thereby reducing the burden of inhaled antimicrobial therapy which requires multiple daily administration due to rapid absorptive clearance of antibiotics from the lungs. However, there is a lack of a predictive methodology available to assess controlled release inhalation delivery systems and their effect on drug disposition. In this study, three ciprofloxacin formulations were evaluated: a liposomal formulation, a solution formulation and a 1:1 combination of the two (mixture formulation). Different methodologies were utilised to study the release profiles of ciprofloxacin from these formulations: (i) membrane diffusion, (ii) air interface Calu-3 cells and (iii) isolated perfused rat lungs. The data from these models were compared to the performance of the formulations in vivo. The solution formulation provided the highest rate of absorptive transport followed by the mixture formulation, with the liposomal formulation providing substantially slower drug release. The rank order of drug release/transport from the different formulations was consistent across the in vitro andex vivo methods, and this was predictive of the profiles in vivo. The use of complimentary in vitro and ex vivo methodologies provided a robust analysis of formulation behaviour, including mechanistic insights, and predicted in vivo pharmacokinetics.     

A metronomic schedule of cyclophosphamide combined with PEGylated liposomal doxorubicin has a highly antitumor effect in an experimental pulmonary metastatic mouse model

Metronomic chemotherapy is a novel approach to the control of advanced cancer, as it appears to preferentially inhibit endothelial cell activity in the growing vasculature of tumors. Doxorubicin-containing sterically stabilized liposomes (DXR-SL) accumulate in large amounts in tumor tissue, resulting in enhanced antitumor effects of the encapsulated DXR. In the present study, it was hypothesized that metronomic chemotherapy may further augment the accumulation of DXR-SL, improving its therapeutic efficacy. This study tests the antitumor efficacy for the combination of a metronomic cyclophosphamide (CPA)-dosing schedule with sequential intravenous injections of DXR-SL in the treatment of lung metastatic B16BL6 melanoma-bearing mice. Three dosing schedules for the combination of metronomic CPA injections (s.c. 170 mg/kg every 6 days) plus either a low or a high dose of DXR-SL (i.v. 1 or 5 mg/kg every 6 days) were set: Schedule I, DXR-SL was given 3 days before the first CPA treatment; Schedule II, DXR-SL and CPA were given simultaneously; and, Schedule III, DXR-SL was given 3 days after the first CPA treatment. Lung weight and median survival time (MST) were evaluated. As expected, both the dosing schedule as well as the dose of DXR-SL improved therapeutic efficacy. Schedule I with the low DXR dose and Schedule II with the low or high DXR dose significantly increased MST, compared with regular metronomic CPA therapy. Under the dosing schedules (Schedule I with the low DXR dose and Schedule II with the high DXR), there was a strong relationship between increased MST and decreased lung weight. However, Schedule I with high DXR dose resulted in significantly lower lung weights, but did not increase MST, suggesting that chemotherapy may result in increased toxicity in some conditions. Although treatment regimens require optimization, the results of the present study may prove useful in further explorations of combining metronomic chemotherapy with liposomal anticancer drugs in the treatment of solid tumors.