Some factors influencing pellet characteristics made by an Extrusion/Spheronisation process Part I.: Effects on size characteristics and moisture content decrease of pellets

Producing High-Dose Liqui-Tablet (Ketoprofen 100 mg) for Enhanced Drug Release Using Novel Liqui-Mass Technology

Purpose

Liqui-Tablet is a dosage form derived from Liqui-Mass technology. It has proven to be a promising approach to improve drug dissolution rate of poorly water-soluble drugs. So far, Liqui-Tablet is feasible for low-dose drugs. In this study, an attempt was made to produce high-dose Liqui-Tablet, whilst maintaining ideal physicochemical properties for ease of manufacturing.

Methods

Liqui-Tablets containing 100 mg of ketoprofen were produced using various liquid vehicles including PEG 200, Span 80, Kolliphor EL, PG, and Tween 85. Investigations that were carried out included saturation solubility test, dissolution test, tomographic study, and typical quality control tests for assessing flowability, particle size distribution, friability, and tablet hardness.

Results

The weight of these Liqui-Tablets was acceptable for swallowing (483.8 mg), and the saturation solubility test showed PEG 200 to be the most suitable liquid vehicle (493 mg/mL). Tests investigating physicochemical properties such as flowability, particle size distribution, friability, and tablet hardness have shown no issue concerning quality control and manufacturability. The drug release test of the best formulation has shown extremely rapid drug release at pH 7.4 (100% after 5 min). At pH 1.2 the drug release was reasonable considering the formulation was yet to be optimized.

Conclusion

Despite the high amount of API and liquid vehicle, it is possible to produce a high-dose dosage form with acceptable size and weight for swallowing using the novel Liqui-Mass technology. This has the potential to diversify the technology by removing the restriction of high dose drug that has been seen in liquisolid technology.

Modelling the Effect of Process Parameters on the Wet Extrusion and Spheronisation of High-Loaded Nicotinamide Pellets Using a Quality by Design Approach

The aim of the present study was to develop an alternative process to spray granulation in order to prepare high loaded spherical nicotinamide (NAM) pellets by wet extrusion and spheronisation. Therefore, a quality by design approach was implemented to model the effect of the process parameters of the extrusion-spheronisation process on the roundness, roughness and useable yield of the obtained pellets. The obtained results were compared to spray granulated NAM particles regarding their characteristics and their release profile in vitro after the application of an ileocolon targeted shellac coating. The wet extrusion-spheronisation process was able to form highly loaded NAM pellets (80%) with a spherical shape and a high useable yield of about 90%. However, the water content range was rather narrow between 24.7% and 21.3%. The design of experiments (DoE), showed that the spheronisation conditions speed, time and load had a greater impact on the quality attributes of the pellets than the extrusion conditions screw design, screw speed and solid feed rate (hopper speed). The best results were obtained using a low load (15 g) combined with a high rotation speed (900 m/min) and a low time (3⁻3.5 min). In comparison to spray granulated NAM pellets, the extruded NAM pellets resulted in a higher roughness and a higher useable yield (63% vs. 92%). Finally, the coating and dissolution test showed that the extruded and spheronised pellets are also suitable for a protective coating with an ileocolonic release profile. Due to its lower specific surface area, the required shellac concentration could be reduced while maintaining the release profile.

Use of extrusion aids for successful production of Kollidon® CL-SF pellets by extrusion-spheronization

OBJECTIVE

Fine particle ethylcellulose (FPEC) or poly(ethylene oxide) (PEO) addition to a Kollidon CL-SF was investigated to address low yield and poor sphericity in extruded-spheronized pellets.

SIGNIFICANCE

The success of crospovidone as a diluent in extrusion-spheronization was dependent on a small particle size of the polymer. FPEC aided production of rugged and spherical pellets using a large particle size grade, Polyplasdone^® XL. PEO acted as an extrusion-spheronization aid when ethylcellulose was the diluent. These extrusion-spheronization aids could serve in this role when Kollidon^® CL-SF (K CL-SF) is the diluent.

METHODS

The influence of formulation and process variables on pellet properties was investigated using design of experiments. A planetary mixer was used to prepare powder blends and the wetted mass after addition of water. An EXD 60 extruder produced extrudate that was spheronized in a Q230 marumerizer. Wet pellets were dried in a forced-air oven.

RESULTS

FPEC improved rounding up but reduced pellet yield. Poly(ethylene oxide) imparted desired characteristics to the wetted mass, the extrudate, and the spheronized pellets. Pellet average diameter, yield, sphericity, aspect ratio, friability, and dissolution profile were assessed. Equations for pellet characteristics facilitated discussion of the influences of factors and their interactions. Optimization was performed on pellets that included PEO.

CONCLUSIONS

PEO proved to be an exceptional extrusion-spheronization aid in the preparation of pellets using K CL-SF. It facilitated wetted mass extrusion with minimal mass loss to the extruder, and markedly improved the sphericity of the pellets produced by marumerization. Immediate release pellets were obtained.

A Quality by Experimental Design Approach to Assess the Effect of Formulation and Process Variables on the Extrusion and Spheronization of Drug-Loaded Pellets Containing Polyplasdone® XL-10

Successful pellet production has been reported in literature with cross-linked poly(vinylpyrrolidone), Polyplasdone® XL-10 and INF-10. In the present study, a quality by experimental design approach was used to assess several formulation and process parameter effects on the characteristics of Polyplasdone® XL-10 pellets, including pellet size, shape, yield, usable yield, friability, and number of fines. The hypothesis is that design of experiments and appropriate data analysis allow optimization of the Polyplasdone product. High drug loading was achieved using caffeine, a moderately soluble drug to allow in vitro release studies. A five-factor, two-level, half-fractional factorial design (Resolution V) with center point batches allowed mathematical modeling of the influence of the factors and their two-factor interactions on five of the responses. The five factors were Polyplasdone® level in the powder blend, volume of water in the wet massing step, wet mixing time, spheronizer speed, and spheronization time. Each factor and/or its two-factor interaction with another factor influenced pellet characteristics. The behavior of these materials under various processing conditions and component levels during extrusion-spheronization have been assessed, discussed, and explained based on the results. Numerical optimization with a desirability of 0.974 was possible because curvature and lack of fit were not significant with any of the model equations. The values predicted by the optimization described well the observed responses. The hypothesis was thus supported.

Production and characterization of pellets using Avicel CL611 as spheronization aid

PURPOSE

The study looked into the feasibility of producing pellet using Avicel CL611 as spheronization aid by the extrusion/spheronization technique.

METHODS

Pellets were formulated to contain either 20% or 40% Avicel CL611 and lactose monohydrate as the other sole ingredient. Water is used as liquid binder. Quality of pellets and extrudates were analyzed for size distribution, shape, surface tensile strength and disintegration profile.

RESULTS

More water was needed when higher Avicel CL611 fraction was used during the production of pellets. The pellets of larger size were obtained by increasing the water content. Pellets with aspect ratios of ∼1.1 were produced with high spheronization speed at short residence time. Higher tensile strength was achieved when increasing the water content and the fraction of Avicel CL611 during pellet production. These pellets also took longer time to disintegrate, nonetheless all the pellets disintegrated within 15 min. A positive linear relationship was obtained between the tensile strength and time for pellets to disintegrate.

CONCLUSION

Strong but round pellets that disintegrate rapidly could be produced with Avicel CL611 as spheronization aid using moderately soluble compounds such as lactose.

Real-time image-based investigation of spheronization and drying phenomena using different pellet formulations

Extrusion-spheronization (ES) is a frequently used agglomeration process in the pharmaceutical industry to manufacture spherical solid units or pellets with a narrow size and shape distribution. In this study, photometric stereo imaging was applied in real-time during the final steps of the ES process, being spheronization and drying. In addition to the pellet size distribution of undispersed (wet) samples, the imaging technique captures visual information on pellet shape and surface brightness. Pellet samples were taken at 20 time points during spheronization and were imaged at-line (during spheronization) and off-line (after spheronization). Particle size distributions and visual image information were both used to characterise the spheronization behaviour of different formulations. Next, particle size distributions and surface brightness values calculated from the at-line obtained images during fluid bed drying of pellets were analysed. The particle size distribution and brightness value changes occurring during pellet drying were explained both by the reduction in residual moisture content and drug solid-state transition. Due to the rapidness of the technique with regard to sample preparation, sample measurement and the acquisition of results in combination with the possibility to measure undispersed (wet) samples, valuable information on spheronization and drying characteristics of different formulations was obtained in real-time.

Pellet starters in layering technique using concentrated drug solution

Characteristics of inert starters in drug solution layering are important for successful active pellet formation. Four types of starters composed of sucrose or microcrystalline cellulose (MCC) or lactose and MCC were compared in our study. The active pellets were prepared using Wurster type apparatus. Yield and pellet quality parameters were determined. The highest yield (85.66-89.41%) was obtained for cores composed of MCC due to their insolubility in water (the drug solvent) and good mechanical properties. On the contrary, soluble and brittle sucrose cores dissolved partially during the process forming undesirable agglomerates and giving lower yield (76.2%). All pellet samples showed good flow properties and drug content from 82.4 to 94.5% of the theoretical drug amount.

The Influence of Drug Solubility and Particle Size on the Pellet Formulation in a Rotoprocessor

Pellets containing drugs of different properties were prepared in a Rotoprocessor in order to study changes in the formulation process and resulting pellet characteristics. Diltiazem hydrochloride, diclofenac sodium, and theophylline were chosen as model drugs. Pellet size distribution, sphericity, density, hardness, friability, and repose angle were determined using standard methods. The amount of water as a wetting agent necessary for successful pellet formulation was observed for each sample and changed depending on drug solubility, concentration, and particle size. The pelletization of freely soluble diltiazem hydrochloride required 24.8-23.1% of the wetting agent and its amount decreased as the drug concentration increased. The demand for water in the formulation of theophylline pellets was 31.0-34.4% and it increased with increasing drug concentration. The pellet samples containing both drugs were easy to prepare. However, the cohesion of micronized diclofenac sodium particles negatively influenced both the pellet size distribution and the formulation process itself. When the drug concentration exceeded 40%, it was not possible to produce pellets of an appropriate size and the process was not reproducible.

Evaluation of the Performance of a New Continuous Spheronizer

This study aims to evaluate the performance of a new continuous spheronizer with multiple concentric chambers. The characteristics of the pellets produced in the different chambers (moisture content, mechanical strength, density, sphericity, size, release of a drug) were compared by multivariate analysis of variance (MANOVA), when different times of spheronization and chambers were considered. The statistical analysis has shown that both the diameter of the chambers and the time of spheronization affected the properties of the pellets, and, thus, they must be considered when the spheronizer is used. To minimize these effects all the forming pellets should be processed in all chambers for a defined period of time.

Pellet manufacturing by extrusion-spheronization using process analytical technology

The aim of this study was to investigate the phase transitions occurring in nitrofurantoin and theophylline formulations during pelletization by extrusion-spheronization. An at-line process analytical technology (PAT) approach was used to increase the understanding of the solid-state behavior of the active pharmaceutical ingredients (APIs) during pelletization. Raman spectroscopy, near-infrared (NIR) spectroscopy, and X-ray powder diffraction (XRPD) were used in the characterization of polymorphic changes during the process. Samples were collected at the end of each processing stage (blending, granulation, extrusion, spheronization, and drying). Batches were dried at 3 temperature levels (60 degrees C, 100 degrees C, and 135 degrees C). Water induced a hydrate formation in both model formulations during processing. NIR spectroscopy gave valuable real-time data about the state of water in the system, but it was not able to detect the hydrate formation in the theophylline and nitrofurantoin formulations during the granulation, extrusion, and spheronization stages because of the saturation of the water signal. Raman and XRPD measurement results confirmed the expected pseudopolymorphic changes of the APIs in the wet process stages. The relatively low level of Raman signal with the theophylline formulation complicated the interpretation. The drying temperature had a significant effect on dehydration. For a channel hydrate (theophylline), dehydration occurred at lower drying temperatures. In the case of isolated site hydrate (nitrofurantoin), dehydration was observed at higher temperatures. To reach an understanding of the process and to find the critical process parameters, the use of complementary analytical techniques are absolutely necessary when signals from APIs and different excipients overlap each other.

Influence of the drying technique on theophylline pellets prepared by extrusion-spheronization

Extrusion-spheronization is frequent method for pellet production and especially extrusion stage has been studied for its influence on pellet properties. However, the formation of pellet structure is not finished before drying stage. The possible influence of different drying methods and used temperatures on some properties of pellets, containing theophylline as active ingredient and Avicel CL-611 as spheronizing agent, is the object of this paper.

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.

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.

Extrusion-spheronization of pH-sensitive polymeric matrix pellets for possible colonic drug delivery

The aim of this study was to investigate extrusion-spheronization pelletization for preparing pH-sensitive matrix pellets for colon-specific drug delivery. The effects of three independent variables (amounts of Eudragit S, citric acid and spheronizing time) on pellet size, shape (roundness and aspect ratio), and drug release were studied with central composite design. The pellets contained ibuprofen as a model drug, citric acid as a pH-adjusting agent, Eudragit S as a pH-sensitive binder and microcrystalline cellulose (MCC). The pellets were prepared with Nica extrusion-spheronizing equipment and subsequently enteric-coated using an air-suspension technique. Eudragit S as a pH-sensitive matrix former in pellets increased the pellet size and influenced pellet roundness. In small amounts Eudragit S increased pellet roundness but in larger amounts pellet roundness was reduced. Citric acid promoted the pelletization process resulting in a narrower area distribution. The pH-sensitive matrix pellet failed to delay the drug release. The combination of citric acid and enteric coating, however, delayed the drug release for 15 min in a pH 7.4 phosphate buffer.

Formulation and process considerations for beads containing Carbopol 974P, NF resin made by extrusion-spheronization

Preliminary studies revealed that Carbopol 974P, NF resin could be incorporated into beads manufactured by extrusion and spheronization, and can slow the release of a highly water soluble drug if calcium chloride was included in the granulating fluid to reduce the tack of the wetted polymer. In this study, the same approach was used to produce high quality chlorpheniramine maleate beads with a prolonged release duration. Because of the complex nature of the extrusion and spheronization process and the various components in the bead formulations, a statistically sound factorial experiment was considered for this study. A one-half fraction of a two level factorial design with three center points was employed to estimate the effects of simultaneously modifying multiple process and formulation variables, including the Carbopol concentration, calcium chloride concentration, water content, and the spheronization speed and time. Product yield, average bead roundness, and the drug release profile were selected as responses. Increasing the Carbopol content across the experimental range resulted in a significant (P<0.05) reduction in the percentage drug released at 25, 40, and 60 min. Results suggest that combining the conditions of high Carbopol, high water, and low calcium chloride levels with low spheronization speeds at long spheronization times produce the highest quality bead with the longest drug release duration.

Influence of process variables on physical properties of the pellets using extruder and spheronizer

Placebo pellets containing lactose and microcrystalline cellulose (Avicel PH101) ratio 60:40 were prepared by the extrusion-spheronization process. The influence of processing variables, including the spheronizer speed, the spheronization time, the binder type, and the concentration and amount of water content on physical properties of the pellets, were studied. The sphericity of pellets was increased with increasing spheronizer speed during wet mass process. When spheronization time was increased, sphericity, smooth surface, and particle size of pellets were increased. Increasing binder concentration will increase particle size. Pellets using HPC-M as a binder at high spheronizer speeds showed spherical shape, narrow size distribution, and good flow properties when compared with Methocel E-15LV, HPC-L, and Methocel A4M. In addition, increasing HPC-M concentration had no effect on shape and particle size of pellets. The amount of water content was found to affect shape, flow rate, and density. In summary, suitable conditions consisted of 2% w/w of HPC-M, 40% w/w of water, and 15 min of spheronization time at 951 rpm of spheronizer speed.

Effect of the formulation parameters on the characteristics of pellets

Pelletization is increasingly applied currently for the preparation of solid oral controlled-release dosage forms. The production of the particles, which are regular in shape and size, can be achieved with the application of the proper polymer auxiliary materials and new pharmaceutical technological methods (extrusion, spheronization). Regularity in shape and size, attained by the optimization of several production parameters, can promote the coating procedure. Under optimal conditions, particles were prepared for coating in a high-shear mixer, which is used to produce uniform particles. The effect of the rotating speed of the applied chopper and the amount of microcrystalline cellulose in the composition on the physical characteristics of the pellets was modeled by a second-order polynomial equation fitted to the data gathered by a face-centered central composite statistical design.

Investigations on the influence of the type of extruder for pelletization by extrusion-spheronization. I. Extrusion behavior of formulations

Three different extruders (the Alexanderwerk gravity feed roll extruder, the Gabler axial, single-screw extruder, and the NICA radial-screw extruder) were compared for their suitability for different placebo formulations and for fenoldopam pellets. A fourth extruder, the experimental ram extruder, was also included in some of the comparisons. Evaluation of the extrusion behavior of the three extruders showed differences as well as similarities among them, depending on the composition of the formulation. Although the NICA and Alexanderwerk units extruded all formulations successfully, the Gabler extruder failed to do so at a content of > 60% of soluble ingredients, such as lactose or mannitol. The extrudate surface improved for all extruders with an increase in water content of formulations, but was generally smoother for the Gabler than for the NICA or the Alexanderwerk units. A formulation with colloidal Avicel as spheronization aid showed an identical extrusion behavior for all of the investigated extruders. Of the three extruders, the Gabler unit showed the highest heat generation during extrusion, especially when extruding formulations with a low water content or high contents of soluble excipients. However, when the loss of water during extrusion or spheronization for various formulations was compared, only a two-way ANOVA test on the differences between the water content after extrusion and after spheronization showed a statistically significant difference between the Alexanderwerk or NICA and the Gabler extruder. The two-way ANOVA also proved that this difference is significant only for some formulations, e.g., lactose + Avicel PH 101 formulations, but not for Avicel PH 101 formulations.

Optimization of the processing of matrix pellets based on the combination of waxes and starch using experimental design

An experimental design was used in order to optimize the one-step production process of matrix pellets based on the combination of waxes and starch. The parameters tested were the impeller speed (x1) and the mixing time (x2). Ibuprofen and theophylline were used as model drugs at a concentration of 60 and 70% (w/w), respectively. The 0.8-1.25 mm yield fraction of the matrix pellets was evaluated as the response factor Y. A quadratic equation was fitted to the experimental data and used to predict the response factor Y of the theophylline and the ibuprofen. The contour plots of both formulations revealed a flat and therefore rugged region from the upper left to the lower right of the domain investigated. The energy input into the system during the production process controlled the pellet growth, the impeller speed having a greater impact on the energy input compared to the mixing time.