Imprinted hydrophilic nanospheres as drug delivery systems for 5-fluorouracil sustained release

Molecularly imprinted hydrogel nanospheres as devices for the controlled/sustained release of 5-fluororacil in biological fluids were synthesized employing one-pot precipitation technique as the polymerization method. Methacrylic acid as a functional monomer and ethylene glycole dimethacrylate as a cross-linker were used in polymeric feed. Morphological and hydrophilic properties were determined by scanning electron microscopy and water content measurement, and recognition and selectivity properties of spherical molecularly imprinted polymers were compared with the spherical non-imprinted polymers, both in organic (acetonitrile) and water media. Finally, in vitro release studies were performed in plasma simulating fluids.     

5-氟尿嘧啶纳米粒的制备及其体外释药的研究

目的以生物可降解材料乳酸/羟基乙酸共聚物(PLGA)制备5-氟尿嘧啶(5-FU)纳米粒,并考察纳米粒的体外释放特性。方法采用复乳-溶剂挥发法结合高压均质法制备5-Fu-PLGA纳米粒,用透射电镜观察纳米粒的形态,并研究了5-Fu纳米粒的粒径、载药量、包封率和体外释药。结果5-FU-PLGA纳米粒为圆整的类球形实体粒子,平均粒径为85.4nm,载药量为12.4%±0.7%,包封率为64.1%±5.3%,体外释药符合H iguch i方程:Q=0.0585t1/2 0.087(r=0.9923)。结论所制5-FU纳米粒具有明显的缓释作用。     

紫杉醇联合铂类药物对局部晚期宫颈癌的近期疗效

目的 探讨术前应用紫杉醇联合铂类药物对局部晚期宫颈癌的近期疗效.方法 局部晚期宫颈癌患者80例随机均分为两组,术前分别采用紫杉醇联合顺铂(TP方案,A组)和5-氟尿嘧啶联合顺铂(FP方案,B组)化疗,治疗1-2个疗程.结果 化疗后肿瘤最大直径均明显缩小(P＜0.05);A组化疗有效率70.0％,明显高于B组的45.0％(P＜0.05).A组胃肠道反应发生率为90.0％,骨髓抑制发生率67.5％(均以Ⅰ度、Ⅱ度为主),低于B组的100.0％和82.5％.结论 紫杉醇联合顺铂治疗局部晚期宫颈癌近期疗效确切,毒副反应可耐受.     

Zero-order release of 5-fluorouracil from PCL-based films featuring trilayered structures for stent application

A trilayered Poly(ε-caprolactone) (PCL)-based film with a coating layer (CL), a drug-storing layer (DSL) loaded with antitumor drug 5-Fluorouracil (5-FU) and a backing layer (BL) are presented for film-based stent application in malignant stricture or stenosis. V-C diffusion cells were used to investigate the drug permeability of the CL, while scanning electron microscopy (SEM) was employed for observing the microscopic architectures and morphologies. Drug release from the trilayered films exhibited a zero-order pattern, and the release process followed an ‘outer-to-inner’ pattern. The formation mechanism and influencing factors of the zero-order drug release pattern were in-depth elucidated, and factors affecting the drug release were also investigated. The reduction of initial drug loading in DSL slowed the drug release and diminished the zero-order release pattern. Drug permeability of the CL depended significantly on CL thickness, but not significantly on PCL molecular weight. Besides, the addition of PEG porogen in the CL accelerated the drug release by elevation of the drug permeability of CL, and the action mechanism of PEG was revealed by the PEG release test and SEM. The loading of 5-FU in the CL could lead to a two-phased release profile. This study revealed the potential of the trilayered film in controlled drug delivery to intraluminal tumor due to its highly tunable zero-order drug release.     

青蒿琥酯通过介导铁死亡逆转结肠癌细胞5-氟尿嘧啶耐药的作用研究

目的 探讨青蒿琥酯(ART)通过介导铁死亡逆转结肠癌细胞对5-氟尿嘧啶(5-FU)耐药的作用。方法 以人结肠癌HT-29/5-FU耐药细胞株为研究对象,采用MTS法检测5-FU、ART以及5-FU+ART对HT-29/5-FU细胞的抑制作用,并计算其逆转耐药倍数;克隆形成实验检测HT-29/5-FU细胞克隆形成能力;流式细胞术检测细胞内活性氧(ROS)水平;试剂盒检测细胞内丙二醛(MDA)水平;Western blotting检测细胞内Nrf2和GPX4蛋白表达水平。结果 40μmol·L^-1ART可逆转HT-29/5-FU细胞对5-FU的耐药,逆转倍数为2.9倍;5-FU联合ART可抑制HT-29/5-FU细胞的克隆形成能力,升高细胞内ROS和MDA水平,并降低Nrf2及GPX4蛋白表达水平,且这些效应能够被铁死亡抑制剂Ferrostatin-1所逆转。结论 ART能够通过抑制Nrf2、GPX4表达诱导铁死亡,从而逆转HT-29/5-FU细胞对5-FU的耐药。     

Drug release mechanism of paclitaxel from a chitosan–lipid implant system: Effect of swelling, degradation and morphology

Localized and sustained delivery of anti-cancer agents to the tumor site has great potential for the treatment of solid tumors. A chitosan–egg phosphatidylcholine (chitosan–ePC) implant system containing PLA-b-PEG/PLA nanoparticles has been developed for the delivery of paclitaxel to treat ovarian cancer. Production of volumes of ascites fluid in the peritoneal cavity is a physical manifestation of ovarian cancer. In vitro release studies of paclitaxel from the implant were conducted in various fluids including human ascites fluid. A strong correlation (r² = 0.977) was found between the release of paclitaxel in ascites fluid and PBS containing lysozyme (pH 7.4) at 37 °C. The drug release mechanism for this system was proposed based on swelling, degradation and morphology data. In addition, in vitro release of paclitaxel was found to be a good indicator of the in vivo release profile (correlation between release rates: r² = 0.965). Release of paclitaxel was found to be sustained over a four-week period following implantation of the chitosan–ePC system into the peritoneal cavity of healthy Balb/C mice. Also, the concentrations of paclitaxel in both plasma and tissues (e.g. liver, kidney and small intestine) were found to be relatively constant.     

Stomach-specific drug delivery of 5-Fluorouracil using ethylcellulose floating microspheres

A multiple-unit-type oral floating dosage form (FDF) of 5-Fluorouracil (5-FU) was developed to prolong gastric residence time for the treatment of stomach cancer. The floating microspheres were prepared by solvent evaporation method. The prepared microspheres were characterized for their micromeretic properties, floating behavior and entrapment efficiency; as well by Fourier transform infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC), X-ray powder diffractometry (XRPD), thin layer chromatography (TLC) and scanning electron microscopy (SEM). The in vitro release studies and floating behavior were performed in HCl buffer pH 1.2, Phosphate buffer pH 4.5 and in Simulated Gastric Fluid (SGF). The best fit release kinetics was achieved with Higuchi plot. The yields of preparation were very high and low entrapment efficiencies were noticed with larger particle size for all the formulations. Mean particle size, entrapment efficiency and production yield were highly influenced by polymer concentration. It was concluded from the present investigation that porous Ethylcellulose microspheres are promising controlled release as well as stomach targeted carriers for 5-FU.     

Sustained release of antineoplastic drugs from chitosan-reinforced alginate microparticle drug delivery systems

Alginate based microparticle drug delivery systems were prepared for the sustained release of antineoplastic drugs. Two drugs, 5-fluorouracil (5-FU) and tegafur, were encapsulated into the microparticles. The drug loaded microparticles were fabricated using a very convenient method under very mild conditions, i.e., directly shredding the drug loaded beads into microparticles in a commercial food processor. The mean sizes of the obtained microparticles were between 100 and 200 μm. To effectively sustain the drug release, alginate microparticles were reinforced by chitosan during gelation. The drug release from the chitosan-reinforced alginate microparticles was obviously slower than that from the unreinforced microparticles. The effect of the reinforcement conditions on the drug release property of the microparticles was studied, and the optimized concentration of chitosan solution for reinforcement was identified. The effects of drug feeding concentration and pH value of the release medium on the drug release were investigated.     

5-Fluorouracil-loaded microspheres prepared by spray-drying poly(D,L-lactide) and poly(lactide-co-glycolide) polymers: Characterization and drug release

5-Fluorouracil (5-FU), a hydrosoluble anti-neoplastic drug, was encapsulated in microspheres of poly(D,L-lactide) (PLA) and poly(lactide-co-glycolide) (PLGA) polymers using the spray-drying technique, in order to obtain small size microspheres with a significant drug entrapment efficiency. Drug-loaded microspheres included between 47?±?11 and 67?±?12?µg 5-FU?mg^?1 microspheres and the percentage of entrapment efficiency was between 52?±?12 and 74?±?13. Microspheres were of small size (average diameter: 0.9?±?0.4–1.4?±?0.8?µm microspheres without drug; 1.1?±?0.5–1.7?±?0.9?µm 5-FU-loaded microspheres) and their surface was smooth and slightly porous, some hollows or deformations were observed in microspheres prepared from polymers with larger T_g. A fractionation process of the raw polymer during the formation of microspheres was observed as an increase of the average molecular weight and also of T_g of the polymer of the microspheres. The presence of 5-FU did not modify the T_g values of the microspheres. Significant interactions between the drug and each one of the polymers did not take place and total release of the included drug was observed in all cases. The time needed for the total drug release (28–129?h) was in the order PLA?>?PLGA 75/25?>?PLGA 50/50. A burst effect (17–20%) was observed during the first hour and then a period of constant release rate (3.52?±?0.82–1.46?±?0.26?µg 5-FU?h^?1 per milligram of microspheres) up to 8 or 13?h, depending on the polymer, was obtained.     

5-氟尿嘧啶控释植入剂在小鼠肿瘤组织的分布

目的 建立5-氟尿嘧啶(5-Fu)在小鼠肿瘤组织中的分析方法,并用于考察5-Fu控释植入剂在小鼠肿瘤组织的分布.方法 荷瘤小鼠瘤周植入分别由PLGA 50/50和PLGA 75/25为载体制备的5-Fu控释植入剂,RP-HPLC测定小鼠肿瘤组织中的药物浓度.结果 肿瘤组织中5-Fu的线性范围为0.5～15.4 μg·g-1,准确度为97.5％～ 104.0％,提取回收率为81.9％～88.3％,日内RSD均＜2.0％,日间RSD均＜7.6％.以PLGA50/50、PLGA75/25为载体的5-Fu控释植入剂在荷瘤小鼠体内的药动学参数:tmax分别为9、15 d;Cmax分别为3.79、2.83 μg·g-1; AUC分别为41.15、43.50 (μg·g 1)×d.结论 该分析方法可用于5-Fu在肿瘤组织中的分布行为研究,2种载体的5-Fu控释植入剂均能维持小鼠肿瘤组织中较长时间的药物分布,延长药效作用时间.     

Transdermal iontophoresis of 5-fluorouracil combined with electroporation and laser treatment

The influence of iontophoresis and other physical enhancement methods such as electroporation and erbium:yttrium-aluminum-garnet (YAG) laser on the skin permeation of 5-fluorouracil (5-FU) was examined. Iontophoresis increased the in vitro transdermal transport of both the anionic and non-ionic forms of 5-FU. A combination of electroporation pretreatment and subsequent iontophoresis resulted in a higher permeation of 5-FU than either technique alone. It appeared that electroporation treatment exerted a disruptive influence on the stratum corneum (SC). The SC layers in the skin were partly ablated by the laser, resulting in a great enhancement effect on the skin permeation of 5-FU. Application of iontophoresis further increased the drug permeation across laser-pretreated skin. The laser was consistently the most potent technique to enhance 5-FU delivery among the physical enhancement methods examined in this study.     

Liposome formulation of paclitaxel with enhanced solubility and stability

Despite its strong antitumor activity, paclitaxel (Taxol®) has limited clinical applications due to its low aqueous solubility and hypersensitivity caused by Cremophor® EL and ethanol which is the vehicle used in the current commercial product. In an attempt to develop a pharmaceutically acceptable formulation that could replace Taxol®, a paclitaxel incorporated liposome has been constructed to improve solubility and physicochemical stability. The effect of various components of the liposome, including cholesterol and lipid, on the solubility and entrapment efficiency (EE) of paclitaxel was systematically investigated. The results showed that 5% (v/v) of polyethylene glycol 400 in the hydration medium of liposome significantly increased the solubility (up to 3.39 mg/mL) as well as the EE and the paclitaxel content in the liposome formulation composed of 10% (w/v) of S₁₀₀PC with cholesterol (cholesterol-to-lipid molar ratio = 10:90). When sucrose (sugar-to-lipid molar ratio = 2.3) was added as a lyoprotectant during the freeze-drying of the liposome, physicochemical stability of liposome was significantly improved. Moreover, the cytotoxicity of the final liposome formulation against MDA-MB-231 human breast cancer cell line was not significantly different from that of Taxol®. The enhanced aqueous solubility as well as the physicochemical stability of paclitaxel in the liposome formulation developed in this study could be a safer and effective alternative to the Cremophor® EL and ethanol formulation.     

Cyclodextrin modified hydrogels of PVP/PEG for sustained drug release

Hydrogels are water swollen networks of polymers and especially hydrogels consisting of poly vinylpyrrolidone/poly ethyleneglycol-dimethacrylate (PVP/PEG-DMA) blends show promising wound care properties. Enhanced functionality of the hydrogels can be achieved by incorporating drugs and other substances that may assist wound healing into the gel matrix. Controlling the release of active compounds from the hydrogels may be possible by carefully modifying the polymer matrix. For this purpose, cyclodextrins (CD) were grafted to the polymer matrix in 4–5 w/w% in an attempt to retard the release of water-soluble drugs. Ibuprofenate (IBU) was chosen as model drug and loaded in IBU/CD ratios of 0.6, 1.2, and 2.5. Vinyl derivatives of α-, β- and γ-CD were produced, added to the prepolymer blend and cured by UV-light. During this curing process the CD derivatives were covalently incorporated into the hydrogel matrix. The modified hydrogels were loaded with ibuprofenate by swelling. The release of the model drug from CD modified hydrogels show that especially covalently bonded β-cyclodextrin can change both the release rate and the release profile of ibuprofen.     

Hyaluronidase enzyme core-5-fluorouracil-loaded chitosan-PEG-gelatin polymer nanocomposites as targeted and controlled drug delivery vehicles

This study examines the performance of novel hyaluronidase enzyme core-5-fluorouracil-loaded chitosan-polyethylene glycol-gelatin polymer nanocomposites, which were prepared using an ionic gelation technique, as targeted and controlled drug delivery vehicles. These hyaluronidase-loaded nanoparticles have recently been proposed as targeted and controlled drug delivery vehicle systems to tissues due to their ability to loosen the intercellular connective matrix of hyaluronic acid. The encapsulation efficiency and loading capacities of the nanoparticles demonstrated that these nanocomposites displayed sufficient binding ability, which depends on the pH and initial concentration of the drug. The cytotoxic effects of the chitosan-hyaluronidase-5-fluorouracil (CS-HYL-5-FU), chitosan-hyaluronidase-5-fluorouracil polyethylene glycol (CS-HYL-5-FU-PEG), and chitosan-hyaluronidase-5-fluorouracil polyethylene glycol-gelatin (CS-HYL-5-FU-PEG-G) nanoparticles were assessed using MTT assays, and the nanovectors were found to be less cytotoxic than the chemotherapeutic 5-FU after incubation for 3–12 h. The particle sizes of the CS-HYL-5-FU, CS-HYL-5-FU-PEG and CS-HYL-5-FU-PEG-G polymer composites were between 300 and 580 nm, as determined by a Zetasizer. Scanning electron microscopy (SEM) analysis indicated that the nanocomposites exhibit a clear, smooth surface and fine morphology. Linkages of the polymers, enzyme, and drug were confirmed by FTIR spectroscopy. Atomic fluorescence microscopy (AFM) analysis confirmed the size of the polymer composite nanoparticles. Therefore, this work established that the drug can be successfully encapsulated in chitosan-polyethylene glycol-gelatin-accompanied hyaluronidase nanoparticles with a homogeneous distribution. These nanoparticles can be potential carriers for targeted and controlled drug delivery to cancer cells.     

Novel hydrogel microspheres of chitosan and pluronic F-127 for controlled release of 5-fluorouracil

Hydrogel microspheres of chitosan (CS) and Pluronic F127 (PF-127) were prepared by the emulsion-crosslinking method employing glutaraldehyde (GA) as a crosslinker. 5-Fluorouracil (5-FU), an anticancer drug with good water solubility, was encapsulated into hydrogel microspheres. Various formulations were prepared by varying the ratio of CS and PF-127, % drug loading and amount of GA. Microspheres were characterized by Fourier transform infrared (FTIR) spectroscopy to confirm the absence of chemical interactions between drug, polymer and the crosslinking agent. Scanning electron microscopy (SEM) was performed to study the surface morphology of the microspheres. SEM showed that microspheres have smooth shiny surfaces. Particle size, as measured by laser light scattering technique, gave an average size ranging from 110 to 382?µm. Differential scanning calorimetry (DSC) and X-ray diffraction (X-RD) studies were performed to understand the crystalline nature of the drug after encapsulation into hydrogel microspheres. Encapsulation of the drug up to 86% achieved was measured by UV spectroscopy. Equilibrium swelling experiments were performed in distilled water. Diffusion coefficients (D) of water through microspheres were estimated by an empirical equation. In vitro release studies indicated the dependence of release rate on the extent of crosslinking, drug loading and the amount of PF-127 used to produce the microspheres; slow release was extended up to 24?h. The release data were also fitted to an empirical equation to compute the diffusional exponent (n), which indicated that the release mechanism followed the non-Fickian trend.     

Effect of H2-receptor antagonists on the pharmacokinetics of 5-fluorouracil in the rat and monkey.

The effect of short term (7 days) and long term (28 days) pretreatment with the imidazole H2-receptor antagonist, cimetidine (CMT), on the pharmacokinetics of 5-fluorouracil (5-FUra) has been studied in the rat and cynomolgus monkey. Short-term pretreatment of rats with CMT significantly increased t1/2.z by 29 per cent and AUC by 40 per cent: total body clearance was decreased by 30 per cent. Long-term pretreatment exaggerated these effects. By contrast, short- and long-term pretreatment with the furan H2-receptor antagonist, ranitidine, caused no significant effect on 5-FUra kinetics. In the monkey, 7 days pretreatment with CMT increased t1/2.z by 32 per cent leaving other 5-FUra kinetic parameters unchanged; 28 days pretreatment increased both t1/2.z by 41 per cent and AUC by 100 per cent with a decrease in total body clearance of 5-FUra of 48 per cent. CMT, but not RNT, inhibited cytosolic dihydropyrimidine dehydrogenase (DPD), the enzyme responsible for 5-FUra catabolism. It is proposed that the observed effects of CMT on 5-FUra kinetics are the result of inhibition of DPD. This interaction has the potential for increasing systemic drug toxicity and it is therefore advisable that where H2-receptor blockade is administered concurrently with 5-FUra that a non-imidazole based H2-receptor antagonist such as RNT should be substituted for CMT.     

Determination of 5-fluorouracil in human plasma by a simple and sensitive reversed-phase HPLC method

A simple and sensitive reversed-phase HPLC method with UV detection was developed and validated for the quantitation of 5-fluorouracil (5-FU) in human plasma. After acidification and salting out, 5-FU was extracted into ethyl acetate and back-extracted into a basic buffer. The extract was adjusted to neutral pH before being injected onto the HPLC column. 5-FU was separated from the matrix components on a YMC ODS-AQ column at 40°C using an aqueous mobile phase of 10 mM potassium phosphate at pH 5.5. A linear gradient of 0–25% methanol wash eluted late peaks, maintained column performance, and increased column stability. The run time was 20 min. The linear range was 25–300 ng ml⁻¹ (r²>0.999). The limit of quantitation was 25 ng ml⁻¹, with a signal-to-noise ratio of 23:1. Interday precision and accuracy of quality control samples were 6.2–8.4%, relative standard deviation and −0.1– + 1.9% relative error.     

一种基于硫胺素二硫化物传递系统的5-Fu脑靶向前药的合成

目的 合成一种基于硫胺素二硫化物传递系统的5-氟尿嘧啶(5-Fu)脑靶向前药.方法 5-Fu在六甲基二硅胺和三甲基氯硅烷的作用下生成中间体Ⅱ,Ⅱ与5-苄氧羰基戊酰氯经选择性酰化形成中间体Ⅲ,Ⅲ再脱苄,得到中间体Ⅳ,将按文献制得的中间体Ⅴ与中间体Ⅳ偶合得到目标化合物.结果 和结论目标化合物及重要中间体均经IR、~1HNMR、MS等确证.     

Layer-by-layer assembly of poly(l-glutamic acid)/chitosan microcapsules for high loading and sustained release of 5-fluorouracil

Hollow polyelectrolyte microcapsules based on poly(l-glutamic acid) (PLGA) and chitosan (CS) with opposite charges were fabricated by layer-by-layer (LbL) assembly technique using melamine formaldehyde (MF) microparticles as sacrificial templates. The LbL assembly of polyelectrolytes and the resultant PLGA/CS microcapsules were characterized. A hydrophilic anticancer drug, 5-fluorouracil (5-FU), was chosen to investigate the loading and release properties of the microcapsules. The PLGA/CS microcapsules show high loading capacity of 5-FU under conditions of high drug concentration and salt adding. The high loading can be ascribed to spontaneous deposition of 5-FU induced by hydrogen bonding between 5-FU and PLGA/CS microcapsules. The PLGA/CS microcapsules show sustained release behavior. The release rate of 5-FU drastically slows down after loading in PLGA/CS microcapsules. The 5-FU release from PLGA/CS microcapsules can be best described using Ritger-Peppas or Baker-Londale models, indicating the diffusion mechanism of 5-FU release from the PLGA/CS microcapsules. In vitro cytotoxicity evaluation by the MTT assay shows good cell viability over the entire concentration range of PLGA/CS microcapsules. Therefore, the novel PLGA/CS microcapsules are expected to find application in drug delivery systems because of the properties of biodegradability, high loading, sustained release and cell compatibility.     

Semi-IPN chitosan/polyvinylpyrrolidone microspheres and films: sustained release and property optimisation

Abstract

A set of chitosan-polyvinylpyrrolidone (CH-PVP) microspheres were prepared as semi-inter penetrating networks (semi-IPN) and loaded with 5-fluorouracil. In vitro release studies showed faster release for semi-IPN microspheres compared to pure CH samples, and the total release was achieved in about 20–30 days, depending on the composition. In vitro cell studies were achieved against human breast adenocarcinoma cell line cells where adsorption of cells on microspheres with a significant decrease in their number was obtained. Meanwhile, the CH-PVP films, which were prepared with the same compositions as in the microspheres, demonstrated an increase in strength from 66 to 118?MPa as the PVP content was decreased. It can be concluded that the prepared CH-PVP semi-IPN microspheres are novel promising carriers compared to pure CH microspheres since it becomes possible to adjust stability and hydrophilicity of the microspheres as well as the release rates of the drugs from the microspheres by changing the ratio of CH/PVP composition.