热定形凝胶溶胶凝胶转变温度乙二醇柠檬酸中英文资料外文翻译

中英文资料外文翻译可逆热固性原位胶凝流变特性的解决方案与甲基纤维素聚乙二醇柠檬酸三元系统Masanobu Takeuchi Shinji Kageyama Hidekazu Suzuki Takahiro著，…..译.[摘要]可逆性溶胶凝胶温度的转变受到甲基纤维素(MC)、聚乙二醇(PEG)、柠檬酸(SC) 三元体系的影响，通过流变学测量得出原位凝胶体系的性能。

当PEG （4000）的浓度在0%到10%范围内变化，MC（25）和SC浓度分别保持在1.5%和3.5%时，随着PEG浓度的增加，可逆性溶胶转变温度从38°C降低至26°C，然而，温度降低的程度不受PEG分子量的影响，随着MC浓度的增加可逆溶胶~凝胶的温度降低，同时随着ph值的降低可逆溶胶~凝胶的温度升高，在流变特性的比较方面，目前原位胶凝的设置解决方案和常规相比，如结冷胶溶液或泊洛沙姆407,显示目前的解决方案从根本上有别于传统的解决方案，这些研究结果表明，这项研究中的三元体系可作为在眼部传递灌输系统的药物。

[关键词] 热定形凝胶；溶胶凝胶转变温度；甲基纤维素聚乙二醇柠檬酸三元体系1 前言本研究提高了眼用溶液在吸收过程中利用度差的问题，例如，在溶液溶解时利用这个属性而由此获得的聚合物。

通过在滴眼液中加入聚合物来延长持续时间，从而增加药物在角膜前停留时间来改善结膜渗透性。

聚合物的使用被认为是有效的，因为他们增加了药物的效用，聚合物的使用也有其缺点，如由于溶液的粘度高会出现灌注困难和不适感。

我们发现了一种热固性凝胶溶液在甲基纤维素聚乙二醇柠檬酸三元系统中的应用，并开发了一种含马来酸噻吗洛尔，可以用来治疗青光眼的眼用溶液，据报道，长效的眼用溶液的流量曲线触变性在32°C，呈现出粘度随温度升高而明显变化的特性。

据报道，眼科溶液流变特性极大地影响角膜滞留时间和眼睛的感觉，我们考察了不同聚合物溶液的性质，以前几乎没有从流变学的观点来研究的先例。

本研究的目的在于评估热定形凝胶溶液流变性质的影响。

此外，从流变性方面与其他原位凝胶在眼科中应用进行比较。

2 实验材料四种不同的甲基纤维素（MC），即，MC（SM 15，25，400，1500），聚乙二醇1000（平均分子量950–1050），4000（平均分子量2600–3800），6000（平均分子量7300–9300）简称PEG 1000，4000，6000）和二水柠檬酸钠（SC），泊洛沙姆407，马来酸噻吗洛尔，氧氟沙星，倍他米松磷酸钠。

按罗齐尔等描述的在0.67克氯化钠、0.20克碳酸钠、0.008克二水氯化钙中加入蒸馏水直到总体积达到100毫升来制备人工泪液。

2.1 原位凝胶溶液的制备将50毫升的蒸馏水加热至90℃后加入MC（0.7克SM150.7：GOF SM400）后搅拌均匀，制备浆料。

将其冷却至5℃，在30ml蒸馏水中混合3.5克SC，然后在15ml 蒸馏水溶液中混合2.0克聚乙二醇400。

搅拌该混合物直到透明。

用3N盐酸调节其pH值至7.8后，在混合物中加蒸馏水至100 mL，作为热硬化性凝胶溶液。

2.2 泊洛沙姆溶液的制备在索伦森缓冲溶液（pH7.0）中溶解25克PM，将所得混合物在5℃下放置24小时，然后混合2.5克甘露糖醇，将所得70毫升溶液与索伦森缓冲溶液（pH 7.0）中和至100mL。

2.3 胶凝温度通过试管倒置法测量通过试管倒置法测定可逆性溶胶凝胶温度。

将5毫升的样品放在玻璃测试管中（12贴片机的直径，内径10.5毫米），然后将测试管放在一个恒温浴中5分钟。

在该温度下的样品没有流出作为可逆的溶胶凝胶的转变温度3 结果与讨论3.1 PEG对可逆溶胶凝胶转变温度的影响有几种方法可用来测量可逆溶胶–凝胶的转变温度，如测试管法，落球法，U型管法，流变仪。

落球法和异型管法用来测定凝胶的熔点。

由于凝胶的熔点和凝固点不同，本研究不太适合用落球法和U形管方法，MO设置凝胶的凝点很重要的一点是利用DSC对温度不敏感的特性。

综合以上考虑，应该使用试管倒置法和弹性力学与流变仪测定法。

在三元（MC~PEG~SC）系统中特别应该注意的是PEG，该添加剂的作用已知。

图1图1 温度对热定形凝胶溶液的表观粘度的影响。

聚乙二醇浓度：0 %，2 %，4 %，6 %，8 %，10 %。

表观粘度测定用流变仪测定。

甲基纤维素（SM 25）和柠檬酸钠二水合物的浓度分别恒定保持在1.5%和3.5%，而聚乙二醇（PEG 4000）的浓度变化范围在0%到10%图2试管反演方法和流变仪测量法，图中x和y分别表示用试管倒置法测量的相转变温度和用流变仪测量的相转变温度，甲基纤维素(SM 25)和柠檬酸钠二水物浓度分别保持恒定在2 %和3.5%，聚乙二醇（PEG 4000）的浓度变化范围在0%到10%之间。

图1和2分别显示了温度对热定形凝胶溶液的表观粘度的影响，试管反演方法和流变仪测量法。

如图所示，当MC（SM 25）和SC浓度保持恒定在1.5%和3.5%不变时，同时PEG 4000浓度的变化范围在0%到10%之间，可逆的溶胶凝胶转变温度随着PEG浓度的增加而下降。

当PEG浓度为10%时，溶液的粘度在24°C 时开始增加,然而当温度增加到34°C时，溶液的粘度不再增加。

胶凝温度测试管反演方法和流变仪方法得到的数据之间有明显的正相关（相关系数R = 0.89）。

MC呈现出溶于水的纤维素，有高的结晶度和低的水溶性部分。

为此，当加热和凝胶分离冷却时，MC的解决方案是可逆的。

其胶凝机理被报道的三甲基葡萄糖序列和交联结晶，可逆的溶胶凝胶转变温度（热固胶凝温度）通常是由盐的加入而降低，它是强阴离子的作用效果，由于柠檬酸强烈的盐析效应，降低了热定形凝胶对MC的脱水温度。

当PEG单独添加到MC中时，溶液的热定形凝胶温度只是略微降低，但大大减少了柠檬酸的加入。

PEG引起了葡聚糖水溶液的相分离，此外，研究发现，过量添加PEG诱导热定形凝胶（MC–PEG–SC系统）相分离（微相分离），通过上述研究发现了PEG通过诱导微相分离加速MC形成交联的解决方案。

PEG的分子量对热定形凝胶温度的影响，当PEG的浓度从0%变化到10%时，MC 的浓度（SM 25）和SC分别保持恒定在1.5%和3.5%时。

当PEG 1000和PEG 6000代替PEG 4000时，热定形凝胶的温度依赖于PEG的浓度而降低。

PEG 1000，4000，和6000他们的影响大致相当于减少热定形凝胶的温度，随着SM 25浓度的增加，由于PEG依赖热定形凝胶温度而使曲线移向较低的温度，这个热定形凝胶温度随MC溶液浓度的增加而减少的趋势，可由三甲基葡萄糖序列之间的距离而缩短，这使结晶和交联的形成变得更容易，这是凝胶发生在一个较低的温度和短距离的结果。

同样的原理似乎将用在低温下的热定形凝胶。

热定形凝胶溶液、结冷胶溶液、和泊洛沙姆溶液表现出不同的流动性，这主要表现为牛顿流体，准粘性流动，和准塑性流动，而所有这些解决方案显示，通过溶胶凝胶改善角膜滞留时间的热定形凝胶溶液和泊洛沙姆溶液从来没有凝胶在靠近眼球表面的温度情况下，这表明他们状况是良好的，此外, 凝胶溶液和结冷胶在剪切应力中的屈服值为零或非常小,表明这些解决方案只是略耐瞬眼并且会对眼睛产生良好的感觉,4 结论我们通过可逆性溶胶~凝胶的过渡温度来研究三元（MC–PEG–SC）系统的影响。

当SC浓度保持恒定，可逆性溶胶凝胶转变温度降低取决于PEG和MC的浓度，但不取决于PEG分子量。

溶胶凝胶转变温度随pH的增加而减少，此外，随着可逆性溶胶溶液的转变温度减低和PEG浓度的增加，将会有更多的眼药类型供选择，通过对热固性凝胶的流变性能和大家熟知的原位凝胶系统以及结冷胶和泊洛沙姆的解决方案相比较，很明显前者的解决方案和后者有明显的不同，其作为药物传递系统灌输到眼部的用处很实用。

参考文献[1] Bourdais CL, Acar L, Zia H, Sado PA , Needham .Leverge R (1998) 前卫视网膜眼研究 17:33[2] Sasaki H, Nishida K, Nakamura J.Ichikawa M (1996) 前卫视网膜眼研究 15:583[3] Chrai SS. RobinsonJR (1974 ) 医药供应链 63:1218[4] Kurimoto K, Eguchi K, Kitajima S,Kishimoto N, Matsumoto N.Otsuki(1991) Atarashii Ganka 8:1259[5] Kabayama T, Suzuki H, Horiuchi T,Akutagawa Y. Matsuzaki H (1979) 日本眼科系统[J]. 83:326[6]TakeuchiM,KageyamaS,SuzukiH,WadaT,ToyodaY,OgumaT,EzureY,TsuriyaY,KatoT.Ishii F(1999) 材料技术 17:445[7] Patton TF.Robinson JR (1975) 药学科学 64:1312[8] Rozier A, Mazuel C, Grove J, Plazon~net. B (1989) 国际药学杂志 57:163[9] Kato T, Yokoyama M. Takahashi A(1978) 胶体高分子科学 265:15[10] Heymann E (1935) 反式法拉Soc 31:846[11] Edmond E. Ogston AG (1968) 生物化学杂志 109:569[12] Miyoshi E .Nishinari K (1998) Kobun~shi Ronbunshu 55:567[13] Vadnere M,AmidonG, LindenbaumS. JohnL (1984) INTJ制药 22:207[14] Cho CW,Shin SC.Oh IJ (1997) Drug DevInd Pharm 23:1227Rheological properties of reversible thermo-setting in situ gelling solutions with themethylcellulose–polyethylene glycol–citric acidternary systemMasanobu Takeuchi Shinji Kageyama Hidekazu Suzuki Takahiro Wada Yoshitada Notsu Fumiyoshi IshiiAbstract The composition of vehicle on the reversible sol–gel transition temperature in a ternary system made up of methylcellulose (MC), polyethylene glycol (PEG), and citric acid (SC) was investigated. The properties of the in situ gelling system were estimated by rheological measurement. When PEG (4000) concentration was varied from 0% to 10% while MC (SM25) and SC concentrations were kept constant at 1.5% and 3.5%, respectively, the reversible sol–gel transition temperature lowered from 38 _C to 26 _C with increasing PEG concentration. However, the extent of lowering in temperature was not influenced by the molecular weight of PEG. The reversible sol–gel transition temperature shifted towards thelower temperature with increasing MC concentration, and towards the higher temperature with decreasing pH. Comparison of rheological properties between the present thermo-setting in situ gelling solution and a conventional one, such as gellan gum solution or Poloxamer 407 solution, revealed that the present solution radically differed from the conventional solutions in the incipient gelling mechanism. These findings suggest that the ternary system in this study would be useful as a drug delivery system for instillation of drugs into the eye.Keywords Thermo-setting gel Sol–gel transition temperature Rheology Methylcellulose–polyethylene glycol–citric acid ternary systemIntroductionStudies have been made to improve the poor bioavailability of ophthalmic solutions in the eye using various drug delivery systems [1, 2]. For example, polymers gain in viscosity when dissolved and this property is utilized. Thus, attempts were made to prolong the duration of effect by adding a polymer to the ophthalmic solution, thereby increasing precorneal residence time of the drug and improving thekerato-conjunctival permeability. The use of biocompatible polymers was found to be effective, because they increased the utility of the preparation [3]. However, the use of polymers also has disadvantages, such as difficulty in instillation and discomfort after instillation due to the high viscosity of the solution.We recently found a thermo-setting gel vehicle that underwent sol–gel transition at around the human eye surface temperature (35 _C [4, 5]) by application of the methylcellulose–polyethylene glycol–citric acid ternary system, and developed a long-acting ophthalmic solution (Rysmon TG) containing timolol maleate that is used in the treatment of glaucoma [6].It was reported that the ade reagents by Wako Pure Chemical Industries (Japan). The gellan gum used was Gelrite by Wako Pure C long-acting ophthalmic solution exhibited thixotropy at temperatures of 32 _C and upward, showing marked changes in flow curve and viscosity curve with rising temperature . It has been reported that the rheological characteristics of ophthalmic solutions greatly influence the precorneal residence time and the feel to the eye [7]. However, there has been almost no research which examined the properties of various polymer solutions from the viewpoint of rheology.The present study aimed at assessing the effect of the composition of athermo-setting gel solution vehicle on its rheological properties. Furthermore, rheological properties were compared among different solutions, with the other in situ gelling systems for ophthalmic use as control.ExperimentalMaterialsFour different kinds of methylcellulose (MC), that is, Metolose (SM 15, 25, 400, 1500) by Shin-Etsu Chemical (Japan) were used. Polyethylene glycol 1000 (mean molecular weight 950–1050), 4000 (mean molecular weight 2600–3800), 6000 (mean molecular weight 7300–9300) (to be abbreviated to PEG 1000, 4000, 6000) and sodium citrate dihydrate (SC) were special grhemical Industries (Japan), and Poloxamer 407 used was Lutrol F127 by BASF (Japan). Timolol maleate waspurchased from Industrie Chemiche Italiane (Italy), ketotifen fumarate from Kyowa Yakuhin Kogyo (Japan), Ofloxacin from Sigma (Japan), and betamethasone sodium phosphate from Sicor (France). The other reagents used were all special class grade on the market.Simulated tear fluid was prepared by adding distilled water to 0.67 g of sodium chloride, 0.20 g of sodium bicarbonate, and 0.008 g of calcium chloride dihydrate until the total volume of solution reached 100 mL according to the preparation described by Rozier et alPreparation of thermo-setting gel vehicleThe thermo-setting gel vehicle was prepared according to the method described in a previous paper with slight modification [6]. A hot slurry was prepared by adding 1.5 g of MC to 50 mL of distilled water heated to 90 _C with stirring and allowing it to disperse sufficiently. The slurry was cooled to 5 _C and mixed with a solution of 3.5 g SC in 30 mL distilled water, then with a solution of varying amounts (2–10 g) of PEG in 15 mL distilled water. The mixture was stirred until it became transparent. After adjusting its pH with 3 N hydrochloric acid, the mixture was made up to 100 mL with distilled water, and used as the thermo-setting gel vehicle. The drug was added after addition of PEG.Preparation of various in situ gelling solutionsA hot slurry was prepared by adding MC (0.7 g of SM15 and 0.7 g of SM 400) to50 mL of distilled water heated to 90 _C with stirring and allowing it to disperse sufficiently. The slurry was cooled to 5 _C, mixed with a solution of 3.5 g SC in 30 mL distilled water, then with a solution of 2.0 g PEG 4000 in 15 mL distilled water. The mixture was stirred until it became transparent. After adjusting its pH to 7.8 with 3 N hydrochloric acid, the mixture was made up to 100 mL with distilled water and used as the thermo-setting gelling solution.Gellan gum solution was prepared by dissolving 0.6 g gellan gum in 90 mL of 0.01 M Tris maleate buffer solution (pH 7.0), then mixing it with 5.5 g mannitol. The resultant solution was made up to 100 mL with 0.01 M Tris maleate buffer solution (pH 7.0) [8].Poloxamer solution was prepared by dissolving 25 g poloxamer in 70 mL of So¨rensen buffer solution (pH 7.0), which was accomplished by allowing the mixture to stand at 5 _C for 24 h, then mixing it with 2.5 g mannitol, and making up the resultant solution to 100 mL with So¨rensen buffer solution (pH 7.0).Measurement of gelling temperature by the test tube inversion method The reversible sol–gel transition temperature for thermo-setting gel solution was measured by the test tube inversion method. A 5 mL portion of sample was placed in a glass test tube (12 mm outer diameter, 10.5 mm inner diameter), then the test tube was allowed to stand for 5 min in a constant temperature bath and was then inverted. The temperature at which the sample did not flow out on inversion was used as the reversible sol–gel transition temperature.Results and discussionEffect of PEG on reversible sol–gel transition temperatureSeveral methods are known for measuring the reversible sol–gel transitiontemperature, such as the test tube inversion method, falling ball method, U-shaped tube method, rheometer method, and differential scanning calorimetry (DSC). The falling ball method and U-shaped tube method are used to measure the melting point of a gel. Since the gel melting point and gelling point greatly differ from each other because of hysteresis,the falling ball method and U-shaped tube method seemed inappropriate in the present study for the thermo-setting gel, where the gelling point was important. DSC is not very sensitive to the temperature change in solutions. From the above considerations, the test tube inversion method and the determination of viscoelasticity with a rheometer were used. In the ternary MC-PEG-SC system, particular attention was paid to PEG,about which the details of the effect of addition were not knownFig. 1 Effects of temperature on the apparent viscosity of the thermo-setting gel solution. Polyethylene glycol concentrations: s 0%, e 2%, h 4%, d 6%, r 8%, j 10%. The apparent viscosity was measured with a rheometer at shear rate 200[1/s]. Methylcellulose (SM 25) and sodium citrate dihydrate concentrations were kept constant at 1.5% and 3.5%, respectively, while the concentration of polyethylene glycol (PEG 4000) was varied from 0 to 10%Fig. 2 Correlation of the phase transition temperature measured by the test tube inversion method and rheometer. In the formula, x and y express phase transition temperature measured with the test tube inversion method and phase transition temperature measured with the rheometer, respectively. Methylcellulose (SM 25) and sodium citrate dihydrate concentrations were kept constant at1.5% and 3.5%, respectively, while the concentration of polyethylene glycol (PEG 4000) was varied from 0 to 10%Figures 1 and 2 show the effect of temperature on the apparent viscosity of the thermo-setting gel solution by rheometer and the relationship between the test tube inversion method and rheometer method, respectively.As shown in Fig. 1, when MC (SM 25) and SC concentrations were kept constant at 1.5% and 3.5%,respectively,and the concentration of PEG 4000 wasvaried from 0 to 10%, the reversible sol–gel transition temperature declined with increase in PEG concentration. When the concentration of PEG was 10%, the viscosity of the solution began to increase at 26_C.However, the viscosity of the solution without PEG increased at 34 _C. On the other hand, from the results of Fig. 2, the gelling temperature changed from 38 _C to 26 _C by the test tube inversion method and from 34 _C to 24 _C by rheometer. There was a positive correlation between the gelling temperatures obtained by the test tube inversion methods and those of the rheometer (least square method, correlation coefficient r=0.89).MC was rendered soluble in water by partial methylation of cellulose that had a high crystallinity and low water solubility. For this reason, MC solution is thermoreversible, gelated when heated and solated when cooled. The mechanism ofits gelation was reported to involve crystallization of a trimethyl-glucose sequence and formation of cross linkage [9]. The reversible sol–gel transition temperature(thermo-setting gelling temperature) is generally reduced by addition of a salt, theeffect of which is strong with anions and varies according to lyotropic series [10]. Citric acid, with its strong salting out effect, reduces the thermo-setting gelling temperature by dehydration of MC.When PEG alone was added to MC solution, the thermo-setting gelling temperature decreased only slightly [6], but the decrease was greatly amplified by the simultaneous addition of citric acid. PEG was reported to cause phase separation of aqueous dextran solution [11]. Furthermore, it was found that excessive addition of PEG induced phase separation (macrophase separation) of the present thermo-setting gel (MC–PEG–SC system). It was inferred from the above findings that PEG accelerated the formation of cross linkage of MC by inducing microphase separation of the solution.The effect of the molecular weight of PEG on the thermo-setting gelling temperature when the PEG concentration was varied from 0 to 10% while the concentrations of MC(SM 25) and SC were kept constant at 1.5% and 3.5%, respectively, is shown in Fig. 3. On the other hand, the effect of the MC (SM 25) concentration on the thermo-setting gelling temperature when the PEG 4000 concentration was varied from 0 to 10%, is shown in Fig. 4. When PEG 1000 or PEG 6000 was used instead of PEG 4000, the thermosetting gelling temperature dependent on PEG concentration was also reduced. PEG 1000, 4000, and 6000 were roughly equivalent in their effect at reducing thermo-setting gelling temperature. When the SM 25 concentration was increased, the PEG-dependent thermo- setting gelling temperature curve shifted toward the lower temperature. There was a tendency for the thermo-setting gelling temperature to decrease with increase in MC solution concentration, which can be explained by a shortening of distances between trimethylglucose sequences [9]. That is, crystallization and formation of cross linkage became easier with a shortening of distances, with a result that gelling occurred at a lower temperature. The same mechanism seemed to be operating in the shift towards the lower temperature in the present thermo-setting gel.Thermo-setting gel solution, gellan gum solution, and poloxamer solution showed different types of fluidity, which were manifested respectively as Newtonian flow, quasi-viscous flow, and quasi-plastic flow. While all these solutions showed improvement in precorneal residence time by sol–gel transition, the thermo-setting gel solution and poloxamer solution never failed to undergo gelation at a temperature near the ocular surface temperature, which suggested that their residence behavior was excellent. In addition, yield value in shear stress waszero or extremely small for the thermo-setting gel solution and gellan gum solution, which indicated that these solutions are only slightly resistant to nictitation and produce a favorable feel to the eye.ConclusionWe investigated the effect of the ternary MC–PEG–SC system vehicle composition on reversible sol–gel transition temperature. A decrease in the reversible sol–gel transition temperature depended on PEG and MC concentrations when the SC concentration was kept constant, but did not depend on PEG molecular weight. The sol–gel transition temperature increased with decrease in pH. Furthermore, decrease in reversible sol–gel transition temperature with increasing PEGconcentration was observed in the presence of various ophthalmic drugs as in their absence. By comparison of the rheological properties of the present thermo-setting gel solution with those of the well-known in situ gelling systems, gellan gum and poloxamer solutions, it became clear that the present solution radically differed from the latter solutions, and its usefulness as a drug delivery system for instillation into the eye was suggested.References1. Bourlais CL, Acar L, Zia H, Sado PA, Needham T, Leverge R (1998) Prog Retin Eye Res 17:332. Sasaki H, Nishida K, Nakamura J, Ichikawa M (1996) Prog Retin Eye Res 15:5833. Chrai SS, Robinson JR (1974) J Pharm Sci 63:12184. Kurimoto K, Eguchi K, Kitajima S, Kishimoto N, Matsumoto N, Otsuki (1991) Atarashii Ganka 8:12595. Kabayama T, Suzuki H, Horiuchi T, Akutagawa Y, Matsuzaki H (1979) J Jpn Ophthalmol Soc 83:3266. Takeuchi M, Kageyama S, Suzuki H, Wada T, Toyoda Y, Oguma T, Ezure Y, Tsuriya Y, Kato T, Ishii F (1999) Mater Technol 17:4457. Patton TF, Robinson JR (1975) J Pharm Sci 64:13128. Rozier A, Mazuel C, Grove J, Plazonnet,B (1989) Int J Pharm 57:1639. Kato T, Yokoyama M, Takahashi A(1978) Colloid Polym Sci 265:1510. Heymann E (1935) Trans Farad Soc 31:84611. Edmond E, Ogston AG (1968) Biochem J 109:56912. Miyoshi E, Nishinari K (1998) Kobunshi Ronbunshu 55:56713. Vadnere M, Amidon G, Lindenbaum S, John L (1984) Int J Pharm 22:20714. Cho CW, Shin SC, Oh IJ (1997) Drug Dev Ind Pharm 23:1227。