A comparative in vitro assessment of the drug release performance of pH-responsive polymers for ileo-colonic delivery

The aim of this study was to investigate the in vitro dissolution characteristics of pH-responsive polymers in a variety of simulated fluids. Prednisolone tablets were fabricated and coated with the following polymer systems: Eudragit S (organic solution), Eudragit S (aqueous dispersion), Eudragit FS (aqueous dispersion) and Eudragit P4135 (organic solution). Dissolution tests were conducted using a pH change method whereby tablets were transferred from acid to buffer. Three different buffer media were investigated: two compendial phosphate buffers (pH range 6.8-7.4) and a physiological buffer solution (Hanks buffer) with very similar ionic composition to intestinal fluid (pH 7.4). There was considerable drug release from tablets coated with Eudragit P4135 in acid, prompting discontinuation of further investigations of this polymer. Eudragit S (organic solution), Eudragit S (aqueous dispersion) and Eudragit FS on the other hand prevented drug release in acid, though subsequent drug release in the buffer media was found to be influenced by the duration of tablet exposure to acid. At pH 7.4 drug release rate from the polymer coated tablets was similar in the two compendial media, however in the physiological buffer, they were found to differ in the following order: Eudragit S (aqueous dispersion)>Eudragit FS>Eudragit S (organic solution). The results indicate that the tablets coated with the newer Eudragit FS polymer would be more appropriate for drug delivery to the ileo-colonic region in comparison to the more established Eudragit S. More importantly, however, dissolution in the physiological buffer was found to be markedly slower for all the coated tablets than in the two compendial buffers, a result akin to reported slower dissolution of enteric coated tablets in vivo. There is therefore the need to adequately simulate the ionic composition of the intestinal fluid in the dissolution media.     

无时滞非达霉素肠溶片的制备及溶出评价

目的: 制备无时滞非达霉素肠溶片,考察其溶出特性。方法: 采用湿法制粒工艺,通过正交实验进行片芯优化,以甲基丙烯酸与丙烯酸乙酯共聚物为肠溶包衣材料,制备非达霉素肠溶片,以体外释放度为指标,考察其溶出行为。结果: 片芯中羟丙甲纤维素和交联羧甲基纤维素钠的用量分别为1.2%和4.5%,微晶纤维素和淀粉的比例为3:1,肠溶层共聚物的比例为50%时,制备的非达霉素肠溶片在pH1.0盐酸中2h释放度小于10%,在pH4.5醋酸盐缓冲液中可以崩解释放,在pH6.8磷酸盐缓冲液中快速释放,10min释放度大于60%。结论: 制备的非达霉素肠溶片与普通肠溶片相比无时滞效应,有望进行工业化生产。     

Phosphate buffer interferes dissolution of prazosin hydrochloride in compendial dissolution testing

The purpose of this study was to elucidate the lack of supersaturation behavior in the dissolution profile of prazosin hydrochloride (PRZ-HCl) in the compendial dissolution test. The equilibrium solubility was measured by a shake-flask method. Dissolution tests were performed by a compendial paddle method with a phosphate buffer solution (pH 6.8, 50 mM phosphate). The solid form of the residual particles was identified by Raman spectroscopy. In the pH range below 6.5, the equilibrium solubility in phosphate buffer was lower than that in the unbuffered solutions (pH adjusted by HCl and NaOH). Raman spectra showed that the residual solid was a phosphate salt of PRZ. In the pH range above 6.5, the pH-solubility profiles in the phosphate buffer solutions and the unbuffered solutions were the same. The residual solid was a PRZ freebase (PRZ-FB). In the dissolution test, PRZ-HCl particles first changed to a phosphate salt within 5 min, then gradually changed to PRZ-FB after several hours. Since the intestinal fluid is buffered by the bicarbonate system in vivo, the dissolution behavior in vivo may not be properly evaluated using a phosphate buffer solution. For drugs with a low phosphate solubility product, it is necessary to consider this aspect.     

Mucoadhesive platforms for targeted delivery to the colon

A novel platform system, comprising a mucoadhesive core and a rapid release carrier, was designed for targeted drug delivery to the colon. Prednisolone pellets containing different carbomers, including Carbopol 971P, Carbopol 974P and Polycarbophil AA-1, with or without organic acids, were produced by extrusion-spheronization. Mucoadhesive pellets were coated with a new enteric double-coating system, which dissolves at pH 7. This system comprises an inner layer of partially neutralized Eudragit^® S and buffer salt and an outer coating of standard Eudragit^® S. A single layer of standard Eudragit S was also applied for comparison purposes. Dissolution of the coated pellets was assessed in USP II apparatus in 0.1 N HCl followed by Krebs bicarbonate buffer pH 7.4. Visualization of the coating dissolution process was performed by confocal laser scanning microscopy using fluorescent markers in both layers. The mucoadhesive properties of uncoated, single-coated and-double coated pellets were evaluated ex vivo on porcine colonic mucosa. Mucoadhesive pellets coated with a single layer of Eudragit^® S release its cargo after a lag time of 120 min in Krebs buffer. In contrast, drug release from the double-coated mucoadhesive pellets was significantly accelerated, starting at 75 min. In addition, the mucoadhesive properties of the core of the double coated pellets were higher than those from single-coated pellets after the core had been exposed to the buffer medium. This novel platform technology has the potential to target the colon and overcome the variability in transit and harmonize drug release and bioavailability.     

Development and validation of a dissolution test method for vitamin A in dietary supplement tablets

A dissolution test method and an analytical procedure by HPLC were developed and validated for evaluation of the dissolution behavior of dietary supplements tablets containing vitamin A in the forms of retinyl acetate or retinyl palmitate. Seven different commercially available products containing retinyl acetate or retinyl palmitate were selected for this study. A dissolution medium containing 1% (w/v) Octoxynol 9 (Triton X-100) and 1% (w/v) (+)-sodium α-ascorbate in 0.05 M phosphate buffer, pH 6.8, was found suitable to ensure sink conditions and chemical stability for both retinyl acetate and retinyl palmitate. Two rotation speeds, 50 and 75 rpm, were evaluated with USP Apparatus 2 and 900 ml dissolution medium. Dissolution profiles were generated over 120 min. Dissolution samples were analyzed with a reversed-phase HPLC method with UV detection at 325 nm. Each product was also assayed for vitamin A content according to USP 32–NF 27. The results from 45 min to the last time point of the dissolution tests performed at 75 rpm were consistent with the Assay results. The dissolution test described here could be proposed as a pharmacopeial standard to assess the performance of tablet formulations containing vitamin A as retinyl esters.     

Advanced formulation design of venlafaxine hydrochloride coated and triple-layer tablets containing hypromellose

The purpose of this research work was to develop venlafaxine hydrochloride-coated and layered matrix tablets using hypromellose adopting wet granulation technique. The granules and the tablets were characterized. The monolithic tablets were coated with different ratios of ethyl cellulose and hypromellose. The in vitro dissolution study was performed in distilled water. In the layered tablets, the middle layer containing drug was covered with barrier layers containing high viscosity grade hypromellose. Simplex lattice design was used for formulating the layered tablets. The dissolution study of the optimized batches and a reference product was carried out in 0.1?N HCl, phosphate buffer and hydroalcoholic solution. Burst drug release was exhibited by the uncoated tablets, probably due to high aqueous solubility of venlafaxine HCl. The coated tablets showed sustained drug release without burst effect. The drug release was best explained by Weibull model. A unified Weibull equation was evolved to express drug release from the coated tablets. The layered tablets also exhibited sustained release without burst effect due to effective area reduction. The optimized batches showed identical drug release in 0.1?N HCl, phosphate buffer and 10% v/v aqueous alcohol. Layered tablets may well be adopted by the industry due to the possibility of achieving a high production rate.     

自制阿托伐他汀钙片与立普妥的体外溶出行为相似性评价

测定了自制阿托伐他汀钙片与立普妥在水、pH l.2盐酸、pH 4.5乙酸盐缓冲液、pH 6.8磷酸盐缓冲液4种溶出介质中的溶出曲线,并进行相似性评价.结果表明,自制片与立普妥在水、pH 4.5乙酸盐缓冲液、pH 6.8磷酸盐缓冲液中,15min时溶出度均达85％以上,在pH 1.2盐酸中相似因子f2为75.1.提示自制阿托伐他汀钙片与立普妥体外溶出行为相似.     

阿魏酸哌嗪片的溶出曲线考察

目的：建立阿魏酸哌嗪片溶出度曲线测定方法,比较4家生产企业阿魏酸哌嗪片在4种不同溶出介质中的溶出行为差异,为药品质量控制与仿制药一致性评价提供参考。方法：以pH 1.2盐酸溶液、醋酸盐缓冲液（pH 4.0）、磷酸盐缓冲液（pH 6.8）和水为溶出介质,分别考察4家企业12批阿魏酸哌嗪片的溶出曲线,采用f2相似因子法评价溶出曲线的相似性。结果：所有批次样品在pH 1.2盐酸溶液中溶出量均低于15%,3家企业9批次样品在pH 6.8磷酸盐缓冲液和水中的溶出行为相似（f2>50）,pH 4.0醋酸盐缓冲液对阿魏酸哌嗪片有较好区分力。结论：建立的测定方法专属性强、灵敏度高、准确可靠,可用于阿魏酸哌嗪片溶出曲线测定,为其质量控制提供参考。     

秋水仙碱片溶出度一致性评价

目的建立秋水仙碱片溶出度测定方法,评价国内5个厂家23批次秋水仙碱片溶出曲线相似性。方法采用《中华人民共和国药典》2015年版溶出度测定第三法测定秋水仙碱片溶出度,使用纯水、pH值4.5醋酸盐缓冲液与pH值6.8磷酸盐缓冲液3种溶出介质,考察秋水仙碱片溶出行为,并通过计算相似因子评价溶出曲线相似性。结果秋水仙碱片在pH值6.8磷酸盐缓冲液中溶出效果较好。国内市售5个厂家秋水仙碱片在3种溶出介质中溶出曲线均相似(f2>50)。结论该方法适用于秋水仙碱片溶出曲线测定,可为秋水仙碱片质量一致性评价提供参考。     

硝苯地平片剂溶出度的考察

目的考察不同生产企业生产的硝苯地平片剂的体外溶出度。方法分别以0.1 mol.L-1盐酸溶液、人工胃液(不含胃蛋白酶)、pH 4.5醋酸钠缓冲液、pH 6.8磷酸盐缓冲液和蒸馏水为溶出介质,采用紫外分光光度法检查;以质量分数为0.25%十二烷基硫酸钠为溶出介质,采用HPLC法检查,比较不同厂家硝苯地平片剂的体外溶出度。用相似因子法评价硝苯地平片剂在0.1 mol.L-1盐酸溶液、人工胃液(不含胃蛋白酶)、pH 4.5醋酸钠缓冲液、pH 6.8磷酸盐缓冲液和蒸馏水中的溶出行为。结果在质量分数为0.25%十二烷基硫酸钠溶液中,硝苯地平的溶出度在60 min均大于65%,而在其他溶出介质中的溶出度均达不到《英国药典》及《美国药典》中规定的标准。相似因子f2均在50~100之间。结论溶出介质的pH值对硝苯地平的溶出度没有影响。从整体来看,国产硝苯地平片剂的体外溶出行为与国外制剂相比有很大差距。     

A novel coating concept for ileo-colonic drug targeting: Proof of concept in humans using scintigraphy

The in vivo proof of concept of a novel double-coating system, based on enteric polymers, which accelerated drug release in the ileo-colonic region, was investigated in humans. Prednisolone tablets were coated with a double-coating formulation by applying an inner layer composed of EUDRAGIT® S neutralised to pH 8.0 and a buffer salt (10% KH₂PO₄), which was overcoated with layer of standard EUDRAGIT® S organic solution. For comparison, a single coating system was produced by applying the same amount of EUDRAGIT® S organic solution on the tablet cores. Dissolution tests on the tablets were carried out using USP II apparatus in 0.1 N HCl for 2 h and subsequently in pH 7.4 Krebs bicarbonate buffer. For comparison, tablets were also tested under the USP method established for modified release mesalamine formulations. Ten fasted volunteers received the double-coated and single-coated tablets in a two-way crossover study. The formulations were radiolabelled and followed by gamma scintigraphy; the disintegration times and positions were recorded. There was no drug release from the single-coated or double-coated tablets in 0.1 N HCl for 2 h. The single-coated tablets showed slow release in subsequent Krebs bicarbonate buffer with a lag time of 120 min, while in contrast drug release from the double-coated tablets was initiated at 60 min. In contrast, using the USP dissolution method, normally employed for modified release mesalamine products, no discrimination was attained. The in vivo disintegration of the single-coated EUDRAGIT® S tablets in the large intestine was erratic. Furthermore, in 2 volunteers, the single-coated tablet was voided intact. Double-coated tablets disintegrated in a more consistent way, mainly in the ileo-caecal junction or terminal ileum. The accelerated in vivo disintegration of the double-coating EUDRAGIT® S system can overcome the limitations of conventional enteric coatings targeting the colon and avoid the pass-through of intact tablets. Moreover, Krebs bicarbonate buffer has the ability to discriminate between formulations designed to target the ileo-colonic region.     

头孢呋辛酯片的制备及其溶出度研究

目的制备头孢呋辛酯片,并与市售头孢呋辛酯片进行体外溶出度比较。方法采用微晶纤维素、交联聚维酮、微粉硅胶压制成头孢呋辛酯片,分别以pH4.0醋酸盐缓冲液、pH6.8磷酸盐缓冲液、水、0.1mol.L-1盐酸溶液作为溶出介质,用桨法实验,绘制不同溶出介质中的溶出曲线,并计算出相似因子(f2)。结果在4种溶出介质中,自制头孢呋辛酯片和市售头孢呋辛酯片的溶出曲线相似因子(f2)分别为73,68,65和82。结论自制头孢呋辛酯片和市售片的溶出行为一致。     

11厂家国产头孢氨苄片的溶出度比较

目的:比较国内11个厂家头孢氨苄片的溶出情况。方法:参照《中国药典》2005年版和日本在"药品品质再评价"拟定流程中对溶出度试验条件的规定,分别考察不同批次头孢氨苄片在水、pH1.2人工胃液、pH4.0醋酸盐缓冲液、pH6.8磷酸盐缓冲液4种溶出介质中的体外溶出度,溶出方法采用转篮法,转速为100r·min-1,测定方法为紫外分光光度法,检测波长为262nm;以其中溶出效果最优的E厂家样品为对照采用相似因子法进行各厂家样品间溶出行为的比较。结果:在上述4种溶出介质中,分别只有4个、3个、5个、8个厂家的样品在45min时累积溶出度在80%以上;多数厂家样品的相似因子结果都远小于50。结论:不同厂家样品的溶出行为不但有显著性差异,且溶出度不符合质量要求。     

Development of an enteric coating formulation and process for tablets primarily composed of a highly water-soluble, organic acid.

The purpose of this study was to define coating conditions for the enteric coating of a highly water soluble, acidic tablet core. Acidic tablet cores containing a marker drug were separated into three groups and seal coated to coverage levels of 0% (uncoated, white), 1% (yellow), and 3% (tan) weight gains. By employing a 'color coding' scheme, the different seal coated tablets could be coated simultaneously to reduce the number of experiments and eliminate potential differences that may exist during separate coating processes. In addition, an allotment of each coded tablet type was sequentially numbered with a marker pen, weighed, and recorded in order to identify the precise level of enteric coating as well as to monitor the variability of a given coating operation. The tablets were coated with five Eudragit((R)) L30D-based enteric formulations containing different amounts of plasticizer (10-20 parts) and talc (10-50 parts). During each enteric coating process, a predetermined amount of labeled tablets were removed after attaining 6, 8, and 10% weight gains. The labeled tablets were re-weighed, sorted, and then tested using USP disintegration and dissolution methods. Weight gain measurements of individual tablets indicated low coating variability (6.2% RSD) during the enteric coating processes. Dissolution results revealed that all enteric coat formulations inhibited drug release for 2 h in 0.1 N HCl. In contrast, it was found that tablets without a seal coat failed the USP disintegration test. In addition, seal coated tablets exhibited ca. 1.5-5 fold greater drug release at most intermediate sampling time points in phosphate buffer, pH 6.8, than tablets without a seal coat, suggesting that the dissolution of the latter was delayed by the generation of an acidic microenvironment at the interface of the enteric coat/acidic tablet core. Prior to enteric coating an acidic, highly water soluble substrate, a seal coat barrier should be applied to prevent retardation in drug release. A simple strategy utilizing color coding and tablet marking can be employed to test the effect of a seal coat, evaluate enteric coating formulations and process with minimal experimentation and analyses.     

6厂家多潘立酮片的溶出度考察

目的：考察不同药厂生产的多潘立酮片的体外溶出情况,为临床用药提供参考。方法：参照日本在“药品品质再评价”拟定流程中对溶出度试验条件的规定,分别考察不同药厂多潘立酮片在水、pH1．2人工胃液、pH4．0醋酸盐缓冲液、pH6．8磷酸盐缓冲液4种溶出介质中的体外溶出行为,同时和部颁标准中规定的多潘立酮片溶出方法进行比较。结果：各药厂生产的多潘立酮片在酸性介质中均溶出良好,在水和pH6．8磷酸盐缓冲液中6h溶出均低于60％。结论：同一批多潘立酮片在不同溶出介质中溶出差异很大;不同药厂多潘立酮片的质量有显著性差异,临床用药时应加以注意。     

国产酒石酸美托洛尔片的溶出度质量评价

目的：通过考察国内7家不同生产企业的酒石酸美托洛尔片与参比制剂（商品名：倍他洛克^TM）的体外溶出情况评价药品质量。方法：参照日本《药品品质再评价工程拟定流程》中对溶出度试验条件的规定,分别考察不同厂家的酒石酸美托洛尔片在水、pH 1.2的氯化钠盐酸溶液、pH 4.0的醋酸盐缓冲液及pH 6.8的磷酸盐缓冲液4种介质中的体外溶出行为,溶出方法为浆法,转速为50 r·min^-1。采用相似因子法比较7家企业的酒石酸美托洛尔片与参比制剂溶出行为的差异。结果： 7家企业酒石酸美托洛尔片的溶出行为存在较大差异,C、F、G企业样品在4种溶出介质中的f₂值均小于50,溶出曲线与参比制剂不相似。结论：国内某些生产企业的酒石酸美托洛尔片与参比制剂的溶出行为有显著差异,仿制药品的质量应予以关注。     

国产与原研复方缬沙坦氨氯地平片质量对比研究

目的 通过测定国产与原研复方缬沙坦氨氯地平片的硬度、崩解时限、溶出度以及体外溶出曲线,评估国产与原研制剂的质量。方法 2020年10月至2022年2月,分别测定国产与原研复方缬沙坦氨氯地平片的硬度、崩解时限、溶出度,并采用f2相似因子法比较了两种制剂分别在pH 1.2盐酸溶液、pH 4.5醋酸盐缓冲液和pH 6.8磷酸盐缓冲液中的溶出相似性。结果国产与原研复方缬沙坦氨氯地平片的硬度略有差异,崩解时限基本一致,在pH 6.8磷酸盐缓冲液30 min内缬沙坦和氨氯地平的溶出度均达到80%以上;两种制剂在三种溶出介质中的溶出曲线的f2相似因子值均大于80,体外溶出相似性较高。结论国产与原研复方缬沙坦氨氯地平片在三种溶出介质中的溶出相似性较好,可为复方缬沙坦氨氯地平片的质量一致性评价提供参考。     

Gastroresistant capsular device prepared by injection molding

In the present work, the possibility of manufacturing by injection molding (IM) a gastro-resistant capsular device based on hydroxypropyl methyl cellulose acetate succinate (HPMCAS) was investigated. By performing as an enteric soluble container, such a device may provide a basis for the development of advantageous alternatives to coated dosage forms. Preliminarily, the processability of the selected thermoplastic polymer was evaluated, and the need for a plasticizer (polyethylene glycol 1500) in order to counterbalance the glassy nature of the molded items was assessed. However, some critical issues related to the physical/mechanical stability (shrinkage and warpage) and opening time of the device after the pH change were highlighted. Accordingly, an in-depth formulation study was carried out taking into account differing release modifiers potentially useful for enhancing the dissolution/disintegration rate of the capsular device at intestinal pH values. Capsule prototypes with thickness of 600 and 900 μm containing Kollicoat^® IR and/or Explotab^® CLV could be manufactured, and a promising performance was achieved with appropriate gastric resistance in pH 1.2 medium and break-up in pH 6.8 within 1 h. These results would support the design of a dedicated mold for the development of a scalable manufacturing process.     

Preparation,characterization, dissolution,and permeation of flibanserin − 2-HP-β-cyclodextrin inclusion complexes

Flibanserin (FLB), an antiserotonin drug, is used to treat women with hypoactive sexual appetite disorder. FLB shows low bioavailability (~33%) probably due to its low water solubility. The current study investigated the impact of hydroxypropyl-β-cyclodextrin (HP-β-CD) and sodium lauryl sulfate (SLS) on the dissolution and permeation of FLB. HP-β-CD–FLB inclusion complexes were prepared using physical mixing and kneading at 1:1 and 1:2 M ratios and characterized using differential scanning calorimetry, Fourier transform infrared spectroscopy, and powder X-ray diffractometry. The dissolution and permeation of the complexes through a cellophane membrane were performed in, 0.1, 0.3 and 0.5% SLS in phosphate buffer (pH 6.8).Derived from the slope of the linear phase solubility diagram, the apparent stability constant (K_1:1) was 372.54 M⁻¹. Kneading changed the crystalline form of FLB to an amorphous appearance characterized by minimal crystalline peaks, indicating successful inclusion complex formation. In addition, the HP-β-CD–FLB inclusion complexes showed twofold increased dissolution efficiency at 6 h. The cumulative FLB amount permeated at 6 h increased from 14.1% to 21.88% and 34.56% in the presence of 0.1% and 0.3% of SLS, respectively. However, increasing SLS to 0.5% did not show an increase in FLB permeation. Therefore, the HP-β-CD–FLB inclusion complex has an improved dissolution rate compared to FLB alone. The presence of SLS in the dissolution medium increases the dissolution rate of pure FLB and its complex with HP-β-CD. kneaded 1:1 complex was formulated bioadhesive buccal tablets and showed enhanced drug release.     

阿齐沙坦片国产品溶出度试验方法的建立及与原研品体外溶出行为比较

目的:建立阿齐沙坦片的溶出度试验方法,并将国产品与原研品进行溶出曲线比较,评价二者体外溶出行为的一致性。方法:筛选各溶出参数,采用紫外-可见分光光度法在246 nm波长处测定吸光度并计算溶出度;分别考察两种产品在pH 6.8磷酸盐缓冲液、pH 4.5醋酸盐缓冲液、0.1 mol/L盐酸、水4种溶出介质中的溶出曲线,采用相似因子f2法与AV值法比较二者的溶出行为。结果:溶出方法采用桨法,转速为50 r/min,溶出介质为pH 6.8磷酸盐缓冲液;阿齐沙坦检测质量浓度线性范围为1.07¹2.80μg/ml(r=0.999 8),平均回收率为99.32%(RSD=0.75%,n=3);在4种溶出介质中,两种产品的f2值均在5012.80μg/ml(r=0.999 8),平均回收率为99.32%(RSD=0.75%,n=3);在4种溶出介质中,两种产品的f2值均在50¹00,AV平均值均小于15,表明二者相似性好。结论:建立的溶出度试验方法专属性强、灵敏、简便,能有效控制阿齐沙坦片的质量;同时国产品与原研品的体外溶出行为一致。