Anti-tuberculosis drug combination for controlled oral delivery using 3D printed compartmental dosage forms: From drug product design to in vivo testing

Comprehensive review of 3D printing techniques emphasizing thermal characterization in biomedical prototyping

The rapid advancement of 3D printing technology has revolutionized biomedical engineering, enabling the creation of complex and personalized prototypes. Thermal properties play a crucial role in the performance and safety of these biomedical devices. Understanding their thermal behavior is essential for ensuring their effectiveness, reliability, and compatibility with the human body. This review article aims to provide a comprehensive overview of the thermal properties of 3D printed biomedical prototypes. It categorizes these prototypes based on thermal characteristics, examines the thermal attributes of various 3D printing materials, explores the thermal considerations for different biomedical devices, and identifies the challenges and future prospects in this dynamic field.

Exploration of Conventional and FDM-Mediated 3D Printed Tablets Fabricated Using HME-Based Filaments for pH-Dependent Drug Delivery

Hot melt extrusion (HME) helps to improve the solubility of BCS class II and IV molecules. The downstream processing of the resulting filaments was crucial in developing the final dosage form. The present work investigates advantages of combining HME with fused deposition modelling (FDM) 3-Dimensional (3D) printing in delivering the naringenin to the colon to treat inflammatory bowel disease. HME filaments were made using a pH-sensitive polymer hydroxypropyl methylcellulose acetate succinate for the localized delivery of naringenin at the colonic pH. Polyethylene glycol (PEG - 4000) and Aerosil 200 were incorporated as plasticizer and flow modulator respectively, to facilitate the extrusion process. Naringenin was converted to amorphous form as confirmed by differential scanning calorimetry and powder x-ray diffraction. The optimized filament showed 0.03, 11.52 and 77.80% drug release at pH 1.2, 6.8 and 7.4 respectively. The tablets produced with the optimized filament by compression and 3D printing also confirmed the presence of naringenin in amorphous form and demonstrated pH-dependent release followed by zero-order release independent of the concentration. The dissolution profiles of FDM 3D printed (3DP) tablets with varying dimensions and infill densities suggested that both significantly influenced drug release from the tablets without altering the composition of tablets, indicating the potential application of 3D printing technology in developing personalized medicine according to patient requirements. These promising results may be valuable in evaluating the potential of naringenin in animal models, which may further facilitate clinical applications.

Preparation and characterization of immediate release 3D printed tablets using hot melt extruded amorphous cyclosporine a filament

3D printing technology is gaining attention as a next-generation approach to drug formulation. Among 3D printing techniques, fused deposition modeling is cost-effective but depends heavily on suitable filaments. Hot melt extrusion enables filament production by incorporating poorly water-soluble drugs like cyclosporine A into polymers to form solid dispersions. However, achieving immediate release formulations with 3D printing remains challenging due to issues such as inadequate tablet disintegration or drug entrapment within the polymer matrix. This study aimed to develop and evaluate immediate release 3D-printed cyclosporine A tablets using HME filaments. Three parameters were modified in the 3D printing process: varying fill speeds, infill densities, and channel lengths. Filaments composed of Kollidon® VA 64 and HPC-SSL (1:1) were used to print tablets. Solid-state analysis confirmed cyclosporine A 's amorphous state and partial crystallinity in Xylisorb® 300. Dissolution studies revealed that lower infill densities (30%) and fewer walls enhanced drug release by increasing internal void space and reducing hardness. Conversely, greater tablet height (channel length) delayed dissolution. These findings emphasize the critical role of geometric design in drug release, showcasing the potential of 3D printing to create personalized dosage forms tailored to patient needs by optimizing structural parameters.

Insight into manufacturing of bespoke combination drug products containing carvedilol and simvastatin by fused deposition modeling

The goal of this study was to explore the fabrication of a combination drug product containing two poorly soluble active pharmaceutical ingredients (APIs), carvedilol (CAR) and simvastatin (SIM), in therapeutically relevant doses (25 mg of each API) with a distinct, easily distinguishable shape. Fused deposition modeling, combined with hot-melt extrusion (HME), was used to produce hollow heart-shaped dual-loaded tablets in which the two APIs were spatially separated with an intermediate API-free layer. Water-soluble hydroxypropyl methylcellulose of varying molecular weights was used as the primary polymer for HME. The incorporation of a processability-improving polymer, such as polycaprolactone, was necessary to facilitate the printing of these delicate geometries and lower the printing temperature. The 3D-printed tablets contained the therapeutic doses of both APIs; however, further optimization of manufacturing processes is required to improve drug content uniformity. The drug release from the printed tablets was sustained, with complete release of CAR observed after 24 h, demonstrating the suitability of the designed drug products for oral delivery.

Sustained dual delivery of metronidazole and viable Lactobacillus crispatus from 3D-printed silicone shells

Bacterial vaginosis (BV) is an imbalance of the vaginal microbiome in which there are limited lactobacilli and an overgrowth of anaerobic and fastidious bacteria such as Gardnerella. The propensity for BV recurrence is high, and therapies involving multiple treatment modalities are emerging to meet this need. However, current treatments requiring frequent therapeutic administration are challenging for patients and impact user compliance. Three-dimensional (3D)-printing offers a novel alternative to customize platforms to facilitate sustained therapeutic delivery to the vaginal tract. This study designed a novel vehicle intended for dual sustained delivery of both antibiotic and probiotic. 3D-printed compartmental scaffolds consisting of an antibiotic-containing silicone shell and a core containing probiotic Lactobacillus were developed with multiple formulations including biomaterials sodium alginate (SA), polyethylene glycol (PEG), polyvinyl alcohol (PVA), polyethylene oxide (PEO), and kappa-carrageenan (KC). The vehicles were loaded with 50 μg of metronidazole/mg polymer and 5 × 107 CFU of L. crispatus/mg scaffold. Metronidazole-containing shells exhibited cumulative drug release of 324.2 ± 31.2 μg/mL after 14 days. Multiple polymeric formulations for the probiotic core demonstrated cumulative L. crispatus recovery of >5 × 107 CFU/mg scaffold during this timeframe. L. crispatus-loaded polymeric formulations exhibited ≥2 log CFU/mL reduction in free Gardnerella in the presence of VK2/E6E7 vaginal epithelial cells. As a first step towards the goal of facilitating patient compliance, this study demonstrates in vitro effect of a novel 3D-printed dual antibiotic and probiotic delivery platform to target BV.

The comprehensive review on 3D printing- pharmaceutical drug delivery and personalized food and nutrition

Three-dimensional printing is one of the emerging technologies that is gaining interest from the pharmaceutical industry as it provides an opportunity to customize drugs according to each patient's needs. Combining different active pharmaceutical ingredients, using different geometries, and providing sustained release enhances the effectiveness of medicine. One of the most innovative uses of 3D printing is producing fabrics, medical devices, medical implants, orthoses, and prostheses. This review summarizes the various 3D printing techniques such as stereolithography, inkjet printing, thermal inkjet printing, fused deposition modelling, extrusion printing, semi-solid extrusion printing, selective laser sintering, and hot-melt extrusion. Also, discusses the drug relies profile and its mechanisms, characteristics, and applications of the most common types of 3D printed API formulations and its recent development. Here, Authors also, summarizes the central flow of 3D food printing process and knowledge extension toward personalized nutrition.

Extrusion-based 3D printing for development of complex capsular systems for advanced drug delivery

This review explores the feasibility of extrusion-based 3D printing techniques for producing complex dosage forms (such as capsular shells/devices) that provide controlled drug release and targeted delivery. The current discussion explores how extrusion-based 3D printing techniques, particularly Fused Deposition Modelling (FDM) and Pressure-Assisted Modelling (PAM), offer significant advantages in fabricating such complex dosage forms. This technology enables the fabrication of single-, dual-, or multi-compartment capsular systems with customized designs/geometry of the capsular shell to achieve delayed, sustained, or pulsatile drug release. The impact of customized design/geometry on the biopharmaceutical performances of loaded therapeutics is comprehensively discussed. The potential of 3D printing techniques for different specialized drug delivery purposes like gastric floating, implants, suppositories, and printfills are also addressed. This technique has the potential to significantly improve the therapeutic outcomes, and patient adherence to medication regimens, and pave the way for personalized medicine.

Fabrication of Polypill Pharmaceutical Dosage Forms Using Fused Deposition Modeling 3D Printing: A Systematic Review

BACKGROUND/OBJECTIVES

The pharmacy profession has undergone significant changes driven by advancements in patient care and healthcare systems. The FDA approval of Spritam® (levetiracetam), the first 3D-printed drug, has sparked increased interest in the use of Fused Deposition Modeling (FDM) 3D printing for pharmaceutical applications, particularly in the production of polypills.

METHODS

This review provides an overview of FDM 3D printing in the development of pharmaceutical dosage forms, focusing on its operation, printing parameters, materials, additives, advantages, and limitations. Key aspects, such as the ability to personalize medication and the challenges associated with the technique, including drug stability at high temperatures, are discussed.

RESULTS

Fourteen studies relevant to FDM 3D-printed polypills were analyzed from an initial pool of 60. The increasing number of publications highlights the growing global interest in this technology, with the UK contributing the highest number of studies.

CONCLUSIONS

FDM 3D printing offers significant potential for personalized medicine by enabling precise control over dosage forms and tailoring treatments to individual patient needs. However, limitations such as high printing temperatures and the lack of standardized GMP guidelines for large-scale production must be addressed to fully realize its potential in pharmaceutical manufacturing.

Tailor-Made Doses of Pharmaceuticals by Tunable Modular Design: A Case Study on Tapering Antidepressant Medication

An abrupt cessation of antidepressant medication can be challenging due to the appearance of withdrawal symptoms. A slow hyperbolic tapering of an antidepressant, such as citalopram hydrobromide (CHB), can mitigate the withdrawal syndrome. However, there are no viable dosage forms on the market to implement the tapering scheme. A solution using a tunable modular design (TMD) approach to produce flexible and accurate doses of CHB is proposed. This design consists of two parts: 1) a module with a fixed amount of preloaded CHB in a freeze-dried polymer matrix, and 2) fine-tuning the CHB dose by inkjet printing. A noncontact food-grade printer, used for the first time for printing pharmaceuticals, is modified to allow for accurate printing of the highly concentrated CHB ink on the porous CHB-free or CHB-preloaded modules. The produced modules with submilligram precision are bench-marked with commercially available CHB tablets that are manually divided. The TMD covers the entire range of doses needed for the tapering (0.5-23.8 mg). The greatest variance is 13% and 88% when comparing the TMD and self-tapering, respectively. Self-tapering is proven inaccurate and showcases the need for the TMD to make available accurate and personalized doses to wean off treatment with CHB.

Assembled pH-Responsive Gastric Drug Delivery Systems Based on 3D-Printed Shells

Gastric acid secretion is closely associated with the development and treatment of chronic gastritis, gastric ulcers, and reflux esophagitis. However, gastric acid secretion is affected by complex physiological and pathological factors, and real-time detection and control are complicated and expensive. A gastric delivery system for antacids and therapeutics in response to low pH in the stomach holds promise for smart and personalized treatment of stomach diseases. In this study, pH-responsive modular units were used to assemble various modular devices for self-regulation of pH and drug delivery to the stomach. The modular unit with a release window of 50 mm2 could respond to pH and self-regulate within 10 min, which is related to its downward floatation and internal gas production. The assembled devices could stably float downward in the medium and detach sequentially at specific times. The assembled devices loaded with antacids exhibited smart pH self-regulation under complex physiological and pathological conditions. In addition, the assembled devices loaded with antacids and acid suppressors could multi-pulse or prolong drug release after rapid neutralization of gastric acid. Compared with traditional coating technology, 3D printing can print the shell layer by layer, flexibly adjust the internal and external structure and composition, and assemble it into a multi-level drug release system. Compared with traditional coating, 3D-printed shells have the advantage of the flexible adjustment of internal and external structure and composition, and are easy to assemble into a complex drug delivery system. This provides a universal and flexible strategy for the personalized treatment of diseases with abnormal gastric acid secretion, especially for delivering acid-unstable drugs.

Leading Paediatric Infectious Diseases-Current Trends, Gaps, and Future Prospects in Oral Pharmacotherapeutic Interventions

Paediatric infectious diseases contribute significantly to global health challenges. Conventional therapeutic interventions are not always suitable for children, as they are regularly accompanied with long-standing disadvantages that negatively impact efficacy, thus necessitating the need for effective and child-friendly pharmacotherapeutic interventions. Recent advancements in drug delivery technologies, particularly oral formulations, have shown tremendous progress in enhancing the effectiveness of paediatric medicines. Generally, these delivery methods target, and address challenges associated with palatability, dosing accuracy, stability, bioavailability, patient compliance, and caregiver convenience, which are important factors that can influence successful treatment outcomes in children. Some of the emerging trends include moving away from creating liquid delivery systems to developing oral solid formulations, with the most explored being orodispersible tablets, multiparticulate dosage forms using film-coating technologies, and chewable drug products. Other ongoing innovations include gastro-retentive, 3D-printed, nipple-shield, milk-based, and nanoparticulate (e.g., lipid-, polymeric-based templates) drug delivery systems, possessing the potential to improve therapeutic effectiveness, age appropriateness, pharmacokinetics, and safety profiles as they relate to the paediatric population. This manuscript therefore highlights the evolving landscape of oral pharmacotherapeutic interventions for leading paediatric infectious diseases, crediting the role of innovative drug delivery technologies. By focusing on the current trends, pointing out gaps, and identifying future possibilities, this review aims to contribute towards ongoing efforts directed at improving paediatric health outcomes associated with the management of these infectious ailments through accessible and efficacious drug treatments.

Perspectives on 3D printed personalized medicines for pediatrics

In recent years, the rapid advancement of three-dimensional (3D) printing technology has yielded distinct benefits across various sectors, including pharmaceuticals. The pharmaceutical industry has particularly experienced advantages from the utilization of 3D-printed medications, which have invigorated the development of tailored drug formulations. The approval of 3D-printed drugs by the U.S. Food and Drug Administration (FDA) has significantly propelled personalized drug delivery. Additionally, 3D printing technology can accommodate the precise requirements of pediatric drug dosages and the complexities of multiple drug combinations. This review specifically concentrates on the application of 3D printing technology in pediatric preparations, encompassing a broad spectrum of uses and refined pediatric formulations. It compiles and evaluates the fundamental principles associated with the application of 3D printing technology in pediatric preparations, including its merits and demerits, and anticipates its future progression. The objective is to furnish theoretical underpinning for 3D printing technology to facilitate personalized drug delivery in pediatrics and to advocate for its implementation in clinical settings.

Binder jetting 3D printing in fabricating pharmaceutical solid products for precision medicine

Current treatment strategies are moving towards patient-centricity, which emphasizes the need for new solutions allowing for medication tailored to a patient. This can be realized by precision medicine where patient diversity is considered during treatment. However, the broader use of precision medicine is restricted by the current technological solutions and rigid manufacturing of pharmaceutical products by mass production principles. Additive manufacturing of pharmaceutical products can provide a feasible solution to this challenge. In this review, a particular subtype of additive manufacturing, that is, binder jetting 3D printing, is introduced as a solution for fabricating pharmaceutical solid products that can be considered as precision medicine. Technical aspects, practical applications, unique advantages and challenges related to this technique are discussed, indicating that binder jetting 3D printing possesses the potential for fabricating already new product prototypes, where diversity in patient treatment in terms of the needs for specific drug type, dose and drug release can be accounted. To further advance this type of mass customization of pharmaceuticals, multidisciplinary research initiatives are needed not only to cover the engineering aspects but also to bridge these innovations with patient-centric perspectives.

Rising role of 3D-printing in delivery of therapeutics for infectious disease

Modern drug delivery to tackle infectious disease has drawn close to personalizing medicine for specific patient populations. Challenges include antibiotic-resistant infections, healthcare associated infections, and customizing treatments for local patient populations. Recently, 3D-printing has become a facilitator for the development of personalized pharmaceutic drug delivery systems. With a variety of manufacturing techniques, 3D-printing offers advantages in drug delivery development for controlled, fine-tuned release and platforms for different routes of administration. This review summarizes 3D-printing techniques in pharmaceutics and drug delivery focusing on treating infectious diseases, and discusses the influence of 3D-printing design considerations on drug delivery platforms targeting these diseases. Additionally, applications of 3D-printing in infectious diseases are summarized, with the goal to provide insight into how future delivery innovations may benefit from 3D-printing to address the global challenges in infectious disease.

Fixed-Dose Combination Formulations in Solid Oral Drug Therapy: Advantages, Limitations, and Design Features

Whilst monotherapy is traditionally the preferred treatment starting point for chronic conditions such as hypertension and diabetes, other diseases require the use of multiple drugs (polytherapy) from the onset of treatment (e.g., human immunodeficiency virus acquired immunodeficiency syndrome, tuberculosis, and malaria). Successful treatment of these chronic conditions is sometimes hampered by patient non-adherence to polytherapy. The options available for polytherapy are either the sequential addition of individual drug products to deliver an effective multi-drug regimen or the use of a single fixed-dose combination (FDC) therapy product. This article intends to critically review the use of FDC drug therapy and provide an insight into FDC products which are already commercially available. Shortcomings of FDC formulations are discussed from multiple perspectives and research gaps are identified. Moreover, an overview of fundamental formulation considerations is provided to aid formulation scientists in the design and development of new FDC products.

3D-printed prednisolone phosphate suppositories with tunable dose and rapid release for the treatment of inflammatory bowel disease

Established medicines are often not tailored to the needs of the pediatric population, causing difficulties with administration or dosing. Three-dimensional (3D) printing technology allows novel approaches for compounding of personalized medicine, as is exemplified in this study for the automated compounding of rectal preparations for children. We investigated the material requirements to print prednisolone phosphate-loaded suppositories with tunable dose and rapid drug release for the treatment of inflammatory bowel diseases. Three formulations containing 4 % w/w prednisolone sodium phosphate (PSP) and different amounts of hydroxypropyl cellulose (HPC) and mannitol as excipients were printed as suppositories with a fused deposition modeling (FDM) 3D-printer. Dissolution studies showed that the PSP release rate was increased when higher weight fractions of mannitol were added as a pore former, with 90 % drug release within 30 min for mannitol 48 % w/w. We further printed suppositories with 48 % mannitol with different infill densities and dimensions to tune the dose. Our findings demonstrated that 3D-printed suppositories with PSP doses ranging from 6 to 30 mg could be compounded without notably affecting the dissolution kinetics, ensuring equivalent therapeutic efficacies for different doses.

Impact of drug load and polymer molecular weight on the 3D microstructure of printed tablets

This study investigates the influence of drug load and polymer molecular weight on the structure of tablets three-dimensionally (3D) printed from the binary mixture of prednisolone and hydroxypropyl methylcellulose (HPMC). Three different HPMC grades, (AFFINISOLTM HPMC HME 15LV, 90 Da (HPMC 15LV); 100LV, 180 Da (HPMC 100LV); 4M, 500 Da (HPMC 4M)), which are suitable for hot-melt extrusion (HME), were used in this study. HME was used to fabricate feedstock material, i.e., filaments, at the lowest possible extrusion temperature. Filaments of the three HPMC grades were prepared to contain 2.5, 5, 10 and 20 % (w/w) prednisolone. The thermal degradation of the filaments was studied with thermogravimetric analysis, while solid-state properties of the drug-loaded filaments were assessed with the use of X-ray powder diffraction. Prednisolone in the freshly extruded filaments was determined to be amorphous for drug loads up to 10%. It remained physically stable for at least 6 months of storage, except for the filament containing 10% drug with HPMC 15LV, where recrystallization of prednisolone was detected. Fused deposition modeling was utilized to print honeycomb-shaped tablets from the HME filaments of HPMC 15LV and 100LV. The structural characteristics of the tablets were evaluated using X-ray microcomputed tomography, specifically porosity and size of structural elements were investigated. The tablets printed from HPMC 15LV possessed in general lower total porosity and pores of smaller size than tablets printed from the HPMC 100LV. The studied drug loads were shown to have minor effect on the total porosity of the tablets, though the lower the drug load was, the higher the variance of porosity along the height of the tablet was observed. It was found that tablets printed with HPMC 15LV showed higher structural similarity with the virtually designed model than tablets printed from HPMC 100LV. These findings highlight the relevance of the drug load and polymer molecular weight on the microstructure and structural properties of 3D printed tablets.

Drug-drug interaction prediction: databases, web servers and computational models

In clinical treatment, two or more drugs (i.e. drug combination) are simultaneously or successively used for therapy with the purpose of primarily enhancing the therapeutic efficacy or reducing drug side effects. However, inappropriate drug combination may not only fail to improve efficacy, but even lead to adverse reactions. Therefore, according to the basic principle of improving the efficacy and/or reducing adverse reactions, we should study drug-drug interactions (DDIs) comprehensively and thoroughly so as to reasonably use drug combination. In this review, we first introduced the basic conception and classification of DDIs. Further, some important publicly available databases and web servers about experimentally verified or predicted DDIs were briefly described. As an effective auxiliary tool, computational models for predicting DDIs can not only save the cost of biological experiments, but also provide relevant guidance for combination therapy to some extent. Therefore, we summarized three types of prediction models (including traditional machine learning-based models, deep learning-based models and score function-based models) proposed during recent years and discussed the advantages as well as limitations of them. Besides, we pointed out the problems that need to be solved in the future research of DDIs prediction and provided corresponding suggestions.

Smart pills and drug delivery devices enabling next generation oral dosage forms

Oral dosage forms are the preferred solution for systemic treatment and prevention of disease conditions. However, traditional dosage forms face challenges regarding treatment adherence and delivery of biologics. Oral therapies that require frequent administrations face difficulties with patient compliance. In addition, only a few peptide- and protein-based drugs have been commercialized for oral administration so far, presenting a bioavailability that is generally low. Therefore, research and development on novel formulation strategies for oral drug delivery has bloomed massively in the last decade to overcome these challenges. On the one hand, approaches based on lumen-release of drugs such as 3D-printed capsules and prolonged gastric residence dosage forms have been explored to offer personalized medicine to the patient and reduce frequent dosing of small drug compounds that are currently in the market as powdered tablet or capsules. On the other hand, strategies based on mucus interfacing such as gastrointestinal patches, or even epithelium injections have been investigated in order to enhance the permeability of biologic macromolecules, which are mostly commercialized in the form of subcutaneous injections. Despite the fact that these methods are at an early development stage, promising results have been revealed in terms of personalized medicine and improved bioavailability. In this review, we offer a critical overview of novel ingestible millimeter-sized devices and technologies for oral drug delivery that are currently used in the clinic as well as those that could emerge on the market in a not too distant future.

The Development of Dermal Self-Double-Emulsifying Drug Delivery Systems: Preformulation Studies as the Keys to Success

Self-emulsifying drug delivery systems (SEDDSs) are lipid-based systems that are superior to other lipid-based oral drug delivery systems in terms of providing drug protection against the gastrointestinal (GI) environment, inhibition of drug efflux as mediated by P-glycoprotein, enhanced lymphatic drug uptake, improved control over plasma concentration profiles of drugs, enhanced stability, and drug loading efficiency. Interest in dermal spontaneous emulsions has increased, given that systems have been reported to deliver drugs across mucus membranes, as well as the outermost layer of the skin into the underlying layers. The background and development of a double spontaneous emulsion incorporating four anti-tubercular drugs, clofazimine (CFZ), isoniazid (INH), pyrazinamide (PZY), and rifampicin (RIF), are described here. Our methods involved examination of oil miscibility, the construction of pseudoternary phase diagrams, the determination of self-emulsification performance and the emulsion stability index of primary emulsions (PEs), solubility, and isothermal micro calorimetry compatibility and examination of emulsions via microscopy. Overall, the potential of self-double-emulsifying drug delivery systems (SDEDDSs) as a dermal drug delivery vehicle is now demonstrated. The key to success here is the conduct of preformulation studies to enable the development of dermal SDEDDSs. To our knowledge, this work represents the first successful example of the production of SDEDDSs capable of incorporating four individual drugs.

A Review on Physicochemical Properties of Polymers Used as Filaments in 3D-Printed Tablets

Three-dimensional (3D) printing technology has presently been explored widely in the field of pharmaceutical research to produce various conventional as well as novel dosage forms such as tablets, capsules, oral films, pellets, subcutaneous implants, scaffolds, and vaginal rings. The use of this innovative method is a good choice for its advanced technologies and the ability to make tailored medicine specifically for individual patient. There are many 3D printing systems that are used to print tablets, implants, and vaginal rings. Among the available systems, the fused deposition modeling (FDM) is widely utilized. The FDM has been regarded as the best choice of printer as it shows high potential in the production of tablets as a unit dose in 3D printing medicine manufacturing. In order to design a 3D-printed tablet or other dosage forms, the physicochemical properties of polymers play a vital role. One should have proper knowledge about the polymer's properties so that one can select appropriate polymers in order to design 3D-printed dosage form. This review highlighted the various physicochemical properties of polymers that are currently used as filaments in 3D printing. In this manuscript, the authors also discussed various systems that are currently adopted in the 3D printing.

Recent Developments in 3D Bio-Printing and Its Biomedical Applications

The fast-developing field of 3D bio-printing has been extensively used to improve the usability and performance of scaffolds filled with cells. Over the last few decades, a variety of tissues and organs including skin, blood vessels, and hearts, etc., have all been produced in large quantities via 3D bio-printing. These tissues and organs are not only able to serve as building blocks for the ultimate goal of repair and regeneration, but they can also be utilized as in vitro models for pharmacokinetics, drug screening, and other purposes. To further 3D-printing uses in tissue engineering, research on novel, suitable biomaterials with quick cross-linking capabilities is a prerequisite. A wider variety of acceptable 3D-printed materials are still needed, as well as better printing resolution (particularly at the nanoscale range), speed, and biomaterial compatibility. The aim of this study is to provide expertise in the most prevalent and new biomaterials used in 3D bio-printing as well as an introduction to the associated approaches that are frequently considered by researchers. Furthermore, an effort has been made to convey the most pertinent implementations of 3D bio-printing processes, such as tissue regeneration, etc., by providing the most significant research together with a comprehensive list of material selection guidelines, constraints, and future prospects.

3D Printed Housing Devices for Segregated Compartmental Delivery of Oral Fixed-Dose Anti-Tubercular Drugs Adopting Print and Fill Strategy

World Health Organization (WHO) recommends the use of first-line anti-tuberculosis drugs, that is, rifampicin (RIF) and isoniazid (INH) fixed-dose combination (FDC) therapies in tuberculosis (TB) disease. The absorption of RIF from an FDC incorporates INH, and it is significantly compromised due to its reaction with INH, resulting in a severe loss of RIF under gastric stomach pH condition. Such reduction in the dose of both drugs from FDC formulations has been alleged to be one of the chief obstacles in effective TB treatment. This emphasizes a need to develop suitable cutting-edge advanced bioengineered delivery devices that can attenuate this severe problem to mitigate this chief obstacle. Therefore, we designed, prototyped, and characterized bioengineered 3D printed housing devices in the form of printed tablets adopting print and fill strategy for segregated compartmental delivery of RIF into the intestine (to avoid stomach gastric pH induced chemical degradation as alone and FDC) and INH into the stomach (no degradation observed as alone and FDC in stomach gastric pH conditions) for the desired treatment outcome against TB. Prepared 3D printed housings showed almost zero friability, enough hardness along weight variations <±3.0%. Different thermal and morphological analyses confirmed the insignificant changes in the nature of the polymer as before and after printing. The in vitro release for INH from polyvinyl alcohol mediated 3D printed housings showed almost 100% release within 2.5 h in acidic medium, whereas poly-lactic acid (PLA) mediated 3D printed housings continued to release RIF above 70% in the presence of physiological enzymes in alkaline medium for 432 h. The in vivo bioavailability assessment correlated with in vitro dissolution behavior for INH and RIF, whereas RIF did not release from 3D printed PLA housings in vivo.

3D printing of pharmaceuticals: approach from bench scale to commercial development

Background

The three-dimensional (3D) printing is paradigm shift in the healthcare sector. 3D printing is platform technologies in which complex products are developed with less number of additives. The easy development process gives edge over the conventional methods. Every individual needs specific dose treatment. 'One size fits all' is the current traditional approach that can shift to more individual specific in 3D printing. The present review aims to cover different perspectives regarding selection of drug, polymer and technological aspects for 3D printing. With respect to clinical practice, regulatory issue and industrial potential are also discussed in this paper.

Main body

The individualization of medicines with patient centric dosage form will become reality in upcoming future. It provides individual's need of dose by considering genetic profile, physiology and diseased condition. The tailormade dosages with unique drug loading and release profile of different geometrical shapes and sizes can easily deliver therapeutic dose. The technology can fulfill growing demand of efficiency in the dose accuracy for the patient oriented sectors like pediatric, geriatric and also easy to comply with cGMP requirements of regulated market. The clinical practice can focus on prescribing each individual's necessity of dose.

Conclusion

In the year 2015, FDA approved first 3D printed drug product, which is initiator in the new phase of manufacturing of pharmaceuticals. The tailormade formulations can be made in future for personalized medications. Regulatory approval from agencies can bring the 3DP product into the market. In the future, formulators can bring different sector-specific products for personalized need through 3DP pharmaceutical product.

Graphical Abstract

Three-Dimensional Bio-Printed Cardiac Patch for Sustained Delivery of Extracellular Vesicles from the Interface

Cardiac tissue engineering has emerged as a promising strategy to treat infarcted cardiac tissues by replacing the injured region with an ex vivo fabricated functional cardiac patch. Nevertheless, integration of the transplanted patch with the host tissue is still a burden, limiting its clinical application. Here, a bi-functional, 3D bio-printed cardiac patch (CP) design is proposed, composed of a cell-laden compartment at its core and an extracellular vesicle (EV)-laden compartment at its shell for better integration of the CP with the host tissue. Alginate-based bioink solutions were developed for each compartment and characterized rheologically, examined for printability and their effect on residing cells or EVs. The resulting 3D bio-printed CP was examined for its mechanical stiffness, showing an elastic modulus between 4-5 kPa at day 1 post-printing, suitable for transplantation. Affinity binding of EVs to alginate sulfate (AlgS) was validated, exhibiting dissociation constant values similar to those of EVs with heparin. The incorporation of AlgS-EVs complexes within the shell bioink sustained EV release from the CP, with 88% cumulative release compared with 92% without AlgS by day 4. AlgS also prolonged the release profile by an additional 2 days, lasting 11 days overall. This CP design comprises great potential at promoting more efficient patch assimilation with the host.

3D Printing of Triamcinolone Acetonide in Triblock Copolymers of Styrene–Isobutylene–Styrene as a Slow-Release System

Additive manufacturing has a wide range of applications and has opened up new methods of drug formulation, in turn achieving attention in medicine. We prepared styrene–isobutylene–styrene triblock copolymers (SIBS; Mn = 10 kDa–25 kDa, PDI 1,3–1,6) as a drug carrier for triamcinolone acetonide (TA), further processed by fused deposition modeling to create a solid drug release system displaying improved bioavailability and applicability. Living carbocationic polymerization was used to exert control over block length and polymeric architecture. Thermorheological properties of the SIBS polymer (22.3 kDa, 38 wt % S) were adjusted to the printability of SIBS/TA mixtures (1–5% of TA), generating an effective release system effective for more than 60 days. Continuous drug release and morphological investigations were conducted to probe the influence of the 3D printing process on the drug release, enabling 3D printing as a formulation method for a slow-release system of Triamcinolone.

Customised 3D printed multi-drug systems: An effective and efficient approach to polypharmacy

INTRODUCTION

Combination therapies continue to improve therapeutic outcomes as currently achieved by polypharmacy. Since the introduction of the polypill, there has been a significant improvement in adherence and patient outcomes. However, the mass production of polypills presents a number of technical, formulation, and clinical challenges. The current one-size-fits-all approach ignores the unique clinical demands of patients, necessitating the adoption of a more versatile tool. That will be the novel, but not so novel, 3D printing.

AREAS COVERED

: The present review investigates this promising paradigm shift from one medication for all, to customised medicines, providing an overview of the current state of 3D-printed multi-active pharmaceutical forms, techniques applied and printing materials. Details on cost implications, as well as potential limitations and challenges are also elaborated.

EXPERT OPINION

: 3D printing of multi-active systems, is not only beneficial but also essential. With growing interest in this field, a shift in manufacturing, prescribing, and administration patterns is at this point, unavoidable. Addressing limitations and challenges, as well as data presentation on clinical trial results, will aid in the acceleration of this technology's implementation. However, it is clear that 3D printing is not the end of it, as evidenced by the emerging 4D printing technology.

Phase-Field Model for Drug Release of Water-Swellable Filaments for Fused Filament Fabrication

This paper treats the drug release process as a phase-field problem and a phase-field model capable of simulating the dynamics of multiple moving fronts, transient drug fluxes, and fractional drug release from swellable polymeric systems is proposed and validated experimentally. The model can not only capture accurately the positions and movements of the distinct fronts without tracking the locations of fronts explicitly but also predict well the release profile to the completion of the release process. The parametric study has shown that parameters including water diffusion coefficient, drug saturation solubility, drug diffusion coefficient, initial drug loading ratio, and initial porosity are critical in regulating the drug release kinetics. It has been also demonstrated that the model can be applied to the study of swellable filaments and has wide applicability for different materials. Due to explicit boundary position tracking being eliminated, the model paves the way for practical use and can be extended for dealing with geometrically complex drug delivery systems. It is a useful tool to guide the design of new controlled delivery systems fabricated by fused filament fabrication.

The Evolution of the 3D-Printed Drug Delivery Systems: A Review

Since the appearance of the 3D printing in the 1980s it has revolutionized many research fields including the pharmaceutical industry. The main goal is to manufacture complex, personalized products in a low-cost manufacturing process on-demand. In the last few decades, 3D printing has attracted the attention of numerous research groups for the manufacturing of different drug delivery systems. Since the 2015 approval of the first 3D-printed drug product, the number of publications has multiplied. In our review, we focused on summarizing the evolution of the produced drug delivery systems in the last 20 years and especially in the last 5 years. The drug delivery systems are sub-grouped into tablets, capsules, orodispersible films, implants, transdermal delivery systems, microneedles, vaginal drug delivery systems, and micro- and nanoscale dosage forms. Our classification may provide guidance for researchers to more easily examine the publications and to find further research directions.

Mesoporous silica nanocarriers as drug delivery systems for anti-tubercular agents: a review

The treatment and management of tuberculosis using conventional drug delivery systems remain challenging due to the setbacks involved. The lengthy and costly treatment regime and patients' non-compliance have led to drug-resistant tuberculosis, which is more difficult to treat. Also, anti-tubercular drugs currently used are poor water-soluble drugs with low bioavailability and poor therapeutic efficiency except at higher doses which causes drug-related toxicity. Novel drug delivery carrier systems such as mesoporous silica nanoparticles (MSNs) have been identified as nanomedicines capable of addressing the challenges mentioned due to their biocompatibility. The review discusses the sol-gel synthesis and chemistry of MSNs as porous drug nanocarriers, surface functionalization techniques and the influence of their physico-chemical properties on drug solubility, loading and release kinetics. It outlines the physico-chemical characteristics of MSNs encapsulated with anti-tubercular drugs.

Feasibility of developing hospital preparation by Semisolid extrusion 3D printing: Personalized Amlodipine Besylate chewable tablets

Semisolid extrusion (SSE) 3D printing is an emerging technology in personalized medicine. To address clinical multi-dose requirements, SSE has been explored to manufacture new preparations. In this study, amlodipine besylate (AMB) was the model drug, and SSE was the pharmaceutical strategy. We developed semisolids suitable for SSE and AMB chewable tablets with six strengths (1.5-5 mg) to meet the needs of 2-16-year-old patients. First, the semisolid extrudability was evaluated by texture analyzer, and then the amounts of carboxymethyl cellulose sodium, sodium starch glycolate, and glycerin were optimized by full factorial design. Then, rheological tests were performed to evaluate the properties of the semisolid and the effect of starch sodium glycolate on printability. Finally, the amount of corrigents was optimized using an electronic tongue. Laboratory amplified semisolids and 3D printed tablets can be stored for a few months, and the whole SSE process had no effect on crystal type. This study validated the feasibility of SSE 3D printing, and tablets with appropriate taste and cartoon appearance can meet or even exceed the traditional preparations. Our study provides a new strategy for multi-dose solid preparations and effectively addresses the need for personalized amlodipine medicine.

The promising rise of bioprinting in revolutionalizing medical science: Advances and possibilities

Bioprinting is a relatively new yet evolving technique predominantly used in regenerative medicine and tissue engineering. 3D bioprinting techniques combine the advantages of creating Extracellular Matrix (ECM)like environments for cells and computer-aided tailoring of predetermined tissue shapes and structures. The essential application of bioprinting is for the regeneration or restoration of damaged and injured tissues by producing implantable tissues and organs. The capability of bioprinting is yet to be fully scrutinized in sectors like the patient-specific spatial distribution of cells, bio-robotics, etc. In this review, currently developed experimental systems and strategies for the bioprinting of different types of tissues as well as for drug delivery and cancer research are explored for potential applications. This review also digs into the most recent opportunities and future possibilities for the efficient implementation of bioprinting to restructure medical and technological practices.

Preformulation Studies to Guide the Production of Medicines by Fused Deposition Modeling 3D Printing

Fused deposition modeling (FDM) 3D printing has demonstrated high potential for the production of personalized medicines. However, the heating at high temperatures inherent to this process causes unknown risks to the drug product's stability. The present study aimed to assess the use of a tailored preformulation protocol involving physicochemical assessments, including the rheological profiles of the samples, to guide the development of medicines by FDM 3D printing. For this, polymers commonly used in FDM printing, i.e., high impact polystyrene (HIPS), polylactic acid (PLA), and polyvinyl alcohol (PVA), and their common plasticizers (mineral oil, triethyl citrate, and glycerol, respectively) were evaluated using the thermolabile model drug isoniazid (INH). Samples were analyzed by chemical and physical assays. The results showed that although the drug could produce polymorphs under thermal processing, the polymeric matrix can be a protective element, and no polymorphic transformation was observed. However, incompatibilities between materials might impact their chemical, thermal, and rheological performances. In fact, ternary mixtures of INH, PLA, and TEC showed a major alteration in their viscoelastic behavior besides the chemical changes. On the other hand, the use of plasticizers for HIPS and PVA exhibited positive consequences in drug solubility and rheologic behavior, probably improving sample printability. Thus, the optimization of the FDM 3D printing based on preformulation studies can assist the choice of compatible components and seek suitable processing conditions to obtain pharmaceutical products.

Modular design principle based on compartmental drug delivery systems

The current manufacturing solutions for oral solid dosage forms are fundamentally based on technologies from the 19th century. This approach is well suited for mass production of one-size-fits-all products; however, it does not allow for a straight-forward personalization and mass customization of the pharmaceutical end-product. In order to provide better therapies to the patients, a need for innovative manufacturing concepts and product design principles has been rising. Additive manufacturing opens up a possibility for compartmentalization of drug products, including design of spatially separated multidrug and functional excipient compartments. This compartmentalized solution can be further expanded to modular design thinking. Modular design is referring to combination of building blocks containing a given amount of drug compound(s) and related functional excipients into a larger final product. Implementation of modular design principles is paving the way for implementing the emerging personalization potential within health sciences by designing compartmental and reactive product structures that can be manufactured based on the individual needs of each patient. This review will introduce the existing compartmentalized product design principles and discuss the integration of these into edible electronics allowing for innovative control of drug release.

3D Printing of Thermo-Sensitive Drugs

Three-dimensional (3D) printing is among the rapidly evolving technologies with applications in many sectors. The pharmaceutical industry is no exception, and the approval of the first 3D-printed tablet (Spiratam^®) marked a revolution in the field. Several studies reported the fabrication of different dosage forms using a range of 3D printing techniques. Thermosensitive drugs compose a considerable segment of available medications in the market requiring strict temperature control during processing to ensure their efficacy and safety. Heating involved in some of the 3D printing technologies raises concerns regarding the feasibility of the techniques for printing thermolabile drugs. Studies reported that semi-solid extrusion (SSE) is the commonly used printing technique to fabricate thermosensitive drugs. Digital light processing (DLP), binder jetting (BJ), and stereolithography (SLA) can also be used for the fabrication of thermosensitive drugs as they do not involve heating elements. Nonetheless, degradation of some drugs by light source used in the techniques was reported. Interestingly, fused deposition modelling (FDM) coupled with filling techniques offered protection against thermal degradation. Concepts such as selection of low melting point polymers, adjustment of printing parameters, and coupling of more than one printing technique were exploited in printing thermosensitive drugs. This systematic review presents challenges, 3DP procedures, and future directions of 3D printing of thermo-sensitive formulations.

Semi-solid extrusion 3D printing of starch-based soft dosage forms for the treatment of paediatric latent tuberculosis infection

OBJECTIVES

The development of age-appropriate dosage forms is essential for effective pharmacotherapy, especially when long-term drug treatment is required, as in the case of latent tuberculosis infection treatment with up to 9 months of daily isoniazid (ISO). Herein, we describe the fabrication of starch-based soft dosage forms of ISO using semi-solid extrusion (SSE) 3D printing.

METHODS

Corn starch was used for ink preparation using ISO as model drug. The inks were characterized physicochemically and their viscoelastic properties were assessed with rheological analysis. The morphology of the printed dosage forms was visualized with scanning electron microscopy and their textural properties were evaluated using texture analysis. Dose accuracy was verified before in-vitro swelling and dissolution studies in simulated gastric fluid (SGF).

KEY FINDINGS

Starch inks were printed with good resolution and high drug dose accuracy. The printed dosage forms had a soft texture to ease administration in paediatric patients and a highly porous microstructure facilitating water penetration and ISO diffusion in SGF, resulting in almost total drug release within 45 min.

CONCLUSIONS

The ease of preparation and fabrication combined with the cost-effectiveness of the starting materials constitutes SSE 3D printing of starch-based soft dosage forms a viable approach for paediatric-friendly formulations in low-resource settings.

Pharmaceutical amorphous solid dispersion: A review of manufacturing strategies

Amorphous solid dispersions (ASDs) are popular for enhancing the solubility and bioavailability of poorly water-soluble drugs. Various approaches have been employed to produce ASDs and novel techniques are emerging. This review provides an updated overview of manufacturing techniques for preparing ASDs. As physical stability is a critical quality attribute for ASD, the impact of formulation, equipment, and process variables, together with the downstream processing on physical stability of ASDs have been discussed. Selection strategies are proposed to identify suitable manufacturing methods, which may aid in the development of ASDs with satisfactory physical stability.

Challenges of fused deposition modeling 3D printing in pharmaceutical applications: Where are we now?

In recent years, fused deposition modeling has become one of the most used three-dimensional printing technologies in the pharmaceutical field. The production of personalized dosage forms for individualized therapy and the modification of the drug release profile by the elaboration of complex geometries make fused deposition modeling a promising tool for small-scale production. However, fused deposition modeling has a considerable number of challenges to overcome. They are divided into three categories of parameters. Material-specific parameters encompass the physicochemical properties of the filament, like thermal, mechanical and rheological properties. They determine the feasibility of the printing process. Operation-specific parameters relate to the processing conditions of printing, such as printing temperature and infill density, which have an influence on the final quality and on the dissolution behavior of the objects. The printer equipment is defined by the machine-specific parameters. Some modifications of this equipment also enhance the performance of the printing process. The aim of this review is to highlight the major fused deposition modeling critical process parameters in the pharmaceutical field and possible solutions in order to speed up the development of objects in the pharmaceutical market.

Harnessing artificial intelligence for the next generation of 3D printed medicines

Artificial intelligence (AI) is redefining how we exist in the world. In almost every sector of society, AI is performing tasks with super-human speed and intellect; from the prediction of stock market trends to driverless vehicles, diagnosis of disease, and robotic surgery. Despite this growing success, the pharmaceutical field is yet to truly harness AI. Development and manufacture of medicines remains largely in a 'one size fits all' paradigm, in which mass-produced, identical formulations are expected to meet individual patient needs. Recently, 3D printing (3DP) has illuminated a path for on-demand production of fully customisable medicines. Due to its flexibility, pharmaceutical 3DP presents innumerable options during formulation development that generally require expert navigation. Leveraging AI within pharmaceutical 3DP removes the need for human expertise, as optimal process parameters can be accurately predicted by machine learning. AI can also be incorporated into a pharmaceutical 3DP 'Internet of Things', moving the personalised production of medicines into an intelligent, streamlined, and autonomous pipeline. Supportive infrastructure, such as The Cloud and blockchain, will also play a vital role. Crucially, these technologies will expedite the use of pharmaceutical 3DP in clinical settings and drive the global movement towards personalised medicine and Industry 4.0.

Translating 3D printed pharmaceuticals: From hype to real-world clinical applications

Three-dimensional (3D) printing is a revolutionary technology that is disrupting pharmaceutical development by enabling the production of personalised printlets (3D printed drug products) on demand. By creating small batches of dose flexible medicines, this versatile technology offers significant advantages for clinical practice and drug development, namely the ability to personalise medicines to individual patient needs, as well as expedite drug development timelines within preclinical studies through to first-in-human (FIH) and Phase I/II clinical trials. Despite the widely demonstrated benefits of 3D printing pharmaceuticals, the clinical potential of the technology is yet to be realised. In this timely review, we provide an overview of the latest cutting-edge investigations in 3D printing pharmaceuticals in the pre-clinical and clinical arena and offer a forward-looking approach towards strategies to further aid the translation of 3D printing into the clinic.

3D printing technology in healthcare: applications, regulatory understanding, IP repository and clinical trial status

Mass consumerization of three-dimensional (3D) printing innovation has revolutionised admittance of 3D-printing in an expansive scope of ventures. When utilised predominantly for industrial manufacturing, 3D-printing strategies have rapidly attained acquaintance in different parts of health care industry. 3D-printing is a moderately new technology that has discovered promising applications in the medication conveyance and clinical areas. This review intends to explore different parts of 3D- printing innovation concerning pharmaceutical and clinical applications. Review on pharmaceutical products like tablets, caplets, films, polypills, microdots, biodegradable patches, medical devices (uterine and subcutaneous), patient specific implants, cardiovascular stents, etc. and prosthetics/anatomical structures, surgical models, organs and tissues created utilising 3D-printing is being presented. In addition, the regulatory understanding and current IP and clinical trial status pertaining to 3D fabricated products/medical applications have also been funnelled, garnering information from different web portals of regulatory agencies and databases. It is additionally certain that for such new innovations, there would be difficulties and questions before these are acknowledged as protected and viable. The circumstance demands purposeful and wary endeavours to acquire regulations which would at last prompt the accomplishment of this progressive innovation, thus various regulatory challenges faced have been conscientiously discussed.