Freeze-drying of itraconazole-loaded nanosphere suspensions: a feasibility study

The present study concerns the stabilization of the association of the new hydrophobic triazole derivative itraconazole within poly-ϵ-caprolactone-nanospheres by means of freeze-drying. We have investigated the freeze-drying of nanospheres, and especially the cryopreservation conditions, with the help of differential scanning calorimetry and zeta potential measurements. Five commonly used cryoprotective agents were evaluated (glucose, sucrose, trehalose, dextran, mannitol at 0, 5, 10, 20, and 30% [w/v]) after freeze-thawing and freeze-drying. The addition of carbohydrates led to a partial protection of the colloidal suspension, with leakage of 30% of itraconazole under the best cryopreservation conditions (10% of glucose or sucrose). Zeta potential measurements revealed that the main destabilization mechanism during freeze-drying was surface modifications of the nanospheres, and particularly drug desorption. Therefore, the hydrophilic surfactant adsorbed at the surface of the nanospheres played an important role in the cryopreservation. Replacing the commonly used non ionic surfactant PLURONIC®PE F68 by the anionic surfactant sodium deoxycholate resulted in a complete stabilization of itraconazole-loaded nanospheres after freeze-drying, with no drug desorption, in the presence of 10% sucrose, but not in the presence of glucose. As shown by thermal analysis, PLURONIC®PE F68 may crystallize during freezing, which could lead to surface modifications and drug desorption, whereas sodium deoxycholate may not. Moreover, the Tg′ of glucose-containing suspensions is 10°C lower than Tg′ of sucrose-containing suspensions, which may explain the shrinkage of the cake observed in the case of glucose and the homogeneous appearance of the dried product in the case of sucrose. © 1996 Wiley-Liss, Inc.     

BIOPHARMACEUTICAL EVALUATION OF THE LIPOSOMES PREPARED BY REHYDRATION OF FREEZE-DRIED EMPTY LIPOSOMES (FDELs) WITH AN AQUEOUS SOLUTION OF A DRUG

We have evaluated a method for preparation of a dispersion of liposomes encapsulating a drug, namely rehydration of freeze-dried empty (not containing drug) liposomes with an aqueous drug solution (FDEL method). In the present study, we characterized and compared this method with the conventional method using a lipid composition of DPPC–DPPG–cholesterol in a molar ratio of 27:3:20. Two hydrophilic compounds, [³H]-inulin and [³H]-mannitol, were used as model drugs. Liposomal preparations by the FDEL method had an encapsulation efficiency of 2.9 and 6.7% for [³H]-inulin and [³H]-mannitol, respectively, when rehydrated and incubated at 70 °C. Since non-specific adsorption of these markers to liposomal membrane is negligible, this method produces liposomes which encapsulate a drug in the intravesicular space. One-tenth of the marker encapsulated in the liposomes prepared by the FDEL method (F-liposomes) was released very rapidly on incubation with rat plasma, followed by the slow release of the remaining fraction thereafter. No such rapid-release phase was observed for the liposomes prepared by the conventional method (C-liposomes). This suggests the existence of two types of encapsulation, loose encapsulation and tight encapsulation, in F-liposomes at least. Pharmacokinetic parameters of marker encapsulated tightly in F-liposomes were comparable to those in C-liposomes. It is likely that amphipathic drugs such as doxorubicin are incorporated into liposomes more easily than inulin and mannitol when formulated by the FDEL method. These results therefore suggest that the FDEL method is useful in the preparation of a liposomal formulation of a drug.     

红细胞冻干保存前对海藻糖的负载

目的探寻红细胞负载海藻糖的有效方法,评价负载海藻糖对红细胞各项理化指标的影响。方法设实验组(负载海藻糖红细胞)和对照组(未负载海藻糖红细胞),使用硫酸-蒽酮法测定胞内海藻糖含量,检测负载后红细胞各项理化指标,通过流式细胞术检测负载后红细胞膜的完整性。结果在37℃条件下,红细胞对海藻糖的摄取随胞外海藻糖浓度的增加而增多,当海藻糖浓度为800mmol/L,水浴7h,红细胞负载海藻糖可达到有效浓度;且2组红细胞各项理化指标比较差异无统计学意义(P>0.05);流式结果显示红细胞在高渗环境中负载海藻糖后,细胞膜结合很少量Annexin-V-FITC,并且破损细胞能被有效清除。结论红细胞37℃孵育7h,胞外海藻糖浓度为800mmol/L,能有效摄取海藻糖,且保持红细胞的理化稳定性和膜结构完整性。     

甘油浓度对红细胞冻干保存效果的影响

目的探讨甘油浓度浓度对红细胞冷冻干燥保存的回收率、溶血率及残余水含量的关系。方法以甘油浓度分别为3%、6%、9%、12%、15%、18%、21%(w/v)的冻干保护剂处理红细胞,冻干,用显微镜观察细胞形态、血细胞计数仪检测细胞数、分光光度计测定游离血红蛋白量,分析细胞复水后红细胞计数、溶血情况。用热重法测定冻干红细胞水分含量,分析不同保护剂组红细胞的水分含量变化情况。结果复水后红细胞形态正常,甘油浓度为9%、12%、15%时,红细胞回收率分别为(77.08±9.41)%、(84.37±3.42)%、(80.21±9.20)%,红细胞溶血率分别为(19.82±2.23)%、(17.66±1.17)%、(15.86±2.23)%,相应的冻干红细胞残余水分含量为(19.43±1.36)%、(22.89±1.57)%、(26.17±1.09)%。结论保护剂中甘油浓度影响红细胞冻干保存的效果;甘油浓度为(9-15)%时对冻干保存的红细胞损伤较小;冻干红细胞残余水分含量随保护剂中甘油浓度的增高而增高。     

西罗莫司纳米脂质载体固化制剂的制备

采用冷冻干燥法以微晶纤维素Avicel PH-101与聚乙烯吡咯烷酮(PVP)K30的混合物(4:1,w,%)为吸附性粉末固化西罗莫司纳米脂质载体分散液,并以再分散时间、平均粒径及分布、流动性和泄漏率等为指标,采用单因素试验优化固化处方。结果表明,3批按优化方法制备的西罗莫司纳米脂质载体固化制剂的休止角为(42.65±0.80)。,振实密度为(0.79±0.03)g/m1,且含量均匀度良好,再分散时间为(10.0±0.4)min,再分散液粒径(132.7+2.6)nm,分布系数0.297±0.01,ξ电位(-12.8±1.05)mV,冻干前后的泄漏率为(10.80±0.41)%。     

Crystalline to Amorphous Transition of Disodium Hydrogen Phosphate During Primary Drying

Purpose. To monitor the phase transitions during freeze-drying of disodium hydrogen phosphate. Methods. The variable temperature sample stage of the X-ray diffractometer (XRD) was attached to a vacuum pump, which enabled the entire freeze-drying process to be carried out in the sample chamber. The phase transitions during the freeze-drying cycle were monitored in real time by XRD. Aqueous buffer solution (containing disodium hydrogen phosphate and sodium dihydrogen phosphate) was cooled at 2°C/min from room temperature to –70°C. It was then heated to –25°C and subjected to primary drying for 2 h at a chamber pressure of 100 mTorr, followed by secondary drying at –10°C. Results. In the frozen solution, disodium hydrogen phosphate had crystallized as the dodecahydrate (Na₂HPO₄12H₂O) as was evident from its characteristic lines at 5.37, 4.27, and 2.81 Å. Primary drying for 2 h resulted in ice sublimation, and the complete disappearance of the dodecahydrate peaks. Conclusion. The dehydration of the crystalline dodecahydrate resulted in an amorphous anhydrate. Thus the amorphous nature of the end product is a result of phase transitions during the process and do not reflect the solid-state of the ingredients during the entire process.     

Characterization of Murine Monoclonal Antibody to Tumor Necrosis Factor (TNF-MAb) Formulation for Freeze-Drying Cycle Development

Purpose. This study was designed to characterize the formulation of protein pharmaceuticals for freeze-drying cycle development. Thermal properties of a protein formulation in a freezing temperature range are important in the development of freezing and primary drying phases. Moisture sorption properties and the relationship between moisture and stability are the bases for the design of the secondary drying phase. Methods. We have characterized the formulation of TNF-MAb for the purpose of freeze-drying cycle development. The methods include: DTA with ER probes, freeze-drying microscopy, isothermal water adsorption, and moisture optimization.Results. The DTA/ER work demonstrated the tendency to noneutectic freezing for the TNF-MAb formulation at cooling rates of –1 to –3°C/min. The probability of glycine crystallization during freezing was quite low. A special treatment, either a high subzero temperature holding or annealing could promote the maximum crystallization of glycine, which could dramatically increase the T_g' of the remaining solution. The freeze-drying microscopy further indicated that, after the product was annealed, the cake structure was fully maintained at a T_p below –25°C during primary drying. The moisture optimization study demonstrated that a drier TNF-MAb product had better stability. Conclusions. An annealing treatment should be implemented in the freezing phase in order for TNF-MAb to be dried at a higher product temperature during primary drying. A secondary drying phase at an elevated temperature was necessary in order to achieve optimum moisture content in the final product.     

地龙冻干粉针对家兔血液流变学的作用

急性缺血性心脑血管病是临床死亡率、致残率很高的常见病,疗法以溶栓为主,而从天然药物中研发新型溶栓药始终是研究热点.近年发现中药地龙提取物有良好溶栓性,并开发出口服制剂如蚓激酶胶囊(主要成分是纤维蛋白水解酶)用于临床[1,2].地龙冻干粉针(DFDP)是在此基础上研发的新型制剂,以鲜地龙为原料,含有纤维蛋白溶解酶和纤溶酶原激活物,酶活性比蚓激酶活性多两倍以上.该制剂对血液流变学的作用目前尚未见报道,本文主要研究DFDP对家兔血液流变学的作用.     

Demonstration of oestrogen and progesterone receptors in freeze-dried, paraffin-embedded sections of breast cancer

Immunohistochemical evaluation of oestrogen and progesterone receptors is of importance in evaluating human breast tumours. Staining techniques can be performed on snap-frozen, cryostat-cut tissues or, as recently reported, on formalin-fixed, paraffin-embedded tissues. These methods are, however, limited by several drawbacks, including difficulties in retrospective studies and in storage of the material, and the relatively high frequency of false negative results for chemically fixed specimens. We therefore investigated the application of freeze-drying technology to assess the feasibility and reliability of this technique as an alternative method for diagnostic breast pathology. Morphological and immunohistochemical studies were performed on snap-frozen, freeze-dried and paraffin-embedded tissue obtained from 16 cases of benign and malignant breast neoplasms. Our results showed good preservation of tissue morphology, similar to standard formalin fixation, and excellent preservation of antigenic reactivity of nuclear receptors, comparable to that obtained with cryostat sections. We therefore suggest that freeze drying and paraffin embedding of frozen tissue blocks is equivalent or even preferable to formalin fixation for the demonstration of oestrogen and progesterone receptors, at least in the case of small tumours.