Effect of processing methods and heat treatment on the formation of wax matrix tablets for sustained drug release.

The objective of this study was to evaluate the effects of processing methods and heat treatment on matrix formation and subsequent drug release from wax matrix tablets for controlled release. Phenylpropanolamine hydrochloride (PPA) and Compritol were processed with appropriate diluent(s) using either dry blending (DB), wet granulation (WG), partial melt granulation (PMG), or melt granulation (MG). Then the tablets were heat-treated at 80 degrees C. Particle size distribution and compressibility, along with drug release, tablet micro-morphology, wettability, porosity, and tortuosity were investigated. The drug release was different for the four processing methods even though the tablet formulation was identical. Heat treatment further retarded drug release and its effect was related to the previous manufacturing processes. Scanning Electron Microscopy (SEM) showed that heat treatment redistributed the wax and formed a film-like structure covering drug and excipients. The contact angle of tablets made from DB, WG, and PMG methods increased after heat treatment, while that of tablets made from MG remained constant. Tablet tortuosity calculated from drug release rate constants increased dramatically after heat treatment. Drug release from the wax tablets with or without heat treatment was best described by the Higuchi equation. Different processing methods produced different matrix structures that resulted in different drug release rates. Heat treatment retarded drug release mainly by increasing tortuosity of the matrix. Contact angle measurement and SEM analysis indicated that heat treatment caused the wax to melt, redistribute, coat the drug and diluents, and form a network structure.     

不同制备方法对水溶性药物氢化蓖麻油骨架缓释片的影响

目的:探索以氢化蓖麻油作为缓释片的骨架时,蜡质骨架片常规制备方法以外的3种不同制备方法对骨架片成型性及水溶性药物释放的影响。方法:以紫外分光光度法为检测方法,以累积释放度为检测指标,并结合流动性及可压性,考察湿法制粒压片、干法制粒压片及全粉末压片法对水溶性模型药物维拉帕米和肉苁蓉提取物的氢化蓖麻油骨架缓释片的成型性及药物释放的影响。结果:采用湿法制粒压片、干法制粒压片、全粉末压片的方法成功制得维拉帕米氢化蓖麻油骨架缓释片和肉苁蓉提取物氢化蓖麻油骨架缓释片。结论:氢化蓖麻油作为蜡质骨架,可以采用湿法制粒压片、干法制粒压片、全粉末压片的方法进行压片。该试验结果可为水溶性药物氢化蓖麻油骨架缓释片的研制提供一定的参考。     

Application of Melt Granulation Technology to Enhance Tabletting Properties of Poorly Compactible High-Dose Drugs

Using metformin HCl as the model drug and hydroxypropylcellulose (HPC) as the polymeric excipient, a melt granulation (MG) process that employs a twin-screw extruder has been developed to enhance compactibility of poorly compactible high-dose drug substances. A high (90%) drug-load tablet formulation, containing 1025 mg of active pharmaceutical ingredients and 109 mg of excipients, was produced. Drug–polymer–powder mixtures were melt granulated at a temperature above glass transition of HPC (130°C) but below melting point of metformin HCl (224°C). MG was compared with modified wet granulation (WG) and solvent granulation (SG) processes. Under identical compression force, the hardness of tablets produced was MG>SG>WG and the friability was MG<SG<WG. The hardness of WG tablets was highly sensitive to moisture content both during compression and subsequent storage, and, although not to the same extent, the hardness of SG tablets was also affected by loss-on-drying levels. MG provided a robust manufacturing process with highest compactibility and lowest friability that were not sensitive to changes in atmospheric moisture level. The process can decrease tablet sizes of high-dose drugs and combination products by decreasing the need for relatively large amounts of excipients generally used to overcome physicochemical limitations of drug substances.     

熔融制粒法制备盐酸二甲双胍缓释片

目的制备盐酸二甲双胍缓释片,并考察其释药行为及影响因素。方法以山嵛酸甘油酯为骨架材料,微晶纤维素为致孔剂,采用熔融制粒技术制备盐酸二甲双胍缓释片,并考察不同释放介质,山嵛酸甘油酯、微晶纤维素的不同用量以及制备工艺参数等对该缓释片体外释放的影响。结果山嵛酸甘油酯和微晶纤维素的用量为药物释放的主要影响因素,制备的缓释片具有明显的缓释特征,体外释药过程符合零级动力学模型。结论采用山嵛酸甘油酯作为蜡质骨架材料,结合其他辅料,采用熔融制粒技术可制备日服1次的盐酸二甲双胍缓释片。     

Influence of processing methods on physico-mechanical properties of Ibuprofen/HPC-SSL formulation

Abstract

The objective of the present study was to investigate the influence of processing methods on the physical and mechanical properties of formulations containing Ibuprofen and HPC-SSL. The powder blends, containing Ibuprofen and HPC-SSL in ratio of 9:0.5, were processed using melt granulation (MG) by hot melt extrusion (HME) and wet granulation (WG) by high shear mixer. Formulated granules and powder blends were compressed into round flat faced tablets using Riva Piccola tablet press. Differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD) studies proved that granulation process did not significantly alter the crystallinity of Ibuprofen, however, particle density and flow properties were significantly improved. Scanning electron microscopy (SEM) and particle size analysis corroborate with the findings that the flow characteristics of granules from MG were relatively superior to other formulations. Formulations were investigated for out-of-die compaction behaviour using Heckel, Kawakita, and CTC profile analysis. Detailed examination revealed that all three formulations differed in particle size due to the granulation, thus conferring to different compaction behaviour. In WG and MG, granulation offered an increase in particle size resulting in high compressibility along with deformation at low compression pressure. This results into low yield pressure, low yield strength, and higher densification, as compared with dry blend. The current work provides an insight into factors affecting physical and mechanical properties tablets, which can facilitate the rational selection of suitable change in processing method instead of changing excipients.     

Properties of lipophilic matrix tablets containing phenylpropanolamine hydrochloride prepared by hot-melt extrusion.

The objective of the present study was to investigate the influence of formulation factors on the physical properties of hot-melt extruded granules and compressed tablets containing wax as a thermal binder/retarding agent, and to compare the properties of granules and tablets with those prepared by a high-shear melt granulation (MG) method. Powder blends containing phenylpropanolamine hydrochloride, Precirol and various excipients were extruded in a single-screw extruder at open-end discharge conditions. The extrudates were then passed through a 14-mesh screen to form granules. The extrusion conditions and the optimum amount of wax to function as the thermal binder were dependent on the properties of the filler excipients. At the same wax level, drug release from tablets decreased in the order of using microcrystalline cellulose (MCC), lactose and Emcompress as the filler excipient. The observed differences in the dissolution properties of the tablets were due to the differences in the solubility, swellability and density of the filler excipients. Replacing Precirol with Sterotex K, a higher melting point wax, resulted in slightly increased dissolution rates, when the extrusion was performed at the same temperature conditions. Hot-melt extruded granules were observed to be less spherical than high-shear melt granules and showed lower values of bulk/tap densities. However, tablets containing MCC or lactose granules prepared by hot-melt extrusion (HME) exhibited higher hardness values. Slower drug release rates were found for tablets containing MCC by HME compared with MG. Analysis of the hot-melt extruded granules showed better drug content uniformity among granules of different size ranges compared with high-shear melt granules, resulting in a more reproducible drug release from the corresponding tablets.     

Effects of the Method of Preparation on the Compression,Mechanical, and Release Properties of Khaya Gum Matrices

A study has been made of the compression properties of khaya gum matrices and the effects of drug concentration and method of preparation of the material on the compression, mechanical and the drug release characteristics of the matrices. Khaya gum matrix tablets were prepared by direct compression and wet granulation methods. The compression properties of the formulations were assessed using the equations of Heckel and Kawakita. The mechanical properties of the tablets were evaluated using crushing strength and friability of the tablets, whereas the release properties of the tablets were evaluated by using the disintegration and dissolution times. The results obtained show that khaya gum deformed mainly by plastic deformation. The compression properties of the formulations were affected by the concentration of the drug and the method of preparation of the materials for compression. Tablets prepared by wet granulation showed faster onset and higher amount of plastic deformation during compression than those prepared by direct compression. Tablets containing dicalcium phosphate showed higher mechanical strength and disintegration and dissolution times. Wet granulation also increased the mechanical strength of the tablet without significantly affecting the drug release characteristics from the matrix tablets. Thus, the wet granulation method could be useful in the preparation of khaya gum matrix tablet with acceptable mechanical properties and drug release properties.     

Effects of the method of preparation on the compression, mechanical, and release properties of khaya gum matrices

A study has been made of the compression properties of khaya gum matrices and the effects of drug concentration and method of preparation of the material on the compression, mechanical and the drug release characteristics of the matrices. Khaya gum matrix tablets were prepared by direct compression and wet granulation methods. The compression properties of the formulations were assessed using the equations of Heckel and Kawakita. The mechanical properties of the tablets were evaluated using crushing strength and friability of the tablets, whereas the release properties of the tablets were evaluated by using the disintegration and dissolution times. The results obtained show that khaya gum deformed mainly by plastic deformation. The compression properties of the formulations were affected by the concentration of the drug and the method of preparation of the materials for compression. Tablets prepared by wet granulation showed faster onset and higher amount of plastic deformation during compression than those prepared by direct compression. Tablets containing dicalcium phosphate showed higher mechanical strength and disintegration and dissolution times. Wet granulation also increased the mechanical strength of the tablet without significantly affecting the drug release characteristics from the matrix tablets. Thus, the wet granulation method could be useful in the preparation of khaya gum matrix tablet with acceptable mechanical properties and drug release properties.     

Single and Dual Drug Release Patterns from Shellac Wax-Lutrol Matrix Tablets Fabricated with Fusion and Molding Techniques

The objective of this investigation was to prepare the shellac wax matrix tablets by fusion and molding technique incorporated with Lutrol in different ratios to modify the hydrophobicity of matrix tablet. The matrix tablets with single drug were loaded either with propranolol hydrochloride or hydrochlorothiazide as hydrophilic and hydrophobic model drugs, and a dual drug formula was also prepared. The single and dual drug release patterns were studied in a dissolution apparatus using distilled water as medium. Propranolol hydrochloride released from matrix was easier than hydrochlorothiazide. Drug release from shellac wax matrix could be enhanced by incorporation of Lutrol. However retardation of drug release from some matrix tablets was evident for the systems that could form dispersion in the dissolution medium. The gel network from high content of Lutrol was hexagonal which was a dense and more compact structure than the other structures found when low amounts of Lutrol were present in the formula. Therefore, the formulae with high content of Lutrol could prolong drug release more efficiently than those containing low content of Lutrol. Hence shellac wax matrix could modulate the drug release with the addition of Lutrol. Sustainable dual drug release was also obtained from these developed matrix tablets. Thus shellac wax-Lutrol component could be used as a potential matrix tablet prepared with fusion and molding technique with excellent controlled drug release.     

Multi-unit dosage formulations of theophylline for controlled release applications

The study was carried out to investigate the drug release profiles of multi-unit dosage formulations of theophylline consisting of both the fast and slow release components in a unit dose. The fast release component consisted of conventional granules of theophylline formed by mixing the drug powder with starch mucilage (20% w/v) while the slow release component consisted of wax granulations of theophylline formed by triturating the drug powder with a melted Carnauba wax (drug:wax ratio, 4:1). The granules were either filled into capsules or tabletted. In the study design, the drug release characteristics of the individual fast or slow release particles were first determined separately and then mixed in various proportions for the purpose of optimizing the drug release profiles. The evaluating parameters were the prompt release in the first 1 h (mp), the maximum release (m infinity) and the time to attain it (t infinity). Total drug content in each capsule or tablet was 300 mg and two of such were used in dissolution studies. The release kinetics and hence the release mechanism was confirmed by measuring the linear regression coefficient (R2 values) of the release data. The release kinetics was generally most consistent with the Higuchi square root of time relationship (R2 = 0.95). indicating a diffusion-controlled mechanism. The mp (mg) and t infinity (h) values for capsules and tablets of the conventional granules were (420 mg, 3 h) and (348 mg, 5 h), respectively, while for the capsules and tablets of the wax granulations mp and t infinity values were (228 mg, 9 h) and (156 mg, 12 h), respectively, indicating that a combination of wax granulation and tableting markedly retarded drug release. In the multi-unit dose formulations where the conventional and wax granulations were mixed in the ratios 2:1, 1:1 and 1:2 (conventional: matrix), the m infinity and t infinity values for the capsules were (378 mg, 6 h), (326 mg, 6 h) and (272 mg, 7 h), reSpectively. The corresponding values of m infinity and t infinity for the tablets were (240 mg, 9 h), (180 mg, 11 h) and (128 mg, 12 h) against the set target (200 mg, 12 h). The indication is that tableting rather than encapsulation can more effectively control drug release from the systems.     

Preparation of Coated Valproic Acid and Sodium Valproate Sustained-release Matrix Tablets

The aim of this research was to investigate the technique for preparation of coated valproic acid and sodium valproate sustained-release matrix tablets. Different diluents were tested and selected as the effective absorbent for oily valproic acid. Effect of the amount of absorbent and hydroxypropylmethylcellulose on drug release from valproic acid-sodium valproate matrix tablets prepared with wet granulation technique was evaluated in pH change system. Colloidal silicon dioxide effectively adsorbed liquid valproic acid during wet granulation and granule preparation. The amounts of colloidal silicon dioxide and hydroxypropylmethylcellulose employed in tablet formulations affected drug release from the tablets. The drug release was prominently sustained for over 12 h using hydroxypropylmethylcellulose-based hydrophilic matrix system. The mechanism of drug release through the matrix polymer was a diffusion control. The drug release profile of the developed matrix tablet was similar to Depakine Chrono^®, providing the values of similarity factor (f2) and difference factor (f1) of 85.56 and 2.37, respectively. Eudragit^® L 30 D-55 was used as effective subcoating material for core matrix tablets before over coating with hydroxypropylmethylcellulose film with organic base solvent. Drug release profile of coated matrix tablet was almost similar to that of Depakine Chrono^®.     

Modulation of drug release kinetics of shellac-based matrix tablets by in-situ polymerization through annealing process.

A new oral-controlled release matrix tablet based on shellac polymer was designed and developed, using metronidazole (MZ) as a model drug. The shellac-based matrix tablets were prepared by wet granulation using different amounts of shellac and lactose. The effect of annealing temperature and pH of medium on drug release from matrix tablets was investigated. The increased amount of shellac and increased annealing temperature significantly affected the physical properties (i.e., tablet hardness and tablet disintegration) and MZ release from the matrix tablets. The in-situ polymerization played a major role on the changes in shellac properties during annealing process. Though the shellac did not dissolve in acid medium, the MZ release in 0.1N HCl was faster than in pH 7.3 buffer, resulting from a higher solubility of MZ in acid medium. The modulation of MZ release kinetics from shellac-based matrix tablets could be accomplished by varying the amount of shellac or annealing temperature. The release kinetics was shifted from relaxation-controlled release to diffusion-controlled release when the amount of shellac or the annealing temperature was increased.     

An Investigation into Formulation and Processing Strategies to Drive Gastroretention of Gabapentin Tablets

Purpose

The aim of the present work was to develop gastroretentive drug delivery system of gabapentin from different matrices prepared by hot melt or conventional wet granulation, which may enhance drug bioavailability. The influence of core type, granulation process, and coating level on the drug release rates was investigated.

Methods

Tablet cores were prepared from hydrophilic system of hypermellose, carboxy melthyl celloulse, and Avicel or hydrophobic system of ethyl cellulose, alginic acid, and stearic acid. The tablets were coated by Eudragit RL with triethyl citrate and compressed directly. These tablets were evaluated according to their in vitro dissolution profiles and release mechanisms.

Results

Hydrophobic matrices allowed the control of drug release. Hot melt granulation was an effective tool over wet granulation or coating for slowing release rates from hydrophobic tablets. Both hydrophobic polymer ratio and coating level influenced the drug release mechanism. The drug release of samples with minor proportion of ethyl cellulose and stearic acid or low Eudragit RL level was driven by anomalous transport and the increase of their proportions contributed to the erosion of the matrix.

Conclusions

Hydrophobic core tablet prepared from hot melt granulation and coated by Eudragit RL has shown to be a promising formulation intended to gastroretentive gabapentin delivery system.

     

Design of pH-independent extended release matrix tablets of minocycline hydrochloride for the treatment of dementia

The aim of this study was to develop a pH-independent extended release matrix tablet of minocycline HCl for the treatment of dementia. The matrix tablets were prepared by wet granulation technique using Eudragit L and S as release modifiers at different w/w ratios (1:0, 1:1 and 0:1) and PEO as a matrix former. In the case of the matrix tablet without any release modifiers, the drug release rate at pH 1.2 was much higher than that of pH 7.4. By adding the release modifier, the drug release rate at pH 7.4 increased close to that of pH 1.2 and the pH-independent release was obtained. In addition, it was shown that lubricants containing a divalent cation such as Mg stearate inhibited minocycline release in basic medium. Therefore, the incorporation of Eudragit L and S (1:1 ratio) as release modifiers and Na stearyl fumarate as a lubricant into PEO-based matrix tablets effectively produced pH-independent minocycline release profiles.     

Solid-state plasticization of an acrylic polymer with chlorpheniramine maleate and triethyl citrate

The influence of in situ plasticization of chlorpheniramine maleate (CPM) on Eudragit RS PO from hot-melt extruded matrix tablets, and from compressed granules prepared by thermal processing was investigated. CPM was studied as both a model drug substance and as a solid-state plasticizer for the acrylic polymer. Triethyl citrate (TEC) was incorporated into the polymer blend as a liquid plasticizer for the polymer. The influence of TEC and CPM concentration on the dissolution properties of CPM tablets was investigated. The glass transition temperature (T(g)) of the samples was determined by modulated differential scanning calorimetry (MDSC). The morphologies of the granules formed by hot-melt extrusion and hot-melt granulation processes were investigated by scanning electron microscopy. The addition of 12% TEC to the polymer reduced the T(g) by 32.5 degrees C, while the reduction in the T(g) for the same level of CPM was 16.4 degrees C. The effect of TEC levels on drug release was dependent on the tablet preparation method. At high TEC levels, the release rate of CPM decreased in tablets prepared by direct compression and tablets made from compressed granules that had been prepared by high shear hot-melt granulation. However, the CPM release rate increased from hot-melt extruded tablets with increasing blends of plasticizer in the extruded tablets. An increase in the CPM content in the tablets resulted in an increase in the drug release rate. During high shear hot-melt granulation, the model drug adhered to the polymer to form a porous discontinuous structure. Following hot-melt extrusion, the drug was distributed at a molecular level in the continuous polymeric structure. The influence of both CPM and TEC levels on the drug release rate from these polymeric drug delivery systems was shown to be a function of whether the granules or tablets were formed by either hot-melt granulation or hot-melt extrusion, as well as the plasticization effects of both TEC and CPM on the acrylic polymer.     

Evaluation of honey locust (Gleditsia triacanthos Linn.) gum as sustaining material in tablet dosage forms

In this study, honey locust gum (HLG) obtained from Gleditsia triacanthos (honey locust) beans was investigated as a hydrophilic matrix material in the tablets prepared at different concentrations (5% and 10%) by wet granulation method. Theophylline was chosen as a model drug. The matrix tablets containing hydroxyethylcellulose and hydroxypropyl methylcellulose as sustaining polymers at the same concentrations were prepared and a commercial sustained release (CSR) tablet containing 200 mg theophylline was examined for comparison of HLG performance. Physical analysis on CSR tablet, matrix tablets and their granules before compression were performed. According to the results obtained from dissolution studies in distilled water, pH 1.2 HCl buffer and pH 7.2 phosphate buffer, no significant difference was found between CSR tablet and the matrix tablet containing 10% HLG in each medium (P > 0.05) and these tablets showed zero-order kinetic model in all the mediums.     

The Influence of Thermal Treatment on the Physical-Mechanical and Dissolution Properties of Tablets Containing Poly(DL-Lactic Acid)

Five molecular weight grades of poly(DL-lactic acid) (PLA) were incorporated as organic and aqueous pseudolatex binders into matrix tablet formulations containing microcrystalline cellulose and the model drug theophylline. The tablets were thermally treated to temperatures above and below the glass transition temperature (T _g) of the PLA. The results of the dissolution studies showed that thermally treating the tablets to temperatures above the T _g of the PLA significantly retarded the matrix drug release compared to tablets which were not thermally treated. The retardation in drug release could be attributed to a stronger compact and a more efficient redistribution of polymer throughout the tablet matrix, based on fundamental principles of annealing. In addition, results from tablet index testing supported the dissolution results. The bonding index of the compact formulations increased after thermal treatment above the T _g of the PLA. Gel permeation chromatography and differential scanning calorimetry studies demonstrated that thermal treatment had no significant effect on the molecular weight and the glass transition temperature of (PLA) alone and in combination with other components of the tablet formulation.     

Physicochemical properties and mechanism of drug release from ethyl cellulose matrix tablets prepared by direct compression and hot-melt extrusion

The objective of this research project was to determine the physicochemical properties and investigate the drug release mechanism from ethyl cellulose (EC) matrix tablets prepared by either direct compression or hot-melt extrusion (HME) of binary mixtures of water soluble drug (guaifenesin) and the polymer. Ethyl cellulose was separated into "fine" or "coarse" particle size fractions corresponding to 325-80 and 80-30 mesh particles, respectively. Tablets containing 30% guaifenesin were prepared at 10, 30, or 50 kN compaction forces and extruded at processing temperatures of 80-90 and 90-110 degrees C. The drug dissolution and release kinetics were determined and the tablet pore characteristics, tortuosity, thermal properties and surface morphologies were studied using helium pycnometry, mercury porosimetry, differential scanning calorimetry and scanning electron microscopy. The tortuosity was measured directly by a novel technique that allows for the calculation of diffusion coefficients in three experiments. The Higuchi diffusion model, Percolation Theory and Polymer Free Volume Theory were applied to the dissolution data to explain the release properties of drug from the matrix systems. The release rate was shown to be dependent on the ethyl cellulose particle size, compaction force and extrusion temperature.     

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 (Tg) 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 Tg 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 degrees C for 30 days.     

Formulation and evaluation of dextromethorphan hydrobromide sustained release tablets

Sustained release (SR) matrix tablets of dextromethorphan hydrobromide were prepared by wet granulation using hydroxypropyl methyl cellulose (HPMC-K-100 CR) as the hydrophilic rate controlling polymer. The effect of the concentration of the polymer and different fillers on the in vitro drug release rate was studied. The studies indicated that the drug release can be modulated by varying the concentration of the polymer and the fillers. A complete cross-over bioavailability study of the optimized formulation of the developed sustained tablets and marketed immediate release tablets was performed on six healthy male volunteers. The extent of absorption of drug from the SR tablets was significantly higher than that for the marketed dextromethorphan hydrobromide tablet because of lower elimination rate and longer half-life.