Application of continuous twin screw granulation for the metformin hydrochloride extended release formulation

Characterizing a design space for a twin-screw wet granulation process: A case study of extended-release tablets

Twin-screw wet granulation is an emerging continuous manufacturing technology for solid oral dosage forms. This technology has been successfully employed for the commercial manufacture of immediate-released tablets. However, the higher polymer content in extended-release (ER) formulations may present challenges in developing and operating within a desired design space. The work described here used a systematic approach for defining the optimum design space by understanding the effects of the screw design, operating parameters, and their interactions on the critical characteristics of granules and ER tablets. The impacts of screw speed, powder feeding rate, and the number of kneading (KEs) and sizing elements on granules and tablets characteristics were investigated by employing a definitive screening design. A semi-mechanistic model was used to calculate the residence time distribution parameters and validated using the tracers. The results showed that an increase in screw speed decreased the mean residence time of the material within the barrel, while an increase in the powder feeding rate or number of KEs did the opposite and increased the barrel residence time. Screw design and operating parameters affected the flow and bulk characteristics of granules. The screw speed was the most significant factor impacting the tablet's breaking strength. The dissolution profiles revealed that granule characteristics mainly influenced the early phase of drug release. This study demonstrated that a simultaneous optimization of both operating and screw design parameters was beneficial in producing ER granules and tablets of desired performance characteristics while mitigating any failure risks, such as swelling during processing.

Validation of model-based design of experiments for continuous wet granulation and drying

This paper presents an application case of model-based design of experiments for the continuous twin-screw wet granulation and fluid-bed drying sequence. The proposed framework consists of three previously developed models. Here, we are testing the applicability of previously published unit operation models in this specific part of the production line to a new active pharmaceutical ingredient. Firstly, a T-shaped partial least squares regression model predicts d-values of granules after wet granulation with different process settings. Then, a high-resolution full granule size distribution is computed by a hybrid population balance and partial least squares regression model. Lastly, a mechanistic model of fluid-bed drying simulates drying time and energy efficiency, using the outputs of the first two models as a part of the inputs. In the application case, good operating conditions were calculated based on material and formulation properties as well as the developed process models. The framework was validated by comparing the simulation results with three experimental results. Overall, the proposed framework enables a process designer to find appropriate process settings with a less experimental workload. The framework combined with process knowledge reduced 73.2% of material consumption and 72.3% of time, especially in the early process development phase.

T-shaped partial least squares for high-dosed new active pharmaceutical ingredients in continuous twin-screw wet granulation: Granule size prediction with limited material information

This work presents a granule size prediction approach applicable to diverse formulations containing new active pharmaceutical ingredients (APIs) in continuous twin-screw wet granulation. The approach consists of a surrogate selection method to identify similar materials with new APIs and a T-shaped partial least squares (T-PLS) model for granule size prediction across varying formulations and process conditions. We devised a surrogate material selection method, employing a combination of linear pre-processing and nonlinear classification algorithms, which effectively identified suitable surrogates for new materials. Using only material properties obtained through four characterization methods, our approach demonstrated its predictive prowess. The selected surrogate methods were seamlessly integrated with our developed T-PLS model, which was meticulously validated for high-dose formulations involving three new APIs. When surrogating new APIs based on Gaussian process classification, we achieved the lowest prediction errors, signifying the method's robustness. The predicted d-values were within the range of uncertainty bounds for all cases, except for d90 of API C. Notably, the approach offers a direct and efficient solution for early-phase formulation and process development, considerably reducing the need for extensive experimental work. By relying on just four material characterization methods, it streamlines the research process while maintaining a high degree of accuracy.

Switching from batch to continuous granulation: A Case Study of metoprolol succinate ER tablets

Continuous manufacturing (CM) has been used to produce several immediate release drug products. No extended-release (ER) product manufactured employing CM technology has been approved yet. This study investigated the critical aspects of switching from the batch mode of high shear granulation to the continuous operation of twin-screw granulation for extended-release tablets. Metoprolol succinate ER tablets was used as a model ER formulation for this purpose. A central composite design (CCD) was employed to determine the effects of high shear granulator (HSG) parameters, namely impeller speed, granulation time, and binder liquid feeding rate, on the critical granulation characteristics important for product performance. These critical granulation characteristics served as a guide for switching from the batch processing to the continuous operation for achieving the same breaking strength and dissolution for this ER metoprolol tablets. The granulation time was the most critical factor affecting the bulk properties of granules which contributed to tablet dissolution. The higher density and lower compressibility of granules were attained at the longest granulation time of 5.4 min with the fastest liquid feeding rate of 75 g/min. The granules' density was the primary factor negatively affecting the dissolution of metoprolol tablets. However, the breaking strength of tablets confounded the effect of granules density on metoprolol dissolution. Switching the processing parameters of high shear granulation to twin-screw granulation achieved similar dissolution profiles (F2 > 50). The screw speed was not found to affect bulk properties of granules. The root cause of granulation failures in twin-screw granulation, such as premature consolidation, excessive swelling, poor cohesion, inconsistent shearing effects, and formation of deformed agglomerates, were identified. In conclusion, the use of critical granulation characteristics through a performance-based approach of ER tablets facilitated the switching of manufacturing of an ER formulation form batch to continuous operation.

Recent Trends in Assessment of Cellulose Derivatives in Designing Novel and Nanoparticulate-Based Drug Delivery Systems for Improvement of Oral Health

Natural polymers are revolutionizing current pharmaceutical dosage forms design as excipient and gained huge importance because of significant influence in formulation development and drug delivery. Oral health refers to the health of the teeth, gums, and the entire oral-facial system that allows us to smile, speak, and chew. Since years, biopolymers stand out due to their biocompatibility, biodegradability, low toxicity, and stability. Polysaccharides such as cellulose and their derivatives possess properties like novel mechanical robustness and hydrophilicity that can be easily fabricated into controlled-release dosage forms. Cellulose attracts the dosage design attention because of constant drug release rate from the precursor nanoparticles. This review discusses the origin, extraction, preparation of cellulose derivatives and their use in formulation development of nanoparticles having multidisciplinary applications as pharmaceutical excipient and in drug delivery, as bacterial and plant cellulose have great potential for application in the biomedical area, including dentistry, protein and peptide delivery, colorectal cancer treatment, and in 3D printable dosage forms.

An Industrial Procedure for Pharmacodynamic Improvement of Metformin HCl via Granulation with Its Paracellular Pathway Enhancer Using Factorial Experimental Design

Background

Sorbitan monostearate is a surfactant used in the food industry. It was proved as a penetration enhancer to metformin HCl via a paracellular pathway. It is solid at room temperature and has a low melting point. Therefore, it was selected, as a granulating agent for metformin HCl.

Methods

Multi-level factorial design was applied to determine the optimized formula for industrial processing. The selected formulations were scanned using an electron microscope. Differential scanning calorimetry was used to ascertain the crystalline state of a drug. A modified non-everted sac technique, suggested by the authors, was used to evaluate the in vitro permeation enhancement of the drug. To simulate the emulsification effect of the bile salt, a tween 80 was added to the perfusion solution. As a pharmacodynamic marker, blood glucose levels were measured in diabetic rats.

Results

The results showed that drug permeability increases in the presence of tween 80. Drug permeability from granules increased than that of the pure drug or pure drug with tween 80. The prepared granules decreased blood glucose levels of diabetic rats than the pure drug and drug plus tween 80. There was an excellent correlation between the results of the drug permeation percent in vitro and the dropping of blood glucose level percent in vivo.

Conclusion

Improving the drug permeation and consequently, the drug pharmacodynamic effect in addition to an excellent micromeritics property of the prepared drug granules showed the dual enhancement effect of the suggested industrial procedure. Therefore, we suggest the same industrial procedure for other class III drugs.

Analysis of the Effects of Process Parameters on Start-Up Operation in Continuous Wet Granulation

Toward further implementation of continuous tablet manufacturing, one key issue is the time needed for start-up operation because it could lead to lower product yield and reduced economic performance. The behavior of the start-up operation is not well understood; moreover, the definition of the start-up time is still unclear. This work investigates the effects of process parameters on the start-up operation in continuous wet granulation, which is a critical unit operation in solid drug manufacturing. The profiles of torque and granule size distribution were monitored and measured for the first hour of operation, including the start-up phase. We analyzed the impact of process parameters based on design of experiments and performed an economic assessment to see the effects of the start-up operation. The torque profiles indicated that liquid-to-solid ratio and screw speed would affect the start-up operation, whereas different start-up behavior resulted in different granule size. Depending on the indicator used to define the start-up operation, the economic optimal point was significantly different. The results of this study stress that the start-up time differs according to the process parameters and used definition, e.g., indicators and criteria. This aspect should be considered for the further study and regulation of continuous manufacturing.

Evaluation of torque as an in-process control for granule size during twin-screw wet granulation

The potential of torque as in-process control (IPC) to monitor granule size in twin-screw wet granulation (TSG) was investigated. An experimental set-up allowing the collection of granules at four different locations (i.e., in the wetting zone, after the first and second kneading zone and at the end of the granulator) of the granulator screws was used to determine the change in granule size, granule temperature and the contribution of each compartment to the overall torque for varying screw speed, mass feed rate and liquid-to-solid ratio. The only observed correlation was between the granule size and torque increase after the first kneading zone because the torque increase was an indication of the degree in granule growth which was consistently observed with all applied granulation process parameters. No correlation was observed in the other locations as changes of torque were accompanied to either granule breakage and/or growth. Moreover, torque increase was correlated to higher granule temperature, suggesting that energy put into the granulator was partly used to heat up the material being processed and explains additionally the lack of correlation between granule size and torque. Therefore, this study showed that torque could not be used as IPC to monitor granule size during TSG.

Advances in Twin-Screw Granulation Processing

Twin-screw granulation (TSG) is a pharmaceutical process that has gained increased interest from the pharmaceutical industry for its potential for the development of oral dosage forms. The technology has evolved rapidly due to the flexibility of the equipment design, the selection of the process variables and the wide range of processed materials. Most importantly, TSG offers the benefits of both batch and continuous manufacturing for pharmaceutical products, accompanied by excellent process control, high product quality which can be achieved through the implementation of Quality by Design (QbD) approaches and the integration of Process Analytical Tools (PAT). Here, we present basic concepts of the various twin-screw granulation techniques and present in detail their advantages and disadvantages. In addition, we discuss the detail of the instrumentation used for TSG and how the critical processing paraments (CPP) affect the critical quality attributes (CQA) of the produced granules. Finally, we present recent advances in TSG continuous manufacturing including the paradigms of modelling of continuous granulation process, QbD approaches coupled with PAT monitoring for granule optimization and process understanding.

Heat Transfer Evaluation During Twin-Screw Wet Granulation in View of Detailed Process Understanding

During the last decade, the pharmaceutical industry has shown a growing interest in continuous twin-screw granulation (TSG). Despite flourishing literature on TSG, limited studies focused on fundamental process understanding on its mechanisms. In current study, granule quality attributes along the length of the TSG barrel were evaluated together with heat transfer in order to achieve a more fundamental understanding of the granulation process. An experimental setup was developed allowing the collection of granules at the different TSG compartments. In addition to the determination of typical granule attributes, mechanical energy, barrel and granule temperature (measured using an in-line implemented infra-red camera) were measured to evaluate heat transfer occurring at the different compartments and to relate them to granulation mechanisms. Collected data identified wetting enthalpy and friction forces as the main sources of heat along the granulator length. Wetting occurred in the wetting zone and generated temperature increase depending on liquid-to-solid ratio and powder wettability. In the kneading zones, granule temperature increase was proportional to mechanical energy. While it is usually admitted that granule consolidation and reshaping are the consequence of the high shear experienced by the granules, it was highlighted that most of the mechanical energy is converted into thermal energy with no correlation between mechanical energy and granule size distribution. Combined mass and energy balance of the granulation process are therefore necessary to capture the interaction between granule properties and physico-chemical and mechanical phenomena occurring in each compartment.

Influence of granulation temperature on particle size distribution of granules in twin-screw granulation (TSG)

This study investigated an influence of granulation temperature during twin-screw granulation (TSG) on particle size distributions (PSDs). The influence of the granulation temperature on granule size distributions varied, depending on the liquid to solid (L/S) ratio, the kind of binders, the method of binder addition, and the filler material. The PSD of granules was broad and bimodal at a barrel temperature of 30 °C. Granules size distributions became narrow and second height decreased at high barrel temperature. While the L/S ratio had an effect on the sharpness of granule size distributions, this effect was minor compared to the granulation temperature. Granule size distributions were influenced by binder addition methods. When the binder was added as solution, PSD became broad. In formulations using lactose as filler, PSD became broad and bimodal at 90 °C. Much lactose was dissolved in granulation solution at high temperature, because the solubility of lactose rises significantly with the solution temperature leading to higher effective L/S ratio in the granulator. Hence, granulation was proceeded and large granules were formed. From these results, the granulation temperature is one of important parameters to obtain mono-modal PSD in TSG.

Use of roller compaction and fines recycling process in the preparation of erlotinib hydrochloride tablets

This study focuses on improving the manufacturing process for a generic immediate-release tablet containing erlotinib hydrochloride by adding a fines recycling process during roller compaction. Due to the large fraction of small-sized API particles, the starting powder mixture was inconsistently fed into the roller compactor. Consequently, poorly flowing granules with a high ratio of fines were produced. A fines recycling step was, therefore, added to the existing roller compaction process to minimize the risks caused by the poor granule flow. A laboratory scale roller compactor and a tablet simulator were used to prepare granules at various process conditions. The effect of dry granulation parameters on size distribution, API distribution, powder flow, compaction properties, and dissolution profile was evaluated. The granule batch after fines recycling had markedly improved size distribution and flowability while maintaining acceptable tablet tensile strength and rapid dissolution profile. The application of the fines recycling process at commercial scale resulted in reliable dissolution performance and batch-to-batch consistency, which were further confirmed by bioequivalence to the reference product. Understanding how granule properties are impacted by the fines recycling process may enable fine-tuning of the dry granulation process for optimal product quality.