氯霉素温敏型眼用原位凝胶的研制

目的制备氯霉素泊洛沙姆眼用原位温敏型凝胶并建立其质量控制方法。方法以泊洛沙姆P407和P188为温敏材料,通过测定溶液-凝胶相转变温度优化处方;采用紫外分光光度法测定氯霉素含量。结果氯霉素温敏型原位凝胶的胶凝温度随P407浓度增大而降低,随P188浓度增加先升高后降低,模拟泪液的稀释可使胶凝温度升高,建立了泪液稀释后相变温度与泊洛沙姆浓度的拟合方程,经Design-Expert软件优化出的氯霉素温敏型原位凝胶最佳处方为25%P407和4.19%P188;优化处方在29.5℃时为自由流动的液体,泪液稀释后在34.6℃能够发生相变形成凝胶。结论该眼用温敏凝胶符合眼部应用要求,体现出良好的应用前景。     

Effect of sodium chloride on the release,absorption and safety of diclofenac sodium delivered by poloxamer gel

Poloxamer solutions prepared with poloxamers and sodium chloride were previously reported to undergo a phase transition to bioadhesive gels at body temperature. For the development of a thermosensitive diclofenac sodium-loaded poloxamer gel, here we investigated the effect of sodium chloride on the release, safety and rectal absorption in rats of diclofenac sodium delivered by the poloxamer gels. P 188 delayed the release rates of diclofenac sodium from poloxamer gels. However, sodium chloride showed no significant effect on the release rates of diclofenac sodium from poloxamer gels. Release mechanism analysis showed the release of diclofenac sodium was proportional to the time. The initial plasma concentrations of diclofenac sodium in the rectal formulation [diclofenac sodium/poloxamer 407 (P 407)/poloxamer 188 (P 188)/sodium chloride (2.5/15/17/0.8%)] were significantly higher compared with those in semi-solid suppository. Furthermore, it gave significantly faster Tmax of diclofenac sodium than did semi-solid suppository, indicating that the diclofenac sodium from poloxamer gel could be absorbed faster than that from semi-solid one in rats. It did not cause any morphological damage to the rectal tissues. These results suggested that poloxamer gel with sodium chloride could be a more effective and safe rectal delivery system of diclofenac sodium.     

川芎嗪眼用脂质体温敏凝胶的制备及体内外特性评价

目的:制备川芎嗪眼用脂质体温敏凝胶,考察其体内外特性.方法:采用硫酸铵梯度法制备川芎嗪脂质体,以正交试验优化制备工艺,并以泊洛沙姆P407为凝胶基质进一步制成温敏凝胶.采用无膜溶出模型对该凝胶的溶蚀性和体外释药特性进行研究;采用改良Franz扩散池考察其角膜透过性,并进一步测定角膜水化值;采用MTT法评价该凝胶对人角膜...     

Liposomes Dispersed Within a Thermosensitive Gel: A New Dosage Form for Ocular Delivery of Oligonucleotides

Purpose. The main goal of this study was to develop an ocular controlled release formulation of a model oligonucleotide (pdT16), contained within liposomes dispersed within a thermosensitive gel composed by poloxamer 407. Methods. The influence of the poloxamer concentration 2% or 27% on the stability of the liposomes (PC: CHOL and PC: CHOL: PEG-DSPE) was investigated. The in vitro release profiles of pdT16 from various poloxamer formulations (free pdT16 dispersed within 20% and 27% poloxamer gels, pdT16 encapsulated within liposomes dispersed within 20% and 27% poloxamer gels) were realized using a membrane-free release model. Results. The dispersion of liposomes within a dilute 2% poloxamer solution resulted in a great leakage of pdT16 from liposomes. However, the destabilization effect of poloxamer was reduced when higher concentration (27%) was used. Poloxamer dissolution was found to control the release process of pdT16, whereas the dispersion of liposomes within 27% poloxamer gel was shown to slow down the diffusion of pdT16 out from the gel. Conclusions. The dispersion of liposomes within a 27% poloxamer gel presented an interesting system to control the release of a model oligonucleotide compare to a simple gel.     

In-situ gel formulations of econazole nitrate: preparation and in-vitro and in-vivo evaluation

Objectives This study describes the in‐situ gelling of econazole nitrate containing thermosensitive polymers composed of poloxamer 407 and 188 as a novel treatment platform for vaginal candidiasis. Methods Aqueous thermosensitive formulations containing 1% of econazole nitrate and poloxamer 407 and/or 188 were prepared and their rheological, mechanical and drug‐release properties determined at 20 ± 0.1°C and/or 37 ± 0.1°C. Based on their biologically suitable thermorheological properties, formulations containing the mixtures of poloxamer 407 and 188 in ratios of 15:15 (F1), 15:20 (F2) and 20:10 (F3) were chosen for comprehensive analysis. Key findings Formulations based on F3 exhibited typical gel‐type mechanical spectra (G′ > G″) at 37°C whereas formulations based on F1 and F2 exhibited properties akin to weakly cross‐linked gels. Texture profile analysis demonstrated that F3 showed the highest cohesiveness, adhesiveness, hardness and compressibility. No statistically significant differences (P > 0.5) were observed in the release of econazole nitrate from the formulations at pH 4.5, which in all cases followed anomalous diffusion kinetics. Formulations based on 20% poloxamer 407:10% poloxamer 188 were chosen for in‐vivo studies and were shown to be effective for the treatment of the vaginal candidiasis. Histopathologic evaluation also supported the effectiveness of the thermosensitive formulation administered intravaginally. Conclusion By careful engineering of the rheological properties, in‐situ thermosensitive gel formulations of econazole nitrate were prepared and were shown to be efficacious in the treatment of vaginal candidiasis.     

Physico-chemical characterisation and transfection efficiency of lipid-based gene delivery complexes.

Cationic liposomes spontaneously interact with negatively charged plasmid DNA to form a transfection competent complex capable of promoting the expression of a therapeutic gene. This work aims to improve the understanding of the poorly defined mechanisms and structural rearrangements associated with the lipid-DNA interaction. Specifically, dimethyl dioctadecylammonium bromide (DDAB):dioleoyl phosphatidylethanolamine (DOPE) and 1,2-dioleoyl-3-trimethylammonium propane (DOTAP) liposomes were mixed with a reporter plasmid (pADbeta or pCMVbeta) to form lipid-DNA complexes. The size and charge characteristics of the complexes as determined by photon correlation spectroscopy and microelectrophoresis were found to be dependent on the lipid:DNA ratio, with both DDAB:DOPE-DNA and DOTAP-DNA complexes aggregating at around neutral zeta potential. Negative stain transmission electron microscopy demonstrated at least three distinct complex structures being formed at the same DOTAP:DNA ratio. We postulate that two of these aggregates are structural moieties involved in the formation of the efficient transfection particle. Gel electrophoresis was used to determine the efficiency and extent of lipid-DNA complex formation. Results showed that only DOTAP liposomes were capable of preventing ethidium bromide intercalation with DNA and protecting the enclosed plasmid from nuclease digestion. When a range of lipid-DNA complexes were transfected into in vitro cell lines, the efficiency of reporter gene (beta-galactosidase) expression was found to depend on the type of liposome used in the complex, the ratio of lipid:DNA and the transfected cell line. Our results challenge the requirement for DOPE to be included in the formulation of cationic lipid vectors, especially in the case of DOTAP containing liposomes.     

盐酸小檗碱眼用温敏原位凝胶制备及兔眼房水内药动学特征

目的:制备盐酸小檗碱眼用温敏凝胶并考察其在家兔眼房水内的药动学特征。方法:以泊洛沙姆为温敏材料,盐酸小檗碱为模型药物制备眼用温敏原位凝胶,高效液相色谱法测定给药后不同时间兔眼房水中的盐酸小檗碱浓度,绘制药-时曲线,计算相关药动学参数。结果:盐酸小檗碱眼用温敏原位凝胶在兔眼内的吸收和消除过程呈线性二室模型动力学特征,其t1/2β、t1/2α,MRT、Tmax、Cmax、AUC0-τ和AUC0-∞分别为4.585 h,0.911 h,1.966 h,1 h,1.4 mg.L-1,2.561 mg.h.L-1,2.581 mg.h.L-1。结论:此方法可用于测定房水中盐酸小檗碱的浓度,对于盐酸小檗碱眼部局部给药药动学研究提供评价方法。     

Gene transfer mediated by sphingosine/ dioleoylphosphatidylethanolamine liposomes in the presence of poloxamer 188

A cationic liposome system consisting of sphingosine (SP) and dioleoylphosphatidylethanolamine (DOPE) was developed for in vitro and in vivo gene transfer. A nonionic surface active agent of poloxamer 188 was incorporated in the formulations to stabilize the DNA/liposome complex. Comparison of the results obtained from systems with and without the effect of poloxamer 188 was made to investigate the efficiency of gene expression. In vitro transfection study of the DNA/liposome complex showed that with the effect of poloxamer 188, gene transfer into some cell lines was enhanced. In vivo systemic delivery of the DNA/liposome complex with poloxamer 188 demonstrated gene expression with improved luciferase activity in all major organs including lung, spleen, heart, liver, and kidney. High level transgene activity was found in lung and spleen with prolonged gene expression. This was attributed to poloxamer 188 that stabilized the liposome system and produced homogeneous DNA/liposome complex for enhancement of gene delivery.     

Gene Transfer Mediated by Sphingosine/ Dioleoylphosphatidylethanolamine Liposomes in the Presence of Poloxamer 188

A cationic liposome system consisting of sphingosine (SP) and dioleoylphosphatidylethanolamine (DOPE) was developed for in vitro and in vivo gene transfer. A nonionic surface active agent of poloxamer 188 was incorporated in the formulations to stabilize the DNA/liposome complex. Comparison of the results obtained from systems with and without the effect of poloxamer 188 was made to investigate the efficiency of gene expression. In vitro transfection study of the DNA/liposome complex showed that with the effect of poloxamer 188, gene transfer into some cell lines was enhanced. In vivo systemic delivery of the DNA/liposome complex with poloxamer 188 demonstrated gene expression with improved luciferase activity in all major organs including lung, spleen, heart, liver, and kidney. High level transgene activity was found in lung and spleen with prolonged gene expression. This was attributed to poloxamer 188 that stabilized the liposome system and produced homogeneous DNA/liposome complex for enhancement of gene delivery.     

Nasal in-situ gels for delivery of rasagiline mesylate: improvement in bioavailability and brain localization

Abstract

Intranasal thermosensitive gel for rasagiline mesylate (RM) was developed for effective treatment of Parkinson’s disease. Intranasal gels were prepared by combination of poloxamer 407 and poloxamer 188 (1:1) with mucoadhesive polymers (carbopol 934?P and chitosan). The formulations were evaluated for sol–gel transition temperature, in-vitro drug release and in-vivo mucociliary transit time. Further, optimal intranasal gel formulations were tested for in-vivo pharmacokinetic behavior, nasal toxicity studies and brain uptake studies. It was found that optimal formulations had acceptable gelation temperature (28–33?°C) and adequate in-vitro drug release profile. Pharmacokinetic study in rabbits showed significant (p?<?0.05) improvement in bioavailability (four- to six-folds) of the drug from intranasal gels than oral solution. Chronic exposure studies in Wistar rats showed that these intranasal gels were non-irritant and non-toxic to rat nasal mucosa. Estimation of RM in rat brain tissue showed significant (p?<?0.01) improvement in uptake of RM form intranasal gel formulations than nasal solution.     

New method for ophthalmic delivery of azithromycin by poloxamer/carbopol-based in situ gelling system

This study focused on preparation and evaluation of a thermosensitive and mucoadhesive in situ gelling ophthalmic system of azithromycin (ATM). Poloxamer 407 (P407) and poloxamer 188 (P188) were used as gelling agents. Addition of Carbopol 974P (CP 974P) to the gelling systems could increase the solubility of ATM by salt effect and enhance the mucoadhesive property of the systems. Gelation temperature of these systems ranged from 31.21–36.31°C depending on the ratio of P407 and P188. Mucoadhesion force of the system composed of P407/P188/CP 974P (21/5/0.3%, w/v) was 2.3-fold that without carbopol 974P. Viscosity of the formulation was in a suitable range at 25°C and pseudoplastic behavior was observed at 35°C. The formulation exhibited a 24-h sustained release of ATM. In vivo resident experiments showed AUC_0–12 of ATM in rabbit tears increased by 1.78-fold for in situ gel compared with eye drop. At 12?h, tear concentrations exceeded minimum inhibitory concentration (MIC) breakpoint for the most common causative pathogens of bacterial conjunctivitis by 2.8-fold. Results in vitro and in vivo indicated that this droppable gel performed better than ATM eye drop did.     

Encapsulation enhancement and stabilization of insulin in cationic liposomes

The purpose of this study was to enhance encapsulation efficiency and sustained-release delivery for parenteral administration of a protein drug. To reduce the administration frequency of protein drugs, it is necessary to develop sustained delivery systems. In this study, protein drug-loaded cationic liposomes were formulated with dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), dioleoyl-3-trimethylammonium-propane (DOTAP), and cholesterol (CH) at a molar ratio of DOPE/DOTAP/CH of 2/1.5/2. Five mol% of distearoylphosphatidyl ethanolamine polyethylene glycol (DSPE-PEG) was added prior to encapsulation of the drug into liposomes. Insulin was chosen as a model protein drug and encapsulation efficiency was evaluated in various liposomes with and without DSPE-PEG. Scanning electron microscopy was used to examine the insulin-loaded cationic liposomes. Structural analysis was performed using spectropolarimetry. Additionally, the stability and cytotoxicity of insulin-loaded cationic liposomes were evaluated. Liposomes coated with DSPE-PEG showed higher insulin encapsulation efficiency than did those without DSPE-PEG, but not significantly. Moreover, among the liposomes coated with DSPE-PEG, those hydrated with 10% sucrose showed higher encapsulation efficiency than did liposomes hydrated in either phosphate-buffered saline or 5% dextrose. In vitro release of insulin was prolonged by cationic liposomes. Our findings suggest that cationic liposomes may be a potential sustained-release delivery system for parenteral administration of protein and peptide drugs to prolong efficacy and improve bioavailability.     

温度敏感型布洛芬缓释液体栓的制备与体内外评价

目的:以泊洛沙姆407(P407)和泊洛沙姆188(P188)为组合基质,添加生物黏附剂卡波姆(Cabopol)以及促渗透剂氮酮(Azone)制备温敏型布洛芬(IBU)缓释液体栓剂,考察液体栓释药的体内外相关性。方法:以凝胶温度、凝胶强度、生物黏附力和液体栓剂体外释放度为指标进行体外筛选;经比格犬直肠给药测定动物体内药物释放曲线进行体内筛选;用3P97程序计算药动学参数。结果:布洛芬体外释放结果符合零级模式,R2>0.9时,体内药物释放出现平台,显示了良好的体内外相关性;药动学研究结果表明,体内过程为一室模型,药动学参数为tmax=3.551 h,Cmax=21.483μg.mL-1,t1/2(Ke)=2.740 h,AUC0→∞=210.850μg.mL-1.h,MRT=7.670 h。结论:所制备的布洛芬液体栓剂具有良好的缓控释特征。     

奥洛他定温度敏感眼用原位凝胶的制备

目的:研制奥洛他定温度敏感眼用原位凝胶。方法:采用泊洛沙姆P407和P188为温敏材料,以胶凝温度为指标,通过星点设计-效应面法优化处方。结果:经过优化筛选出的处方在室温条件下是自由流动的液体,在生理条件下发生胶凝形成凝胶。结论:所研制奥洛他定眼用温度敏感原位凝胶符合眼部应用要求,体现出良好的临床应用前景。     

星点设计-效应面法优化氨来呫诺眼用温敏凝胶的处方

目的研制氨来呫诺眼用温敏凝胶。方法采用冷法工艺制备氨来呫诺眼用温敏凝胶,以泊洛沙姆407和泊洛沙姆188为温敏凝胶材料,以二者用量为考察因素,以人工模拟泪液稀释前后的胶凝温度为考察指标,采用星点设计-效应面法进行处方优化并验证。结果氨来呫诺眼用温敏凝胶优化处方P407和P188的质量浓度配比为190∶40,胶凝温度为28.37℃,经模拟泪液稀释后胶凝温度为32.63℃。结论星点设计-效应面法优化处方的方法可行,建立的数学模型预测性好,该眼用温敏凝胶满足眼部用药的设计要求,可进一步研究开发。     

眼用盐酸倍他洛尔脂质体-原位凝胶的研制及体外释药的研究

目的制备盐酸倍他洛尔(BH)眼用脂质体-原位凝胶(ISG),并对其体外释药特性进行考察。方法采用逆向蒸发法制备BH脂质体(BHL);以泊洛沙姆407和188(P407,P188)为温敏性ISG基质,以胶凝温度为指标,筛选P407与P188的最佳配比;采用无膜溶出模型对BHL的体外释放行为进行考察。结果 BHL的平均包封率为(88.24±5.46)%(n=3);当P407与P188的处方用量分别为21%及6%时,胶凝温度最接近人眼表温度(34℃);BHL-ISG体外药物释放和凝胶溶蚀均呈现零级释放特征,两者相关性良好。结论 BHL-ISG结合脂质体和原位凝胶的特点,延缓药物释放,为其角膜滞留性研究奠定了基础。     

In vitro and in vivo characteristics of a thermogelling and bioadhesive delivery system intended for rectal administration of quinine in children

The aim of this work was to improve the rectal bioavailability of quinine hydrochloride by designing thermosensitive and mucoadhesive gels intended for rectal delivery. The rheological and mucoadhesive properties of poloxamer 407 solutions have been modulated by addition of hydroxypropylmethycellulose (HPMC) and propanediol-1,2. In vitro release and rectal absorption of quinine have been highlighted by a dialysis dissolution testing method and by the determination of bioavailability of the different formulations in rabbits. Increasing the proportions of HPMC and poloxamer in the formulations resulted in a prolonged release of quinine. Indeed, compared to the DT 50% of a rectal solution and a simple HPMC gel (27 and 65 min, respectively) the DT 50% of thermosensitive ternary systems was increased and ranged between 80 and 138 min, depending on the system composition. The release rate depended strongly on the elasticity of the gels after thermogelation. The absolute rectal bioavailability of quinine determined in rabbits was significantly improved with these thermosensitive and adhesive systems. It increased from 62% for the rectal solution to 98% for a ternary system 16/0.5/30 (poloxamer (16%)/HPMC (0.5%)/propanediol-1,2 (30%)). As a result of combined bioadhesion and prolonged release of quinine in vivo, higher average values of MRT and t_max (9.1 ± 0.2 h and 30 min, respectively) were obtained compared to the rectal solution (6.9 ± 0.9 h and 15 min, respectively). Moreover, these formulations presented a very good rectal tolerance.

Modulation by HPMC of the viscoelastic and mucoadhesive properties of poloxamer 407 thermogelling solutions allowed a prolonged release of quinine hydrochloride and an improvement of bioavailability in rabbit.     

硝酸毛果芸香碱温敏凝胶的研制及溶蚀性能研究

目的制备硝酸毛果芸香碱温敏凝胶,考察其载药凝胶溶蚀行为。方法以泊洛沙姆为温敏凝胶基质制备硝酸毛果芸香碱眼用凝胶,通过凝胶相变温度筛选最佳处方,采用无膜溶蚀实验研究凝胶释药特性。结果18%、19%、20%的泊洛沙姆407溶液在体温范围内发生相变形成凝胶,其pH≈7,凝胶中硝酸毛果芸香碱释放速度分别为0.462、0.393、0.294 mg.min-1。结论18%-20%泊洛沙姆407溶液适合作为眼部给药的温敏凝胶基质,凝胶中药物释放基本符合零级释放行为。     

Properties of bioadhesive ketoprofen liquid suppositories: preparation,determination of gelation temperature,viscosity studies and evaluation of mechanical properties using texture analyzer by 4 × 4 factorial design

Abstract

Context: Development and evaluation of thermosensitive and bioadhesive liquid suppositories containing ketoprofen (KP).

Objective: This study was conducted to develope thermosensitive and bioadhesive liquid suppositories containing KP using poloxamer and different bioadhesive polymers and to investigate their gelation temperature, viscosity and mechanical properties.

Materials and methods: Bioadhesive liquid suppositories were prepared by the cold method using poloxamer 407 (P 407), Poloxamer 188 (P 188) and various amounts of different bioadhesive polymers. Their gelation temperatures, viscosity values and mechanical properties were determined using texture analyzer by 4?×?4 factorial design.

Results: It was seen that in presence of KP, gelation temperature of formulation P 407/P 188 (4/20%) significantly decreased from 64 to 37.1?°C. It is to be noted that addition of increasing concentrations of bioadhesive polymers lowered gelation temperature and its decrease was highest with addition of Carbopol 934 P (C). Results of texture profile analysis (TPA) showed that formulations containing C have significantly higher hardness and adhesiveness values than other bioadhesive formulations. According to TPA, gel structure of liquid suppository formulation F5, containing P 407/P 188/KP/C (4/20/2.5/0.8%), exhibited the greatest hardness, compressibilty, adhesiveness and besides greatest viscosity.

Discussion and conclusion: According to mechanical properties and viscosity values, it was concluded that F5 could be a promising formulation.     

The choice of a suitable oligosaccharide to prevent aggregation of PEGylated nanoparticles during freeze thawing and freeze drying

In a previous study we have shown that the oligosaccharide inulin can prevent aggregation of poly(ethylene glycol) (PEG) coated plasmid DNA/cationic liposome complexes ("PEGylated lipoplexes") during freeze thawing and freeze drying [Hinrichs et al., 2005. J. Control. Release 103, 465]. By contrast, dextran clearly failed as stabilizer. These results were ascribed to the fact that inulin and PEG are compatible while dextran and PEG are not. In this study the stabilizing capacities of inulin and dextran (of various molecular weights) during freeze thawing and freeze drying of four different types of nanoparticles, each type with different amounts of PEG at their surface, were investigated. Freeze drying and freeze thawing of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)/dioleoyl-phosphatidyl-ethanolamine (DOPE) liposomes and egg phosphatidyl choline (EPC)/cholesterol (CHOL) liposomes showed that inulins are excellent stabilizers even for highly PEGylated liposomes while (especially higher molecular weight) dextrans dramatically lost their stabilizing capacity when increasing the degree of PEGylation of the liposomes. The same results were obtained for plasmid DNA/DOTAP/DOPE complexes. Finally, both inulin and dextran could prevent full aggregation of plasmid DNA/polyethylenimine (PEI) complexes independent whether PEI was PEGylated or not. It is concluded that inulins are preferred as stabilizers over dextrans for various types of PEGylated nanoparticles due to their compatibility with PEG.