Hydrophilic Excipient-Independent Drug Release from SLA-Printed Pellets

3D printing of pharmaceutical dosage forms: Recent advances and applications

Three-dimensional (3D) printing, also referred to as additive manufacturing, is considered to be a game-changing technology in many industries and is also considered to have potential use cases in pharmaceutical manufacturing, especially if individualization is desired. In this review article the authors systematically researched literature published during the last 5 years (2019 - spring 2024) on the topic of 3D printed dosage forms. Besides all kinds of oral dosage forms ranging from tablets and capsules to films, pellets, etc., numerous reports were also identified on parenteral and cutaneous dosage forms and also rectal, vaginal, dental, intravesical, and ophthalmic preparations. In total, more than 500 publications were identified and grouped according to the site of administration, and an overview of the manuscripts is presented here. Furthermore, selected publications are described and discussed in more detail. The review highlights the very different approaches that are currently used in order to develop 3D printed dosage forms but also addresses remaining challenges.

Trends in Photopolymerization 3D Printing for Advanced Drug Delivery Applications

Since its invention in the 1980s, photopolymerization-based 3D printing has attracted significant attention for its capability to fabricate complex microstructures with high precision, by leveraging light patterning to initiate polymerization and cross-linking in liquid resin materials. Such precision makes it particularly suitable for biomedical applications, in particular, advanced and customized drug delivery systems. This review summarizes the latest advancements in photopolymerization 3D printing technology and the development of biocompatible and/or biodegradable materials that have been used or shown potential in the field of drug delivery. The drug loading methods and release characteristics of the 3D printing drug delivery systems are summarized. Importantly, recent trends in the drug delivery applications based on photopolymerization 3D printing, including oral formulations, microneedles, implantable devices, microrobots and recently emerging systems, are analyzed. In the end, the challenges and opportunities in photopolymerization 3D printing for customized drug delivery are discussed.

From design to 3D printing: A proof-of-concept study for multiple unit particle systems (MUPS) printed by dual extrusion fused filament fabrication

MUPS (multiple unit particle systems) are oral dosage forms consisting of small particles which are filled into capsules or compressed into tablets. Compared to monolithic sustained-release tablets, MUPS tablets rapidly disintegrate inside the stomach releasing the contained small particles, which can be emptied from the stomach independent of housekeeping waves. Control of release can be achieved by adapting the particle composition. Despite the advantages of MUPS, only a limited number of preparations are available on the market. 3D printing could be a new advantageous method to produce MUPS tablets compared to the conventional production via tableting. Due to the increasing research interest in personalised medicine, especially regarding dose adjustments, this flexible production approach could be a promising concept. Therefore, this work proposes a concept for printing MUPS tablets using a dual extrusion fused filament fabrication 3D printer. The general idea is that the two print heads can be used independently to print a water-soluble tablet shell with the first print head and incorporate functional particles into the tablet shell with a second print head using different materials for each step. In this study, a modular four-particle-layered tablet computer model containing 196 cylindrical particles with a diameter of 1.4 mm, a height of 1.0 mm and a total tablet size of 22.6 × 8.5 × 6.0 mm is proposed. A first proof-of-concept study with drug-free commercially available polylactic acid filament for the particles and polyvinyl alcohol filament for the tablet shell revealed critical parameters (such as filament retraction, z-offset and water content of filaments) for the successful printing of the proposed computer model. In addition, the successfully printed model 3D-MUPS tablets and incorporated particles were characterised, revealing a reproducible manufacturing process. The printed model particles had a diameter of 1.27 ± 0.04 mm and a height of 1.05 ± 0.01 mm. One of the challenges of the new approach was to avoid particle agglomeration because of remelting processes during the printing with two print heads. 57.54 ± 18.59 % of the 196 printed particles were present as single particles. Finally, the transferability and suitability with a model API-loaded (paracetamol) hydroxypropyl methylcellulose filament for the particles and a polyvinyl alcohol tablet shell was successfully tested. On average, 80 % of paracetamol was released within 3 h (2-4 h). Overall, this work shows an innovative new manufacturing method for dose-adjustable personalised MUPS tablets but also considers new challenges arising from the different manufacturing processes.

3D-printed dosage forms for oral administration: a review

Oral administration is the most commonly used form of treatment due to its advantages, including high patient compliance, convenient administration, and minimal preparation required. However, the traditional preparation process of oral solid preparation has many defects. Although continuous manufacturing line that combined all the unit operations has been developed and preliminarily applied in the pharmaceutical industry, most of the currently used manufacturing processes are still complicated and discontinuous. As a result, these complex production steps will lead to low production efficiency and high quality control risk of the final product. Additionally, the large-scale production mode is inappropriate for the personalized medicines, which commonly is customized with small amount. Several attractive techniques, such as hot-melt extrusion, fluidized bed pelletizing and spray drying, could effectively shorten the process flow, but still, they have inherent limitations that are challenging to address. As a novel manufacturing technique, 3D printing could greatly reduce or eliminate these disadvantages mentioned above, and could realize a desirable continuous production for small-scale personalized manufacturing. In recent years, due to the participation of 3D printing, the development of printed drugs has progressed by leaps and bounds, especially in the design of oral drug dosage forms. This review attempts to summarize the new development of 3D printing technology in oral preparation and also discusses their advantages and disadvantages as well as potential applications.

Reverse Engineering and 3D Printing of Medical Devices for Drug Delivery and Drug-Embedded Anatomic Implants

In recent years, 3D printing (3DP) has advanced traditional medical treatments. This review explores the fusion of reverse engineering and 3D printing of medical implants, with a specific focus on drug delivery applications. The potential for 3D printing technology to create patient-specific implants and intricate anatomical models is discussed, along with its ability to address challenges in medical treatment. The article summarizes the current landscape, challenges, benefits, and emerging trends of using 3D-printed formulations for medical implantation and drug delivery purposes.

A Bibliometric Analysis of 3D Printing in Personalized Medicine Research from 2012 to 2022

In recent years, the 3D printing of personalized drug formulations has attracted the attention of medical practitioners and academics. However, there is a lack of data-based analyses on the hotspots and trends of research in this field. Therefore, in this study, we performed a bibliometric analysis to summarize the 3D printing research in the field of personalized drug formulation from 2012 to 2022. This study was based on the Web of Science Core Collection Database, and a total of 442 eligible publications were screened. Using VOSviewer and online websites for bibliometric analysis and scientific mapping, it was observed that annual publications have shown a significant growth trend over the last decade. The United Kingdom and the United States, which account for 45.5% of the total number of publications, are the main drivers of this field. The International Journal of Pharmaceutics and University College London are the most prolific and cited journals and institutions. The researchers with the most contributions are Basit, Abdul W. and Goyanes Alvaro. The keyword analysis concluded that the current research hotspots are "drug release" and "drug dosage forms". In conclusion, 3D printing has broad application prospects in the field of personalized drugs, which will bring the pharmaceutical industry into a new era of innovation.

Effect of Tartrazine as Photoabsorber for Improved Printing Resolution of 3D Printed "Ghost Tablets": Non-Erodible Inert Matrices

Stereolithography (SLA) 3D printing of pharmaceuticals suffers from the problem of light scattering, which leads to over-curing, resulting in the printing of objects that are non-compliant with design dimensions and the overloading of drugs. To minimize this problem, photoabsorbers such as tartrazine (food grade) can be used to absorb the stray light produced by scattering, leading to unintended photopolymerization. Ghost tablets (i.e., non-erodible inert matrices) were additively manufactured using SLA with varying ratios of polyethylene glycol diacrylate (PEGDA): polyethylene glycol (PEG) 300, along with tartrazine concentrations. The 3D printed ghost tablets containing maximum (0.03%) tartrazine were extremely precise in size and adhered to the nominal value of the metformin hydrochloride content. Resolution analysis reinstated the influence of tartrazine in achieving highly precise objects of even 0.07 mm² area. Furthermore, 3D printed ghost tablets were characterized using analytical means, and swelling studies. Additionally, ghost tablets were tested for their mechanical robustness using dynamic mechanical and texture analysis, and were able to withstand strains of up to 5.0% without structural failure. The printed ghost tablets displayed a fast metformin hydrochloride release profile, with 93.14% release after 12 h when the PEG 300 ratio was at its maximum. Ghost tablets were also subjected to in vivo X-ray imaging, and the tablets remained intact even after four hours of administration and were eventually excreted in an intact form through fecal excretion.

Three-Dimensional-Printed Oral Films Based on LCD: Influence Factors of the Film Printability and Received Qualities

As an oral mucosal drug delivery system, oral films have been of wide concern in recent years because of their advantages such as rapid absorption, being easy to swallow and avoiding the first-pass effect common for mucoadhesive oral films. However, the currently utilized manufacturing approaches including solvent casting have many limitations, such as solvent residue and difficulties in drying, and are not suitable for personalized customization. To solve these problems, the present study utilizes liquid crystal display (LCD), a photopolymerization-based 3D printing technique, to fabricate mucoadhesive films for oral mucosal drug delivery. The designed printing formulation includes PEGDA as the printing resin, TPO as the photoinitiator, tartrazine as the photoabsorber, PEG 300 as the additive and HPMC as the bioadhesive material. The influence of printing formulation and printing parameters on the printing formability of the oral films were elucidated in depth, and the results suggested that PEG 300 in the formulation not only provided the necessary flexibility of the printed oral films, but also improved drug release rate due to its role as pore former in the produced films. The presence of HPMC could greatly improve the adhesiveness of the 3D-printed oral films, but excessive HPMC increased the viscosity of the printing resin solution, which could strongly hinder the photo-crosslinking reaction and reduce printability. Based on the optimized printing formulation and printing parameters, the bilayer oral films containing a backing layer and an adhesive layer were successfully printed with stable dimensions, adequate mechanical properties, strong adhesion ability, desirable drug release and efficient in vivo therapeutic efficacy. All these results indicated that an LCD-based 3D printing technique is a promising alternative to precisely fabricate oral films for personalized medicine.

3D printed oral solid dosage form: Modified release and improved solubility

Oral solid dosage form is currently the most common used form of drug. 3D Printing, also known as additive manufacturing (AM), can quickly print customized and individualized oral solid dosage form on demand. Compared with the traditional tablet manufacturing process, 3D Printing has many advantages. By rationally selecting the formulation composition and cleverly designing the printing structure, 3D printing can improve the solubility of the drug and achieve precise modify of the drug release. 3D printed oral solid dosage form, however, still has problems such as limitations in formulation selection. And the selection process of the formulation lacks scientificity and standardization. Structural design of some 3D printing approaches is relatively scarce. This article reviews the formulation selection and structure design of 3D printed oral solid dosage form, providing more ideas for achieving modified drug release and solubility improvement of 3D printed oral solid dosage form through more scientific and extensive formulation selection and more sophisticated structural design.