The influence of four selected processing and formulation factors on the production of spheres by extrusion and spheronisation

In Situ Co-Amorphization of Olanzapine in the Matrix and on the Coat of Pellets

In situ amorphization is a promising approach, considered in the present work, to enhance the solubility and dissolution rate of olanzapine, while minimizing the exposure of the amorphous material to the stress conditions applied during conventional processing. The production of pellets by extrusion/spheronization and the coating of inert beads were investigated as novel methods to promote the co-amorphization of olanzapine, a poorly water-soluble drug, and saccharin. Samples were characterized using differential scanning calorimetry, X-ray powder diffraction, Fourier-transform infrared spectroscopy and scanning electron microscopy, and dissolution and stability testing. The co-amorphous produced were compared with crystalline olanzapine, or physical mixture of olanzapine and saccharin. Results suggested that the addition of water to mixtures containing olanzapine and saccharin during the production of pellets, and the coating of inert beads, induced the in situ co-amorphization of these substances. The coating of inert beads enhanced the solubility and dissolution rate of olanzapine, especially when compared to pellets coated with the crystalline drug, but also with pellets containing the co-amorphous entity in the matrix of beads. Nine months stability tests (23 °C/60% RH) confirmed the preservation of the solid-state properties of the co-amorphous form on/in pellets. Overall, results highlighted the feasibility and benefits of in situ co-amorphization, either when the drug was entrapped in the pellets matrix, or preferentially applied directly on the surface of pellets.

Liquisolid Technology: A State-of-the-Art Review on the Current State, Challenges, New and Emerging Technologies for Next Generation

Nowadays, the focus has been shifted to new technologies for improving drug solubility, permeability, and bioavailability, amid unprecedentedly increasing the number of newly discovered Active Pharmaceutical Ingredients (APIs), which are mostly categorized under Biopharmaceutical Classification System (BCS) as class-II and class IV. Traditional technologies and classical formulation strategies often fail to address most of the formulation problems associated with new APIs, particularly solubility and bioavailability. Therefore, exploring new and innovative technologies on an industrial scale is a prerequisite and requires modernization of manufacturing processes, as well as more advanced research and development. Liquisolid technology is a new, innovative industrial technology, particularly designed for either improving the release rates of poorly absorbed drugs or controlling their release pattern by achieving sustained-release profiles with zero-order release kinetics. Besides, it is a promising photoprotective system for photosensitive drugs and can further be used for modulating the drug microenvironmental pH. The next generation of liquisolid systems stems from a set of emerging technologies, such as liqui-pellet technology, which originates from combining liquisolid technology with pelletization technique, particularly extrusion-spheronization technique. This review article highlights the current state of liquisolid technology, ongoing challenges, characterization and applications, possible future prospects, the advent of new and emerging technologies, and the revolution of the next generation of liquisolid technology.

Elucidation of mass transfer mechanisms in pellet formation by spheronization

Previously published mechanisms of pellet formation during extrusion-spheronization include a transfer of material between different granules. This research aimed to specify the origin of this transfered mass, enabling further insight into the extrusion-spheronization process. Granules of various diameters were rounded simultaniously in a spheronizer to ascertain if mass transfer between smaller and larger granules is truly in balance, or if mass transfer from smaller to larger granules is preferred. Granules were also marked with a fluorescent tracer to enable quantification of mass transfer. By using differently sized and shaped granules as starting material, different modes of mass transfer were investigated. Samples were taken after various process durations to investigate the kinetics of the tranfer mechanism. It was found that both small and large granules dispense and receive mass during spheronization. In general, small granules increase their size, while large granules maintain their size or show a slight size decrease, resulting in the particularly narrow monomodal size distribution.

Liqui-Pellet: the Emerging Next-Generation Oral Dosage Form Which Stems from Liquisolid Concept in Combination with Pelletization Technology

In spite of the major advantages that the liquisolid technology offers, particularly in tackling poor bioavailability of poorly water-soluble drugs (i.e., BCS Class II drugs), there are a few critical drawbacks. The inability of a high liquid load factor, poor flowability, poor compactibility, and an inability to produce a high dose dosage form of a reasonable size for swallowing are major hurdles, hampering this technology from being commercially feasible. An attempt was therefore made to overcome these drawbacks whilst maintaining the liquisolid inherent advantages. This resulted in the emerging next generation of oral dosage forms called the liqui-pellet. All formulations were incorporated into capsules as the final product. Solubility studies of naproxen were conducted in different liquid vehicles, namely polyethylene glycol 200, propylene glycol, Tween 80, Labrafil, Labrasol, and Kolliphor EL. The scanning electron microscopy studies indicated that the liquid vehicle tends to reduce the surface roughness of the pellet. X-ray powder diffraction (XRPD) indicated no significant differences in the crystalline structure or amorphous content between the physical mixture and the liqui-pellet formulation. This was due to the presence of a high concentration of amorphous Avicel in the formulation which overshadowed the crystalline structure of naproxen in the physical mixtures. Flowability and dissolution tests confirmed that this next-generation oral dosage form has excellent flowability, whilst maintaining the typical liquisolid enhanced drug release performance in comparison to its physical mixture counterpart. The liqui-pellet also had a high liquid load factor of 1, where ~ 29% of the total mass was the liquid vehicle. This shows that a high liquid load factor can be achieved in a liqui-pellet without compromising flowability. Overall, the results showed that the poor flowability of a liquisolid formulation could be overcomed with the liqui-pellet, which is believed to be a major advancement into the commercial feasibility of the liquisolid concept.

Upgrading wet granulation monitoring from hand squeeze test to mixing torque rheometry

With over 50 years of research in granulation technology, however more research is required to elucidate this widely applicable technology. Wetting phenomena could influence redistribution of individual ingredients within a granule according their solubility and also could affect the drying processes. Binder selection for a particular system is quite often empirical and dependent on the skills and experience of the formulator. Hand squeeze test was and still the main way for determination of wet granulation end point, but it is subjected to individual variation. It depends mainly on operator experience, so it is not possible to be validated. Literature reveals a variety of advanced monitoring techniques following up different wet massing stages. Torque measurement has been proved to be the most reliable control method as its tight relation to mass resistance. Many reports showed successful applications of mixing torque rheometer (MTR) for monitoring the wet massing procedure and scale up in addition to some preformulation applications. MTR as a new approach allows formulators to select a liquid addition range where the granule growth behavior is more predictable.

Preparation and In Vitro Evaluation of pH, Time-Based and Enzyme-Degradable Pellets for Colonic Drug Delivery

The preparation of pH-dependent, time-based and enzyme degradable pellets was investigated for use as an oral colonic drug delivery system. It was expected that drug would be released immediately once the pellets reached the colon. The pellets were prepared using extrusion-spheronizing equipment and subsequently coated with three layers of three functional polymers by an air-suspension technique. The core consisted of 5-aminosalicylic acid (5-ASA) as a model drug, CaP as an enzyme-degradable material and microcrystalline cellulose (MCC) as an additive. As far as the three coated layers were concerned, the outer layer was coated with Eudragit L30D-55 for protection against gastrointestinal juices, the intermediate layer was coated with ethylcellulose (EC) to inhibit drug release during passage through the small intestine, and the inner film was coated with pectin for swelling and enzyme-degradation, which required a 30, 10, and 12% weight gain, respectively. Several micromeritic properties of the core pellets, including particle size distribution, particle size, degree of circularity, and friability, were evaluated to investigate the effects of the formulations of the cores and preparation conditions. Also, dissolution testing of the cores showed that the presence of calcium pectinate (CaP) markedly increased the drug release rate from the cores, as determined by scanning electron microscopy (SEM). In-vitro release studies indicated that the coated pellets completely protected the drug release in 0.1 mol/L HCl, while the drug release was delayed for 3-4 hr in pH 6.8 PBS. A synergistic effect of enzyme dependence for the coated pellets was seen following removal of the coated layer and during contact with colonic enzymes. Consequently, it was possible to achieve colon-specific drug delivery using this triple-dependence system.

Fast and Controlled Release of Triamcinolone Acetonide from Extrusion-Spheronization Pellets Based on Mixtures of Native Starch with Dextrin or Waxy Maize Starch

Pellets composed chiefly of inexpensive starches allow modulation of the rate of release of the poorly soluble drug triamcinolone acetonide in media of pH 1.2-6.8. Wheat- or maize-starch-based pellets with 20% of white dextrin release the drug in vitro almost completely within 20 min, while maize-starch-based pellets with 5-35% of waxy maize starch sustain gradual release over periods of 9-12 hr or longer when prepared using appropriate amounts of granulation fluid.

A comparative study of the utility of two superdisintegrants in microcrystalline cellulose pellets prepared by extrusion–spheronization

This study evaluated the utility of including superdisintegrants (croscarmellose sodium or sodium starch glycolate) in microcrystalline cellulose extrusion-spheronization pellets as a means of increasing the dissolution rate of poorly water-soluble drugs. The model drug was hydrochlorothiazide, with water or water/ethanol as wetting agent for pellet preparation. Neither disintegrant had significant effects on pellet morphology, flow properties or mechanical resistance. Neither disintegrant caused disintegration of the pellet in drug dissolution medium. Nevertheless, the disintegrants afforded a modest increase in drug dissolution rate, attributable to the observed increase in pellet micropore volume. Drug dissolution rate was slightly higher in pellets prepared with sodium starch glycolate, probably because of this disintegrant's higher swelling capacity.

A Novel Preformulation Tool to Group Microcrystalline Celluloses Using Artificial Neural Network and Data Clustering

PURPOSE

To group microcrystalline celluloses (MCCs) using a combination of artificial neural network (ANN) and data clustering.

METHODS

Radial basis function (RBF) network was used to model the torque measurements of the various MCCs. Output from the RBF network was used to group the MCCs using a data clustering technique known as discrete incremental clustering (DIC). Rheological or torque profiles of various MCCs at different combinations of mixing time and water:MCC ratios were obtained using mixer torque rheometry (MTR). Correlation analysis was performed on the derived torque parameter Torque(max) and physical properties of the MCCs.

RESULTS

Depending on the leniency of the predefined threshold parameters, the 11 MCCs can be assigned into 2 or 3 groups. Grouping results were also able to identify bulk and tapped densities as major factors governing water-MCC interaction. MCCs differed in their water retentive capacities whereby the denser Avicel PH 301 and PH 302 were more sensitive to the added water.

CONCLUSIONS

An objective grouping of MCCs can be achieved with a combination of ANN and DIC. This aids in the preliminary assessment of new or unknown MCCs. Key properties that control the performance of MCCs in their interactions with water can be discovered.

Time- and pH-dependent colon-specific drug delivery for orally administered diclofenac sodium and 5-aminosalicylic acid

AIM: To investigate Time- and pH-dependent colon-specific drug delivery systems (CDDS) for orally administered diclofenac sodium (DS) and 5-aminosalicylic acid (5-ASA), respectively.

METHODS: DS tablets and 5-ASA pellets were coated by ethylcellulose (EC) and methacrylic acid copolymers (Eudragit^® L100 and S100), respectively. The in vitro release behavior of the DS coated tablets and 5-ASA coated pellets were examined, and then in vivo absorption kinetics of DS coated tablets in dogs were further studied.

RESULTS: Release profile of time-dependent DS coated tablets was not influenced by pH of the dissolution medium, but the lag time of DS release was primarily controlled by the thickness of the coating layer. The thicker the coating layer, the longer the lag time of DS release is. On the contrary, in view of the pH-dependent 5-ASA coated pellets, 5-ASA release was significantly governed by pH. Moreover, the 5-ASA release features from the coated pellets depended upon both the combination ratio of the Eudragit^® L100 and S100 pH-sensitive copolymers in the coating formulation and the thickness of the coating layer. The absorption kinetic studies of the DS coated tablets in dogs demonstrated that in vivo lag time of absorption was in a good agreement with in vitro lag time of release.

CONCLUSION: Two types of CDDS, prepared herein by means of the regular coating technique, are able to achieve site-specific drug delivery targeting at colon following oral administration, and provide a promising strategy to control drug release targeting the desired lower gastrointestinal region.

Extruded and Spheronized Beads Containing No Microcrystalline Cellulose: Influence of Formulation and Process Variables

The purposes of this study were to investigate the use of chitosan in the manufacture of beads by extrusion-spheronization without inclusion of microcrystalline cellulose, and to study the effect of formulation and process variables on the characteristics of the beads. Beads containing chitosan, fine particle ethylcellulose, hydroxypropyl methylcellulose (HPMC), and caffeine as the model drug were manufactured. Bead size, yield, shape, friability, density, porosity, and release studies were determined. Spherical beads with good mechanical properties could be manufactured without microcrystalline cellulose. Release studies showed that there was immediate release of drug from the beads. A five factor, half fraction screening design was employed to study the effect of formulation variables and process variables on the properties of the beads. Statistical analysis indicated that formulation variables such as the chitosan content, HPMC content, and water content, and process variables such as the spheronizer speed and extruder speed significantly affected the physical properties of the beads. The bead size decreased with an increase in chitosan content. Significant two-factor interactions exist between the variables for several of the measured responses. Beads with high percentage yield and high sphericity can be obtained at high chitosan content, and low HPMC content, water content, spheronizer speed, and extruder speed. Less friable beads can be obtained at high levels of studied formulation variables and low levels of studied process variables. Beads of high density and low porosity can be manufactured at high levels of the studied formulation and process variables. Regression equations were generated using Statgraphics Plus software that can be used to develop formulations with desired bead properties. Chitosan was useful to provide beads of acceptable physical properties using water as a granulating fluid in the extrusion-spheronization process.

Image Analysis of the Shape of Granulated Powder Grains

This study presents and evaluates two new form factors for the characterization of pharmaceutical microparticles using image analysis techniques. The first factor, denoted Vr, is mean percentage variation in radial chord length (for a large number of radial chords drawn at small angular intervals) with respect to mean radial chord length. The second factor, denoted Vp, is percentage deviation of measured perimeter from the perimeter of a circle with radius equal to the mean radial chord length of the particle. Considering both ideal shapes and real pharmaceutical particle populations, these factors are compared with other form factors widely used in pharmaceutical technology. Our results indicate that Vr and Vp allow effective assessment of whether the particles of a given population show pharmaceutically significant deviations from sphericity. The two factors additionally facilitate identification of the basic shapes of particle outlines (notably ellipsoid, rectangular, and irregular). These factors may thus be of value for the characterization and monitoring of pharmaceutical pelleting processes.

Development of 400 µm Pellets by Extrusion‐Spheronization Application with Gelucire 50/02 to Produce a “Sprinkle” Form

The aim of this study was to develop monodimensional, spherical particles of 400 microm by extrusion-spheronization. An Alexanderwerk GA65 cylinder extruder with two counter-rotating rollers associated with a Caleva model 15 spheronizer were used. The study was made with an auxiliary substance of fatty consistency and with amphiphilic properties: Gelucire 50/02. The plasticity of the mass can be deduced using a piston extruder. Pellet quality can be determined by particle-size analysis and shape estimation by microscopy. Modifications to the cylinders and the extruder itself are required for feasibility studies of extruded materials of 400 microm. The horizontal plate of the spheronizer had to be adapted to take into account the small size of the extruded materials. For the chosen auxiliary substance, Gelucire 50/02, the formulation of the wet mass to be extruded and the conditions required to obtain this mass were defined. The results show the feasibility of 400 microm pellets with Gelucire 50/02. At least 90% of the pellets have a particle size of between 250 microm and 500 microm and particle shape is acceptable. In this form the dose can be adapted to individual patients. After proving the feasibility of 400 microm spheroids of Gelucire 50/02, the association of a drug with it was considered.

Powdered cellulose as excipient for extrusion-spheronization pellets of a cohesive hydrophobic drug

This study compared a powdered cellulose (PC) and a microcrystalline cellulose (MCC) as sole excipients in the preparation of furosemide pellets by extrusion-spheronization. Pellets prepared with PC and 25 or 50% furosemide showed smaller mean size, a broader particle size distribution, similar sphericity, greater surface roughness and higher friability than equivalent pellets prepared with MCC. Furosemide release rate was markedly higher from PC pellets, which may be attributable to their higher micropore volume.

Production of inert cushioning beads: effect of excipients on the physicomechanical properties of freeze-dried beads containing microcrystalline cellulose produced by extrusion-spheronization

Conventional highly compactible fillers such as microcrystalline cellulose (MCC) can be mixed with drug-loaded membrane-coated beads and compressed to form a tablet. However, due to particle size differences, there is substantial risk of segregation leading to weight variation and content uniformity problems. Furthermore, whenever modified release beads are included in a tablet matrix, care must be taken to assure the integrity of the coated beads. This paper describes the development of placebo beads containing MCC whose properties make them uniquely suitable for tableting modified release beads. These placebo beads have high compactibility and the ability to rapidly disintegrate. They deform readily and may provide a high degree of protection to drug-loaded membrane-coated beads during compression ('cushioning effect'). They can be produced in size ranges that provide minimal segregation propensity. Beads containing different MCC/lactose ratios and different types and levels of superdisintegrants were produced by extrusion-spheronization followed by freeze drying. The presence of high levels of MCC and different superdisintegrants, especially croscarmellose sodium, increased the granulation liquid requirement, thus producing freeze-dried beads with higher porosities and compactibility. Athy-Heckel analysis studies revealed that beads rich in MCC exhibited lower mean yield pressures than those containing high levels of lactose. The freeze-dried beads exhibited both plastic deformation and brittle fracture characteristics.

Micromeritic and packing properties of diclofenac pellets and effects of some formulation variables

The effects of two common diluents (microcrystalline cellulose and calcium phosphate dihydrate), two binding agents (gelatin and methacrylic polymer), and spheronization on the micromeritic (size, shape, density), flow, and packing properties of sodium diclofenac pellets were examined. The shape was assessed as the aspect ratio and was correlated to the flow rate and to the deviation of the tapped porosity from the value of 26%, which corresponds to the ideal rhombohedral packing of spheres. It was found that porosity deviation decreased greatly with spheronization, but it increased with hinder addition. Porosity deviation was proportional to the aspect ratio, while flow rate decreased logarithmically with porosity deviation. Porosity deviation may be a useful index for monitoring the quality of pellets, similar to the aspect ratio, as a successful, simple, and indirect indication of sphericity and of surface roughness as well.

Multiunit controlled-release diclofenac sodium capsules using complex of chitosan with sodium alginate or pectin

This study explored the application of chitosan-alginate (CA) and chitosan-pectin (CP) complex films as drug release regulator for the preparation of multiunit controlled-release diclofenac sodium capsules. Pellets containing drug and microcrystalline cellulose, in a ratio of 3:5, were prepared in a fluidized rotary granulator. The pellets were coated with CA, CP, sodium alginate, pectin, and chitosan solutions. The pellets, equivalent to 75 mg drug, were filled into capsules. After 2 h of dissolution test in acidic medium, the amount of the drug released from any preparation was negligible. The pellets were further subject to pH 6.8 phosphate buffer More than 80% drug release at 12 h was observed with the uncoated pellets and those coated with sodium alginate, pectin or chitosan. Both 1% CA and 3% CP coated pellets exhibited drug release profiles similar to that of Voltaren SR75. It was found that approximately 60% and 85% of the drug were released at 12 and 24 h, respectively. Both Differential thermal analysis (DTA) and Fourier transform infrared spectroscopy (FTIR) analyses revealed complex formation between chitosan and these anionic polymers. It could be concluded that CA and CP complex film could be easily applied to diclofenac sodium pellets to control the release of the drug.

Optimization of the pelletization process in a fluid-bed rotor granulator using experimental design

This study examined the effect of rotor speed, amount of water sprayed, and atomizing air pressure on the geometric mean diameter and geometric standard deviation of pellets produced in a fluid-bed rotor granulator using a 23 factorial design and an optimization technique. Pellets were prepared by wet granulation. Equal amounts of microcrystalline cellulose, alpha-lactose monohydrate, and distilled water were used as the granulation liquid. The size and the size distribution of the pellets were determined by sieve analysis. The size of the pellets was found to be dependent on the amount of water added, while an increase in rotor speed decreased their size. Both factors were found to be statistically significant (P <.05). The effect of atomizing air pressure on pellet size was not statistically significant. None of the 3 factors significantly affected the geometric standard deviation of the pellets. The rotor speed and the amount of water sprayed were further selected in order to construct a mathematical model that correlates these factors with the geometric mean diameter of the pellets. For this purpose, the optimization technique 3(2) was used. The derived equation described the relationship between the selected factors and the size of the pellets. As a result, the experimental design techniques applied were found to be suitable in optimizing the pelletization process carried out in a fluid-bed rotor granulator.

Use of cellulose ether containing excipients with microcrystalline cellulose for the production of pellets containing metformin hydrochloride by the process of extrusion-spheronization

The project is concerned mainly with the evaluation of two cellulose ether containing excipients, Aquacoat WG and Avicel 955 MCC for the improved extrusion-spheronization of metformin hydrochoride. Factorially designed experiments subject to statistical analyses were employed and products obtained were evaluated by sieve, packing density and image analysis, scanning electron microscopy and dissolution testing at pH 6.8. Aquacoat WG did not improve the ease of spheronization of drug mixes containing microcrystalline cellulose wetted with the optimum level of water. However, Avicel 955 MCC, which is a new experimental excipient containing 95% microcrystalline cellulose and 5% methylcellulose, did aid ease of spheronization facilitating acceptable yield of good spheres with high drug loadings (70%). Avicel 955 MCC containing drug mixes were more tolerant to minor alterations in level of hydration and yielded spheres which showed a small retardation of drug release despite the very high solubility of metformin hydrochloride.

The power-consumption-controlled extruder: a tool for pellet production

Based on the assumption that there is a link between power consumption of an extruder and pellet properties, a control circuit for power consumption was developed. Powder and granulation liquid are fed separately into a twin-screw extruder. The power consumption is controlled by varying the pump rate at a given powder-feed rate; consequently each level of power consumption results in a specific water content of the extrudate for a particular formulation. The shape of pellets depends almost entirely on the level of power consumption irrespective of formulation. The size of dry pellets is additionally affected by a shrinking factor which depends on the water content. The power-consumption-controlled extruder is an appropriate tool for the production of pellets. The system is able to adapt the water content for a formulation automatically.