Effectiveness of binders in wet granulation: a comparison using model formulations of different tabletability

Evaluation of binders in twin-screw wet granulation - Optimization of tabletability

The influence of hydroxypropyl cellulose type (HPC-SSL SFP, HPC-SSL), concentration (2 %, 3.5 %, 5 %) and filler (lactose, calcium hydrogen phosphate (DCP)/microcrystalline cellulose (MCC)) on twin-screw wet granulation and subsequent tableting was studied. The aim was to identify the formulation of the highest tabletability which still fulfills the requirements of the disintegration. Lactose combined with 5 % binder enabled a higher tabletability and a faster disintegration than DCP/MCC. It was found that tabletability of lactose formulations can be increased by higher binder concentration and higher compression pressure while tabletability of DCP/MCC formulations can be only increased by higher compression pressure. It was observed that batches containing DCP/MCC failed the disintegration test, if the highest binder concentration and the highest compression pressure were used. To ensure a fast disintegration, the compression pressure or at least the binder concentration had to be low. Changing the disintegrant and its localization improved the DCP/MCC formulation, resulting in faster disintegration than lactose tablets. However, it also resulted in a lower tabletability. In this study best tablets were achieved with 3.5 % or 5 % binder and lactose as filler. These tablets presented the highest tabletability but still disintegrated in less than 500 s.

High-Shear Granulation of Hygroscopic Probiotic-Encapsulated Skim Milk Powder: Effects of Moisture-Activation and Resistant Maltodextrin

A fine, hygroscopic, and poorly flowable probiotic powder encapsulating Lactobacillus rhamnosus GG (LGG) was granulated using a high-shear granulation process, wherein a small amount of water (4%, w/w) was used for moisture-activation with or without 10% (w/w) resistant maltodextrin (RM). The process consisted of four steps; premixing, agglomeration, moisture absorption, and drying steps. The moisture content, water activity, and viable cell count were monitored during the granulation. The size, morphology, and flowability of the granules were determined. The powder was successfully converted to about 10-times-larger granules (mass mean diameter = 162–204 µm) by this process, and the granules had a ‘snowball’ morphology. The LGG cells were well preserved under the high-shear granulation conditions, and the viable cell count of the granules greatly exceeded the minimum therapeutic level recommended for probiotic powders. The addition of RM decreased the moisture content of the granules; improved cell resistance to drying stress; narrowed the particle size distribution, with reductions seen in both very fine and very large particles; and produced more flowable granules. Moisture sorption analysis and differential scanning calorimetry demonstrated that these positive effects of RM on granulation were primarily attributed to its water distribution ability rather than its glass transition-related binding ability.

Additive Manufacturing of Solid Products for Oral Drug Delivery Using Binder Jetting Three-Dimensional Printing

Binder jetting (BJ) three-dimensional (3D) printing is becoming an established additive manufacturing technology for manufacturing of solid products for oral drug delivery. Similar to traditional solutions based on compaction of powder mixture, successful processing of BJ products requires control of bulk powder properties. In contrast to traditional compaction-based process, BJ 3D printing allows for flexible modifications on microstructure, material composition and dose in the printed pharmaceutical products. Currently, systematic strategies for selecting excipients and optimizing the printing process have not been fully established. To address this challenge, a summary of the published work and selected patent literature around BJ 3D printing to fabricate pharmaceutical solid products for oral administration purposes is presented. First, an overview of characteristics of printed products as a part of the product design and a description of the commonly used excipients and active pharmaceutical ingredients is given. The critical powder and ink properties, as well as physical geometries and inner structures of a final product, are discussed in term of the mechanisms that determine the formation of a printed solid product and finally the quality of this product. This review is also summarizing the technical features of printers, printheads, and the critical considerations for post-processing procedures. BJ 3D printing is one of the most promising additive manufacturing technologies for mass customization of pharmaceutical products.

Effect of Manufacturing Process on the Retention of Abuse-Deterrent Properties of PEO-Matrix Tablets

Polyethylene oxide (PEO) is a widely used polymer in the development of abuse-deterrent oral formulations. Different manufacturing processes including direct compression (DC) followed by sintering, wet granulation (WG) followed by compression and sintering, and hot melt extrusion (HME) can be used to manufacture abuse-deterrent oral drug products. Three different manufacturing processes (DC, WG, HME) were evaluated to test the retention of their abuse-deterrent features following attempts to grind the tablets or extrudates. In vitro drug release studies were conducted on 10% and 32% drug-loaded tablets/extrudates prepared using these manufacturing methods, and the release profiles from all formulations showed good extended-release properties. Drug content analysis on the granules obtained from tablets prepared by direct compression showed non-uniform drug distribution where an unexpectedly high drug content was present in the smallest size (< 250 µm) granules, sizes which are likely to be inhaled by abusers. Granules from tablets prepared by wet granulation showed improved drug distribution across all granule sizes formed after grinding. Drug content testing on the granules obtained from extrudates prepared using hot melt extrusion showed excellent drug content uniformity along with sufficient strength to resist grinding into smaller particles. The retention of the abuse-deterrent properties of a dosage form following attempts to extract or abuse the drug is an important product characteristic, and the product design, formulation components, and manufacturing processes can all play critical roles in the retention of the desired abuse-deterrent properties.

Enabling the direct compression of metformin hydrochloride through QESD crystallization

Metformin hydrochloride is a drug used in the treatment of type 2 diabetes. It shows very poor flowability and agglomeration under storage so that a direct compression of the material into tablets has not yet been successfully realized. In a previous study the authors showed that a quasi-emulsion solvent-diffusion (QESD) crystallization technique can be used to drastically improve the flowability and reduce storage agglomeration of this drug. This study set out to evaluate whether QESD metformin hydrochloride can be directly compressed into high dose (> 89.5% drug load) tablets without the use of an intermediary step such as granulation. The direct compression into tablets was successful, however it was important to evaluate the tabletability of the material under actual production speeds of the tablet press. The porous structure of the metformin agglomerates lead to deaeration issues, however these could be avoided by reducing the punch speed or using a precompression step. Furthermore, the influence of surfactants used to stabilize the QESD crystallization on the strength of tablets produced was analyzed because the literature is still scarce on this topic.

Fixed Dose Single Tablet Formulation with Differential Release of Amlodipine Besylate and Simvastatin and Its Pharmacokinetic Profile: QbD and Risk Assessment Approach

Purpose

A differential release fixed dose matrix tablet of amlodipine besylate (AML-B) and simvastatin (SIM) was formulated to enhance patient compliance.

Material and Method

In the first phase, release controlling parameters of AML-B and SIM granules were identified and in the second phase a fixed dose AML-B and SIM tablet formulation was prepared and optimized for a differential release of the drugs using a quality by design (QbD) and risk assessment approach. A validated HPLC method was employed for simultaneous determination of AML-B and SIM for FDC formulation. A pharmacokinetics of the above drugs was studied in healthy dogs in the third phase.

Results

In QbD-based optimized formulation, Eudragit^® RSPO-dicalcium phosphate (DCP) blend controlled the release of AML-B over 8 h, though this diffusion-controlled release assumed first order kinetics. DCP and Eudragit^® RS 100 also retarded release of SIM causing SIM release over 8 h after AML-B release from the optimized FDC tablet formulation. The HPLC retention times of AML-B and SIM were 2.10 and 15.52 min, respectively. Linearity for AML-B was 5.0–50 ng/mL and 0.01–2.0 µg/mL for SIM with percent recoveries of 92.85–101.53% and 94.51–117.75% for AML-B and SIM. AUC_0-∞ of AML-B was increased 3 fold, while AUC_0-∞ of SIM was decreased 2 fold. The t_max values for AML-B and SIM were 12 and 6 h, respectively. AML-B was absorbed without any lag time (t_lag) while t_lag was 6.33 ± 0.81 h for SIM, thus met the study objective.

Conclusion

The pharmacokinetic study showed an immediate absorption of AML-B while that of SIM was withheld for 6 h, close to the desired delay time of 8 h.

Evaluation of Binders in Twin-Screw Wet Granulation

The binders povidone (Kollidon 30), copovidone (Kollidon VA64), hypromellose (Pharmacoat 606), and three types of hyprolose (HPC SSL‑SFP, HPC SSL, and HPC SL‑FP) were evaluated regarding their suitability in twin-screw wet granulation. Six mixtures of lactose and binder as well as lactose without binder were twin-screw granulated with demineralized water at different barrel fill levels and subsequently tableted. A screening run with HPC SSL determined the amount of water as an influential parameter for oversized agglomerates. Subsequent examination of different binders, especially Kollidon 30 and Kollidon VA64 resulted in large granules. All binders, except Pharmacoat 606, led to a reduction of fines compared to granulation without a binder. The molecular weight of applied hyproloses did not appear as influential. Tableting required an upstream sieving step to remove overlarge granules. Tableting was possible for all formulations at sufficient compression pressure. Most binders resulted in comparable tensile strengths, while Pharmacoat 606 led to lower and lactose without a binder to the lowest tensile strength. Tablets without a binder disintegrated easily, whereas binder containing tablets of sufficient tensile strength often nearly failed or failed the disintegration test. Especially tablets containing Pharmacoat 606 and HPC SL‑FP disintegrated too slowly.

Improvements in sticking, hygroscopicity, and compactibility of effervescent systems by fluid-bed coating

Recently, effervescent tablets (ETs) have become increasingly popular with patients in clinics due to their fast disintegration by acid–alkali reactions in water. However, certain undesirable properties of ETs (e.g., sticking and high hygroscopicity) can limit their production and application. In particular, frequent sticking always severely decreases the tablet quality and productivity. Therefore, in this study, polyvinylpyrrolidone (PVP) at different usage levels, grades, or spray solution concentrations was coated onto the surfaces of both acidic and alkaline granules of ETs by means of the fluid-bed coating technique. In terms of fully characterized powder, tableting, and tablet properties, the following points were concluded: (i) a uniform coating of PVP onto the surfaces of these two granules not only resolved the sticking problem, but also effectively decreased the hygroscopicity and enhanced the compactibility; (ii) the improvements increased with an increase in the PVP content or PVP molecular weight and a decrease in the PVP spray solution concentration owing to the formation of an increasingly even and cohesive coating layer; (iii) the process of fluid-bed coating was not the simple superposition or simple mixing of two different materials' properties; (iv) the coating process did not cause significant influences on the disintegration time of ETs. Overall, it is fairly meaningful to further promote the development of ETs in practice since these problems have been overcome.

Recently, effervescent tablets (ETs) have become increasingly popular with patients in clinics due to their fast disintegration by acid–alkali reactions in water.

Development and Optimization of a Wet Granulation Process at Elevated Temperature for a Poorly Compactible Drug Using Twin Screw Extruder for Continuous Manufacturing

The objective of this study was to enhance tabletability of a poorly compactible drug, acetaminophen, by wet granulation using twin screw extruder at high temperature. It was desired that there would be minimum amounts of excipients used and the granules obtained after extrusion would be dry and fall within a size range suitable for tableting without any further processing. Mixtures of acetaminophen (95%) with binders (5% povidone or partially pregelatinized starch) were wet granulated through twin screw extruder at 70°C by adding 7% w/w water. The process had a short granulation time (<1 min), and, on account of the elevated processing temperature used, no drying after extrusion was needed. By optimizing formulation and processing parameters, >90% granules in the size range of 125 to 1000 μm (<3% above 1000 μm and <7% below 125 μm) were obtained without any milling. When the granules were compressed by adding 1% disintegrant and 0.5% lubricant extragranularly, tablets produced (93.6% drug load) had good mechanical strength having hardness >1.7 MPa, which was superior to that of tablets prepared by conventional high shear wet granulation. As the granules could be extruded continuously and did not require drying and milling, the method was amenable to continuous processing.

Multiphase versus Single Pot Granulation Process: Influence of Process and Granulation Parameters on Granules Properties

High-shear wet granulation is widely used for the production of pharmaceutical dosage forms. Different equipment is available for high-shear granulation and drying. This review focuses on two main processes for granules production: multiphase consisting of high-shear granulation followed by drying in a separate apparatus, and single pot granulation/drying. At present, formulas are specifically developed with regard to the production equipment, which raises many problems when different industrial manufacturing equipment is used. Indeed, final granules properties are likely to depend on equipment design, process, and formulation parameters. Therefore, a good understanding of these parameters is essential to facilitate equipment changes. The aim of this review is to present the influence of equipment, process, and formulation parameters on granules properties, considering both the granulation and the drying steps of multiphase and single pot processes.

Influence of metronidazole particle properties on granules prepared in a high-shear mixer-granulator

Metronidazole is a good example of high-dose drug substance with poor granulating and tableting properties. Tablets are generally produced by liquid granulation; however, the technological process failure is quite frequent. In order to verify how the metronidazole particle characteristics can influence granule properties, three metronidazole batches differing for crystal habit, mean particle size, BET surface area and wettability were selected, primarily designed according to their different elongation ratio: needle-shaped, stick-shaped, and isodimensional. In the presence of lactose monohydrate and pregelatinized maize starch, respectively as diluent and binder, they were included in a formula for wet granulation in a high-shear mixer-granulator. In order to render the process comparable as far as possible, all parameters and experimental conditions were maintained constant. Four granule batches were obtained: granules from placebo (G-placebo), granules from needle-shaped crystals (G-needle-shaped), granules from stick-shaped crystals (G-stick-shaped), and granules from isodimensional crystals (G-isodimensional). Different granule properties were considered, in particular concerning porosity, friability, loss on drying (LOD), and flowability. In order to study their tabletability and compressibility, the different granules obtained were then compressed in a rotary press. The best tabletability was obtained with the isodimensional batch, while the poorest was exhibited by the stick-shaped one. Differences in tabletability are in good accordance with compressibility results: to a better tabletability corresponds an important granule ability to undergo a volume reduction as a result of an applied pressure. In particular, it was proposed that the greatest compressibility of the G-isodimensional must be related to the greatest granule porosity percentage.

Extrusion Granulation and High Shear Granulation of Different Grades of Lactose and Highly Dosed Drugs: A Comparative Study

Formulations containing different lactose grades, paracetamol, and cimetidine were granulated by extrusion granulation and high shear granulation. Granules were evaluated for yield, friability, and compressibility. Tablets were prepared from those granules and evaluated for tensile strength, friability, disintegration time, and dissolution. The different lactose grades had an important effect on the extrusion granulation process. Particle size and morphology affected powder feeding and power consumption, but had only a minor influence on the granule and tablet properties obtained by extrusion granulation. In contrast, the lactose grades had a major influence on the granule properties obtained by high shear granulation. Addition of polyvinylpyrrolidone (PVP) was required to process pure paracetamol and cimetidine by high shear granulation, whereas it was feasible to granulate these drugs without PVP by extrusion granulation. Granules prepared by extrusion granulation exhibited a higher yield and a lower friability than those produced by high shear granulation. Paracetamol and cimetidine tablets compressed from granules prepared by extrusion granulation showed a higher tensile strength, lower friability, and lower disintegration time than those prepared from granules produced by high shear granulation. Paracetamol tablets obtained via extrusion granulation exhibited faster dissolution than those obtained via high shear granulation. For all lactose grades studied, extrusion granulation resulted in superior granule and tablet properties in comparison with those obtained by high shear granulation. These results indicate that extrusion granulation is more efficient than high shear granulation.

Experience with the Diosna mini-granulator and assessment of process scalability

A small-scale appliance for the high-shear granulation of pharmaceutical materials (the Diosna P 1-6) was tested in a study investigating the influence of various granulation parameters and formulations on granule size distribution. Increasing the granulation time, the impeller speed and the amount of binder all resulted in an increase in granule size, whilst high fill ratios resulted in an increased proportion of fines. The speed of the chopper did not affect granule size distribution for the formulations tested. Granule size distribution was highly reproducible within individual bowl sizes. Scale-up to the P 10 granulator could be accomplished without changing the formulation or the granulation conditions providing that the different bowl sizes of the laboratory-scale equipment yielded granulates with comparable size distributions. Further scale-up to Diosna P 25 and P 100 granulators, which are larger scale machines, resulted in granules which were smaller than those prepared in the laboratory-scale equipment. The Diosna P 1-6 seems to be a useful tool for experimentation carried out in the early phase of pharmaceutical development work. Granulates can be prepared reproducibly and differences in granule size distribution due to machine scale can be assessed.

Cold extrusion as a continuous single-step granulation and tabletting process

The potential of cold extrusion as a continuous granulation/tabletting technique was investigated. Extrudates (X, 9 mm) were produced using twin-screw extrusion, cut manually into tablets (thickness, 4 mm) and dried at 25 degrees C for 20 h. alpha-Lactose monohydrate (200 M) was used as an excipient, PVP (Kollidon K30) and water as binders, and hydrochlorothiazide as the model drug. The influence of formulation (water content, PVP addition, drug incorporation) and process (total input rate and screw speed) parameters on the process (torque, die pressure, visual evaluation of tablets) and on the tablet properties (tensile strength, friability, disintegration time, porosity) was evaluated. Formulation, as well as process parameters, affected the process feasibility, but had only a minor effect on the tablet properties at conditions that allowed continuous tablet production. All alpha-lactose monohydrate tablets formulated without and with PVP and produced at optimum conditions showed tensile strengths above 0.7 and 1.5 MPa, friabilities below 1.0 and 0.9%, and disintegration times below 1 and 8 min, respectively. This technique allows single-step granulation/tabletting of pure alpha-lactose monohydrate, indicating that cold extrusion could be used as alternative tablet production technique for ingredients with poor compaction properties. As the tablets prepared by extrusion have a much higher porosity compared with conventional tablets, this technique could also be useful for tablet production of formulations with poor disintegrating properties.