包衣处方和工艺对对乙酰氨基酚缓释微丸释放度的影响

目的研究包衣处方和工艺对离心法制备的膜控型缓释微丸的体外释药行为的影响。方法以对乙酰氨基酚为模型药,采用BZJ-360型离心造粒包衣机以液相层积法制备含药丸芯,以微丸的体外释放度为考察指标,分别用单因素考察和正交试验的方法来探讨包衣处方、工艺因素对缓释微丸的释药特征的影响,并筛选出最佳水平,通过对药物释放度曲线的药动学模型拟合确定微丸的缓释机制。结果以丙烯酸树脂(Eudragit RS PO∶RL PO=10∶1)为包衣材料,包衣增重为10%,聚合物浓度为6%时包衣微丸在pH 6.2的磷酸盐缓冲液中呈现良好的缓释效果,释药机制主要是以膜控为主的扩散作用,骨架溶蚀也起到了一定的协同作用。结论该技术制备的对乙酰氨基酚缓释微丸包衣均匀,操作简便,质量可靠,可工业化生产。     

丙烯酸聚合物包衣制备控释微丸

以渗透性丙烯酸聚合物（EudragitRS)为包衣材料制备盐酸地尔硫Zhuo控释微丸,体外释放度呈零级释放,释药速率常数为0.0635h^-1。释放度符合美国药典XXⅢ版规定,微丸经3个月加速试验。质量稳定。     

洛索洛芬钠缓释微丸的制备

目的:本文拟制备洛索洛芬钠缓释微丸,以期达到降低毒副作用,维持平稳的血药浓度,提高病人顺应性之目的.方法:采用Eudragit(r)NE 30D水分散体作为包衣材料,用流化床悬浮包衣法对洛索洛芬钠微丸进行缓释包衣.结果:以释放度为指标,通过对包衣工艺及处方影响因素的考察,确定了包衣工艺.     

Pulsatile Drug Release from an Insoluble Capsule Body Controlled by an Erodible Plug

Purpose. The objective of this study was to develop and evaluate a pulsatile drug delivery system based on an impermeable capsule body filled with drug and an erodible plug placed in the opening of the capsule body. Methods. The erodible plugs were either prepared by direct compression followed by placing the tablets in the capsule opening or by congealing a meltable plug material directly within the capsule opening. The disintegration/erosion properties of these plugs were determined and optimized for the final delivery system. In order to assure rapid drug release of the capsule content after erosion of the plug, various excipients (fillers, effervescent agents) and drugs with different solubilities were evaluated. The lag time prior to drug release and the subsequent drug release were investigated as function of capsule content, plug composition, plug preparation technique, plug hardness, weight, and thickness. Results. The erosion time of the compressed plugs increased with increasing molecular weight of the hydrophilic polymer (e.g. hydroxypropyl methylcellulose, polyethylene oxide), decreasing filler (lactose) content and decreased with congealable lipidic plugs with increasing HLB-value and inclusion of surfactants. For complete and rapid release of the drug from the capsule body, effervescent agents had to be included in the capsule content. The drug delivery system showed typical pulsatile release profiles with a lag time followed by a rapid release phase. The lag time prior to the pulsatile drug release correlated well with the erosion properties of the plugs and, besides the composition of the plug, could be controlled by the thickness (weight) of the plug. Conclusions. A single-unit, capsular-shaped pulsatile drug delivery system was developed wherein the pulsatile release was controlled by the erosion properties of a compressed or congealed plug placed within the opening of the capsule opening.     

聚合物水性分散体在茶碱控释小丸包衣上的应用

将Ｓｕｒｃｌｅａｓｅ、Ｓｕｒｅｔｅｒｉｃ、Ｏｐａｒｌｒｙ等聚合物水性分散体应用于茶碱小丸的包衣,得到释放度符合美国药典要求的控释小丸。     

Simultaneous FTIR Spectroscopic Imaging and Visible Photography to Monitor Tablet Dissolution and Drug Release

Purpose Previous studies of hydroxypropyl methylcellulose (HPMC)-based tablet during exposure to water showed a number of ‘fronts’ moving into the tablet but led to contradictory interpretations. These fronts are related to water penetration into and dissolution of the tablet, but the exact nature can not be derived from visible photographic evidence. A method to study tablet dissolution simultaneously by Fourier transform infrared-attenuated total reflection (FTIR-ATR) imaging and macro-photography can assist in providing correct interpretation of the observed fronts. Methods Therefore, the combination of macro-photography and FTIR-ATR spectroscopic imaging was developed and used to interpret the physical changes leading to the observed fronts. Buflomedyl pyridoxal phosphate (BPP), a coloured drug, was used as a model drug. Results The quantitative results obtained by FTIR-ATR imaging enabled the attribution of the three observed fronts (inside to outside) to: (1) true water penetration, possibly combined with (partial) dissolution of buflomedyl pyridoxal phosphate (BPP); (2) total gellification of HPMC; (3) erosion front. Conclusions The method to study dissolution of a tablet simultaneously by FTIR-ATR imaging and macro-photography has been developed and used to obtain reliable interpretation of the fronts observed during tablet dissolution.     

pH-Sensitive Polymer Blends Used as Coating Materials to Control Drug Release from Spherical Beads: Elucidation of the Underlying Mass Transport Mechanisms

Purpose To elucidate the drug release mechanisms from pellets coated with pH-sensitive polymer blends.Methods Verapamil hydrochloride-loaded beads were coated with various blends of a water-insoluble and an enteric polymer, ethylcellulose:Eudragit L and Eudragit NE:Eudragit L, respectively. Both experimental and theoretical techniques were used to characterize the systems before and upon exposure to 0.1 M HCl and phosphate buffer (pH 7.4).Results Using analytical solutions of Fick’s second law of diffusion, optical and scanning electron microscopy, and mechanical and gravimetric analysis, new insight into the underlying drug release mechanisms could be gained. More importantly, the latter can be effectively altered by varying the type of polymer blend and blend ratio. For example, at low pH drug release is primarily controlled by diffusion through the intact film coatings in Eudragit NE:Eudragit L blends, whereas crack formation is of major importance in ethylcellulose:Eudragit L-coated systems. At high pH, the (partial) leaching of the enteric polymer out of the coatings plays an important role. In all cases, the observed drug release profiles could be explained based on the occurring mass transport processes.Conclusions The obtained new knowledge can be used to effectively adjust desired drug release mechanisms and, thus, release patterns.     

特布他林脉冲控释微丸体外释放度影响因素的研究

目的:考察硫酸特布他林脉冲控释微丸释放度的影响因素.方法:采用滚制法制备载药丸芯,使用水溶胀性材料为内包衣溶胀层,乙基纤维素水分散体为外包衣控释层制备脉冲控释微丸,并考察十二烷基硫酸钠(SDS)含量、溶胀层和控释层包衣增重量对药物释放的影响.结果:药物通过控释层衣膜破裂而释放,内包衣层中SDS的加入与否、溶胀层和控释层厚度对脉冲控释微丸的释药时滞和释药速率均具有显著性影响.结论:制备的脉冲控释微丸,在模拟人体内胃肠道pH值变化条件下达到了时滞为4.5 h,时滞后1.5 h累积释药80%以上的脉冲释药效果.     

控释包衣膜中增塑剂含量的HPLC测定

建立了高效液相色谱法测定控释包衣膜中增塑剂含量,采用Hypersil C18柱,甲醇为流动相,检测波长为217和260nm,分别测定柠檬酸三乙酯（TEC）,柠檬酸三丁酯（TBC）,三醋酸甘油酯（TR）,邻苯二甲酸二甲酯（DMP）,邻苯二甲酸二乙酯（DEP）,邻苯二甲酸二丁酯（DBP）的含量,其中DMP,DEP和DBP在5－87ug/ml,TEC,TBC,TR在130－2300ug/ml浓度范围内与峰高呈良好的线性关系（r=0.9999),方法的日内及日间精密度,回收率均符合药物分析要求。     

pH敏感结肠宁靶向微丸的制备及体外释药性能评价

目的研制pH敏感结肠宁靶向口服微丸。方法由结肠宁药粉、微晶纤维素、交联羧甲基纤维钠和羧甲基淀粉钠制备软材,经挤出滚圆机制备素丸,以Eudragit S100、滑石粉和柠檬酸三乙酯为主要成分的包衣材料对干燥的素丸进行包衣,包衣分别增重10％,15％,18％,并评价体外药物释放度。结果包衣增重10％,15％,18％的靶向微丸在pH=1．0的盐酸溶液中的释放度分别为19．64％,9．67％,6．50％,在pH=6．8的磷酸盐缓冲液中的释放度分别为77．80％,89．13％,92．37％。结论以Eudragit。S100、滑石粉和柠檬酸三乙酯为包衣材料,包衣增重15％以上,可制备出较理想的结肠宁靶向微丸。     

Prediction of Drug Release from Hydroxypropyl Methylcellulose (HPMC) Matrices: Effect of Polymer Concentration

Pharmaceutical Research -     

HPMC-Matrices for Controlled Drug Delivery: A New Model Combining Diffusion,Swelling, and Dissolution Mechanisms and Predicting the Release Kinetics

Purpose. The purpose of this study was to investigate the drug release mechanisms from hydroxypropyl methylcellulose (HPMC)-matrices, and to develop a new model for quantitative predictions of controlled drug delivery. Methods. The dissolved mass of pure HPMC-matrices and the drug release rate from propranolol HCl-loaded HPMC-matrices were determined experimentally. Based on Fick's second law of diffusion for cylinders, the transport of water and drug were modeled considering (i) both radial and axial diffusion, (ii) concentration-dependent drug diffusivities, (iii) matrix swelling and (iv) HPMC dissolution. Results. Good agreement between theory and experiment (dissolved mass and drug release studies) was obtained, proving the validity of the presented model. The water and drug diffusivities are strongly dependent on the matrix swelling ratio. Diffusion, swelling and dissolution are the governing mechanisms involved in the overall drug release process. Conclusions. The practical benefit of the presented model is to identify the required shape and dimensions of drug-loaded HPMC-matrices in order to achieve desired release profiles, thus facilitating the development of new controlled drug delivery products. This will be demonstrated in a future study.     

External Cross-linked Mucoadhesive Microbeads for Prolonged Drug Release: Development and In vitro Characterization

Mucoadhesive microbeads of low methoxyl pectin were prepared, either alone or in combinations with hydroxypropyl methyl cellulose, sodium carboxymethyl cellulose, methyl cellulose and carbopol 934P, by ionotropic gelation. The influence of copolymers on mucoadhesivity, microbeads characteristics and in vitro drug release was investigated. Spherical microbeads with 78.69±0.59 to 85.84±0.78% drug entrapment and of a size of 791.90±4.58 to 960.88±4.61 μm were prepared. The concentration of cross linking agent affects the encapsulation efficiency of microbeads. Mucoadhesiveness of microbeads was dependent on the concentration of copolymers. The formulations exhibiteda pH-dependent release and followed diffusion-controlled first-order kinetics.     

复方丹参脉冲控释滴丸的制备及其体外释放度考察

目的 制备复方丹参脉冲控释滴丸,并考察其体外释放度.方法 以复方丹参滴丸为载药丸芯,对包衣材料配比及包衣材料用量进行选择,对控释滴丸体外释药情况进行考察.结果 溶胀层的种类与包衣增重、控释层的包衣增重对药物的释放影响显著,采用交联羧甲基纤维素钠（CMC-Na）作为溶胀层材料,乙基纤维素水分散体作为控释层材料,溶胀层包衣增重12％,控释层包衣增重20％,所制备的微丸时滞时间为4h左右,时滞后3h内累积释药达到80％.结论 制备的复方丹参脉冲控释滴丸体外释放可达到脉冲控释效果.     

Synchronized Release of Sulpiride and Sodium Decanoate from HPMC Matrices: A Rational Approach to Enhance Sulpiride Absorption in the Rat Intestine

Purpose. (a) To improve the absorption of sulpiride (SP) through the intestinal wall by incorporating it together with sodium decanoate (SD) into erodible matrices, designed to synchronize the release of SP and SD over different periods of time; (b) to test, in vivo the hypothesis that this simultaneous release increases SP absorption from the intestinal lumen. Methods. Matrix tablets, possessing different erosion rates, were prepared by changing the ratios between SD and hydroxypropyl methylcellulose (HPMC). The amounts of HPMC varied from 2.5% to 17% w/w. Double layer tablets, containing similar amounts of SP, SD, and HPMC were used as nonsynchronous controls. The erosion kinetics of the tablets was assessed gravimetrically in vitro in USP basket dissolution apparatus and in vivo in the intestine of the anesthetized rat after intra-intestinal administration. SP absorption was studied after intra-intestinal administration of the different kinds of tablets to anesthetized rats, by monitoring SP blood levels. SP and SD levels in the withdrawn samples from the dissolution systems and blood were analyzed by HPLC. Results. The controlled erosion of the tablets resulted in equal release rates of SP and SD during the initial linear phase of the process. This synchronized release lasted over different time periods depending on the relative amount of HPMC in the formulations (from 1 hour to 4 hours for 2.5 and 17 % w/w of HPMC, respectively). The synchronous matrices increased SP bioavailability after intra-intestinal administration. The increase varied from 1.4 to 2.3-fold for the slow and the fast release formulations, respectively (compared with the nonsynchronous, SD containing control formulations), indicating the ability to control both erosion rate and length of intestinal segment in which absorption is taking place. Conclusions. SP bioavailability after intestinal administration can be improved only if SP is released together with SD along the entire intestinal route. This can be accomplished by the design of synchronous matrices capable of concomitant release of SP and SD despite the differences in their water solubility. The ability to manipulate and control the duration of the synchronous phase of the matrices makes it possible for SP to be absorbed at different parts of the intestine.     

An in Vitro/in Vivo Correlation for the Disintegration and Onset of Drug Release from Enteric-Coated Pellets

An empirical mass-transfer model for enteric-coating dissolution that uses in vitro dissolution data to characterize the pH-dependent solubility properties of the polymer film and a mass-transfer coefficient determined from in vivo dissolution or disintegration studies is developed. Once the in vivo mass- transfer coefficient has been evaluated, it can be used in conjunction with in vitro dissolution data from other formulations to predict the in vivo time to disintegration and onset of drug release. Results of in vitro dissolution experiments using the USP basket dissolution apparatus and in vivo disintegration experiments using gamma scintigraphy with four enteric-coated pellet formulations are presented. The good agreement among the in vivo mass-transfer coefficients that were determined supports the validity of the model.     

A method for the preparation of sustained release-coated Metoprolol Succinate pellet-containing tablets

The purpose of this study was to develop a method to prepare Metoprolol Succinate (MS) sustained release pellets and compress them into pellet-containing tablets without losing sustained release property. The drug layered pellets were coated with Eudragit NE 30D to obtain a sustained release (SR) property. The mechanical properties and permeability of the coating film were tailored by adjusting the proportion of talc in the coating dispersion and the weight gain of the coating film. Pellets with different MS release rates were tested and then mixed together by different ratios to optimize drug release rate. The mixed pellets were compressed into tablets with cushioning excipients. The results showed that when the ratio of talc and coating material was 1:4, the coating operation could be conducted successfully without pellet conglutination and the mechanical property of the coating film was enhanced to withstand the compress force during tableting. Blending SR-coated pellets of 20% weight gain with SR-coated pellets of 40% weight gain at the ratio of 1:5 could produce a constant and desired drug release rate. The formulation and the procedure developed in the study were suitable to prepare MS pellet-containing tablets with selected SR properties.     

Oral Solid Controlled Release Dosage Forms: Role of GI-Mechanical Destructive Forces and Colonic Release in Drug Absorption Under Fasted and Fed Conditions in Humans

Purpose. This study was undertaken to examine the effects of mechanical destructive forces on drug release from controlled release (CR) dosage forms in vitro and in vivo and their colonic release, using two CR tablets of acetaminophen A and B, showing slower and faster erosion rates, respectively. Methods. In vitro release rates were determined by several official methods. Tablets were administered to healthy volunteers under fasting and fed conditions. Results. Both tablets showed similar release rates under mild destructive conditions (e.g., paddle method at 10 rpm) but CR-B showed faster release under highly destructive conditions (e.g., rotating basket method at 150 rpm), where the tablet was eroded. The in vivo release from CR-B was faster than from CR-A, possibly because of enhanced erosion. The variable in vivo release from CR-B indicated large inter-subject differences in destructive GI forces. The fastest in vivo release from CR-B among individuals was approximated by the in vitro dissolution determined by destructive methods such as the rotating basket at 150 rpm. The slowest in vivo release from tablets A and B was lower than the dissolution by the paddle method at 10 rpm. The release from both tablets was markedly reduced at 3–4 hrs after dosing irrespective of feeding conditions which can be attributed to release inhibition in the colon. Conclusions. Effects of GI destructive forces on the tablet erosion and the release inhibition in the colon must be considered in the development of CR dosage forms.     

Development of Dividable One-Step Dry-Coated Tablets (Dividable-OSDRC) and Their Evaluation as a New Platform for Controlled Drug Release

PURPOSE: The purpose of this study is to develop novel dividable coated tablets that retain their characteristics even after they are divided. METHODS: We prepared dividable one-step dry-coated tablets (dividable-OSDRC) using our own manufacturing process with double structure punches. The release pattern of the dividable-OSDRC with hydroxypropyl methylcellulose (HPMC) or methacrylic acid copolymer LD (Eudragit) as an outer layer was investigated before and after the division, and dissolution profiles were statistically compared using difference factor f1 and similarity factor f2. RESULTS: The dividable-OSDRC with HPMC for sustained-release (compression pressure, 150 MPa; crashing strength, 6.1 N; friability, 0.05%; CV of divided tablet weight, 7.8%) showed statistically equivalent release patterns between the one-half and the whole (f1, 13.9; f2, 55.5) and between the one-half and the two-halves (5.5, 72.5). The surface area of the tablets affected the sustained-release profiles. Furthermore, the tablets made with Eudragit LD for timed-release (150 MPa. 12.8 N, 0.18%, 9.6%) also showed approximated release patterns before and after the division. CONCLUSIONS: We proved that dividable-OSDRC maintain their release characteristics after they are divided. We conclude that the dividable-OSDRC could be used as a new platform for the controlled release of drugs.     

Evaluation of Pyrrolobenzodiazepine-Loaded Nanoparticles: A Targeted Drug Delivery Approach

We describe the development and evaluation of pyrrolobenzodiazepines (PBDs) in poly(dl-lactide-co-glycolide) and lipid nanoparticle drug delivery systems. We have established that the partition coefficient (LogP) of PBD is a key influencer of the encapsulation efficiency in nanoparticle systems, with higher LogP values associated with higher encapsulation efficiencies toward increased drug payload delivery and better antitumor efficacy. Cytotoxicity assays demonstrated that compounds with higher LogP values demonstrated higher 50% inhibitory concentration values than the free drug. In vivo efficacy studies in mice demonstrated that a single injection of nanoparticle PBD formulations could inhibit tumor growth for nearly 3 weeks, whereas the free drug failed to inhibit growth. Importantly, mice treated with PBD-loaded nanoparticles did not experience significant loss of body weight. These data demonstrate that nanoparticles containing PBD molecules can be used as an alternative to the widely used antibody drug conjugate approach in delivering cytotoxic PBDs.