Injectable and biodegradable poly(organophosphazene) gel containing silibinin: its physicochemical properties and anticancer activity

The biodegradable poly(organophosphazene) hydrogels were developed as a locally injectable drug carrier for a hydrophobic silibinin to overcome its limited bioavailability. The aqueous solution of poly(organophosphazene) enhanced the solubility of silibinin up to 2000 times compared with that of phosphate buffered saline (0.0415 vs. 84.55 mg/mL). Both aqueous polymer solutions with and without silibinin showed a sol-gel transition as a function of temperature. A faster in vitro degradation rate of the gel and drug release rate from the gel at pH 6.8 than those at pH 7.4 were observed when the degradation and release study on hydrogels were conducted at 37 °C. Silibinin was sustainedly released from the hydrogel mainly by a diffusion-controlled mechanism. The silibinin released from the hydrogel was shown to be effective considering the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. In the HT-29 xenografted mice model, the intratumorally injected hydrogel containing silibinin exhibited a good antitumor effect in comparison with the control groups. The Western blotting indicated that one of the reasons for the enhanced antitumor effect of the hydrogel system was the sustained antiangiogenic effect of silibinin. The poly(organophosphazene) gels are expected to be an effective candidate of the locally injectable drug carrier for silibinin.     

温敏在体凝胶给药系统的研究与应用

综述N-异丙基丙烯酰胺类聚合物、聚氧乙烯-聚氧丙烯共聚物、聚氧乙烯-聚乳酸羟基乙酸共聚物和多糖类衍生物等温敏聚合物的性质、特点、胶凝机制及在温敏在体凝胶给药系统中的应用进展。温敏在体凝胶作为一种智能水凝胶,可用作药物缓、控释和靶向输送的有效载体。     

A thermosensitive chitosan-based hydrogel for the local delivery of paclitaxel.

A novel injectable thermosensitive in situ gelling hydrogel has been developed. The system, which falls under the BST-Gel platform technology developed at Biosyntech Inc. (Laval, QC, Canada), consists of a chitosan solution (C) neutralized with beta-glycerophosphate (GP) that is liquid at room temperature but gels when heated to body temperature. We propose to use this thermosensitive hydrogel for the sustained release of paclitaxel at tumor resection sites in order to prevent local tumor recurrence. The in vitro release profiles demonstrated controlled delivery over 1 month. The initial drug loading substantially affected the release. Local delivery of paclitaxel from the formulation injected intratumorally was investigated using EMT-6 tumors implanted subcutaneously on Balb/c mice. These experiments showed that one intratumoral injection of the thermosensitive hydrogel containing paclitaxel was as efficacious as four intravenous injections of Taxol in inhibiting the growth of EMT-6 cancer cells in mice, but in a less toxic manner. Further histological analysis revealed that while the proportion of necrotic areas was similar for the C/GP/paclitaxel and the Taxol-treated tumors, a disparity between tumor-associated inflammatory cell populations may suggest differing anti-tumor mechanisms.     

A thermo- and pH-sensitive hydrogel composed of quaternized chitosan/glycerophosphate

The quaternized chitosan was synthesized by the reaction of chitosan and glycidyltrimethylammonium chloride (GTMAC) and named as N-[(2-hydroxy-3-trimethylammonium) propyl] chitosan chloride (HTCC). A novel hydrogel system composed of HTCC/glycerophosphate (HTCC/GP) with thermo- and pH-sensitivity was synthesized and used as an intelligent drug carrier. The formulation was solution below or at room temperature, which allowed it injectable and to incorporate living cells, proteins, enzymes or other therapeutic drugs easily. Once the surrounding temperature was up to 37 degrees C, the system was transformed to a non-flowing hydrogel, and the formed hydrogel can release the trapped drug as a function of pH values. The swelling behavior of the system and the release profiles of doxorubicin hydrochloride (DX) as a model drug at different pH values were investigated. At acidic condition the hydrogel dissolved and released drug quickly, while it absorbed water and released drug slowly at neutral or basic conditions. Hydrogel composed of chitosan hydrochloride and glycerophosphate (CS/GP) was also prepared to compare with HTCC/GP hydrogel. The HTCC/GP hydrogel in this study was transparent which made it suitable for some specific uses such as ocular drug formulation.     

注射用蜂毒多肽温度敏感型缓释凝胶的制备及体外释放研究

目的制备注射用蜂毒多肽的温度敏感型缓释凝胶制剂并对其体外释药进行考察。方法以新型温度敏感聚丙交酯乙交酯聚乙二醇嵌段共聚物(PLGAPEGPLGA)为载体材料制备注射用蜂毒多肽缓释凝胶制剂,采用福林酚试剂法测定制剂在磷酸盐缓冲溶液中(pH7.4)的体外释放度,并对体外释放数据用KorsmeyerPeppas方程进行拟合。结果蜂毒多肽体外持续释放36d,其释药速率随聚合物的质量分数增加而降低,且聚合物分子结构中丙交酯比例增大对释药速率几乎没有影响。蜂毒多肽从凝胶中的释放初期以扩散为主,体外释放行为符合KorsmeyerPeppas方程,后期为凝胶溶蚀和药物扩散结合的作用机制。结论注射用蜂毒多肽的温度敏感型缓释凝胶制剂制备工艺简便,药物释放达到预期要求,同时说明温度敏感PLGAPEGPLGA嵌段共聚物作为注射用缓释给药系统的载体材料具有很好的应用前景。     

可注射美洛昔康温敏凝胶的研制

目的:研制一种新型的、可注射的、具有缓释作用的美洛昔康温敏凝胶。方法:以壳聚糖-甘油-硼砂凝胶为载体制备美洛昔康温敏凝胶,考察温度、pH值、甘油与壳聚糖的比例对凝胶形成的影响,同时考察样品的体外释放行为。结果:温度为37℃、pH=7.0、甘油与壳聚糖比例为3∶10时凝胶形成时间最短;样品释放288h时平均累积释放百分率达76%。结论:本凝胶制备方法简单,温度敏感性高,并具有缓释作用。     

Anti-inflammatory and pharmacokinetics evaluation of PEGylated ibuprofen tablet formulation

Abstract

To develop a novel PEGylated ibuprofen tablet formulations and evaluate its anti-inflammatory activity and pharmacokinetics profile in an animal model. Six batches of PEGylated ibuprofen tablets were prepared by direct compression using Avicel® and lactose as the binder diluents. In vivo anti-inflammatory activity of the tablets was carried out as well as the pharmacokinetics profiles. The PEGylated ibuprofen tablet reduced carrageenan-induced inflammation in experimental animals and sustained its anti-inflammatory action for over 10?h. The pharmacokinetics profile of the optimized formulations were greater than that of the marketed sample and the pure drug sample. In conclusion, PEGylation of ibuprofen conferred a high level of anti-inflammatory activity and slowed plasma clearance level, indicating sustained release. Thus, further exploration of this novel formulation to be used as an alternative carrier for this drug is required.     

Novel thermosensitive hydrogels based on methoxy polyethylene glycol-co-poly(lactic acid-co-aromatic anhydride) for cefazolin delivery

Thermosensitive micelles composed of a copolymer of methoxy polyethylene glycol (mPEG), polylactic acid (PLA), and 1,6-bis (p-carboxyphenoxy) hexane (CPH), namely methoxy polyethylene glycol-co-polylactic acid-co-aromatic anhydride (mPEG-PLCPHA), were fabricated for application as a promising hydrophilic drug carrier. The copolymer can self-assemble into micelles in PBS by hydrophobic interaction. The diameters of these micelles increased as the environmental temperature increased. An increase in viscosity with sol-to-gel transition occurred as temperature increased from room temperature to body temperature. During the in vitro degradation process, hydrogels demonstrated a more stable degradation rate. Both in vitro and in vivo cytotoxicity results showed that the materials had excellent biocompatibility due to less acidic products formation. In vitro cefazolin release profiles showed a stable release for 30 days. The hydrogel encapsulated cefazolin exhibited a good antibacterial effect. Based on these results, mPEG-PLCPHA can serve as an injectable depot gel for drug delivery.From the Clinical EditorIn this study, thermosensitive hydrogel encapsulated cefazolin was found to exhibit good antibacterial effects with sustained levels for up to 30 days, enabling the development of an injectable depot gel for long-term drug delivery.     

A novel injectable local hydrophobic drug delivery system: Biodegradable nanoparticles in thermo-sensitive hydrogel

In this article, a novel local hydrophobic drug delivery system: nanoparticles in thermo-sensitive hydrogel, was demonstrated. First, honokiol, as a model hydrophobic drug, loaded poly(varepsilon-caprolactone)-poly(ethylene glycol)-poly(varepsilon-caprolactone) (PCEC) nanoparticles were prepared by emulsion solvent evaporation method, and then were incorporated into thermo-sensitive F127 hydrous matrix. The obtained injectable hydrophobic drug delivery system can act as a depot for sustained release of honokiol in situ. The lower critical solution temperature (LCST) of the composite matrix increases with increase in the mass of incorporated nanoparticles, or with decrease in the amount of residual organic solvent in the system. Honokiol release profile in vitro was studied, and the results showed that honokiol could be sustained released from the system. The described injectable drug delivery system might have great potential application for local delivery of hydrophobic drugs such as honokiol.     

嵌段共聚物OSM1-PCLA-PEG-PCLA-OSM1的pH和温度敏感性质及体外释药特性考察

目的 为嵌段共聚物磺胺甲嘧啶低聚物-聚-ε-己内酯-丙交酯-聚乙二醇-聚-ε-己内酯-丙交酯-磺胺甲嘧啶低聚物（sulfamerazine oligomers-poly(ε-caprolactone-co-DL-lactide-b-ethyleneglycol-b-ε-caprolactone-co-DL-lactide)-sulfamerazine oligomers,OSM₁-PCLA-PEG-PCLA-OSM1)作为缓控释给药系统的载体提供依据。方法 采用激光粒度仪对不同pH和温度下嵌段共聚物OSM₁-PCLA-PEG-PCLA-OSM₁胶束粒径大小、分布进行考察;通过表面张力和相转变温度测定对其临界胶束浓度和溶液-凝胶相转变行为进行考察;以5-氟尿嘧啶为模型药,通过透射电镜观察载药和空白共聚物胶束形态;采用物理混合法制备5-氟尿嘧啶载药水凝胶;采用HPLC法测定载药水凝胶中药物释放速率。结果 嵌段共聚物OSM₁-PCLA-PEG-PCLA-OSM₁胶束溶液具有pH和温度双重敏感的性质,在一定pH和温度条件下可发生溶液-凝胶相转变;5-氟尿嘧啶载药水凝胶体外释放可持续9 d,具有较好的缓释作用。结论 pH和温度双重敏感型嵌段共聚物OSM₁-PCLA-PEG-PCLA-OSM₁作为注射缓释给药系统载体材料具有良好的应用前景。     

Development of thermo-sensitive injectable hydrogel with sustained release of doxorubicin: rheological characterization and in vivo evaluation in rats

To develop a thermo-sensitive injectable hydrogel that is easy to administer, gels quickly in the body, and allows sustained release of the drug, various poloxamer-based hydrogels containing doxorubicin were prepared with poloxamer and hydrochloric acid under light protection using the cold method. Their rheological characterization, dissolution, and pharmacokinetics after intramuscular administration to rats were evaluated. Hydrochloric acid decreased the viscosity and retarded the gelation time of the injectable gel. The drug was dissolved from the hydrogels by Fickian diffusion through the extramicellar aqueous channels of the gel matrix. P 188 and hydrochloric acid barely affected the dissolution mechanism. However, P 188 increased and hydrochloric acid decreased the dissolution rate of the drug from the injectable gels. The thermo-sensitive injectable gel composed of 0.6% doxorubicin, 15% P 407, 6% P 188, and 0.1% hydrochloric acid was easy to administer intramuscularly and gelled quickly in the body. Moreover, it maintained the plasma concentrations of drug for 60 h and gave an ~ 5-fold higher AUC compared to doxorubicin solution. Thus, it would be useful for delivering doxorubicin in a pattern that allows sustained release for a long time, leading to better bioavailability.     

可注射硫酸延胡索总碱温度敏感型原位凝胶的 制备及其体外释药评析

 目的：研究可注射硫酸延胡索总碱原位凝胶的制备方法及其体外释药特性。方法：以泊洛沙姆407为载体材料制备注射用硫酸延胡索总碱温敏型原位凝胶制剂;采用高效液相色谱法测定释放介质中药物含量,考察凝胶体外释放特性;并对制剂进行评价。结果：原位凝胶最佳配方为：16%泊洛沙姆407、11%泊洛沙姆188、0.2%壳聚糖、0.5%硫酸延胡索总碱,该原位凝胶在室温下为流体,在体温下发生相转变形成凝胶;药物在48 h释放了88.4%,无突释现象,释药规律符合Higuchi方程;凝胶属Ostwald流体。结论：可注射硫酸延胡索总碱原位凝胶制备工艺简便,有良好的缓释作用,为研究中药植入型给药系统提供了依据。     

Pharmacokinetic Evaluation of Thermosensitive Sustained Release Formulations Developed for Subcutaneous Delivery of Protein Therapeutics

Injectable, thermosensitive hydrogels, constructed from cross-linked polymers, can offset the limitations of other sustained release delivery systems, overcome constrains of available therapies, and improve patient compliance to chronic therapy. The goal of this project was to identify and evaluate such sustained release, in situ formulations that can help achieve prolonged exposure of protein therapeutics with a short systemic half-life. Natural polymers were used to develop injectable, thermosensitive in situ hydrogels and single-chain variable fragment (scFv) of trastuzumab was used as the model protein with a short half-life. The three polymer combinations tested were: (1) Chitosan and β-glycerophosphate, (2) Chitosan, β-glycerophosphate, and Hyaluronic Acid, and (3) Hyaluronic Acid and Dextran. In vitro drug release experiments were conducted, using different combinations of various polymer concentrations and different drug loading amounts, to identify optimal combinations with prolonged and controlled drug release while exhibiting minimal burst release effect. Select formulations were injected subcutaneously in normal mice to evaluate the pharmacokinetics of scFv for 14 days and identify drug release kinetics in vivo. A two-compartment PK model was also established to quantitatively characterize the release kinetics and disposition of scFv following in vivo administration of the hydrogels. The scFv was undetectable in plasma after 4 and 24 hours following intravenous and subcutaneous administration, respectively. However, all three hydrogel systems were found to provide controlled release of scFv in vivo and maintain detectable concentrations of scFv for at least 14 days. The results suggested that subcutaneous injection of thermosensitive in situ hydrogels may be used to achieve sustained exposure of protein therapeutics which have a very short half-life and thus require frequent administration.     

温敏壳聚糖凝胶共混环糊精对布洛芬的体外缓释性能

目的研究壳聚糖/甘油磷酸钠（CS/GPS）温敏性水凝胶共混β-CD包合物对药物的缓释性能。方法试管倒置法研究不同配比的CS/GPS温敏凝胶化性能;饱和水溶液法制备布洛芬/β-CD包合物,红外光谱表征包合物;紫外分光光度法测定包合物载药量和药物的累积释放度。结果体积配比5/1的2%CS/56%GPS体系（pH6.9）在37℃下可实现快速凝胶化。分别以布洛芬和布洛芬/β-CD包合物为模型药物,考察在温敏凝胶中的缓释行为,载有布洛芬凝胶24h药物累积释放度为81.5%,载有布洛芬/β-CD包合物凝胶累积释放度为69.1%。而24h布洛芬原药累积释放度为98.1%,布洛芬/β-CD包合物的累积释放度为82.2%。结论温敏性凝胶共混β-CD包合物,比单纯使用凝胶包埋药物或β-环糊精包合对药物具有更加明显缓释效果。CS/GPS凝胶体系有望作为温度敏感性给药系统的理想载体。     

In situ forming hydrogels based on chitosan for drug delivery and tissue regeneration

In situ forming hydrogels with simple sol–gel transition are more practicable as injectable hydrogels for drug delivery and tissue regeneration. State-of-the-art in situ gelling systems can easily and efficiently be formed by different mechanisms in situ. Chitosan is a kind of natural polysaccharide that is widely exploited for biomedical applications due to its good biocompatibility, low immunogenicity and specific biological activities. Chitosan-based in situ gelling systems have already gained much attention as smart biomaterials in the development of several biomedical applications, such as for drug delivery systems and regeneration medicine. Herein, we review the typical in situ gelling systems based on chitosan and mechanisms involved in hydrogel forming, and report advances of chitosan-based in situ gels for the applications in drug delivery and tissue regeneration. Finally, development prospects of in situ forming hydrogels based on chitosan are also discussed in brief.     

The delivery of platinum drugs from thermosensitive hydrogels containing different ratios of chitosan

New thermosensitive hydrogels of poly(N-isopropylacrylamide) (PNIPAAm) with chitosan (CPN) were prepared and evaluated for use in the delivery of the platinum drugs, cisplatin and carboplatin. The effects of polymers containing different ratios of chitosan on the physicochemical and drug release characteristics were examined. The sol-gel transition temperature of the hydrogels was determined by differential scanning calorimetry (DSC) and viscometry. Discrepancies in the transition temperature among the various polymer systems were more pronounced when determined by viscosity compared by DSC, with the CPN showing a higher transition temperature than PNIPAAm. The cross-sectional structure and surface topography of the hydrogels were examined by scanning electronic microscopy (SEM) and atomic force microscopy (AFM), respectively. The incorporation of chitosan further increased the entanglement of the hydrogel network. An increase in the chitosan ratio in the polymers (CPN-H) also increased the cross-linking structure. A smoother surface of hydrogel matrices was observed for CPN compared with PNIPAAm. All hydrogels tested significantly reduced drug release compared with an aqueous solution. The release rate of platinum drugs from PNIPAAm was retarded at the late stage. CPN matrices could continuously deliver platinum drugs during the experiment. The rate of release from CPN-H was generally slower than that from hydrogels and had a lower chitosan ratio (CPN-L), presumably due to the more-tortuous pathways in the hydrogels. Thermosensitive hydrogels like those prepared in this study may be a promising carrier for the delivery of platinum drugs, as the drug release can be controlled and sustained using CPN networks.     

Intratumoral delivery of paclitaxel using a thermosensitive hydrogel in human tumor xenografts

Poly(organophosphazene), a novel thermosensitive hydrogel, is an injectable drug delivery system (DDS) that transforms from sol to gel at body temperature. Paclitaxel (PTX) is a mitotic inhibitor used in the treatment of various solid tumors. Due to its poor solubility in water and efflux systems in the gastrointestinal tract, PTX is a good candidate for local DDS. Here, we evaluated the penetration kinetics of PTX released from the PTX-poly(organophosphazene) hydrogel mixture in multicellular layers (MCLs) of human cancer cells. We also investigated the tumor pharmacokinetics of PTX (60 mg/kg) when administered as an intratumoral injection using poly(organophosphazene) in mice with human tumor xenografts. When PTX was formulated at 0.6 % w/w into a 10 % w/w hydrogel, the in vitro and in vivo release were found to be 40 and 90 % of the dose, respectively, in a sustained manner over 4 weeks. Exposure of MCLs to PTX-hydrogel showed time-dependent drug penetration and accumulation. In mice, the hydrogel mass was well retained over 6 weeks, and the PTX concentration in the tumor tissue was maximal at 14 days, which rapidly decreased and coincided with rebound tumor growth after 14 days of suppression. These data indicate that PTX-hydrogel should be intratumorally injected every 14 days, or drug release duration should be prolonged in order to achieve a long-term antitumor effect. Overall, poly(organophosphazene) represents a novel thermosensitive DDS for intratumoral delivery of PTX, which can accommodate a large dose of the drug in addition to reducing its systemic exposure by restricting biodistribution to tumor tissue alone.     

自组装短肽原位凝胶用作蛋白药物载体的初步研究

目的:研究自组装短肽原位凝胶用作蛋白药物载体的可能性。方法:以自组装短肽RAD16-Ⅰ为代表,以溶菌酶为模型蛋白,通过流变学试验表征含蛋白的自组装短肽溶液原位成水凝胶特性,并通过体外试验初步研究蛋白的释放特性。结果:含蛋白的自组装短肽溶液在接触到磷酸盐缓冲溶液后能够迅速形成水凝胶;蛋白容易从中释放并表现出一定的控释作用,8h累积释药量均大于80%,1.5%的RAD16-Ⅰ载蛋白水凝胶24h蛋白累积释药量小于90%;蛋白的结构完整性和活性得到了很好的保持,释放样品中溶菌酶相对活性为98%～115%。结论:自组装短肽具有作为蛋白类药物原位水凝胶载体的潜力。     

Investigation of a new injectable thermosensitive hydrogel loading solid lipid nanoparticles

For improving the effectiveness of cancer chemotherapy and avoiding rapid clearance of solid lipid nonoparticles (SLN) from the systemic circulation following systemic administration, 2-methoxyestradiol (2-ME) as model drug, PLGA-PEG-PLGA as hydrogel material, an injectable SLN loaded hydrogel was developed. Integrity of SLN within and released from the hydrogel was confirmed by direct visualization by a scanning electron microscope (SEM), particle size measurement by laser light scattering, and free drug concentration in the release medium by ultracentrifugation. Moreover, in vitro release, thermo-sensitive properties and rheological behavior were investigated. The results indicated that SLN were stable in the hydrogel. In the release medium, most 2-ME existed in the SLN and intact 2-ME SLN could be released from the hydrogel for a prolonged period over 46 days. Their concentration showed a significant effect on the release rate, in contrast to particle size and pH value of the release medium. In addition, the SLN loaded hydrogel could still exhibit reversible thermo-sensitive properties and better syringeability. These results suggested that the SLN loaded hydrogel could transport SLN to the target site and control prolonged release of SLN, which may increase the efficacy of cancer chemotherapy.     

pH-Sensitive Black Phosphorous–Incorporated Hydrogel as Novel Implant for Cancer Treatment

In this study, black phosphorus nanosheets (BPNSs) were incorporated into a hydrogel formed from dibenzaldehyde-functionalized polymer (DF-PEG) and polyaspartylhydrazide (PAHy) polymer to create an injectable and pH-sensitive DF-PEG-PAHy/BPNSs hydrogel, which can be used as a smart depot for synergistic chemo-photothermal cancer therapy. The DF-PEG-PAHy/BPNSs hydrogel exhibited excellent gelation characteristics, pH sensitivity, and near-infrared responsiveness. The nanocomposite hydrogel provided controlled drug release and near-infrared irradiation speeded up release of drug from the hydrogel because of the photothermal effect of the BPNSs. Cytotoxicity tests confirmed that the hydrogel has good biocompatibility and exerts its photothermal effect in vitro. Antitumor tests in mice demonstrated the capacity of DF-PEG-PAHy/BPNSs hydrogel for synergistic chemo-photothermal therapy in vivo. The hydrogel showed reduced adverse effects because of stable drug release in the tumor area and an efficient photothermal effect. Together, these data demonstrated the potential of DF-PEG-PAHy/BPNSs hydrogel containing a chemotherapy drug to serve as a novel smart delivery system for combined chemo-photothermal cancer therapy.