Crystal coating via spray drying to improve powder tabletability

Study on Improving the Performance of Traditional Medicine Extracts with High Drug Loading Based on Co-spray Drying Technology

The purpose of this study is to develop modified particles with different structures to improve the flowability and compactibility of Liuwei Dihuang (LWDH) powder using co-spray drying technology, and to investigate the preparation mechanism of modified particles and their modified direct compaction (DC) properties. Moreover, tablets with high drug loading contents were also prepared. Particles were designed using polyvinylpyrrolidone (PVP K30) and hydroxypropyl methylcellulose (HPMC E3) as shell materials, and sodium bicarbonate (NaHCO3) and ammonium bicarbonate (NH4HCO3) as pore-forming agents. The porous particles (Ps), core-shell particles (CPs), and porous core-shell particles (PCPs) were prepared by co-spray drying technology. The key DC properties and texture properties of all the particles were measured and compared. The properties of co-spray drying liquid were also determined and analyzed. According to the results, Ps showed the least improvement in DC properties, followed by CPs, and PCPs showed a significant improvement. The modifier, because of its low surface tension, was wrapped in the outer layer to form a shell, and the pore-forming agent was thermally decomposed to produce pores, forming core-shell, porous, and porous core-shell composite structures. The smooth surface of the shell structure enhances fluidity, while the porous structure allows for greater compaction space, thereby improving DC properties during the compaction process.

Lactose in tablets: Functionality, critical material attributes, applications, modifications and co-processed excipients

Lactose is one of the most widespread excipients used in the pharmaceutical industry. Because of its water solubility and acceptable flowability, lactose is generally added into tablet formulation to improve wettability and undesirable flowability. Based on Quality by Design, a better understanding of the critical material attributes (CMAs) of raw materials is beneficial in guiding the improvement of tablet quality and the development of lactose. Additionally, the modifications and co-processing of lactose can introduce more-desirable characteristics to the resulting particles. This review focuses on the functionality, CMAs, applications, modifications and co-processing of lactose in tablets.

Updates on applications of low-viscosity grade Hydroxypropyl methylcellulose in coprocessing for improvement of physical properties of pharmaceutical powders

Hydroxypropyl methylcellulose (HPMC) is an important polymeric excipient. Its versatility in terms of molecular weights and viscosity grades is the basis for its wide and successful application in the pharmaceutical industry. Low viscosity grades of HPMC (like E3 and E5) have been used as physical modifiers for pharmaceutical powders in recent years due to their unique physicochemical and biological properties (e.g., low surface tension, high T_g, strong hydrogen bonding ability, etc.). Such modification is the co-processing of HPMC with a drug/excipient to create composite particles (CPs) for the purpose of providing synergistic effects of functional improvement as well as of masking undesirable properties of the powder (e.g., flowability, compressibility, compactibility, solubility, stability, etc.). Therefore, given its irreplaceability and tremendous opportunities for future developments, this review summarized and updated studies on improving the functional properties of drugs and/or excipients by forming CPs with low-viscosity HPMC, analyzed and exploited the improvement mechanisms (e.g., improved surface properties, increased polarity, hydrogen bonding, etc.) for the further development of novel co-processed pharmaceutical powders containing HPMC. It also provides an outlook on the future applications of HPMC, aiming to provide a reference on the crucial role of HPMC in various areas for interested readers.

Surface Modifiers on Composite Particles for Direct Compaction

Direct compaction (DC) is considered to be the most effective method of tablet production. However, only a small number of the active pharmaceutical ingredients (APIs) can be successfully manufactured into tablets using DC since most APIs lack adequate functional properties to meet DC requirements. The use of suitable modifiers and appropriate co-processing technologies can provide a promising approach for the preparation of composite particles with high functional properties. The purpose of this review is to provide an overview and classification of different modifiers and their multiple combinations that may improve API tableting properties or prepare composite excipients with appropriate co-processed technology, as well as discuss the corresponding modification mechanism. Moreover, it provides solutions for selecting appropriate modifiers and co-processing technologies to prepare composite particles with improved properties.

Binder jetting 3D printing of challenging medicines: from low dose tablets to hydrophobic molecules

Increasing access to additive manufacturing technologies utilising easily available desktop devices opened novel ways for formulation of personalized medicines. It is, however, challenging to propose a flexible and robust formulation platform which can be used for fabrication of tailored solid dosage forms composed of APIs with different properties (e.g., hydrophobicity) without extensive optimization. This manuscript presents a strategy for formulation of fast dissolving tablets using binder jetting (BJ) technology. The approach is demonstrated using two model APIs: hydrophilic quinapril hydrochloride (QHCl, logP = 1.4) and hydrophobic clotrimazole (CLO, logP = 5.4). The proposed printing method uses inexpensive well known and easily available FDA approved pharmaceutical excipients. The obtained model tablets had uniform content of the drug, excellent mechanical properties and highly porous structure resulting in short disintegration time and fast dissolution rate. The tablets could be scaled and obtained in predesigned shapes and sizes. The proposed method may find its application in the early stages of drug development where high flexibility of the formulation is required and the amount of available API is limited.

Co-processing of small molecule excipients with polymers to improve functionality

INTRODUCTION

Polymers have various applications such as binder, film coating agent, stabilizer, drug release modification, and as primary packaging materials. Recently, they have been explored in co-processing technique to improve the functionality of small molecule excipients (SMEs). Co-processing is a concept wherein two or more excipients interact at sub-particle level to provide synergy in functionality and minimize drawbacks of individual excipients.

AREA COVERED

The present review highlights the application of co-processing to improve the functionality of SMEs using polymers; physicochemical and mechanical properties of polymers for co-processing; advantages of co-processed excipients for different applications; functionality enhancement of co-processed excipients; novel concepts/methods for co-processing; mechanistic insights on co-processing and commercial products available in the market.

EXPERT OPINION

Most of the SMEs do not possess optimal multifunctional properties like flow, compressibility, compactibility, and disintegration ability, required to compensate for poorly compactable drugs. Some of these drawbacks can be overcome by co-processing of SMEs with polymers. For example, co-processing of a brittle SME and plastic material (polymer) can provide a synergistic effect and result in the generation of single entity multi-functional excipient. Besides, novel co-processed excipients generated using combinations of SMEs and polymers can also generate intellectual property rights.

The Fundamental and Functional Property Differences Between HPMC and PVP Co-Processed Herbal Particles Prepared by Fluid Bed Coating

Core-shell composite particles (CPs) are the most preferred choice for direct compaction (DC), but their application in herbal tablets is limited. Hydroxypropyl methylcellulose (HPMC) and polyvinylpyrrolidone (PVP) are usually employed as the shell materials, but there are few, if any, researches exploring the different effects of HPMC and PVP on the properties of herbal CPs. In this study, the CPs containing HPMC (CP X-H) and CPs containing PVP (CP X-P) were prepared based on herbal powders (X). Their physical properties were characterized comprehensively. The differences in properties between CP X-H and CP X-P were explored, and their mechanism analysis was also performed profoundly. The results demonstrated that (i) CP X-H and CP X-P exhibited similar flowability; (ii) CP X-H generally exhibited better compactibility, larger particle size, and more uniform particle size distribution, and lower bulk density, tap density, and hygroscopicity than CP X-P; (iii) compared with the tablets produced with CP X-P, ones with CP X-H exhibited similar weight variation (%), lower friability, and longer disintegration time. The mechanism analysis manifested that the differences in physical properties between HPMC and PVP were the important and fundamental factors, which led to the differences in structure and surface morphology of particles, and in fundamental properties of CPs. These findings are beneficial to the development of herbal core-shell CPs for DC.

Crystallo-co-spray drying as a new approach to manufacturing of drug/excipient agglomerates: Impact of processing on the properties of paracetamol and lactose mixtures

The novel process of crystallo-co-spray drying of paracetamol and α-lactose monohydrate was investigated by varying the spray dryer inlet temperature and inlet feed solvent composition. A crystalline agglomerate was obtained with no change to the physical structure of either component throughout both investigations and with possible interactions between the hydroxyl groups of the α-lactose monohydrate and the amide and hydroxyl groups of the paracetamol detected. The percentage soluble fraction of the components in the inlet feed had the largest influence on the morphology of the final dried agglomerate. Low excipient soluble fraction resulted in an increase in paracetamol surface coating and high excipient soluble fraction produced agglomerates of highly mixed components. The use of crystallo-co-spray drying can serve as a method of producing an agglomerated blend of crystalline co-spray dried components leading to possible opportunities for process intensification with the reduction of process steps such as blending, agglomeration, drying and milling into one single stage.

Direct compaction properties of Zingiberis Rhizoma extracted powders coated with various shell materials: Improvements and mechanism analysis

Direct compaction (DC) attracts more and more attention for tablet manufacturing; however, its application in natural plant product (NPP) tablets is still extremely limited. In this study, 8 kinds of composite particles (CPs) based on the Zingiberis Rhizoma extracted powder (ZR) (a natural plant product powder with poor DC properties) were prepared with different shell materials, including hydroxypropyl methylcellulose (HPMC), polyvinylpyrrolidone (PVP), dextran, inulin, mannitol, silica, and their combinations. Their physical properties and compacting parameters were characterized comprehensively. The results demonstrated that (i) fluid bed coating was not a simple process of superposition and transmission of the physical properties of raw materials; and (ii) all the shell materials studied could improve the DC properties of problematic ZR to some degree and the combination of 7% HPMC and 1% silica showed to be the best to markedly improve both the compactibility and flowability of ZR. As a whole, by virtue of the design of core-shell particles, qualified tablets with high ZR loadings were successfully produced via continuous DC in this study. These findings are beneficial to boosting the development of natural plant tablets through DC.

Overcoming Poor Tabletability of Bulky Absorption Enhancers by Spray Drying Technology

Absorption enhancers are often a major component of solid oral peptide formulations as compared to the active pharmaceutical ingredient and excipients. This commonly results in poor tabletability that is hard to mitigate in direct compaction by addition of small amounts of excipients. To improve the tabletability of bulky absorption enhancers, the model absorption enhancers, sodium cholate and deoxycholic acid, were co-spray-dried with hydroxypropyl methylcellulose E5, where the percentage of absorption enhancers was not lower than 90% (w/w). The physicochemical properties of the resulting powders were assessed by laser diffraction, scanning electron microscopy, X-ray powder diffraction, thermogravimetric analysis, and differential scanning calorimetry. The powders were compressed into tablets, and the tabletability was evaluated. Co-spray drying with 10% of hydroxypropyl methylcellulose significantly improved the tabletability of the both absorption enhancers. Moreover, it was demonstrated that small particle size and amorphous state rather than high moisture content contributed to the improved tabletability of the spray-dried powders. The study suggests that spray drying technology can be promising to overcome the poor tabletability of oral peptide formulation consisting of large amounts of absorption enhancers.

Differences in fundamental and functional properties of HPMC co-processed fillers prepared by fluid-bed coating and spray drying

This study aimed to develop novel co-processed tablet fillers based on the principle of particle engineering for direct compaction and to compare the characteristics of co-processed products obtained by fluid-bed coating and co-spray drying, respectively. Water-soluble mannitol and water-insoluble calcium carbonate were selected as representative fillers for this study. Hydroxypropyl methylcellulose (HPMC), serving as a surface property modifier, was distributed on the surface of primary filler particles via the two co-processing methods. Both fundamental and functional properties of the products were comparatively investigated. The results showed that functional properties of the fillers, like flowability, compactibility, and drug-loading capacity, were effectively improved by both co-processing methods. However, fluid-bed coating showed greater advantages over co-spray drying in some aspects, which was mainly attributed to the remarkable differences in some fundamental properties of co-processed powders, like particle size, surface topology, and particle structure. For example, the more irregular surface and porous structure induced by fluid-bed coating could contribute to better compaction properties and lower lubricant sensitivity due to the increasing contact area and mechanical interlocking between particles under pressure. More effective surface distribution of HPMC during fluid-bed coating was also a contributor. In addition, such a porous agglomerate structure could also reduce the separation of drug and excipients after mixing, resulting in the improvement in drug loading capacity and tablet uniformity. In summary, fluid-bed coating appears to be more promising for co-processing than spray drying in some aspects, and co-processed excipients produced by it have a great prospect for further investigations and development.

Direct compaction: An update of materials, trouble-shooting, and application

Direct compaction (DC) is the preferred choice for tablet manufacturing; however, only less than 20% of active pharmaceutical ingredients could be compacted via DC as its high requirement for functional properties of materials. Materials with improper functionalities could lead to serious troubles during DC manufacturing, such as content non-uniformity, sticking, and capping, all of which profoundly affect the properties of final products and, thus, severely restrict the practical application of DC. With undoubted importance, these seem to be unexpectedly ignored by reviewers but not researchers in terms of many original research articles published recently. Therefore, as an informative supplement and update, this review mainly focused on trouble-shooting and application situation of DC, together with several newly reported materials.

Surface modification of acetaminophen particles by atomic layer deposition

Active pharmaceutical ingredients (APIs) are predominantly organic solid powders. Due to their bulk properties many APIs require processing to improve pharmaceutical formulation and manufacturing in the preparation for various drug dosage forms. Improved powder flow and protection of the APIs are often anticipated characteristics in pharmaceutical manufacturing. In this work, we have modified acetaminophen particles with atomic layer deposition (ALD) by conformal nanometer scale coatings in a one-step coating process. According to the results, ALD, utilizing common chemistries for Al₂O₃, TiO₂ and ZnO, is shown to be a promising coating method for solid pharmaceutical powders. Acetaminophen does not undergo degradation during the ALD coating process and maintains its stable polymorphic structure. Acetaminophen with nanometer scale ALD coatings shows slowed drug release. ALD TiO₂ coated acetaminophen particles show cytocompatibility whereas those coated with thicker ZnO coatings exhibit the most cytotoxicity among the ALD materials under study when assessed in vitro by their effect on intestinal Caco-2 cells.

Recent progress in continuous and semi-continuous processing of solid oral dosage forms: a review

CONTEXT

Continuous processing is an innovative production concept well known and successfully used in other industries for many years. The modern pharmaceutical industry is facing the challenge of transition from a traditional manufacturing approach based on batch-wise production to a continuous manufacturing model.

OBJECTIVE

The aim of this article is to present technological progress in manufacturing based on continuous and semi-continuous processing of the solid oral dosage forms.

METHODS

Single unit processes possessing an alternative processing pathway to batch-wise technology or, with some modification, an altered approach that may run continuously, and are thus able to seamlessly switch to continuous manufacturing are briefly presented. Furthermore, the concept of semi-continuous processing is discussed. Subsequently, more sophisticated production systems created by coupling single unit processes and comprising all the steps of production, from powder to final dosage form, were reviewed. Finally, attempts of end-to-end production approach, meaning the linking of continuous synthesis of API from intermediates with the production of final dosage form, are described.

RESULTS

There are a growing number of scientific articles showing an increasing interest in changing the approach to the production of pharmaceuticals in recent years. Numerous scientific publications are a source of information on the progress of knowledge and achievements of continuous processing. These works often deal with issues of how to modify or replace the unit processes in order to enable seamlessly switching them into continuous processing. A growing number of research papers concentrate on integrated continuous manufacturing lines in which the production concept of "from powder to tablet" is realized. Four main domains are under investigation: influence of process parameters on intermediates or final dosage forms properties, implementation of process analytical tools, control-managing system responsible for keeping continuous materials flow through the whole manufacturing process and the development of new computational methods to assess or simulate these new manufacturing techniques. The attempt to connect the primary and secondary production steps proves that development of continuously operating lines is possible.

CONCLUSION

A mind-set change is needed to be able to face, and fully assess, the advantages and disadvantages of switching from batch to continuous mode production.