Preparation and Characterization of Doxorubicin-Loaded Sterically Stabilized Immunoliposomes

Purpose. To compare the performance of sterically stabilized, doxorubicin-loaded liposomes with and without surface attached specific antibodies (D-SSIL and D-SSL, respectively). Methods. Small ( 120 nm) unilamellar liposomes were prepared composed of hydrogenated soy phosphatidylcholine, hydrogenated phosphatidylethanolamine (HPE), cholesterol, and ²⁰⁰⁰Da polyethylene glycol (²⁰⁰⁰PEG) attached to the primary amino group of distearoyl phosphatidylethanolamine. Doxorubicin was remote-loaded into these liposomes by an ammonium sulfate gradient to form the D-SSL. Monoclonal IgG₃ NI32/2 antibodies directed against a polyoma virus tumor-associated antigen expressed on A9 etc 102 murine fibrosarcoma cells were attached to the D-SSL HPE via a thioether bond to form the D-SSIL-32/2. A control of nonspecific D-SSIL was prepared by attaching nonspecific IgG₃-enriched immunoglobulins to D-SSL. All liposomes were physically and chemically characterized and then tested in vitro for tumor cell binding, specificity, and uptake by macrophages; and in vivo for the drug plasma pharmacokinetics after intravenous administration in mice. Results. (i) The attachment of antibodies to D-SSL did not impair their chemical or physical stability and had a minimal effect on their size and level of loaded drug, (ii) The combination of specific antibodies and ²⁰⁰⁰PEG grafted in the liposomes improved the specific binding to relevant target cells by reducing the level of unspecific binding to nonrelevant cells. (iii) D-SSIL retained the prolonged circulation and slow clearance typical of SSL lacking the antibodies. Conclusions. Sterically stabilized immunoliposomes exhibited stability, ability to recognize target cells, and prolonged circulation time. This study also shows that it is feasible to prepare them in pharmaceutically acceptable dosage form. Thus, further investigation for tumor targeting and efficacy is warranted.     

chTNT-3-空间稳定脂质体的制备及理化性质考察

将人鼠嵌合抗肿瘤细胞核单抗(chTNT-3)共价连接到多柔比星脂质体表面,制得的chTNT-3-空间稳定脂质体粒径分布为(123.1±28.4)nm,多柔比星包封率大于98%。初步稳定性考察表明,在低温(4℃)贮存7d,制品平均粒径及分布变化小,药物泄漏少于3%,免疫活性保持不变,理化性质尚较稳定。     

Enhanced Intracellular Uptake of Sterically Stabilized Liposomal Doxorubicin <Emphasis Type="Italic">in Vitro</Emphasis> Resulting in Improved Antitumor Activity <Emphasis Type="Italic">in Vivo</Emphasis>

Purpose To investigate the correlation between the in vitro intracellular uptake and the in vivo antitumor activity of anticancer drugs delivered by sterically stabilized liposomes (SSL).Methods Arginine-glycine-aspartic acid (RGD) peptide or RGD mimetic (RGDm) was coupled onto the surface of SSL to obtain the cell-binding carrier to facilitate the intracellular delivery of the encapsulated drugs. DOX-loaded SSL (SSL-DOX), DOX-loaded RGD-modified SSL (RGD-SSL-DOX) and DOX-loaded RGDm-modified SSL (RGDm-SSL-DOX) were prepared by lipid film dispersion followed by remote loading of DOX. The intracellular uptake of DOX from the various liposomal formulations was evaluated in vitro with melanoma B16 cells, and the pharmacokinetics, biodistribution, and antitumor activity were compared in C57BL/6 mice carrying melanoma B16 tumors.Results In vitro intracellular uptake of DOX by B16 cells and in vivo antitumor activity in terms of tumor growth inhibition and mice survival time prolongation for various liposomal DOX were in the following order: RGD-SSL-DOX > RGDm-SSL-DOX > SSL-DOX. The mean survival time of the mice treated with RGD-SSL-DOX, RGDm-SSL-DOX, and SSL-DOX was 55, 49, and 44 days, respectively. The three liposomal DOX formulations produced very close DOX accumulation in tumor, which is significantly higher than that of free DOX. RGD- or RGDm-SSL-DOX demonstrated prolonged circulation time similar to that of SSL-DOX, whereas they showed significantly lower DOX level in blood and remarkably higher uptake by spleen than SSL-DOX.Conclusions Enhanced intracellular uptake of DOX encapsulated in SSL could produce an improved therapeutic effect for the melanoma B16 tumors. Enhancing intracellular delivery of the anticancer drugs encapsulated in SSL may be a promising strategy to improve their therapeutic efficacy for solid tumors.     

Targeted Delivery of Doxorubicin by HPMA Copolymer-Hyaluronan Bioconjugates

Purpose. Overexpression of hyaluronan (HA) receptors on cancer cells results in enhanced endocytotic uptake of the drug conjugate. An N-(2-hydroxypropyl)methacrylamide (HPMA)-HA polymeric drug delivery system was used for targeted delivery of doxorubicin to cancer cells. Methods. HA-doxorubicin (DOX) bioconjugates (HA-DOX), and HPMA copolymer-DOX conjugates containing HA as a side chain (HPMA-HA-DOX) were synthesized. The cytotoxicity of the polymer-drug conjugate was evaluated via in vitro cell culture. The internalization of the conjugate was visualized by fluorescence microscopy. Results. Cytotoxicity of HPMA-HA-DOX targeted bioconjugate was higher against human breast cancer (HBL-100), ovarian cancer (SKOV-3), and colon cancer (HCT-116) cells when compared to the non-targeted HPMA-DOX conjugate. Fluorescence confocal microscopy revealed that the targeted HPMA-HA-DOX conjugates were internalized more efficiently by cancer cells relative to the non-targeted HPMA-DOX conjugate. Both HPMA-DOX and HPMA-HA-DOX showed minimal cytotoxicity toward mouse fibroblast NIH 3T3 cells. The internalization of polymer conjugates was correlated with their cytotoxicity. Conclusions. Selective delivery of anti-cancer agents to cancer cells was achieved by biochemical targeting. The HA-modified HPMA copolymer showed improved toxicity due to receptor-mediated uptake of the macromolecular drug.     

Pharmacokinetics and Biodistribution of Novel Aptamer Compositions

No HeadingPurpose. Aptamers are highly selective nucleic acid–based drugs that are currently being developed for numerous therapeutic indications. Here, we determine plasma pharmacokinetics and tissue distribution in rat of several novel aptamer compositions, including fully 2-O-methylated oligonucleotides and conjugates bearing high-molecular weight polyethylene glycol (PEG) polymers, cell-permeating peptides, and cholesterol.Methods. Levels of aptamer conjugates in biological samples were quantified radiometrically and by a hybridization-based dual probe capture assay with enzyme-linked fluorescent readout. Intact aptamer in urine was detected by capillary gel electrophoresis and matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF).Results. Aptamer compositions examined exhibited a wide range of mean residence times in circulation (0.6–16 h) and significant variation in distribution levels among organs and tissues. Among the conjugates tested, in vivo properties of aptamers were altered most profoundly by conjugation with PEG groups. Complexation with a 20 kDa PEG polymer proved nearly as effective as a 40 kDa PEG polymer in preventing renal clearance of aptamers. Conjugation with 20 kDa PEG prolonged aptamer circulatory half-life, while reducing both the extent of aptamer distribution to the kidneys and the rate of urinary elimination. In contrast, the fully 2-O-Me aptamer composition showed rapid clearance from circulation, and elimination with intact aptamer detectable in urine at 48 h post-administration.Conclusions. We find that conjugation and chemical composition can alter fundamental aspects of aptamer residence in circulation and distribution to tissues. Though the primary effect of PEGylation was on aptamer clearance, the prolonged systemic exposure afforded by presence of the 20 kDa moiety appeared to facilitate distribution of aptamer to tissues, particularly those of highly perfused organs.     

Macromolecular Carrier Systems for Targeted Drug Delivery: Pharmacokinetic Considerations on Biodistribution

This review article describes the current status and future perspectives of site-specific drug delivery by means of macromolecular carrier systems. Basic aspects and recent advances of targeted delivery of 1) conventional drugs, 2) protein drugs, and 3) gene medicines including antisense oligonucleotides and plasmid DNA, are reviewed from a pharmacokintic perspective. Successful in vivo application of macromolecular carrier systems requires pharmacokinetic considerations at whole body, organ, cellular and subcellular levels. The integration of simultaneous research progress in the multidisciplinary fields such as biochemistry, cell and molecular biology, pharmacology, and pharmacokinetics will accelerate the emergence of marketed drugs with macromolecular carrier systems.     

Pharmacokinetics of Differently Designed Immunoliposome Formulations in Rats with Or Without Hepatic Colon Cancer Metastases

Purpose. Compare pharmacokinetics of tumor-directed immunoliposomes in healthy and tumor-bearing rats (hepatic colon cancer metastases). Methods. A tumor cell-specific monoclonal antibody was attached to polyethyleneglycol-stabilized liposomes, either in a random orientation via a lipid anchor (MPB-PEG-liposomes) or uniformly oriented at the distal end of the PEG chains (Hz-PEG-liposomes). Pharmacokinetics and tissue distribution were determined using [³H]-cholesteryloleylether or bilayer-anchored 5-fluoro[³H]deoxyuridine-dipalmitate ([³H]FUdR-dP) as a marker. Results. In healthy animals clearance of PEG-(immuno)liposomes was almost log-linear and only slightly affected by antibody attachment; in tumor-bearing animals all liposomes displayed biphasic clearance. In normal and tumor animals blood elimination increased with increasing antibody density; particularly for the Hz-PEG-liposomes, and was accompanied by increased hepatic uptake, probably due to increased numbers of macrophages induced by tumor growth. The presence of antibodies on the liposomes enhanced tumor accumulation: uptake per gram tumor tissue (2-4% of dose) was similar to that of liver. Remarkably, this applied to tumor-specific and irrelevant antibody. Increased immunoliposome uptake by trypsin-treated Kupffer cells implicated involvement of high-affinity Fc-receptors on activated macrophages. Conclusions. Tumor growth and immunoliposome characteristics (antibody density and orientation) determine immunoliposome pharmacokinetics. Although with a long-circulating immunoliposome formulation, efficiently retaining the prodrug FUdR-dP, we achieved enhanced uptake by hepatic metastases, this was probably not mediated by specific interaction with the tumor cells, but rather by tumor-associated macrophages.     

Development of a Novel Bioactive Formulation of Vasoactive Intestinal Peptide in Sterically Stabilized Liposomes

Pharmaceutical Research -     

Pharmacokinetics and Biodistribution of a Nucleotide-Based Thrombin Inhibitor in Rats

Purpose. To characterize the pharmacokinetic and tissue distribution profiles of a nucleotide-based thrombin inhibitor (GS522, phosphodiester oligonucleotide, GGTTGGTGTGGTTGG) following intravenous administration to rats. Methods. Pharmacokinetic study: 10 mg/kg, 20 mg/kg, 30 mg/kg (6 animals/dose) were administered to rats by rapid injection into the femoral vein. Blood samples were collected over a 45 minute period. Plasma concentrations of GS522 were determined using capillary gel electrophoresis with laser-induced fluorescence detection. Biodistribution Study: l0mg/kg (400l, 31.46 Ci/ml) of ³H-GS522 was administered to rats by rapid injection into the femoral vein. The animals were sacrificed by decapitation at 1, 5, 10, 30, 60, 360 minutes post-dose (3 rats/point). Brain, blood, duodenum, eyes, heart, kidney, liver, lungs, muscle, pancreas, skin, spleen and vein samples were collected, processed and quantitated using liquid scintillation counting. Results. The pharmacokinetic profile declines in multiexponential manner, exhibiting extremely fast distribution and elimination (t_1/2 = 7.6–9.0 min, Cl = 22.0–28.0 ml/min, V = 83.9–132.4 ml/kg). GS522 follows linear pharmacokinetics, with the area under the curve being proportional to the dose (Rsq = 0.9744). Highest radioactivity levels were detected in kidney, liver and blood (39.7, 15.7 and 15.3% dose/ respective organ). Less than 1% of the dose was detected in the heart, spleen and lungs, and >0.3% of the dose was found in the brain and eyes. The oligonucleotide associated radioactivity was uniformly distributed between the brain regions (left and right lobe and cerebellum). Six hours following the dose administration a statistically significant increase (p < 0.05) in radioactivity levels was observed in the brain, eyes, skin, liver, pancreas and vein. Conclusions. The pharmacokinetic and biodistribution profiles of GS522 following intravenous administration to rats at three doses were characterized. The oligonucleotide associated radioactivity was widely distributed in tissues. The amount of radioactivity sharply decreased with time in most tissues. Kidney, liver and muscle were the main sites of accumulation. The oligonucleotide associated radioactivity did not cross the blood brain barrier to an appreciable extent. In addition, a statistically significant increase (p < 0.05) in the radioactivity levels observed in select tissues suggested a re-uptake mechanism for intact oligonucleotide or its degradation products.     

Targeted delivery of levofloxacin-liposomes for the treatment of pulmonary inflammation

The present study systematically studied the intravenous injectable formulation of liposomes loaded with levofloxacin, an amphipathic antibiotic. The aim of the present study was to design passive targeting liposomes, which might improve the antibacterial activity by accumulating in lung and reduce side effects such as neurotoxicity and hematotoxicity associated with direct injection of the drug. Levofloxacin-loaded liposomes were prepared by the ammonium sulfate gradients method. The formulated liposomes were found to be relatively uniform in size (7.424 ± 0.689 μm) with a positive zeta potential (+13.11 ± 1.08 mV). The entrapment efficiency of levofloxacin-loaded liposomes ranged from 82.19% to 86.23%. The administered liposomes were composed of soybean phosphatides, cholesterol, levofloxacin, and sulfate which existed in inner liposomes. In vitro drug release was monitored for up to 3 days, and the release behavior was in accordance with the Weibull equation. The levofloxacin-loaded liposomes exhibited a longer elimination half-life (t_1/2β) in vivo compared with the levofloxacin solution after intravenous injection to New Zealand rabbits. The encapsulation of levofloxacin in liposomes also changed its biodistribution in mice after intravenous injection in caudal vein. Liposomal levofloxacin performed significant lung targeting efficiency with area under the concentration–time curve, targeting efficacy (Te), and The intake rate (Re) of lung, all showing obvious increase. In addition, liposomal formulations presented accumulative activity in spleen and liver. Conversely, the biodistribution of liposomal formulation in non-RES sites, such as kidney, brain, heart, and plasma, decreased with descending peak concentration ration (Ce) compared to levofloxacin injection, which potentially resulted in the reduction of the side effects of free drug. These results indicated that the levofloxacin-loaded liposomes were promising passive targeting to lung for pulmonary infection treatment.     

PEG化脂质体多柔比星在动物体内的药动学及组织分布

比较研究了PEG化脂质体多柔比星(阿霉素)受试制剂与进口同类参比制剂静注后,在动物体内的药动学及组织分布.采用HPLC法测定Beagle犬的血药浓度和荷瘤(Walker256)Wistar大鼠各组织药物浓度.结果显示,Beagle犬静注1 mg/kg受试制剂及参比制剂后,药动学参数分别为t1/2β23.0和23.5 h,表观分布容积0.060和0.062 L/kg,AUC0-∞500.29和531.57μg·ml-1h,多柔比星在犬体内的药代动力学过程均符合二室模型的特征.荷瘤(Walker256)Wistar大鼠静注5 mg/kg受试制剂及参比制剂后,脾中含量最高,其次为肿瘤、小肠、肝,皮肤中含量最低.统计学分析显示,两制剂在犬体内主要药动学参数及大鼠组织肝、心、脾、肾、小肠、皮肤和肿瘤内的分布,无显著性差异(P>0.05).     

基于药动学及代谢物组学研究多柔比星在大鼠体内的心脏毒性

目的 测定多柔比星大剂量给药后原型药物及代谢产物的药动学特征及组织分布,以明确代谢产物在多柔比星急性心脏毒性中的作用。方法 测定多柔比星血清及心脏组织源性代谢物的变化特点,寻找与心脏毒性发生相关的代谢生物标志物及心脏毒性的潜在机制。利用LC-MS/MS测定多柔比星及多柔比星醇的浓度,利用GC-MS进行血清及心脏组织的代谢物组学分析。结果 多柔比星大鼠体内单剂量给药后,在心脏组织呈现高分布,且高剂量（10 mg·kg^-1）时分布显著增加。多柔比星醇的代谢转换率很低,且在心脏组织中的分布较低。代谢物组学研究结果表明,小分子能量物质酮体及脂肪酸为血清样本中的主要差异性物质。心脏组织中主要差异性物质为脂肪酸和甘油单酯。结论 多柔比星单剂量给药后,其在心脏中分布较高,且高剂量时特异性分布增加。多柔比星醇在血清及心脏组织中的浓度较低,推测其在急性毒性中的作用有限。多柔比星单剂量给药会引起心脏组织内的以脂质代谢为主的能量代谢异常,能量代谢对多柔比星相关的急性心肌毒性具有重要作用。     

依托泊苷白蛋白微球小鼠体内分布及药代动力学

目的 :制备依托泊苷白蛋白微球 ,并对其动物体内分布及药代动力学进行研究。方法 :用高效液相色谱法测定各组织中依托泊苷浓度。结果 :小鼠尾静脉注射微球后15min ,肺内依托泊苷量占注入总量的(47.88±2.56) %,微球小鼠肺组织内药代动力学方程为 :C=149.0897e -1.7780t +3.9627e -0.0398t—153.0524e -3.5054t。结论 :依托泊苷白蛋白微球具有明显的肺靶向效果 ,小鼠肺组织中药代动力学规律可以二室模型拟合。     

Biodistribution and Pharmacokinetics of Dapivirine-Loaded Nanoparticles after Vaginal Delivery in Mice

Purpose

To assess the potential of polymeric nanoparticles (NPs) to affect the genital distribution and local and systemic pharmacokinetics (PK) of the anti-HIV microbicide drug candidate dapivirine after vaginal delivery.

Methods

Dapivirine-loaded, poly(ethylene oxide)-coated poly(epsilon-caprolactone) (PEO-PCL) NPs were prepared by a nanoprecipitation method. Genital distribution of NPs and their ability to modify the PK of dapivirine up to 24 h was assessed after vaginal instillation in a female mouse model. Also, the safety of NPs upon daily administration for 14 days was assessed by histological analysis and chemokine/cytokine content in vaginal lavages.

Results

PEO-PCL NPs (180–200 nm) were rapidly eliminated after administration but able to distribute throughout the vagina and lower uterus, and capable of tackling mucus and penetrate the epithelial lining. Nanocarriers modified the PK of dapivirine, with higher drug levels being recovered from vaginal lavages and vaginal/lower uterine tissues as compared to a drug suspension. Systemic drug exposure was reduced when NPs were used. Also, NPs were shown safe upon administration for 14 days.

Conclusions

Dapivirine-loaded PEO-PCL NPs were able to provide likely favorable genital drug levels, thus attesting the potential value of using this vaginal drug delivery nanosystem in the context of HIV prophylaxis.     

Thermosensitive Sterically Stabilized Liposomes: Formulation and in Vitro Studies on Mechanism of Doxorubicin Release by Bovine Serum and Human Plasma

Purpose. To formulate thermosensitive sterically stabilized liposomes and to study the effects of plasma and serum components in vitro. Methods. The rate of release of encapsulated doxorubicin (Dox) from liposomes of various compositions was followed by fluorometric assay at 37°, 42° and 45°C, in buffer and also in both calf serum and human plasma up to 50% by volume. Results. The optimal composition for the maximal differential release of doxorubicin between 37°C and 42°C in human plasma was a mixture of dipalmitoylphosphatidylcholine/hydrogenated soy phosphatidylcholine/cholesterol and distearoylphosphatidylethanolamine derivatized with polyethylene glycol at a molar ratio of 100:50:30:6. In experiments designed to study the mechanism causing increased permeability of liposomes in bovine serum, we found two different distinct release patterns: a slow linear rise of rate of Dox release for fluid liposomes and fast exponential rise reaching plateau within 5 minutes for solid phase (rigid) liposomes. This release of Dox from rigid but not fluid liposomes was inhibited by pre-heating serum at 55°C for 30 minutes or by addition of EDTA (but not EGTA) or antiserum to the C3 component of complement. Conclusions. A formulation of sterically stabilized liposomes with the proper thermal sensitivity in human plasma has been obtained. In addition, the results suggest that complement may play an important role in the interaction of rigid but not fluid liposomes with bovine serum. Human plasma did not show this effect.     

Pharmacokinetics and Antitumor Effect of Doxorubicin Carried by Stealth and Remote Loading Proliposome

Purpose. The aim of the study was to prepare stealth and remoteloading proliposome (SRP-L) to carry doxorubicin (DXR) and evaluatethe pharmacokinetics, acute toxicity, and anticancer effect of DXRcarried with SRP-L. Methods. SRP-L was transparent solution. When SRP-L was injectedinto 0.9% NaCl aqueous solution containing DXR, liposomes formedand automatically loaded DXR (SRP-L-DXR). The long circulation ofSRP-L-DXR was evaluated using the pharmacokinetics ofSRP-L-DXR, cardiolipin liposomal DXR (CL-DXR) and free DXR (F-DXR).The acute toxicity and anticancer effect of SRP-L-DXR were evaluatedin C57BL/6 mice and murine hystocytoma M5076 tumor model. Results. The average diameter of SRP-L-DXR in pure water was112.9 ± 8.6 (nm) and the encapsulation efficiency of SRP-L-DXRwas 96.5 ± 0.2% in pure water, 95.5 ± 0.1% in 5% glucose and 98.01± 0.6% in 0.9% NaCl. The plasma concentration of SRP-L-DXR wasmuch higher than those of F-DXR and CL-DXR. Compared with thatof F-DXR, the SRP-L-DXR had lower acute toxicity and its anticancereffects depended upon the therapeutic treatment. Conclusions. A novel proliposome (SRP-L) was developed, whichcould automatically load DXR and form SRP-L-DXR with excellentcharacteristics. SRP-L-DXR had lower acute toxicity but was notalways more effective for the treatment of the ascitic M5076 thanF-DXR.     

Biodistribution of Amphotericin B When Delivered Through Cholesterol Hemisuccinate Vesicles in Normal and A. Fumigatus Infected Mice

Purpose. This study compared the biodistribution of two amphotericin B formulations in normal and Aspergillus infected mice. Amphotericin B cholesterol hemisuccinate vesicles (ABCV) which reduces the toxicity of amphotericin B and thereby enhances its therapeutic efficacy in a murine model of aspergillosis was compared with conventional amphotericin B deoxycholate suspension (AmB_DOC). Methods. ABCV (12 mg/kg wt) and AmB_DOC (2 mg/kg wt) were intravenously administered to normal and A.fumigatus infected mice. The concentration of amphotericin B in plasma and other organs was determined at different time points. Results. It was observed that ABCV had a significantly different pharmacokinetic profile compared to conventional amphotericin B. In comparison to AmB_DOC significantly lower levels of amphotericin B were observed in kidneys and plasma, the major target organs of toxicity. Animals receiving ABCV demonstrated high levels of amphotericin B in liver (38% retention till 48 h) and spleen (2.6% retention till 48 h) in comparison to AmB_DOC (7.3% and 0.21% retention in liver and spleen respectively till 48 h). Biodistribution studies of ABCV in infected mice demonstrated that there was a moderate enhancement in levels of amphotericin B in liver, spleen, lungs and kidneys as compared to normal mice and the plasma levels were reduced. However, such observations were not made after AmB_DOC administration to infected mice except for kidneys in which there was a marked increase in uptake as compared to normal mice. Conclusions. Our results suggest that prolonged retention of high concentrations of ABCV in reticuloendothelial system organs is the reason for its reduced toxicity. Enhanced localization of the drug at the infected site may lead to improvement in therapeutic efficacy.     

两种紫杉醇注射剂在荷瘤小鼠体内药动学与组织分布的比较研究

目的比较以聚氧乙烯蓖麻油为增溶剂的紫杉醇注射液（Taxol）与以白蛋白为载体的紫杉醇纳米注射剂（ABI）在荷瘤小鼠体内药动学及组织分布的差异。方法 BALB/c小鼠经前肢腋下皮下接种鼠源乳腺癌EMT6细胞,待瘤体长到约1 g,按既定分组经尾静脉分别给予Taxol和ABI,给药剂量以紫杉醇计均为20 mg.kg-1。HPLC-UV测定血浆、瘤组织及心、肝、脾、肺、肾等主要组织器官中紫杉醇含量,并计算相应药动学参数。结果 ABI组动物瘤组织中的紫杉醇AUC高于Taxol组23.3%,而血浆中紫杉醇的AUC则显著低于Taxol组,并具有更大的Vd和CL（P〈0.05）。两种不同制剂给药,紫杉醇在心、肝、脾、肾中的分布趋势基本一致,但ABI组动物肺中的紫杉醇分布显著低于Taxol组（P〈0.05）。结论和传统紫杉醇注射液相比,白蛋白紫杉醇纳米粒制剂的瘤组织分布靶向性和药动学特性显著改善,应用前景广阔。     

A Polymeric Nanoparticle Consisting of mPEG-PLA-Toco and PLMA-COONa as a Drug Carrier: Improvements in Cellular Uptake and Biodistribution

No HeadingPurpose. To evaluate a new polymeric nanoparticulate drug delivery formulation that consists of two components: i) an amphiphilic diblock copolymer having tocopherol moiety at the end of the hydrophobic block in which the hydrophobic tocopherol moiety increases stability of hydrophobic core of the nanoparticle in aqueous medium; and ii) a biodegradable copolyester having carboxylate end group that is capable of forming ionic complex with positively charged compounds such as doxorubicin.Methods. A doxourubicin-loaded polymeric nanoparticle (Dox-PNP) was prepared by solvent evaporation method. The entrapment efficiency, size distribution, and in vitro release profile at various pH conditions were characterized. In vitro cellular uptake was investigated by confocal microscopy, flow cytometry, and MTT assay using drug-sensitive and drug-resistant cell lines. Pharmacokinetics and biodistribution were evaluated in rats and tumor-bearing mice.Results. Doxorubicin (Dox) was efficiently loaded into the PNP (higher than 95% of entrapment efficiency), and the diameter of Dox-PNP was in the range 20~25 nm with a narrow size distribution. In Vitro study showed that Dox-PNP exhibited higher cellular uptake into both human breast cancer cell (MCF-7) and human uterine cancer cell (MES-SA) than free doxorubicin solution (Free-Dox), especially into drug-resistant cells (MCF-7/ADR and MES-SA/Dx-5). In pharmacokinetics and tissue distribution study, the bioavailability of Dox-PNP calculated from the area under the blood concentration-time curve (AUC) was 69.8 times higher than that of Free-Dox in rats, and Dox-PNP exhibited 2 times higher bioavailability in tumor tissue of tumor-bearing mice.Conclusions. Dox-PNP exhibited enhanced cellular uptake of the drug. In the cytotoxic activity study, this improved cellular uptake was proved to be more advantageous in drug-resistant cell. Dox-PNP exhibited much higher bioavailability in blood plasma and more drug accumulation in tumor tissue than conventional doxorubicin formulation. The results of this study suggest that the PNP system is an advantageous carrier for drug delivery.     

多柔比星壳聚糖聚合物胶束的制备及其在小鼠体内的组织分布

本文制备了多柔比星壳聚糖聚合物胶束(doxorubicin-loaded N-octyl-N′-succinyl chitosan，DOX-OSC)，研究其在小鼠体内的组织分布并进行靶向性评价。采用透析法制备DOX-OSC，以多柔比星注射液(doxorubicin for injection，DOX-INJ)为对照，小鼠分别尾静脉注射5 mg·kg^-1的DOX-OSC和DOX-INJ，HPLC法测定各组织中不同时间的药物量，以各组织药代动力学参数(AUC、MRT)和靶向参数(R_e、C_e、T_e)为靶向评价指标。DOX-OSC载药量为(35.8±0.4)%，包封产率为(75.3±1.1)%，粒径为(174±12)nm，zeta电位为(-37.1±3.0)mV，形态为球形结构。小鼠尾静脉注射DOX-OSC和DOX-INJ后，DOX-OSC表现出较好的长循环及缓释特性。与对照组比较，DOX-OSC具有肝和脾靶向特性及滞留特性，AUC分别提高20.0和47.4倍，MRT分别延长11.2和37.2倍；在心脏和肾脏中药物分布显著降低，AUC分别为对照组的17.0%和11.4%。结果表明DOX-OSC具有优良的载药性能，有利于肝和脾靶向，并能显著降低心脏和肾脏毒性，对于DOX的临床应用具有重要意义。