Liposomal diltiazem HCl as ocular drug delivery system for glaucoma

In this study, unilamellar liposomal vesicles of diltiazem HCl (DH) were prepared using either reversed phase evaporation (REV) or proliposome methods. Soya phosphatidylcholine (SPC) was used for preparing the liposomes, and the vesicles were rigidified using cholesterol (Chol) or cetyl alcohol (CA) in different molarities. The major differences in both the entrapment efficiency percent (EE%) and drug release were evaluated as a function of the method of preparation, Chol or CA contents, and charging lipids. Moreover, the morphology of the vesicles was confirmed by transmission electron microscopy. The effects of Chol or CA incorporation into the liposomes were discussed based on thermal analysis. The in vivo evaluation of liposomal DH was assessed using intra-ocular pressure (IOP), reducing effects in rabbit eyes. Liposomes prepared via REV exhibited higher EE% and lower release rates when compared with those prepared from proliposomes. The incorporation of either Chol or CA in the liposomes enhanced the EE% and decreased the release rates; however, Chol yielded higher results than CA. In addition, both dicetyl phosphate (DCP; negative charge inducer) and stearyl amine (SA, positive charge inducer) decreased the EE% and increased the DH release rate. The in vivo antiglaucoma effects of the liposomes were calculated according to the area above the IOP/Time curve, the maximum response and the time for the maximum response and were compared with effects of the DH solution. The results were in the following order: DH solution?proliposomes)?相似文献   

羧甲基壳聚糖包覆薏苡仁油前体脂质体的稳定性研究

为评价羧甲基壳聚糖包覆薏苡仁油前体脂质体（CM-PL）的贮藏稳定性及复水稳定性,本研究以贮藏过程中薏苡仁油（CSO）渗漏率、丙二醛（MDA）生成量为主要指标系统考察了CM-PL在不同贮藏条件下的贮藏稳定性;以CSO渗漏率为指标考察了氯化钠溶液、葡萄糖溶液对CM-PL复水稳定性的影响。结果表明:光照、高温以及空气接触均影响CM-PL的稳定性,其影响顺序为温度>空气>光照;其中温度升高可提高芯材渗漏量,加速脂质氧化;贮藏初期,光照组及空气接触组与对照组相差不大,可能与羧甲基壳聚糖能在一定程度上延缓体系的光致氧化及自氧化进程有关,但其保护作用有限,因此CM-PL应真空、避光、低温贮藏;复水稳定性结果显示CM-PL对氯化钠的耐受性高于葡萄糖,与二者共存贮藏14 d后CSO渗漏率分别为14.3%,21.1%。      

薏苡仁油脂质体特性及体外释放度的研究

采用冷冻干燥法制备薏苡仁油前体脂质体,通过扫描电镜(SEM)、差示扫描量热仪(DSC)、红外光谱仪(RTIR)研究脂质体的特性,并考察其体外释放度.结果表明,薏苡仁油前体脂质体外观饱满,成圆球形;添加聚乙二醇后薏苡仁油前体脂质体的相转变温度有所降低;红外光谱仪显示,C＝O、PO2-和(CH3)3N+的变化等现象表明磷脂极性头基和聚乙二醇之间发生了作用,通过其羟基形成了氢键,对脂膜有保护作用;体外释放研究结果表明聚乙二醇包覆薏苡仁油脂质体具有长效缓释效果,体外释放规律符合Higuchi方程.     

Improved oral bioavailability of valsartan using proliposomes: design,characterization and in vivo pharmacokinetics

Abstract

The objective of our investigational work was to develop a proliposomal formulation to improve the oral bioavailability of valsartan. Proliposomes were formulated by thin film hydration technique using different ratios of phospholipids:drug:cholesterol. The prepared proliposomes were evaluated for vesicle size, encapsulation efficiency, morphological properties, in vitro drug release, in vitro permeability and in vivo pharmacokinetics. In vitro drug-release studies were performed in simulated gastric fluid (pH 1.2) and purified water using dialysis bag method. In vitro drug permeation was studied using parallel artificial membrane permeation assay (PAMPA), Caco-2 monolayer and everted rat intestinal perfusion techniques. In vivo pharmacokinetic studies were conducted in male Sprague Dawley (SD) rats. Among the proliposomal formulations, F-V was found to have the highest encapsulation efficiency of 95.6?±?2.9% with a vesicle size of 364.1?±?14.9?nm. The in vitro dissolution studies indicated an improved drug release from proliposomal formulation, F-V in comparison to pure drug suspension in both, purified water and pH 1.2 dissolution media after 12?h. Permeability across PAMPA, Caco-2 cell and everted rat intestinal perfusion studies were higher with F-V formulation as compared to pure drug. Following single oral administration of F-V formulation, a relative bioavailability of 202.36% was achieved as compared to pure valsartan.     

7-Ethyl-10-hydroxycamptothecin proliposomes with a novel preparation method: optimized formulation,characterization and in-vivo evaluation

Context:?The proliposomes were used to solve the stability of the ordinary liposomes. Objective: 7-ethyl-10-hydroxycamptothecin (SN-38) proliposomes for intravenous (i.v.) administration were prepared successfully by a new method.

Materials and methods:?SN-38 liposomes solution was reconstituting automatically from proliposomes on contact with the acetic acid buffer solution (0.2 M, pH 2.6). The formulation was optimized by the Box–Behnken design. The physicochemical characteristics of the SN-38 proliposomes were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The stability studies were also carried on. The FLU–HPLC system was served to study the concentration of SN-38 in the plasma of Sprague Dawley (SD) rats.

Results:?The optimized formulation was SN-38: 0.03 g; Soybean phospholipid (SP): 0.6 g; dextrose: 3.00 g. The entrapment efficiency of the optimized formulation was >85% and the mean particle size was about 231 nm. The stability studies showed that SN-38 proliposomes were stable in dark at 20–25°C for 6 months at least. The pharmacokinetic parameters of i.v. administration demonstrated that the half-life of SN-38 loaded in the liposomes was prolonged in vivo.

Discussion and conclusion:?The SN-38 proliposomes was prepared successful by the analysis of TEM, SEM, DSC and XRD, and SN-38 liposomes could be reconstituted on contact with the hydration medium. SN-38 liposomes circulated for a longer time in the blood circulating system than SN-38 solution, which contributed to maintaining the drug action.     

Liposomes encapsulating beta‐carotene produced by the proliposomes method: characterisation and shelf life of powders and phospholipid vesicles

The objective of this study was to investigate the feasibility of producing proliposomes incorporating beta‐carotene by spray drying and to assess the capacity of the liposomes produced by the hydration of the dry phospholipid particles to preserve the encapsulated carotenoid. Powders containing beta‐carotene, hydrogenated phosphatidylcholine and sucrose were obtained and characterised in terms of crystallinity, morphology, thermal behaviour, density, solubility and hygroscopicity. The preservation of beta‐carotene in the powder was evaluated for two storage conditions under normal atmosphere and vacuum. The proliposome was highly soluble, with all components embedded in the matrix and capable of preserving more than 90% of the incorporated beta‐carotene for 60 days of refrigerated storage under vacuum. The liposome dispersions maintained their average size, polydispersity index and zeta potential for 100 days of storage. After 60 days, the degradation of encapsulated beta‐carotene was minimal, and the colour of the dispersions was preserved.     

V_C纳米脂质体悬浮液及其前体脂质体的制备与稳定性研究

通过单因素与正交实验优化了乙醇注入-高压均质法制备VC纳米脂质体悬浮液的工艺,并制备了VC前体脂质体。得到VC纳米脂质体悬浮液的最佳制备工艺为:VC添加量160mg,胆固醇与卵磷脂的质量比1∶5,Tween80与卵磷脂的质量比4∶5,水合温度55℃;按此最佳工艺制备的VC纳米脂质体悬浮液平均包封率、平均粒径、多分散指数分别为78.11%、89.62nm、0.160;经冷冻干燥后得到的VC前体脂质体的平均粒径、多分散指数分别为121.14nm、0.195。贮存稳定性实验结果表明,VC纳米脂质体悬浮液与VC前体脂质体的稳定性都受贮存温度与贮存时间的影响;但后者贮存稳定性高于前者。