Properties of Tablets Containing Granulations of Ibuprofen and an Acrylic Copolymer Prepared by Thermal Processes

The objective of this study was to investigate the properties of tablets containing granulations of ibuprofen (Ibu) and Ammonio Methacrylate Copolymer, Type B (Eudragit RS PO) prepared by hot-melt processing. Tablets were compressed from granules prepared by hot-melt granulation (HMG) or direct compression (DC). For the hot-melt extrusion (HME) process, tablets were prepared by cutting the extrudate, manually. The physicochemical properties of tablets were investigated using thermal analysis, powder X-ray diffraction analysis, tablet hardness, and drug dissolution. The effect of thermal treatment of tablets on the dissolution characteristics of Ibu was also investigated. The results demonstrated that the Ibu lowered the glass transition temperature (T_g) of the Eudragit RS PO and the softened polymer functioned as a thermal binder in the granulation. Ibu was demonstrated to be an effective plasticizer for Eudragit RS PO in the thermal processes. The efficiency of the granulation process increased with increasing levels of Eudragit RS PO in the powder blend. Higher levels of Eudragit RS PO in the tablets prepared by HMG or HME resulted in a decrease in the dissolution rate of the Ibu. An increase in the amount of Ibu in the tablets prepared by HMG or DC led to a decrease in the initial dissolution rate of the Ibu. Following the thermal treatment of the Ibu tablets prepared by HMG, the dissolution rate was significantly decreased due to structural changes in the tablets that resulted from the fusion and coalescence of plasticized polymer particles, causing a reduction in tablet porosity. The Ibu tablets prepared by HME demonstrated minimal changes in their release properties following thermal treatment even at temperatures higher than the T_g of the polymer. HME was shown to be a novel method to prepare matrix tablets and stable dissolution properties were obtained when tablets were stored at 40°C for 30 days.     

Study of drug release and tablet characteristics of silicone adhesive matrix tablets

Matrix tablets of a model drug acetaminophen (APAP) were prepared using a highly compressible low glass transition temperature (T_g) polymer silicone pressure sensitive adhesive (PSA) at various binary mixtures of silicone PSA/APAP ratios. Matrix tablets of a rigid high T_g matrix forming polymer ethyl cellulose (EC) were the reference for comparison. Drug release study was carried out using USP Apparatus 1 (basket), and the relationship between the release kinetic parameters of APAP and polymer/APAP ratio was determined to estimate the excipient percolation threshold. The critical points attributed to both silicone PSA and EC tablet percolation thresholds were found to be between 2.5% and 5% w/w. For silicone PSA tablets, satisfactory mechanical properties were obtained above the polymer percolation threshold; no cracking or chipping of the tablet was observed above this threshold. Rigid EC APAP tablets showed low tensile strength and high friability. These results suggest that silicone PSA could eliminate issues related to drug compressibility in the formulation of directly compressed oral controlled release tablets of poorly compressible drug powder such as APAP. No routinely used excipients such as binders, granulating agents, glidants, or lubricants were required for making an acceptable tablet matrix of APAP using silicone PSA.     

Correlation between the viscoelastic properties of the gel layer of swollen HPMC matrix tablets and their in vitro drug release

Abstract

Drug release from hydroxypropyl methylcellulose (HPMC) hydrophilic matrix tablets is controlled by drug diffusion through the gel layer of the matrix-forming polymer upon hydration, matrix erosion or combination of diffusion and erosion mechanisms. In this study, the relationship between viscoelastic properties of the gel layer of swollen intact matrix tablets and drug release was investigated. Two sets of quetiapine fumarate (QF) matrix tablets were prepared using the high viscosity grade HPMC K4M at low (70?mg/tablet) and high (170?mg/tablet) polymer concentrations. Viscoelastic studies using a controlled stress rheometer were performed on swollen matrices following hydration in the dissolution medium for predetermined time intervals. The gel layer of swollen tablets exhibited predominantly elastic behavior. Results from the in vitro release study showed that drug release was strongly influenced by the viscoelastic properties of the gel layer of K4M tablets, which was further corroborated by results from water uptake studies conducted on intact tablets. The results provide evidence that the viscoelastic properties of the gel layer can be exploited to guide the selection of an appropriate matrix-forming polymer, to better understand the rate of drug release from matrix tablets in vitro and to develop hydrophilic controlled-release formulations.     

用渗滤理论研究乙基纤维素骨架片的最适压片力范围

目的　用渗滤理论研究制备阿司匹林-乙基纤维素骨架片的最适压片力范围。方法　使用不同的压片力(3～30 kN)制备了含阿司匹林40%的阿司匹林-乙基纤维素骨架片,测定了溶出曲线,用Higuchi方程和Ritger-Peppas方程对溶出数据进行拟合。将拟合的Higuchi方程的斜率b值和计算得到的片剂的孔隙率ε,代入渗滤理论推导出的公式中,可计算出表观扩散系数D和片剂溶出性能参数β,分别以D对ε及β对ε回归,可得到临界孔隙率ε_c,由β-ε,D-ε和β-ε₀曲线可推知最适压片力范围。结果　压片力在9～18 kN时,药物释放遵从Higuchi模型方程,片剂以骨架扩散机制释药,且释药速度适中,因此9～18 kN为最适压片力范围。低于9 kN时,片子的初始孔隙率太大,药物溶出过快;高于18 kN时,药物溶出过慢,呈异常扩散机制释放药物。结论　渗滤理论可较清楚地阐明阿司匹林骨架片的释药机制,并可得到制备阿司匹林片的最适压片力范围。     

Characterization of 5-Fluorouracil Release from Hydroxypropylmethylcellulose Compression-Coated Tablets

Hydrogel compression-coated tablets are able to release the core drug after a period of lag time and have potential for colon-specific drug delivery based on gastrointestinal transit time concept. This study investigated the factors influencing in vitro release characteristics of a model drug 5-fluorouracil from hydroxypropylmethycellulose (HPMC) compression-coated tablets. The core tablet, prepared by a wet granulation compression method, was designed to disintegrate and dissolute quickly. To prepare the compression-coated tablets, 50% of the HPMC/lactose coat powder was precompressed first, followed by centering the core tablet and compressing with the other 50% of the coat powder. Release characteristics were evaluated in distilled water by using a Chinese Pharmacopoeia rotatable basket method. Effect of HPMC viscosity, lactose content in outer shell, and overall coating weight of outer shell on release lag time (T_lag), and zero-order release rate (k) were studied. Release of drug from compression-coated tablets began after a time delay as a result of hydrogel swelling/retarding effect, followed by zero-order release for most of the formulations studied. HPMC of higher viscosity (K4M and K15M) provided better protection of the drug-containing core, showing increased release lag time and slower release rate. Incorporating lactose in outer shell led to decrease of T_lag and increase of k. T_lag and k are exponentially and linearly correlated to lactose content, expressed as weight percentage of the outer shell. Larger coating weight (W) of outer shell produced larger coating thickness (D) around core tablet, which resulted in increase in T_lag and decrease in k. There was good fitting of a linear model for each of the four variables W, D, T_lag, and k. Hardness of the compression-coated tablets and pHs of the release media had little effect on drug release profile. It is concluded that the release lag time and release rate are able to be tailored through adjusting the formulation variables to achieve colon-specific drug delivery of 5-fluorouracil.     

IN VIVO/IN VITRO CORRELATIONS FOR FOUR DIFFERENTLY DISSOLVING KETOROLAC TABLETS

This study assesses whether in vitro immediate release ketorolac tablet dissolution profiles (utilizing the recently proposed USP dissolution test for ketorolac tablets) can be correlated with in vivo plasma pharmacokinetic parameters. Four batches of ketorolac tablets were utilized: a ketorolac tablet batch that demonstrated a rapid dissolution rate during USP in vitro dissolution testing, two tablet batches that were manufactured such that they dissolved at moderate rates, and a tablet batch that was manufactured such that it dissolved at a distinctly slow rate. The single-dose mean pharmacokinetic characteristics and relative bioavailability of the four different 10 mg ketorolac tromethamine tablets were evaluated in 12 healthy volunteers in a randomized study of Latin square design. The amount dissolved of the various tablets at 10, 20, and 30 min was in the order of fast-dissolving tablets > medium-1-dissolving tablets=medium-2-dissolving tablets > slow-dissolving tablets. In general, the profiles of the average plasma concentrations for ketorolac were similar for the fast- and the two medium-dissolving tablet batches (even though a statistically significant difference was found between the t_max of the fast-dissolving tablet and one of the medium-dissolving tablet batches). The mean plasma concentrations for the slow-dissolving tablet, however, reached peak levels much later, with the peak also being significantly smaller. There were no statistically significant differences in the total AUC or in the mean plasma half-lives among the four formulations. Good correlations were obtained for mean t_max versus the percentage dissolved at 20, 30, and 45 min. Correlations were generally weaker for percentage dissolved versus C_max or percentage bioavailability. This indicates that in vitro dissolution testing for immediate release ketorolac tablets can be a useful indicator of in vivo time to maximum plasma concentration when comparing similarly formulated tablets. Further, the proposed USP dissolution test and specification would have appropriately failed the slow-dissolving tablet batch, which demonstrated a significantly slower rate of absorption as per t_max and C_max.     

Effect of Compaction Temperature on Consolidation of Amorphous Copolymers with Different Glass Transition Temperatures

Purpose. The purpose of this study was to relate the combination of glass transition temperature (T _g) and temperature of measurement with the mechanical and compaction properties of some test materials. Methods. Copolymers with different T _gs were synthesised by free radical copolymerisation of methyl methacrylate with lauryl methacrylate. Elastic moduli were measured by dynamic mechanical analysis at different strain rates and temperatures. Compaction experiments were performed at different compaction speeds and temperatures. Results. The difference between temperature of measurement and T _g appears to determine both elastic modulus and yield strength completely. They both decrease with decreasing difference between temperature of measurement and Tg and increase with strain rate. At temperatures of measurement higher than the T _g, the elastic modulus is extremely low because the materials behave as rubbers. Consequently, the amount of energy stored during compaction decreases when the compaction temperature approaches the T _g and increases with strain rate. When the compaction temperature is higher than the T _g, the amount of stored energy is extremely large. The compaction experiments show that the final tablet porosity is completely determined by stress relaxation phenomena. Consequently, the final tablet porosity follows exactly the same relation as that of stored energy. Conclusions. The final tablet porosity is unequivocally determined by the amount of stored energy. This implies that tablet production at a temperature of about 20 K under the glass transition temperature of the material yields tablets with minimum porosity.     

莲子心总碱缓释片体外释放度试验

目的 考察莲子心总碱缓释片体外释放度。方法 模拟人体体内环境,用紫外分光光度法测定莲子心总碱的体外释放度。结果 莲子心总碱释药方程:log(100-R_n)=2.112-0.128t(F=219.310,P<0.001),r=-0.982(P<0.001),T₅₀=3.233h,T_d=4.274h,K_r=0.128h^-1。结论 莲子心总碱缓释片体外释药符合一级释药模式,具有缓释特点。     

Development of gastroretentive drug delivery system for cefuroxime axetil: In vitro and in vivo evaluation in human volunteers

The objective of this investigation was to develop the cefuroxime axetil sustained-release floating tablets to prolong the gastric residence time and compare their pharmacokinetic behavior with marketed conventional tablets (Zocef). The floating tablets were developed using polymers like HPMC K4M and HPMC K100M alone, and polymer combination of HPMC K4M and Polyox WSR 303 by effervescent technique. Tablets were prepared by slugging method and evaluated for their physical characteristics, in vitro drug release, and buoyancy lag time. The best formulation (F10) was selected based on in vitro characteristics and used in vivo radiographic and bioavailability studies in healthy human volunteers. All the formulations could sustain drug release for 12 h. The dissolution profiles were subjected to various kinetic release models and it was found that the mechanism of drug release followed Peppas model. The in vivo radiographic studies revealed that the tablets remained in stomach for 225±30 min. Based on in vivo performance, the developed floating tablets showed superior bioavailability than Zocef tablet. Based on in vivo performance significant difference was observed between C_max, t_max, t_1/2, AUC_0–∞, and mean residence time of test and reference (p<0.05). The increase in relative bioavailability of test was 1.61 fold when compared to reference.     

格列齐特片的制备工艺和溶出一致性评价

目的 制备格列齐特片,进行体外溶出一致性评价。方法 通过单因素实验考察黏合剂的浓度、外加崩解剂的量、外加润滑剂和助流剂的量、颗粒的大小和片剂的硬度几个因素对溶出的影响,进行处方工艺的筛选。放大制备3批格列齐特片,考察在4种不同溶出介质中自制片和参比制剂的溶出一致性。结果 3批自制片在磷酸盐缓冲液（pH7.4）中15 min内溶出大于85%,在水、pH1.2盐酸溶液、pH6.0磷酸盐溶液中的f₂均大于50。结论 在4种不同的溶出介质中,自制片与参比制剂体外溶出一致。     

Effect of Overencapsulation on the Disintegration and Dissolution of Licensed Formulations for Blinding in Randomized Controlled Trials

Overencapsulation is a technique used to conceal tablet products for blinding in randomized controlled trials. A tablet is inserted in an opaque capsule shell with backfill excipient to prevent rattling. Regulatory authorities require evidence that such modification does not materially alter drug release to approve their use in trials. The objective of this study was to assess impact of overencapsulation on disintegration and dissolution of 4 immediate-release drug products (penicillin V, gemfibrozil, ciprofloxacin, and furosemide). Each unmodified tablet was compared to 3 overencapsulated tablets with differing backfill excipient (colloidal silica, lactose monohydrate, or microcrystalline cellulose). All 12 overencapsulated tablets met disintegration and dissolution acceptance criteria. Dissolution acceptance was dependent on apparatus as only 4/12 formulations met specifications using the rotating basket compared to 12/12 using the rotating paddle. Significant differences in release were observed at early time points (T₅-T₁₅). No correlation was observed between aqueous solubility and release, although dissolution of the lipophilic drug gemfibrozil was least impacted by overencapsulation. There was evidence that type/quantity of backfill delays release at early time points. These findings indicate that under the specified conditions, overencapsulated formulations of 4 drugs, 1 from each class of the Biopharmaceutics Classification System, met compendial requirements for release testing.     

Compression of coated drug beads for sustained release tablet of glipizide: formulation,and dissolution

Abstract

A promising glipizide formulation comprising compression of four-layer coated beads into tablets was prepared. The tablet offered the advantages of: a two-hour lag time before drug release, retaining sustained release characteristics and providing approximately zero-order drug release. Drug release was nearly independent of paddle speeds of 50 and 100?rpm releasing 80% over 14?h similar to the commercial glipizide osmotic pump tablet during dissolution testing while keeping the benefits of multiparticular dosage forms. The tablets contain beads with four layers: (1) the innermost layer consists of 2.5?g glipizide and 3.75?g solid ethylcellulose (Surelease®) coated onto 71.25?g of sugar beads; (2) next a hardening layer of 5?g of hypromellose; (3) the controlled release layer of 7.5?g of Surelease®:lactose at a solids ratio of 100:7 and (4) an outermost layer of 20?g of lactose:sodium starch glycolate (Explotab®) at a 2:1 ratio. Then, beads were compressed into tablets containing 11?mg of glipizide using 1500?lbs of compression pressure. The dissolution test similarity factor (f₂) was above 50 for all test conditions for formulation F13 and Glucotrol® with a high of 69.9. The two Surelease® layers both aid controlling drug release, with the Surelease®-drug layer affecting drug release to a greater extent.     

曲尼司特缓释片的制备及其释药影响因素研究

目的 制备了曲尼司特凝胶骨架片。方法 采用HPMC K4M、K15M为凝胶骨架材料，进行了处方研究；通过测定制剂体外释放度，评价了该缓释片处方。结果 曲尼司特缓释片体外释药符合Higuchi方程，其释药速率常数Kr为0．193h^1/2。影响缓释片体外释药的因素有骨架材料的种类、用量、粘合剂的种类和释药介质的pH等。结论 缓释片具有明显的缓释作用，可缓慢释药12h。     

Nanoscale mechanical measurement determination of the glass transition temperature of poly(lactic acid)/everolimus coated stents in air and dissolution media

Localized atomic force microscopy (AFM) force analysis on poly(lactic acid) (PLA) and poly(lactic acid)/everolimus coated stents has been performed under ambient conditions. Similar Young's modulus were derived from both PLA and PLA/everolimus stent surface, namely 2.25 ± 0.46 and 2.04 ± 0.39 GPa, respectively, indicating that the drug, everolimus does not significantly effect the mechanical properties of PLA up to a 1:1 (w/w) drug loading. Temperature controlled force measurements on PLA only coated stents in air and in a 1% Triton surfactant solution allowed the glass transition temperature (T_g) of the polymer to be determined. A significant drop of the Young's modulus in solution was observed at 36 °C, suggests that in vivo the T_g of the polymer is below body temperature. The possible consequences on drug release and the mechanisms by which this may occur are considered.     

消炎痛缓释胶囊的生物利用度研究

消炎痛普通制剂口服吸收迅速,可出现不必要的高血药浓度,导致不良反应。为此我们对三种消炎痛缓释胶囊(A,B,C)和一种常用片剂(D)作了体外溶出试验和体内生物利用度比较。胶囊制剂由丙烯酸类树脂材料E₃₀D包衣的药物小丸制成,其体外溶出行为显示缓慢释放图象。在8名成年男性交叉实验中,不同胶囊制剂和普通片剂之间的Tmax,Cmax和AUC_0～12h经方差分析无统计学差异,但是在给药后4至12小时的血清浓度—时间曲线,均比普通片剂高而平滑。在第12小时,三种胶囊产生的血清浓度显著高于普通片剂(P<0.1)。根据体外溶出行为和体内生物利用度发现T₅₀或Tmax和包衣厚度呈良好线性关系。     

氨氯地平混悬液包衣替米沙坦片芯的制备

目的 采用氨氯地平混悬液包衣替米沙坦片芯制备替米沙坦氨氯地平片,并对其溶出行为和稳定性进行评价。方法 采用流化床一步造粒工艺制备替米沙坦颗粒,用普通旋转压片机制备替米沙坦片芯,然后用氨氯地平混悬液对替米沙坦片芯进行包衣,并以溶出曲线相似性f₂值作为评价指标,通过正交设计进行处方优化,用HPLC进行含量和杂质检测,通过加速和长期试验考察片剂稳定性和溶出度。结果 制备的替米沙坦氨氯地平片质量稳定,具有与原研制剂一致的溶出特征。结论 以氨氯地平包衣替米沙坦片芯制备替米沙坦氨氯地平片具有一定的可行性。     

Stabilizing Effect of Four Types of Disaccharide on the Enzymatic Activity of Freeze-dried Lactate Dehydrogenase: Step by Step Evaluation from Freezing to Storage

Purpose In order to understand the stabilizing effects of disaccharides on freeze-dried proteins, the enzymatic activity of lactate dehydrogenase (LDH) formulations containing four types of disaccharide (trehalose, sucrose, maltose, and lactose) at two relative humidity (RH) levels (about 0 and 32.8%) was investigated after three processes: freeze-thawing, freeze-drying, and storage at three temperatures (20, 40, and 60°C) above and/or below the glass transition temperature (T _g). Materials and Methods The enzymatic activity was determined from the absorbance at 340 nm, and T _g of the samples was investigated by differential scanning calorimetry. Results At each RH condition, T _g values of sucrose formulations were lower than those of other formulations. Although effects of the disaccharides on the process stability of LDH were comparable, storage stability was dependent on the type of disaccharide. All the formulations were destabilized significantly during storage at temperature above T _g. During storage at temperature below T _g, the LDH activity decreased with increases in the storage temperature and moisture. Maltose and lactose formulations showed significant destabilization with the change of color to browning. Conclusions Taking the storage stability of freeze-dried proteins under the various conditions (temperature and RH) into consideration, trehalose is better suited as the stabilizer than other disaccharides.     

Formulation development of Carvedilol compression coated tablet

Purpose: The aim of present research was to produce carvedilol compression coated tablet to provide biphasic drug release.

Method: A compressed coated tablet made of a sustained release core tablet and an immediate release coat tablet. Both the core and the coat contained carvedilol. The sustained release effect was achieved with polymers (HPMC K₄M and PEO WSR 205) to modulate the release of the drug. The powder blends for core and coat tablets were evaluated for angle of repose, bulk density, compressibility index, and drug content. Compressed coated tablets were evaluated for thickness, diameter, weight variation test, drug content, hardness, friability, disintegration and in vitro release studies.

Result: The powder blends showed satisfactory flow properties, compressibility, drug content and all the tablet formulations showed acceptable pharmaco-technical properties. Carvedilol contained in the fast releasing component was released within 3?min, whereas the drug in the core tablet was released at different times up to 24?h, depending on the composition of the matrix tablet. The mechanism of drug release was fickian diffusion or anomalous behavior.

Discussion: Batch F7, containing 10?mg PEO WSR 205 and 5?mg HPMC K₄M, showed maximum similarity with theoretical profile and zero order drug release kinetic.     

尼莫地平微粉化物双层渗透泵控释片的制备

目的 制备尼莫地平微粉化物双层渗透泵控释片。方法 以尼莫地平为模型药物,将微粉化增溶技术应用于控释双层渗透泵剂型中,设计并制备体外控释12 h的尼莫地平双层渗透泵片,采用相似因子法（f₂）对不同处方释药行为的相似性进行评价,并对处方进行优化。结果 成功制备了尼莫地平微粉化物双层渗透泵控释片,零级释放特征明显,符合渗透泵的释药机制。结论 将微粉化增溶技术与控释双层渗透泵技术相结合,显著提高了难溶性药物尼莫地平的体外释放,成功制备了控释制剂。     

Bond Cleavage Reactions in Solid Aqueous Carbohydrate Solutions

Purpose. To investigate chemical reactivity in water soluble glasses. Methods. Rates of bond cleavage reactions in freeze-dried and freeze-concentrated aqueous carbohydrate solutions were measured above and below the glass transition temperatures (T_g). The kinetics of two reactions have been determined in formulations containing di- and polysaccharides: (1) fission of the Asp-Pro peptide bond in Physalaemin and Hamburger peptide by following the release of proline, using a ninhydrin based reaction and (2) the unimolecular dissociation of 2-(4-nitrophenoxy) tetrahydropyran by following the release of the 4-nitrophenoxy anion. Results. The results show clearly that reaction occurs below the glass transition temperature, albeit at very reduced rates. No significant enhancement of the temperature dependence of the rate constant was observed near T_g. Different water soluble glasses provide different degrees of stability. The order of stabilisation was sucrose> Ficoll (low mol. weight)> Byco A Ficoll (high mol. weight)> dextran. The density of the matrix, and therefore the degrees of freedom of mobility of the reactant, is thought to be responsible for these differences. Conclusions. The storage of therapeutic agents, such as proteins, in glassy matrices below T_g does not confer indefinite stability. When formulating products, notice should be taken of the differing stabilisation properties of excipients.