混合膜材及添加剂对包衣膜性质的影响

目的制备肠溶性包衣膜,考察混合膜材以及添加剂对膜材性质的影响。方法采用平面铸膜法制备Eudragit NE30D/L 30D-55及Eudragit FS 30D/L 30D-55游离膜,并以膜的透湿性、机械性能为指标,考察膜材比例及添加剂[增塑剂柠檬酸三乙酯(TEC)、抗黏剂单硬脂酸甘油酯(GMS)、乳化剂吐温80(Tween-80)]对游离膜的影响。结果 Eudragit NE 30D及Eudragit FS 30D的加入能够增加Eudragit L 30D-55膜材的延展性、弹性和耐撞击负载的能力,同时也会减小膜材的强度、增加其透湿性。Eudragit L 30D-55与Eudragit NE 30D的混合膜材透湿性较大,对于湿度敏感性药物,应尽量避免选择透湿性大的包衣膜材。TEC和Tween-80的加入可改善膜材的柔韧性和弹性,降低膜材的强度,同时,TEC的加入可以增加膜材的透湿性,而GMS对膜材各项机械性质和透湿性影响不大。结论通过简单的调节混合膜材的种类、比例、添加剂的用量可以制得符合要求的肠溶游离膜。     

柠檬酸三乙酯在奥美拉唑肠溶微丸中的应用

目的研究柠檬酸三乙酯（triethyl citrate,TEC）在奥美拉唑肠溶微丸中的应用。方法分别比较包衣中含TEC和不含TEC对Eudragit L30D-55膜（尤特奇肠溶包衣材料）性质的影响和对奥美拉唑肠溶微丸释药及其表面衣膜质量的影响。结果含10％TEC的Eudragit L30D-55膜较不含TEC的Eudragit L30D-55膜的玻璃化转变温度（Tg）值降低19．75℃。含10％TEC和含5％TEC的肠溶微丸释放度分别为98．7％和82．6％,远远高于不含TEC的微丸。结论TEC能显著改善树脂类包衣材料的Tg,提高膜的柔韧性和完整性,并且能够有效地控制药物释放,可广泛应用于制剂包衣中。     

对乙酰氨基酚肠溶小丸片的制备工艺研究和质量考察

目的:考察衣膜材料、缓冲小丸的种类以及用量对肠溶型小丸片释药行为的影响。方法:以Eudragit NE30D和FS30D分别与Eudragit L30D-55以不同比例混合后,对含有对乙酰氨基酚的小丸进行包衣。包衣小丸分别与不同的辅料混合后压制成片剂,通过比较压片小丸和未压片小丸释药曲线的相似度(f2)值,来考察包衣膜材的延伸性。同时采用铸膜法制备与包衣处方相同的游离膜,并考察游离膜的机械性能。结果:Eudragit NE30D或Eudragit FS30D与Eudragit L30D-55以2∶1,1∶1和1∶2混合包衣小丸,压成片剂和未压成片的小丸的溶出曲线f2值分别为82,70,65和70,58,41,表明EudragitNE30D和Eudragit FS30D在加入一定量的Eudragit L30D-55后仍可以保护小丸压片时不破裂。采用不同材料制备的缓冲小丸,与包衣小丸混合压片,缓冲材料的种类对片剂的溶出曲线影响不大,主要是通过影响片剂的硬度和崩解时限而影响片剂的质量。结论:Eudragit NE30D和Eudragit FS30D均有着良好的延展性,添加Eudragit L30D-55后延展性变差...     

克拉霉素缓释包衣微丸的制备及体外释放度研究

目的制备克拉霉素缓释包衣微丸,并对其体外释放度进行考察。方法采用挤出滚圆技术制备克拉霉素含药微丸。以优化的丙烯酸树脂类Eudragit NE30D和Eudragit L30D-55混和水分散体为包衣材料,采用流化床包衣技术,制备缓释包衣微丸。考察自制缓释微丸的体外释药速率,并与市售的克拉霉素缓释胶囊进行比较。结果通过释药行为的评价,得到优化的包衣处方为5∶1的Eudragit NE30D和Eudragit L30D-55混和包衣材料,其体外释放行为在不同的pH溶出介质中与市售制剂产品没有明显差异,体外释药过程符合一级释放模型。结论采用挤出滚圆和流化床技术,以及优化的Eudragit NE30D和Eudragit L30D-55混和水分散体包衣材料,成功制备了克拉霉素缓释包衣微丸。     

盐酸青藤碱肠溶缓释微丸的制备

目的：制备盐酸青藤碱肠溶缓释微丸。方法：分别以Eudragit NE30D为缓释膜材，HPMC E5为隔离层膜材，Eudragit L30D-55为肠溶层膜材，采用流化床包衣法制备盐酸青藤碱肠溶缓释微丸，并考察缓释层、隔离层和肠溶层包衣增重对药物释放的影响。结果：制备的肠溶缓释微丸在人工胃液中释放度<10%，人工肠液中缓慢释放8 h。结论：该制备工艺简单易行，重现性好，有望应用于工业化生产。     

泮托拉唑钠肠溶微丸型片剂的制备

研究泮托拉唑钠肠溶微丸型片剂制备方法。采用流化床包衣法制备泮托拉唑钠肠溶微丸, 将肠溶微丸与适合的辅料混合采用直接压片法制备泮托拉唑钠微丸型片剂。用体外释放度法及扫描电镜法观察压片前后药物的体外累计释放量及微丸形态。结果表明, 优化处方: 衣膜增重55%, 增塑剂含量20%, Eudragit L30D-55/ NE30D为8∶2, 肠溶微丸/辅料 (MCC/PPVP/PEG 6000, 2∶1∶1) 为5∶5时, 肠溶片在0.1 mol·L⁻¹盐酸中2 h累积释放百分数<10%, pH 6.8磷酸盐缓冲液中1 h累积释放百分数>85%。制备的泮托拉唑钠肠溶微丸片的释药行为较好, 有望应用于工业生产。     

双氯芬酸钠肠溶微丸型片剂的研制

本文制备了双氯芬酸钠肠溶微丸型片剂。以丙烯酸树脂EudragitNE30D和EudragitL30D-55不同比例的混合物作为衣膜材料，对不同粒径大小的双氯芬酸钠速释丸芯进行不同增重水平的包衣，并与不同压缩特性和用量比例的缓冲微丸混合，压片。所得的双氯芬酸钠肠溶微丸型片剂在人工胃液中2 h内累积释放百分数<10%，在人工肠液中1 h内累积释放百分数为(83±2.42)%。结果表明EudragitNE30D与EudragitL30D-55以一定比例混合制备得到适合压片的肠溶微丸，硬脂酸制备的缓冲微丸可用于微丸型片剂的制备。     

厄贝沙坦缓释微丸的制备及体外释药特性的考察

目的制备厄贝沙坦缓释微丸,并对其体外释放度进行考察。方法采用流化床包衣技术,以丙烯酸树脂类Eudragit NE30D和Eudragit L30D-55混合水分散体为包衣材料,制备缓释微丸。考察不同释放介质、转速对其体外释药行为的影响。结果优化后的包衣处方为Eudragit NE30D/Eudragit L30D-55的比例为4︰1,抗粘剂和致孔剂的用量分别为聚合物干重的75%及20%,增重10%,熟化24h,释放介质的p H值对微丸释药的影响最明显,其体外释药过程符合一级释药模型。结论成功制备了厄贝沙坦缓释微丸,经考察其释放度符合要求。     

增塑剂及肠溶致孔剂对醋酸纤维素游离膜性能的影响

目的 研究增塑剂及肠溶致孔剂对醋酸纤维素游离膜性能的影响,以此为肠溶渗透泵制剂的包衣处方设计奠定基础。方法 采用平面铸膜法制备游离膜,以膜的机械性能、透湿性、吸水率及洗脱率为评价指标,考察增塑剂及肠溶致孔剂对游离膜性能的影响。 结果 增塑剂添加量增大,游离膜的刚性降低,韧性增强,透湿性增大,吸水率及洗脱率增大;肠溶致孔剂添加量增大,游离膜的刚性、韧性均降低,透湿性增大,吸水率及洗脱率显著增大。结论 本文的研究结果可为肠溶渗透泵制剂的包衣处方设计提供依据。     

采用国产聚丙烯酸树脂Ⅱ制备奥美拉唑肠溶微丸的研究

目的考察采用国产的聚丙烯酸树脂Ⅱ作为肠溶包衣材料制备奥美拉唑肠溶丸的可行性。方法分别的采用国产聚丙烯酸树脂Ⅱ与EudragitL30D作为肠溶包衣材料制备奥美拉唑肠溶丸。并对包衣质量加以比较。结果未碱化聚丙烯酸树脂1160％与95％的乙醇溶液均可包出合格的奥美拉唑小丸,质量与用L30D所制小丸相近。结论采用国产聚丙烯酸树脂Ⅱ可以用于制备奥美拉唑肠溶微丸。     

Compression of pellets coated with various aqueous polymer dispersions

Pellets coated with a new aqueous polyvinyl acetate dispersion, Kollicoat SR 30 D, could be compressed into tablets without rupture of the coating providing unchanged release profiles. In contrast, the compression of pellets coated with the ethylcellulose dispersion, Aquacoat ECD 30, resulted in rupture of the coating and an increase in drug release. Plasticizer-free Kollicoat SR coatings were too brittle and ruptured during compression. The addition of only 10% w/w triethyl citrate as plasticizer improved the flexibility of the films significantly and allowed compaction of the pellets. The drug release was almost independent of the compression force and the pellet content of the tablets. The inclusion of various tabletting excipients slightly affected the drug release, primarily because of a different disintegration rate of the tablets. The core size of the starting pellets had no influence on the drug release. Pellets coated with the enteric polymer dispersion Kollicoat 30 D MAE 30 DP [poly(methacrylic acid, ethyl acrylate) 1:1] lost their enteric properties after compression because of the brittle properties of this enteric polymer. Coating of pellets with a mixture of Kollicoat MAE 30 DP and Kollicoat EMM 30 D [poly(ethyl acrylate, methyl methacrylate) 2:1] at a ratio of 70/30 and compaction of the pellets resulted in sufficient enteric properties.     

An investigation into the characteristics of chitosan/Kollicoat SR30D free films for colonic drug delivery

The purpose of the study was to establish the physico-mechanical, digestibility, permeability and swelling properties of chitosan/Kollicoat SR30D films as potential coatings for colonic drug delivery. Free films containing different ratios of chitosan to Kollicoat SR30D were prepared by casting/solvent evaporation method. The resultant mixed films were characterized in terms of puncture strength and elongation (%), glass transition temperature, swellability, polymer miscibility, permeability, and digestibility under different media. The mixed films possessed good mechanical properties, which could be used as film-coating materials for drug delivery. The extent of digestion was directly proportional to the amount of chitosan present within the film. No apparent miscibility was detected between the chitosan and Kollicoat SR30D, regardless of the film composition. The films were found to be susceptible to digestion by bacterial or β-glucosidase enzymes in simulated colonic fluid (SCF). The SCF with rat cecal bacterial enzymes had a more profound hydrolytic activity than that with β-glucosidase enzyme for the digestion of chitosan within the mixed films. Overall, the results indicated that such chitosan/Kollicoat SR30D films had potential as a coating system for drug delivery to the colon.     

Drug release mechanisms from Kollicoat SR:Eudragit NE coated pellets

Thin, free films based on Kollicoat SR:Eudragit NE blends were prepared by casting or spraying aqueous dispersions of these polymers, and were thoroughly characterized with respect to their water uptake behavior, water permeability, dry mass loss kinetics, mechanical properties and drug release patterns. A mechanistic mathematical model based on Fick's law of diffusion was used to quantify the experimentally measured release of metoprolol succinate from various types of systems. With increasing Eudragit NE content the films became more hydrophobic, resulting in decreased water permeability as well as water uptake rates and extents. In addition, the dry mass loss upon exposure to the release medium decreased. Consequently, the films' permeability for the drug decreased. Importantly, metoprolol succinate release from thin films was mainly controlled by pure diffusion, allowing for the determination of the apparent diffusion coefficient of the drug in the different polymeric systems. Knowing these values, drug release from coated pellets could be quantitatively predicted, assuming intact film coatings throughout the observation period. Comparison with independent experimental results showed that crack formation set on very rapidly in the polymeric membranes upon exposure to the release medium in the case of sugar starter cores, irrespective of the polymer:polymer blend ratio and investigated coating level. In contrast, the onset of crack formation was delayed as a function of the blend ratio and coating thickness in the case of microcrystalline cellulose starter cores, attracting less water into the pellets core. The obtained new insight into the underlying drug release mechanisms can be very helpful during device optimization and improve the safety of this type of advanced drug delivery systems.     

Influence of hydroxyethylcellulose on the drug release properties of theophylline pellets coated with Eudragit RS 30 D.

The objective of this study was to investigate the influence of a hydrophilic polymer, hydroxyethylcellulose (HEC), on the release properties of theophylline from pellets coated with Eudragit RS 30 D, and the physicochemical properties of Eudragit RS 30 D cast films. The release rate of theophylline from Eudragit RS 30 D coated pellets decreased during storage at 25 degrees C/60% RH due to the further coalescence of colloidal acrylic particles. In addition, water-vapor permeability and tensile strength of Eudragit RS 30 D cast film decreased after 1-month storage at 25 degrees C/60% RH. The presence of 10% hydroxyethylcellulose in the coating formulation was shown to stabilize the drug release rate from coated pellets, the water-vapor permeability and the tensile strength of free films. Atomic force microscopy and scanning electronic microscopy were used to demonstrate that the HEC was immiscible with Eudragit RS 30 D in the cast films. The stabilization effect of HEC was investigated and determined to be due to the formation of an incompatible phase between the latex particles which impaired further coalescence of the colloidal acrylic particles.     

pH-independent release of a basic drug from pellets coated with the extended release polymer dispersion Kollicoat SR 30 D and the enteric polymer dispersion Kollicoat MAE 30 DP.

The objective of this study was to obtain pH-independent release profiles from coated pellets containing drugs with pH-dependent solubility. pH-independent release of the basic model drug verapamil HCl was achieved by coating with a combination of the neutral polymer dispersions Kollicoat SR 30 D (aqueous dispersion of polyvinyl acetate) and the enteric polymer dispersion Kollicoat MAE 30 DP (aqueous dispersion of methacrylic acid and ethyl acrylate copolymer; methacrylic acid copolymer type C). The two polymers where applied either as separate layers (enteric polymer + extended release polymer or vice versa) or as a polymer blend. A careful balance of the ratios of the polymers allowed the achievement of a pH-independent release. Higher amounts of the enteric polymer in the polymer blend resulted in a reversal of the pH-dependency, e.g. a faster release at pH 6.8 than in 0.1 N HCl.     

Evaluation of the drug release patterns and long term stability of aqueous and organic coated pellets by using blends of enteric and gastrointestinal insoluble polymers

The major aim of this study was to identify an efficient tool to adjust drug release patterns from aqueous and organic ethylcellulose (a gastrointestinal insoluble polymer) coated pellets and to evaluate the long term stability of the film coatings. Drug release was monitored during open and closed storage at 25 °C/60% RH (ambient conditions) and 40 °C/75% RH (stress conditions) for up to 24 months. Release of vatalanib succinate, a poorly soluble drug that demonstrates pH-dependent solubility, from pure ethylcellulose coated pellets was slow irrespectively of the type of coating and release medium. By addition of the enteric polymer methacrylic acid/ethyl acrylate copolymer (applied as aqueous Kollicoat MAE 30 DP dispersion or organic solution of Kollicoat MAE 100 P) to ethylcellulose broad ranges of drug release patterns could be achieved. For aqueous film coatings the addition of Kollicoat MAE 30 DP to ethylcellulose dispersions resulted in unaltered drug release kinetics during closed storage at ambient and stress conditions. The storage stabilizing effect of the added enteric polymer might be explained by the more hydrophilic nature of Kollicoat MAE 30 DP compared to ethylcellulose trapping water during film formation and improving polymer particle coalescence. However, during open storage of aqueous coated ethylcellulose:Kollicoat MAE 30 DP pellets at stress conditions drug release decreased due to further gradual polymer particle coalescence. In contrast, drug release rates from organic coated ethylcellulose:Kollicoat MAE 100 P pellets stored at ambient and stress conditions did not change which could be explained by differences in the film formation process. This clearly indicates that the presented concept of the addition of methacrylic acid/ethyl acrylate copolymer to ethylcellulose film coatings in combination with an organic coating process is able to achieve broad ranges of drug release patterns and to overcome storage instability.     

Suitability of κ-carrageenan pellets for the formulation of multiparticulate tablets with modified release

κ-Carrageenan is a novel pelletisation aid with high formulation robustness and quick disintegration leading to fast drug release unlike the matrix-like release from non-disintegrating microcrystalline cellulose pellets. Compression of pellets into tablets is cost effective. The feasibility of formulating multiparticulate tablets with coated κ-carrageenan pellets was investigated. Pellets containing a highly soluble drug in acid, namely bisacodyl and κ-carrageenan or MCC as pelletisation aid were prepared, enteric coated with a mixture of Kollicoat(?) MAE 30 DP and Eudragit(?) NE 30 D and compressed using silicified microcrystalline cellulose as embedding powder. The effect of coating level, type of pellet core, compression force and punch configurations on drug release were studied. A sufficient coating thickness for κ-carrageenan pellets was necessary to obtain multiparticulate tablets with adequate resistance in the acid stage regardless of the compression pressure used. While κ-carrageenan pellets and their tablets released over 80% of the drug during the neutral stage only about 20-24% was released from MCC pellets and their tablets. The type of punches used (oblong or round) did not significantly influence the drug release from the prepared tablets. Moreover, sufficient prolonged release properties were obtained with κ-carrageenan pellets containing theophylline as a model drug and coated with Kollicoat(?) SR 30 D using Kollicoat(?) IR as pore former. A lower coating level and higher amount of pore former were needed in case of theophylline pellets formulated with MCC as pelletisation aid. The sustained release properties of both coated pellet formulations were maintained after compression at different compression pressures.     

Pectin/Kollicoat SR30D isolated films for colonic delivery [I]: a comparison of normal and colitis‐induced models to assess the efficiency of microbially triggered drug delivery

Objectives The purpose of the study was to evaluate digestion of pectin/Kollicoat SR30D free films for colonic delivery in vitro and in vivo. Methods Free films containing different ratios of pectin to Kollicoat SR30D were prepared by casting/solvent evaporation method. An in‐vitro comparison of swelling, degradation and permeability of the free films was carried out in simulated colon fluids containing caecal contents from normal rats with colitis induced by 2,4,6‐trinitrobenzene sulfonic acid (TNBS) or oxazolone. A comparative in‐vivo evaluation of degradation was also conducted in normal and colitis‐induced model rats. Key findings The pectin within the mixed films was susceptible to rat colonic bacterial enzymes. The extent of digestion correlated with the amount of pectin present within the film. In vitro, the swelling index, drug permeability and extent of film digestion in simulated colon fluids with caecal contents obtained from normal rats were higher than from TNBS‐ or oxazolone‐induced model rats, whereas in‐vivo degradation was similar in the three groups of rats. The pectin/Kollicoat SR30D free films were completely degraded in the colitis‐induced rats. Conclusions Pectic/Kollicoat SR30D films may be useful as coatings to target delivery of drugs to the colon.     

Influence of an enteric polymer on drug release rates of theophylline from pellets coated with Eudragit RS 30D

The purpose of this research study was to investigate the influence of an enteric polymer on the drug release properties of theophylline pellets coated with Eudragit RS 30D. Theophylline pellets were coated with aqueous colloidal dispersions of Eudragit RS 30D containing various amounts of Eudragit L 100-55. The effect of storage conditions on the release of drug from coated pellets was determined as a function of the pH of the dissolution medium. The results from the dissolution study showed significant changes in the dissolution rate of theophylline from pellets coated with Eudragit RS 30D when cured at 40 degrees C for 4 days. No change in the drug release rate was observed when Eudragit L100-55 was present in the Eudragit RS 30D dispersion. Increasing the ratio of Eudragit L100-55 to Eudragit RS 30D resulted in faster drug release rates from the coated pellets. An increase in the pH of the dissolution medium was found to enhance drug release from the pellets coated with Eudragit RS 30D containing Eudragit L 100-55. Theophylline pellets when coated with Eudragit RS 30D containing the enteric polymer Eudragit L100-55 demonstrated no aging effects when stored at elevated temperatures. The overcoating of the pellets with Eudragit RD 100 did not affect the drug release profiles and prevented the particles from agglomerating during curing and storage.     

Sustained-release of buspirone HCl by co spray-drying with aqueous polymeric dispersions

Sustained-release of buspirone HCl (BUH) was attempted by spray drying after dissolving in two commercially available aqueous polymeric dispersions (Eudragit RS 30 D or Kollicoat SR 30 D) at five different drug:polymer ratios (1:1, 1:2, 1:3, 1:6 and 1:9). The produced spray-dried agglomerates were evaluated in terms of their particle size and morphology, production yield, encapsulation efficiency and in-vitro release of BUH. Possible drug-polymer interactions were checked by Differential Scanning Calorimetry (DSC) and FT-IR spectroscopy. Scanning electron microscopy (SEM) was employed for the qualitative characterization of particle size and morphology. Encapsulation efficiency was generally high (around 100%) and independent of the polymeric dispersion type, while production yield was generally low (7.2-31.0%) and significantly lower for the case of Kollicoat SR 30 D (KSR) than for Eudragit RS 30 D (ERS). Scanning electron micrographs showed remarkable changes in size and shape of agglomerates due to the type of aqueous polymeric dispersion and drug:polymer ratio. In-vitro release of BUH from compacted co spray-dried agglomerates was remarkably slower and incomplete for the case of Kollicoat at drug:polymer ratio below 1, presumably due to increased plastic deformation of the developed coating instead of fragmentation in the case of Eudragit coating during compaction.