葛根素固体分散体的制备及体内药动学

目的研究葛根素固体分散体的制备及其在家兔体内药动学,以提高葛根素口服给药的生物利用度。方法采用溶出度法,确定葛根素固体分散体的最佳制备处方;采用HPLC法,测定家兔血浆中葛根素的含量,药动学参数经3P97药动学软件处理。结果葛根素固体分散体的最佳制备处方为葛根素:PEG6000:pluronicF-68=1:4:1(m/m/m);葛根素及葛根素固体分散体的血药浓度-时间过程均符合二室模型,主要药动学参数:α分别为(2.040±0.327)、(0.870±0.191)·h~(-1),β分别为(0.21 2±0.021)、(0.351±0.022)·h~(-1),AUC_(0-∞)分别为(11.966±1.370)、(91.419±3.531)mg·L~(-1)·h,t_(max)分别为(0.491±0.026)、(1.423±0.035)h,ρ_(max)分别为(3.917±0.066)、(20.416±1.870)mg·L~(-1)。葛根素固体分散体对葛根素的相对生物利用度为763.99%。结论葛根素固体分散体可提高葛根素口服给药在家兔体内的生物利用度。     

Characteristics of rofecoxib-polyethylene glycol 4000 solid dispersions and tablets based on solid dispersions

The aim of this work was to report the properties of rofecoxib-PEG 4000 solid dispersions and tablets prepared using rofecoxib solid dispersions. Rofecoxib is a poorly water soluble nonsteroidal anti-inflammatory drug with a poor dissolution profile. This work investigated the possibility of developing rofecoxib tablets, allowing fast, reproducible, and complete rofecoxib dissolution, by using rofecoxib solid dispersion in polyethylene glycol (PEG) 4000. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the solid state of solid dispersions. The effect of PEG 4000 concentration on the dissolution rate of rofecoxib from its solid dispersions was investigated. The dissolution rate of rofecoxib from its solid dispersions increased with an increasing amount of PEG 4000. The extent of dissolution rate enhancement was estimated by calculating the mean dissolution time (MDT) values. The MDT of rofecoxib decreased significantly after preparing its solid dispersions with PEG 4000. The FTIR spectroscopic studies showed the stability of rofecoxib and absence of well-defined rofecoxib-PEG 4000 interaction. The DSC and XRD studies indicated the amorphous state of rofecoxib in solid dispersions of rofecoxib with PEG 4000. SEM pictures showed the formation of effective solid dispersions of rofecoxib with PEG 4000 since well-defined change in the surface nature of rofecoxib and solid dispersions were observed. Solid dispersions formulation with highest drug dissolution rate (rofecoxib: PEG 4000 1:10 ratio) was used for the preparation of solid dispersion-based rofecoxib tablets by the direct compression method. Solid dispersion-based rofecoxib tablets obtained by direct compression, with a hardness of 8.1 Kp exhibited rapid drug dissolution and produced quick anti-inflammatory activity when compared to conventional tablets containing pure rofecoxib at the same drug dosage. This indicated that the improved dissolution rate and quick anti-inflammatory activity of rofecoxib can be obtained from its solid dispersion-based oral tablets.     

双氯芬酸钠—乙基纤维素固体分散物释放动力学研究

目的：研究双氯芬酸钠-乙基纤维素固体分散物颗粒及其缓释胶囊的药物释放动力学特征。方法：测定不同粒径、不同浓度的双氯芬酸钠-乙基纤维素固体分散物颗粒及其缓释胶囊在pH6.8磷酸盐缓冲液中的释放曲线,以零级动力学方程、一级动力学方程及Higuchi方程分别对释放曲线进行拟合,根据所得方程的相关系数,探讨不同粒径、不同浓度的固体分散物颗粒及其缓释胶囊的释放特征。结果：固体分散物颗粒释放动力学拟合优劣顺序为：Higuchi模型方程、一级动力学方程、零级动力学方程;缓释胶囊释放动力学拟合结果的优劣顺序为：Higuchi模型方程、零级动力学方程、一级动力学方程、零级动力学方程;缓释胶囊释放动力学拟合结果的优劣顺序为：Higuchi模型方程、零级动力学方程、零级动力学方程、一级动力学方程。结论：不同浓度、不同粒度的双氯芬酸钠-乙基纤维素固体分散物颗粒及缓释胶囊释放均遵从Higuchi方程,为骨架扩散机制。     

尼群地平固体分散体的休外溶出特性

目的：制备尼群地平固体分散体,增加其溶解度和溶出速度。方法：以聚乙二醇6000（PEG6000）、聚乙二醇4000（PEG4000）、聚乙烯吡咯烷酮（PVPk30)为载体,以溶剂－熔融法和共沉淀法制备尼群地平固体分散体。应用差热分析鉴别药物在载体中的存在状态,同时进行溶解测定和溶出度研究。结果：尼群地平与载体形成了共熔物,药物以微细结晶存在于载体中,载体比例越大,药物溶出越快,溶解度越大,结论：尼群地平与3种载体形成的固体散全在水中的溶解度均有显著增加（P＜0．05）。当尼群地平－载体比例达1：4时,尼群地平从固体分散体中的溶出速度明显大于尼群地平纯药和尼发群地平－载体（1：8）物理混合物（P＜0．05）。3种载体中以PVPK30对尼群地平的溶解度及溶出速度增加最为显著。     

(噁)丙嗪固体分散体的制备

目的:制备噁丙嗪固体分散体.方法:以聚乙二醇(PEG 6000)为载体,采用熔融法制备噁丙嗪固体分散体,桨法测定体外溶出度,X-射线衍射法分析结构状态.结果:噁丙嗪-PEG 6000固体分散体是一种简单低共熔混合物,噁丙嗪以超细结晶状态分散在PEG载体中.1:5,1:7,1:9,1:11比例固体分散体的标示含量均在98%～106%范围.与原料药及物理混合物相比,固体分散体的溶出速度和程度均显著增加(P＜0.01);且随着载体比例的逐渐增大,固体分散体的药物溶出加快.结论:以PEG 6000为载体制备的噁丙嗪固体分散体体外溶出迅速,可用于制备速效、高效的噁丙嗪口服制剂.     

Characterization of nifedipine solid dispersions

The sublingual administration of nifedipine (NIF) is currently used in clinical practice. The sublingual administration of NIF solid dispersions (SD), by using a suitable dispenser, appears an interesting approach in the treatment of moderate and severe hypertensive emergencies. With this aim nine SD made of NIF and a low viscosity hydroxypropylmethylcellulose (HPMC) in different ratio were prepared by means of spray-drying technique and their structure was studied. Moreover, the drug dissolution properties from SD were verified. The characteristic peaks of crystalline NIF were not detectable by using the X-ray analysis when the NIF/HPMC ratios were lower than 50/50 w/w. In thermograms obtained from SD, the NIF melting endothermic peak disappeared when NIF/HPMC ratios were lower than 30/70 w/w; the experimental Tg values of SD were lower than the Tg values predicted by Gordon Taylor equation suggesting some type of non-ideality of mixing. In the SD FTIR spectra the NH stretching vibrations and the C=O stretch in esteric groups of NIF shift to free NH and C=O regions indicating the rupture of intermolecular hydrogen bond in the crystalline structure of NIF. The prepared SD improved the NIF dissolution rate in comparison with that of commercial NIF or NIF/HPMC physical mixtures. Moreover, the concentration of NIF in the dissolution medium increased decreasing the NIF content.     

Solid-state characterization of nifedipine solid dispersions

The purpose of this study is to characterize the nature and solid-state properties of a solid dispersion system of nifedipine (33.3% w/w) in a polymer matrix consisting of Pluronic F68 (33.3% w/w) and Gelucire 50/13 (33.3% w/w). The nature of nifedipine dispersed in the matrix was studied by powder X-ray diffractometry (PXRD), differential scanning calorimetry (DSC) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The rate and extent of water uptake of the solid dispersion were determined by weight gain. The dissolution rate of nifedipine solid dispersion was determined using Apparatus 2 of USP XXIII (1995). Quantitative PXRD showed that the saturation solubility of nifedipine in the polymer matrix is 2.1-3.0% w/w and indicated an excess of crystalline nifedipine in the solid dispersion. The maximum water uptake by the solid dispersion exposed to 75% RH at 45 degrees C was 3.3 times higher than for the dispersion exposed to 65% RH at 25 degrees C. Over 8 weeks, PXRD and DRIFTS of the nifedipine matrix stored at 25 or 4 degrees C were unchanged, showing constancy of crystallinity and intermolecular interactions. For a given mass of nifedipine (20 mg) and for a given particle size of nifedipine (<850 microm), the initial release rate of nifedipine from the solid dispersion was faster (46.2% of the nifedipine dissolved in 20 min) than that of the pure drug (1.2% of the nifedipine dissolved in 20 min). The results indicate that the nifedipine solid dispersion is physically stable over 8 weeks. Nifedipine is released faster from the solid dispersion than from the pure crystalline drug of the same particle size.     

Solubility of erythromycin from solid dispersions

The effect of solid dispersion (SD) formation on the solubility of the antibiotic erythromycin has been studied using the parent substance of erythromycin and its SDs with polyethyleneglycol (PEG-1500), polyvinylpyrrolidone (PVP-10000), and β-cyclodextrin. It is established that SD formation increases the solubility of the antibiotic by a factor of 1.3 – 1.8; the dissolution rate, 1.5 – 2.0. Results using a complex of physical and chemical methods suggest that the increase in erythromycin release from SDs takes place due to a decrease in the degree of crystallinity and the formation of intermolecular complexes.     

Microwave generated solid dispersions containing Ibuprofen

The purpose of this study was to apply the attractive technique of the microwaves irradiation (MW) for the preparation of solvent-free solid dispersions (SD). In particular, the microwave technology has been considered in order to prepare an enhanced release dosage form for the poorly soluble drug Ibuprofen (IBU), employing PVP/VA 60/40 (PVP/VA 64) and hydroxypropyl-beta-cyclodextrin (HP-beta-CD) as hydrophilic carriers. Their physico-chemical characteristics and dissolution properties were compared to the corresponding physical mixtures and the drug alone. The results of physico-chemical characterization attested a correspondence of the solid state of the drug before and after irradiation treatment and that an amorphous form of the drug was obtained. This result, together with the presence of the hydrophilic polymers determined a remarkable enhancement of the in vitro dissolution rate of the drug suggesting that the microwave technique could be considered as a new and interesting method to prepare drug-polymer systems.     

杨梅素固体分散体的制备以及体外溶出试验

目的运用固体分散技术制备杨梅素固体分散体并提高其体外溶出速率。方法选用PEG6000和PVPK30为载体,采用溶剂法和溶剂-熔融法制备杨梅素固体分散体,采用紫外分光光度法进行含量测定,并进行溶解度、体外溶出试验。结果两种载体的固体分散体均能增加药物的溶解度和溶出速率,杨梅素在载体中以高度分散状态存在。结论以PVPK30为载体的杨梅素固体分散体体外溶解度和溶出速率明显提高。杨梅素固体分散体能显著提高杨梅素的溶出速率。     

The compression of granulates containing solid dispersions

In the present work granulates containing solid dispersions of diazepam were compressed into tablets. The results show that polyethyleneglycol (PEG 6000) give the best tablets which disintegrate when a strong disintegrant is added extragranularly. The tablets keep their good physical properties when stored in normal or low humidity conditions.     

他达那非固体分散体的制备和性质研究

目的制备他达那非(tadalafil,TD)固体分散体并进行性质研究。方法利用喷雾干燥法制备固体分散体,以表观溶解度和溶出度为指标筛选处方,采用差示扫描量热(DSC)、粉末X-射线衍射(PXRD)和接触角测定等技术研究药物的存在状态和润湿性等理化性质。结果固体分散体将他达那非的表观溶解度提高22.6倍;20min内药物的累积溶出超过90%;固体分散体药物以分子或无定形状态存在;接触角减小,润湿性增大。结论采用十二烷基硫酸钠(SDS)和介孔硅为载体制备的他达那非固体分散体,能明显提高药物的表观溶解度和溶出度。     

Anomalous properties of spray dried solid dispersions

The use of solid dispersions for oral dosage forms can increase the dissolution rate of poorly soluble drugs. Spray drying is one process that can be used to prepare solid dispersions. Spray dried solid dispersions of griseofulvin, poly[N-(2-hydroxypropyl)methacrylate] (PHPMA) and polyvinylpyrrolidone (PVP) were prepared from acetone and water. When methanol was substituted for water, the morphology, stability and dissolution properties of the solid dispersion changed dramatically. The glass transition temperature for the ternary solid dispersion (GF, PHPMA, and PVP) shifted from 83°C (acetone/water) to 103°C for the acetone/methanol system. These differences in the dispersions are thought to derive from conformational variations of the polymers in solution prior to spray drying. Both PHPMA and PVP formed globules in solution of a size range between 16 and 33 nm. The effect of drug and polymer concentration in solution (before spray drying) on the properties of the solid dispersion was studied. It was found that solid dispersions that were prepared using lower concentrations of drug and polymers in solutions resulted in the formation of particles that display a lower relaxation rate. This result supports the hypothesis that the polymer conformation may significantly change the properties of the solid dispersion. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:4724–4737, 2009     

Review: physical chemistry of solid dispersions

Objectives With poorly soluble drug candidates emerging in the drug discovery pipeline, the importance of the solid dispersion formulation approach is increasing. This strategy includes complete removal of drug crystallinity, and molecular dispersion of the poorly soluble compound in a hydrophilic polymeric carrier. The potential of this technique to increase oral absorption and hence bioavailability is enormous. Nevertheless, some issues have to be considered regarding thermodynamic instability, as well in supersaturated solutions that are formed upon dissolution as in the solid state. Key findings After a brief discussion on the historical background of solid dispersions and their current role in formulation, an overview will be given on the physical chemistry and stability of glass solutions as they form supersaturated solutions, and during their shelf life. Conclusions Thorough understanding of these aspects will elicit conscious evaluation of carrier properties and eventually facilitate rational excipient selection. Thus, full exploitation of the solid dispersion strategy may provide an appropriate answer to drug attrition due to low aqueous solubility in later stages of development.     

Methods of studying aging and stabilization of spray-congealed solid dispersions with carnauba wax. 1. Microcalorimetric investigation

Rapidly cooled materials are often unstable as a result of changes in their physical properties due to imperfect crystallization. In the process of spray-congealing, melted material is atomized into droplets which very quickly solidify. This increases the possibility of the material crystallizing in different metastable forms. In this study it is shown that isothermal microcalorimetry can be used to observe the change in the thermodynamic state of spray-congealed carnauba wax during storage. In order to accelerate the thermodynamic change in the spray-congealed wax, three annealing procedures have been developed and compared using isothermal microcalorimetry. By means of annealing, a spray-congealed product closer to a thermodynamically stable state has been achieved.     

Assessing the performance of amorphous solid dispersions

The characterization and performance of stable amorphous solid dispersion systems were evaluated in 40 research papers reporting active pharmaceutical ingredient (API) dissolution and bioavailability from various systems containing polymers. The results from these studies were broadly placed into three categories: amorphous dispersions that improved bioavailability (～82% of the cases), amorphous dispersions possessing lower bioavailability than the reference material (～8% of the cases), and amorphous dispersions demonstrating similar bioavailabilities as the reference material (～10% of the cases). A comparative analysis of these studies revealed several in vitro and in vivo variables that could have influenced the results. The in vitro factors compared primarily centered on dissolution testing and equipment, content and amount of dissolution media, sink or nonsink conditions, agitation rates, media pH, dissolution characteristics of the polymer, and dispersion particle size. The in vivo factors included reference materials used for bioavailability comparisons, animal species utilized, fasting versus fed conditions, and regional differences in gastrointestinal (GI) content and volume. On the basis of these considerations, a number of recommendations were made on issues ranging from the assessment of physical stability of API-polymer dispersions to in vivo GI physiological factors that require consideration in the performance evaluation of these systems.     

Nanoscale thermal analysis of pharmaceutical solid dispersions

Formation of a solid solution of a drug in a water-soluble polymer is one of the primary techniques used to improve the dissolution rate and thus bioavailability of a poorly water-soluble drug. Understanding and detecting the state of the drug inside such a polymer matrix is critically important since issues such as drug stability, safety and efficacy can be greatly affected. In this study, two model formulations were prepared containing low and high levels of drug content. The heterogeneity of the formulations has been investigated using a novel nanothermal analysis technique. This technique has demonstrated a promising capability for imaging and quantitatively characterising the nanoscale properties of solid dispersion formulations.