A new chapter in pharmaceutical manufacturing: 3D-printed drug products

3D printing of extended-release tablets of theophylline using hydroxypropyl methylcellulose (HPMC) hydrogels

An extrusion based 3D printer was used to prepare the semi-solid tablets with different drug loading dosages (75, 100, 125 mg) under ambient temperature. The active pharmaceutical ingredient, theophylline, was uploaded within the hydrogels prepared of hydroxypropyl methylcellulose (HPMC) K4M or E4M. The HPMC concentrations were adjusted to different levels (10 and 12% w/w) to fulfill the requirements for 3D printing. Rheological and textural properties, as well as release profiles, were significantly affected by the type and concentration of excipient regardless of theophylline doses used. The printing material should exhibit shear-thinning behavior, keeping yield stress less than 4000 Pa and a loss factor (tanδ = G''/G') between 0.2 and 0.7, especially for 3D printing purposes using the current platform. The SEM images demonstrated that the hydrogel matrix exhibited a porous structure, which had the potential to encapsulate the theophylline clusters within its microstructure. The in vitro dissolution test showed that the release of all tablets was extended over 12 h, and the calculation of drug release kinetic models revealed that the 3D printed HPMC matrices release the theophylline by diffusion and erosion mechanisms. The excipient HPMC K4M 12% w/w hydrogel was optimal to load the theophylline with flexible dosage combinations due to the great extrudability and shape retention ability. The exploration of rheological properties was investigated in this study, and the results revealed that it is a feasible method to predict the SSE 3D printability and quality of hydrogel-API blend materials for the drug delivery system.

Three dimensional bioprinting technology: Applications in pharmaceutical and biomedical area

3D bioprinting is a technology based on the principle of three-dimensional printing of designed biological materials, which has been widely used recently. The production of biological materials, such as tissues, organs, cells and blood vessels with this technology is alternative and promising approach for organ and tissue transplantation. Apart from tissue and organ printing, it has a wide range of usage, such as in vitro/in vivo modeling, production of drug delivery systems and, drug screening. However, there are various restrictions on the use of this technology. In this review, the process steps, classification, advantages, limitations, usage and application areas of 3D bioprinting technology, materials and auxiliary materials used in this technology are discussed.

3D Printing of Solid Oral Dosage Forms: Numerous Challenges With Unique Opportunities

Since the FDA approval of Spritam, there has been a growing interest in the application of 3D printing in pharmaceutical science. 3D printing is a method of manufacturing involving the layer-by-layer deposition of materials to create a final product according to a digital model. There are various techniques used to achieve this method of printing including the SLS, SLA, FDM, SSE and PB-inkjet printing. In biomanufacturing, bone and tissue engineering involving 3D printing to create scaffolds, while in pharmaceutics, 3D printing was applied in drug development, and the fabrication of drug delivery devices. This paper aims to review the use of some 3D printing techniques in the fabrication of oral solid dosage forms. FDM, SLA SLS, and PB-Inkjet printing processes were found suitable for the fabrication of oral solid dosage forms, though a great deal of the available research was focused on fused deposition modelling due to its availability and flexibility. Process parameters as well as strategies to control the characteristics of printed dosage forms are analysed and discussed. The review also presents the advantages and possible limitations of 3D printing of medicines.

The impact of 3D-printed LAY-FOMM 40 and LAY-FOMM 60 on L929 cells and human oral fibroblasts

Objectives

LAY-FOMM is a promising material for FDA-approved Fused Deposition Modeling (FDM) applications in drug delivery. Here we investigated the impact on oral cells.

Materials and methods

We evaluated the impact of 3D-printed LAY-FOMM 40, LAY-FOMM 60, and biocompatible polylactic acid (PLA) on the activity of murine L929 cells, gingival fibroblasts (GF), and periodontal ligament fibroblasts (PDLF) using indirect (samples on cells), direct monolayer culture models (cells on samples), and direct spheroid cultures with resazurin-based toxicity assay, confirmed by MTT and Live-dead staining. The surface topography was evaluated with scanning electron microscopy.

Results

The materials LAY-FOMM 40 and LAY-FOMM 60 led to a reduction in resazurin conversion in L929 cells, GF, and PDLF, higher than the impact of PLA in indirect and direct culture models. Fewer vital cells were found in the presence of LAY-FOMM 40 and 60 than PLA, in the staining in both models. In the direct model, LAY-FOMM 40 and PLA showed less impact on viability in the resazurin-based toxicity assay than in the indirect model. Spheroid microtissues showed a reduction of cell activity of GF and PDLF with LAY-FOMM 40 and 60.

Conclusion

Overall, we found that LAY-FOMM 40 and LAY-FOMM 60 can reduce the activity of L292 and oral cells. Based on the results from the PLA samples, the direct model seems more reliable than the indirect model.

Clinical relevance

A material modification is desired in terms of biocompatibility as it can mask the effect of drugs and interfere with the function of the 3D-printed device.

An explorative study of polymers for 3D printing of bioanalytical test systems

BACKGROUND

The 3D printing is relevant as a manufacturing technology of functional models for forensic, pharmaceutical and bioanalytical applications such as drug delivery systems, sample preparation and point-of-care tests.

OBJECTIVE

Melting behavior and autofluorescence of materials are decisive for optimal printing and applicability of the product which are influenced by varying unknown additives.

METHODS

We have produced devices for bioanalytical applications from commercially available thermoplastic polymers using a melt-layer process. We characterized them by differential scanning calorimetry, fluorescence spectroscopy and functional assays (DNA capture assay, model for cell adhesion, bacterial adhesion and biofilm formation test).

RESULTS

From 14 tested colored, transparent and black materials we found only deep black acrylonitrile-butadiene-styrene (ABS) and some black polylactic acid (PLA) useable for fluorescence-based assays, with low autofluorescence only in the short-wave range of 300-400 nm. PLA was suitable for standard bioanalytical purposes due to a glass transition temperature of approximately 60°C, resistance to common laboratory chemicals and easy print processing. For temperature-critical methods, such as hybridization reactions up to 90°C, ABS was better suited.

CONCLUSIONS

Autofluorescence was not a disadvantage per se but can also be used as a reference signal in assays. The rapid development of individual protocols for sample processing and analysis required the availability of a material with consistent quality over time. For fluorescence-based assays, the use of commercial standard materials did not seem to meet this requirement.

3D printing promotes the development of drugs

3D printing is an emerging field that can be found in medicine, electronics, aviation and other fields. 3D printing, with its personalized and highly customized characteristics, has great potential in the pharmaceutical industry. We were interested in how 3D printing can be used in drug fields. To find out 3D printing's application in drug fields, we collected the literature by combining the keywords "3D printing"/"additive manufacturing" and "drug"/"tablet". We found that 3D printing technology has the following applications in medicine: firstly, it can print pills on demand according to the individual condition of the patient, making the dosage more suitable for each patient's own physical condition; secondly, it can print tablets with specific shape and structure to control the release rate; thirdly, it can precisely control the distribution of cells, extracellular matrix and biomaterials to build organs or organ-on-a-chip for drug testing; finally, it could print loose porous pills to reduce swallowing difficulties, or be used to make transdermal microneedle patches to reduce pain of patients.

Polymer Selection for Hot-Melt Extrusion Coupled to Fused Deposition Modelling in Pharmaceutics

Three-dimensional (3D) printing offers the greatest potential to revolutionize the future of pharmaceutical manufacturing by overcoming challenges of conventional pharmaceutical operations and focusing design and production of dosage forms on the patient’s needs. Of the many technologies available, fusion deposition modelling (FDM) is considered of the lowest cost and higher reproducibility and accessibility, offering clear advantages in drug delivery. FDM requires in-house production of filaments of drug-containing thermoplastic polymers by hot-melt extrusion (HME), and the prospect of connecting the two technologies has been under investigation. The ability to integrate HME and FDM and predict and tailor the filaments’ properties will extend the range of printable polymers/formulations. Hence, this work revises the properties of the most common pharmaceutical-grade polymers used and their effect on extrudability, printability, and printing outcome, providing suitable processing windows for different raw materials. As a result, formulation selection will be more straightforward (considering the characteristics of drug and desired dosage form or release profile) and the processes setup will be more expedite (avoiding or mitigating typical processing issues), thus guaranteeing the success of both HME and FDM. Relevant techniques used to characterize filaments and 3D-printed dosage forms as an essential component for the evaluation of the quality output are also presented.

New gellan gum-graft-poly(d,l-lactide-co-glycolide) copolymers as promising bioinks: Synthesis and characterization

This research focused on the aim of tackling the urgent demand of printable biomaterials, hence we synthetized and characterized three gellan gum-graft-poly(d,l-lactide-co-glycolide) copolymers (GGm-PLGA a, b and c) which differed in the graft substitution degree. We investigated the effect of the polyester chain grafted onto hydrophilic backbone of gellan gum in terms of physicochemical properties and the ability of the system to print 3D cell laden constructs. In particular, we evaluated thermo-rheological, ionotropic crosslinking, shear thinning, swelling and stability properties of these copolymers and their derived biomaterials and findings related to the degree of functionalization. Moreover, the optimization of the 3D process parameters and the effect of different water/DPBS mixtures was investigated, demonstrating the feasibility of the system to print 3D constructs. Finally, biological tests revealed that fibroblasts and chondrocytes remained viable after printing and over a culture period of seven days into scaffolds.

3D Printing Technologies: Recent Development and Emerging Applications in Various Drug Delivery Systems

The 3D printing is considered as an emerging digitized technology that could act as a key driving factor for the future advancement and precise manufacturing of personalized dosage forms, regenerative medicine, prosthesis and implantable medical devices. Tailoring the size, shape and drug release profile from various drug delivery systems can be beneficial for special populations such as paediatrics, pregnant women and geriatrics with unique or changing medical needs. This review summarizes various types of 3D printing technologies with advantages and limitations particularly in the area of pharmaceutical research. The applications of 3D printing in tablets, films, liquids, gastroretentive, colon, transdermal and intrauterine drug delivery systems as well as medical devices have been briefed. Due to the novelty and distinct features, 3D printing has the inherent capacity to solve many formulation and drug delivery challenges, which are frequently associated with poorly aqueous soluble drugs. Recent approval of Spritam® and publication of USFDA technical guidance on additive manufacturing related to medical devices has led to an extensive research in various field of drug delivery systems and bioengineering. The 3D printing technology could be successfully implemented from pre-clinical phase to first-in-human trials as well as on-site production of customized formulation at the point of care having excellent dose flexibility. Advent of innovative 3D printing machineries with built-in flexibility and quality with the introduction of new regulatory guidelines would rapidly integrate and revolutionize conventional pharmaceutical manufacturing sector.

3D printed gummies: Personalized drug dosage in a safe and appealing way

Obtention of customized dosage forms is one of the main attractions of 3D printing in pharmaceuticals. In this sense, children are one of the groups within the population with a greater need for drug doses adapted to their requirements (age, weight, pathological state…), but most 3D printed oral dosages are solid forms and, therefore, not suitable for them. This work developed patient-tailored medicinal gummies, an alternative oral dosage form with eye-catching appearance and appropriate organoleptic characteristics. Four inks were formulated, characterised and 3D printed by means of syringe-based extrusion mechanism. Different tests were performed to ensure reproducibility of the process and validate work methodology for dosage unit fabrication applying basic manufacturing standards. Rheological test helped in evaluating inks printability. Visual characterization concluded that drugmies, apart from a high fidelity in the 3D model shape reproduction, had a bright and uniformly coloured appearance and a pleasant aroma, which made them highly appetising and attractive. The printed gummy oral dosages complied comfortably with the mass uniformity assay regardless of the formulated ink used or the 3D model selected for printing. Ranitidine hydrochloride individual contents were determined using uv-vis spectrophotometry, showing successful results both in dose accuracy, uniformity of drug content and dissolution.

3D Printed Drug Delivery Systems Based on Natural Products

In the last few years, the employment of 3D printing technologies in the manufacture of drug delivery systems has increased, due to the advantages that they offer for personalized medicine. Thus, the possibility of producing sophisticated and tailor-made structures loaded with drugs intended for tissue engineering and optimizing the drug dose is particularly interesting in the case of pediatric and geriatric population. Natural products provide a wide range of advantages for their application as pharmaceutical excipients, as well as in scaffolds purposed for tissue engineering prepared by 3D printing technologies. The ability of biopolymers to form hydrogels is exploited in pressure assisted microsyringe and inkjet techniques, resulting in suitable porous matrices for the printing of living cells, as well as thermolabile drugs. In this review, we analyze the 3D printing technologies employed for the preparation of drug delivery systems based on natural products. Moreover, the 3D printed drug delivery systems containing natural products are described, highlighting the advantages offered by these types of excipients.

Tunable structural color of bottlebrush block copolymers through direct-write 3D printing from solution

Additive manufacturing of functional materials is limited by control of microstructure and assembly at the nanoscale. In this work, we integrate nonequilibrium self-assembly with direct-write three-dimensional (3D) printing to prepare bottlebrush block copolymer (BBCP) photonic crystals (PCs) with tunable structure color. After varying deposition conditions during printing of a single ink solution, peak reflected wavelength for BBCP PCs span a range of 403 to 626 nm (blue to red), corresponding to an estimated change in d-spacing of >70 nm (Bragg- Snell equation). Physical characterization confirms that these vivid optical effects are underpinned by tuning of lamellar domain spacing, which we attribute to modulation of polymer conformation. Using in situ optical microscopy and solvent-vapor annealing, we identify kinetic trapping of metastable microstructures during printing as the mechanism for domain size control. More generally, we present a robust processing scheme with potential for on-the-fly property tuning of a variety of functional materials.

Selective laser sintering 3D printing - an overview of the technology and pharmaceutical applications

Food and Drug Administration (FDA) has approved a drug product (Spritam®) and many medical devices manufactured by three-dimensional printing (3DP) processes for human use. There is immense potential to print personalized medicines using 3DP. Many 3DP methods have been reported in the literature for pharmaceutical applications. However, selective laser sintering (SLS) printing has remained least explored for pharmaceutical applications. There are many advantages and challenges in adopting a SLS method for fabrication of personalized medicines. Solvent-free nature, availability of FDA approved thermoplastic polymer/excipients (currently used in hot melt-extrusion process), minimal/no post-processing step, etc. are some of the advantages of the SLS printing process. Major challenges of the technology are requirement of at least one thermoplastic component in the formulation and thermal stability of drug and excipients. This review provides an overview of the SLS printing method, excipient requirements, process monitoring, quality defects, regulatory aspects, and potential pharmaceutical applications.

Implantable Medical Devices and Tissue Engineering: An Overview of Manufacturing Processes and the Use of Polymeric Matrices for Manufacturing and Coating their Surfaces

Medical devices are important diagnosis and therapy tools for several diseases which include a wide range of products. Technological advances in this area have been proposed to reduce adverse complication incidences. New technologies and manufacturing processes, as well as the development of new materials or medical devices with modified surface and the use of biodegradable polymeric devices such as a substrate for cell culture in the field of tissue engineering, have attracted considerable attention in recent years by the scientific community intended to produce medical devices with superior properties and morphology. This review article focused on implantable devices, addresses the major advances in the biomedical field related to the devices manufacture processes such as 3D printing and hot melting extrusion, and the use of polymer matrices composed of copolymers, blends, nanocomposites or grafted with antiproliferative drugs for manufacturing and/or coating the devices surface.

Understanding the relationship between slicing and measured fill density in material extrusion 3D printing towards precision porosity constructs for biomedical and pharmaceutical applications

Background

Fill density is a critical parameter affecting the functional performance of 3D printed porous constructs in the biomedical and pharmaceutical domain. Numerous studies have reported the impact of fill density on the mechanical properties, diffusion characteristics and content release rates of constructs. However, due to the way in which slicing toolpath calculations are performed, there is substantial deviation between the measured and slicing fill density for relatively small sized constructs printed at low fill densities (high porosities). The purpose of the current study was to investigate this discrepancy using a combination of mathematical modeling and experimental validation.

Methods

The open source slicer Slic3r was used to 3D print 20 mm × 20 mm × 5 mm constructs at three identified slicing fill density values, 9.58%, 20.36% and 32.33% (exact values entered into software), in triplicates. A mathematical model was proposed to accurately predict fill density, and the measured fill density was compared to both the predicted as well as the slicing fill density. The model was further validated at two additional slicing fill densities of 15% and 40%. The total material within the construct was analyzed from the perspective of material extruded within the beads as well as the bead to bead interconnects using the predictive model.

Results

The slicing fill density deviated substantially from measured fill density at low fill densities with absolute errors larger than 26% in certain instances. The proposed model was able to predict fill density to within 5% of the measured fill density in all cases. The average absolute error between predicted vs. measured fill density was 3.5%, whereas that between slicing vs. measured fill density was 13%. The material extruded in the beads varied from 86.5% to 95.9%, whereas that extruded in the interconnects varied from 13.5% to 4.1%.

Conclusions

The proposed model and approach was able to predict fill density to a reasonable degree of accuracy. Findings from the study could prove useful in applications where controlling construct fill density in relatively small sized constructs is important for achieving targeted levels of functional criteria such as mechanical strength, weight loss and content release rate.

Materials and technical innovations in 3D printing in biomedical applications

3D printing is a rapidly growing research area, which significantly contributes to major innovations in various fields of engineering, science, and medicine. Although the scientific advancement of 3D printing technologies has enabled the development of complex geometries, there is still an increasing demand for innovative 3D printing techniques and materials to address the challenges in building speed and accuracy, surface finish, stability, and functionality. In this review, we introduce and review the recent developments in novel materials and 3D printing techniques to address the needs of the conventional 3D printing methodologies, especially in biomedical applications, such as printing speed, cell growth feasibility, and complex shape achievement. A comparative study of these materials and technologies with respect to the 3D printing parameters will be provided for selecting a suitable application-based 3D printing methodology. Discussion of the prospects of 3D printing materials and technologies will be finally covered.

Challenges of 3D printing technology for manufacturing biomedical products: A case study of Malaysian manufacturing firms

Additive manufacturing has attracted increasing attention worldwide, especially in the healthcare, biomedical, aerospace, and construction industries. In Malaysia, insufficient acceptance of this technology by local industries has resulted in a call for government and local practitioners to promulgate the development of this technology for various industries, particularly for biomedical products. The current study intends to frame the challenges endured by biomedical industries who use 3D printing technology for their manufacturing processes. Qualitative methods, particularly in-depth interviews, were used to identify the challenges faced by manufacturing firms when producing 3D printed biomedical products. This work was able to identify twelve key challenges when deploying additive manufacturing in biomedical products and these include issues related to binder selection, poor mechanical properties, low-dimensional accuracy, high levels of powder agglomeration, nozzle size, distribution size, limited choice of materials, texture and colour, lifespan of materials, customization of fit and design, layer height, and, lastly, build-failure. Furthermore, there also are six challenges in the management of manufacturing biomedical products using 3D printing technology, and these include staff re-education, product pricing, limited guidelines, cyber-security issues, marketing, and patents and copyright. This study discusses the reality faced by 3D printing players when producing biomedical products in Malaysia, and presents a primary reference for practitioners in other developing countries.

Progressive 3D Printing Technology and Its Application in Medical Materials

Three-dimensional (3D) printing enables patient-specific anatomical level productions with high adjustability and resolution in microstructures. With cost-effective manufacturing for high productivity, 3D printing has become a leading healthcare and pharmaceutical manufacturing technology, which is suitable for variety of applications including tissue engineering models, anatomical models, pharmacological design and validation model, medical apparatus and instruments. Today, 3D printing is offering clinical available medical products and platforms suitable for emerging research fields, including tissue and organ printing. In this review, our goal is to discuss progressive 3D printing technology and its application in medical materials. The additive overview also provides manufacturing techniques and printable materials.

In vitro modeling of the neurovascular unit: advances in the field

The blood–brain barrier (BBB) is a fundamental component of the central nervous system. Its functional and structural integrity is vital in maintaining the homeostasis of the brain microenvironment. On the other hand, the BBB is also a major hindering obstacle for the delivery of effective therapies to treat disorders of the Central Nervous System (CNS). Over time, various model systems have been established to simulate the complexities of the BBB. The development of realistic in vitro BBB models that accurately mimic the physiological characteristics of the brain microcapillaries in situ is of fundamental importance not only in CNS drug discovery but also in translational research. Successful modeling of the Neurovascular Unit (NVU) would provide an invaluable tool that would aid in dissecting out the pathological factors, mechanisms of action, and corresponding targets prodromal to the onset of CNS disorders. The field of BBB in vitro modeling has seen many fundamental changes in the last few years with the introduction of novel tools and methods to improve existing models and enable new ones. The development of CNS organoids, organ-on-chip, spheroids, 3D printed microfluidics, and other innovative technologies have the potential to advance the field of BBB and NVU modeling. Therefore, in this review, summarize the advances and progress in the design and application of functional in vitro BBB platforms with a focus on rapidly advancing technologies.

Three-dimensional printing technology as a promising tool in bioavailability enhancement of poorly water-soluble molecules: A review

Poor aqueous solubility of active pharmaceutical ingredients (API) is nowadays a major issue in the pharmaceutical field. The combinatorial chemistry provides more and more API with a great therapeutic potential, but with a low aqueous solubility. Among the strategies to overcome this drawback, the use of amorphous solid dispersions (ASD), as well as the increase of surface area, is widely used. The three dimensional (3D) printing technologies appear to be innovative tools allowing the construction of any unconventional forms with different composition, structure or infill; especially by using ASD materials. This review aims to deliver notions about the different 3D printing techniques found in the literature to improve aqueous solubility of several API, namely nozzle-based method, inkjet methods and laser- based methods, as well as guide formulator in terms of formulation parameters that have to be optimized to allow the most suitable impression of innovative medicines.

On-demand fully customizable drug tablets via 3D printing technology for personalized medicine

Personalized medicine should ideally be prescribed to every individual because of the unique characteristics (e.g., biological, physical, and medical) of each individual. It is, however, challenging to provide personalized medicine for the mass population of specific individuals effectively and efficiently. This manuscript describes a method of fabricating fully customizable drug tablets for personalized medicine by the 3D printing technology. This method involves the versatile fabrication of the tablets via the specifically designed 3D printed molds of different shapes and sizes, and an intuitive 1-dimensional release of drug that relates the shape of the drug-containing matrix to the release profile. The customization includes all the aspects of varying dosage, duration, release profiles, and combination of multiple drugs. In particular, it has previously been technically difficult to devise a single platform that fabricates carriers that release drug with any desired type of release profiles. This method of fabricating fully customizable tablets is simple, inexpensive, and efficient. Detailed selection and investigation of the materials ensured that the tablet and the method of fabrication are safe (e.g., biocompatible, FDA-approved ingredients used) and other desirable features (e.g., sustained release and high dosage) are achieved. These desirable characteristics of the method thus allow fully customizable drug tablets to be fabricated efficiently on the spot after the diagnosis of individual patients; at the same time, the method can be made widely accessible to the mass population. Hence, the concept of personalized medicine can truly be realized.

A Feasibility Study of an Extrusion-Based Fabrication Process for Personalized Drugs

Developing a high-efficiency manufacturing system for personalized medicine plays an important role in increasing the feasibility of personalized medication. The purpose of this study is to investigate the feasibility of a new extrusion-based fabrication process for personalized drugs with a faster production rate. This process uses two syringe pumps with a coaxial needle as an extruder, which extrudes two materials with varying ratios into a capsule. The mixture of hydrogel, polyethylene glycol (PEG), hydroxypropyl methylcellulose, poly acrylic acid and the simulated active pharmaceutical ingredient, Aspirin, was used. To validate the method, samples with different ratios of immediate release (IR) and sustained release (SR) mixtures were fabricated. The results of a dissolution test show that it is feasible to control the release profile by changing the IR and SR ratio using this fabrication setup. The fabrication time for each capsule is about 20 seconds, which is significantly faster than the current 3D printing methods. In conclusion, the proposed fabrication method shows a clear potential to step toward the feasibility of personalized medication.

Preparation and application of subdivided tablets using 3D printing for precise hospital dispensing

This study aimed to use three-dimensional printing technology to provide patients with accurate, safe and convenient subdivided drugs and bring the transformation of subdivided drugs' fabrication in the hospital. The formulation, preparation process, model and printing parameters, relationship between dose and preset model for printing of spironolactone of 2 mg, 4 mg and hydrochlorothiazide of 5 mg subdivided tablets prepared by three-dimensional printers were investigated in the study. The three-dimensional printed material consists of commercial tablets powders and other excipients, including lactose, corn starch, microcrystalline cellulose, and so on. Mass variation, drug content and drug content uniformity of subdivided tablets obtained by three-dimensional printing were compared with the pharmacists splitting subdivided tablets. Besides, the results from fourier transform infrared spectroscopy, differential scanning calorimetry and X-ray powder diffraction confirmed that the preparation process of spironolactone of 2 mg, 4 mg and hydrochlorothiazide of 5 mg did not change the crystal structure of the active pharmaceutical ingredient. Furthermore, mass variation, drug content range and drug content uniformity of spironolactone of 2 mg, 4 mg and hydrochlorothiazide of 5 mg tablets split by pharmacists failed to comply with European Pharmacopoeia and Chinese Pharmacopoeia, while those of the three-dimensional printed subdivided tablets did. After the review of the ethics committee as a new technology for hospital dispensing, three-dimensional printed spironolactone subdivided tablets of 2 mg have been used in clinical inpatients and was accepted by pharmacists, nurses and patients. Compared with tablets subdivided split by pharmacists, three-dimensional printed spironolactone tablets of 2 mg were more accurate, safer and more customized, which indicated considerable potential in using three-dimensional printing technology as a new method for hospital dispensing.

Global Diffusion of Innovation during the Fourth Industrial Revolution: The Case of Additive Manufacturing or 3D Printing

Additive manufacturing can be considered an innovative and high-technology and one of its characteristics is that it has limited dependency on the location. The purpose of this study is to examine this aspect by investigation how additive manufacturing is spreading globally. The focus is on established manufacturers of industrial additive manufacturing machines. It was found that the early-stage diffusion of this technology is primarily in advanced economies. Furthermore, many of the currently established companies that manufacture industrial 3D printers come from already existing companies that expanded into AM or that led to spin-off companies. The complexity of AM which requires expert knowledge across a range of fields may be the key reason for this finding. Recommendations for further research are provided.

Addressing present pitfalls in 3D printing for tissue engineering to enhance future potential

Additive manufacturing in tissue engineering has significantly advanced in acceptance and use to address complex problems. However, there are still limitations to the technologies used and potential challenges that need to be addressed by the community. In this manuscript, we describe how the field can be advanced not only through the development of new materials and techniques but also through the standardization of characterization, which in turn may impact the translation potential of the field as it matures. Furthermore, we discuss how education and outreach could be modified to ensure end-users have a better grasp on the benefits and limitations of 3D printing to aid in their career development.

Vat polymerization-based bioprinting-process, materials, applications and regulatory challenges

Over the years, the field of bioprinting has attracted attention for its highly automated fabrication system that enables the precise patterning of living cells and biomaterials at pre-defined positions for enhanced cell-matrix and cell-cell interactions. Notably, vat polymerization (VP)-based bioprinting is an emerging bioprinting technique for various tissue engineering applications due to its high fabrication accuracy. Particularly, different photo-initiators (PIs) are utilized during the bioprinting process to facilitate the crosslinking mechanism for fabrication of high-resolution complex tissue constructs. The advancements in VP-based printing have led to a paradigm shift in fabrication of tissue constructs from cell-seeding of tissue scaffolds (non-biocompatible fabrication process) to direct bioprinting of cell-laden tissue constructs (biocompatible fabrication process). This paper, presenting a first-time comprehensive review of the VP-based bioprinting process, provides an in-depth analysis and comparison of the various biocompatible PIs and highlights the important considerations and bioprinting requirements. This review paper reports a detailed analysis of its printing process and the influence of light-based curing modality and PIs on living cells. Lastly, this review also highlights the significance of VP-based bioprinting, the regulatory challenges and presents future directions to transform the VP-based printing technology into imperative tools in the field of tissue engineering and regenerative medicine. The readers will be informed on the current limitations and achievements of the VP-based bioprinting techniques. Notably, the readers will realize the importance and value of highly-automated platforms for tissue engineering applications and be able to develop objective viewpoints towards this field.

Polymers for Extrusion-Based 3D Printing of Pharmaceuticals: A Holistic Materials-Process Perspective

Three dimensional (3D) printing as an advanced manufacturing technology is progressing to be established in the pharmaceutical industry to overcome the traditional manufacturing regime of 'one size fits for all'. Using 3D printing, it is possible to design and develop complex dosage forms that can be suitable for tuning drug release. Polymers are the key materials that are necessary for 3D printing. Among all 3D printing processes, extrusion-based (both fused deposition modeling (FDM) and pressure-assisted microsyringe (PAM)) 3D printing is well researched for pharmaceutical manufacturing. It is important to understand which polymers are suitable for extrusion-based 3D printing of pharmaceuticals and how their properties, as well as the behavior of polymer-active pharmaceutical ingredient (API) combinations, impact the printing process. Especially, understanding the rheology of the polymer and API-polymer mixtures is necessary for successful 3D printing of dosage forms or printed structures. This review has summarized a holistic materials-process perspective for polymers on extrusion-based 3D printing. The main focus herein will be both FDM and PAM 3D printing processes. It elaborates the discussion on the comparison of 3D printing with the traditional direct compression process, the necessity of rheology, and the characterization techniques required for the printed structure, drug, and excipients. The current technological challenges, regulatory aspects, and the direction toward which the technology is moving, especially for personalized pharmaceuticals and multi-drug printing, are also briefly discussed.