Advanced Pharmaceutical Applications of Hot-Melt Extrusion Coupled with Fused Deposition Modelling (FDM) 3D Printing for Personalised Drug Delivery

A Design Approach to Optimise Secure Remote Three-Dimensional (3D) Printing: A Proof-of-Concept Study towards Advancement in Telemedicine

Telemedicine is defined as the delivery of healthcare services at a distance using electronic means. The incorporation of 3D printing in the telemedicine cycle could result in pharmacists designing and manufacturing personalised medicines based on the electronic prescription received. Even with the advantages of telemedicine, numerous barriers to the uptake hinder the wider uptake. Of particular concern is the cyber risk associated with the remote digital transfer of the computer-aided design (CAD) file (acting as the electronic prescription) to the 3D printer and the reproducibility of the resultant printed medicinal products. This proof-of-concept study aimed to explore the application of secure remote 3D printing of model solid dosage forms using the patented technology, DEFEND3D, which is designed to enhance cybersecurity and intellectual property (IP) protection. The size, shape, and colour of the remote 3D-printed model medicinal products were also evaluated to ensure the end-product quality was user-focused. Thermoplastic polyurethane (TPU) and poly(lactic) acid (PLA) were chosen as model polymers due to their flexibility in preventing breakage printing and ease of printing with fused deposition modelling (FDM). Our work confirmed the potential of secure remote 3D (FDM) printing of prototype solid dosage forms resulting in products with good reproducibility, resolution, and quality towards advancements in telemedicine and digital pharmacies. The limitation of the work presented here was the use of model polymers and not pharmaceutically relevant polymers. Further work could be conducted using the same designs chosen in this study with pharmaceutically relevant polymers used in hot-melt extrusion (HME) with shown suitability for FDM 3D printing. However, it should be noted that any challenges that may occur with pharmaceutically relevant polymers are likely to be related to the polymer's printability and printer choice as opposed to the ability of the CAD file to be transferred to the printer remotely.

Simultaneous Release of Silver Ions and 10–Undecenoic Acid from Silver Iron–Oxide Nanoparticles Impregnated Membranes

The bio-medical benefits of silver ions and 10–undecenoic acid in various chemical-pharmaceutical preparations are indisputable, thus justifying numerous research studies on delayed and/or controlled release. This paper presents the effect of the polymer matrix in the simultaneous release of silver ions and 10–undecenoic acid in an aqueous medium of controlled pH and ionic strength. The study took into consideration polymeric matrices consisting of cellulose acetate (CA) and polysulfone (PSf), which were impregnated with oxide nanoparticles containing silver and 10–undecenoic acid. The studied oxide nanoparticles are nanoparticles of iron and silver oxides obtained by an accessible electrochemical method. The obtained results show that silver can be released, simultaneously with 10–undecenoic acid, from an impregnated polymeric membrane, at concentrations that ensure the biocidal and fungicidal capacity. Concentrations of active substances can be controlled by choosing the polymer matrix or, in some cases, by changing the pH of the target medium. In the studied case, higher concentrations of silver ions are released from the polysulfone matrix, while higher concentrations of 10–undecenoic acid are released from the cellulose acetate matrix. The results of the study show that a correlation can be established between the two released target substances, which is dependent on the solubility of the organic compound in the aqueous medium and the interaction of this compound with the silver ions. The ability of 10–undecenoic acid to interact with the silver ion, both through the carboxyl and alkene groups, contributes to the increase in the content of the silver ions transported in the aqueous medium.

3D Printing: An Emerging Technology for Biocatalyst Immobilization

Employment of enzymes as biocatalysts offers immense benefits across diverse sectors in the context of green chemistry, biodegradability, and sustainability. When compared to free enzymes in solution, enzyme immobilization proposes an effective means of improving functional efficiency and operational stability. The advance of printable and functional materials utilized in additive manufacturing, coupled with the capability to produce bespoke geometries, has sparked great interest towards the 3D printing of immobilized enzymes. Printable biocatalysts represent a new generation of enzyme immobilization in a more customizable and adaptable manner, unleashing their potential functionalities for countless applications in industrial biotechnology. This review provides an overview of enzyme immobilization techniques and 3D printing technologies, followed by illustrations of the latest 3D printed enzyme-immobilized industrial and clinical applications. The unique advantages of harnessing 3D printing as an enzyme immobilization technique will be presented, alongside a discussion on its potential limitations. Finally, the future perspectives of integrating 3D printing with enzyme immobilization will be considered, highlighting the endless possibilities that are achievable in both research and industry. This article is protected by copyright. All rights reserved.

Sensing and 3D printing technologies in personalized healthcare for the management of health crises including the COVID-19 outbreak

A major threat that has surrounded human civilization since the beginning of the year 2020 is the outbreak of coronavirus disease 2019 (COVID-19). It has been declared a pandemic by the World Health Organization and significantly affected populations globally, causing medical and economic despair. Healthcare chains across the globe have been under grave stress owing to shortages of medical equipments necessary to address a pandemic. Furthermore, personal protective equipment supplies, mandatory for healthcare staff for treating severely ill patients, have been in short supply. To address the necessary requisites during the pandemic, several researchers, hospitals, and industries collaborated to meet the demand for these medical equipments in an economically viable manner. In this context, 3D printing technologies have provided enormous potential in creating personalized healthcare equipment, including face masks, face shields, rapid detection kits, testing swabs, biosensors, and various ventilator components. This has been made possible by capitalizing on centralized large-scale manufacturing using 3D printing and local distribution of verified and tested computer-aided design files. The primary focus of this study is, "How 3D printing is helpful in developing these equipments, and how it can be helpful in the development and deployment of various sensing and point-of-care-testing (POCTs) devices for the commercialization?" Further, the present study also takes care of patient safety by implementing novel 3D printed health equipment used for COVID-19 patients. Moreover, the study helps identify and highlight the efforts made by various organizations toward the usage of 3D printing technologies, which are helpful in combating the ongoing pandemic.

Introducing Fiber-Assisted Colorimetric Measurements as a Quality Control Tool of Hot Melt Extruded Filaments

Pharmaceutical and medicinal printing technologies allow personalization and on-demand manufacturing of drug and medicinal products. Being able to manufacture patient tailored dosage forms or medical devices in a pharmacy, medical office, dental laboratory, or hospital at the point of care raises new demands on quality control procedures. For Fused Deposition Modeling, for example, it must be ensured that the starting materials, the (drug-loaded) filaments, are not accidentally exchanged by the operator. This study investigated the potential of colorimetric measurements for direct and indirect determination of the identity of extruded filaments consisting of polymer matrix, different API and/or coloring agents. Since reflection measurements were affected by surface properties of the filaments, a self-constructed filament holder was utilized with an optical fiber positioned in a 180° angle to a white light LED to perform transmission measurements. It was possible to distinguish filaments with different API concentrations by their color values, taking into account that transmission partially decreased by increased API concentration. Therefore, the intensity of the light source had to be adjusted depending on the transparency of the filament. It was shown that colorimetry can be used as a quality control tool to detect differences in drug-loading and is able to distinguish various extruded batches. Additionally, if differences in API/polymer concentrations do not lead to significant changes in L*a*b values, coloring agents were used as additives in low concentrations to color code filaments. In future studies, the setup must be supplemented with a standardized light source and obscuring filters for light intensity adjustments.

Development and Validation of a Novel Tool for Assessing the Environmental Impact of 3D Printing Technologies: A Pharmaceutical Perspective

Technological advancements have created infinite opportunities and rendered our life easier at several fronts. Nonetheless, the environment has suffered the aftermaths of modernization. Ironically, the pharmaceutical industry was found to be a significant contributor to environmental deterioration. To tackle this issue, continuous eco-evaluation of newly introduced technologies is crucial. Three-dimensional printing (3DP) is rapidly establishing its routes in different industries. Interestingly, 3DP is revolutionising the production of pharmaceuticals and is regarded as a promising approach for the fabrication of patient-centric formulations. Despite the increasing applications in the pharmaceutical field, tools that evaluate the environmental impacts of 3DP are lacking. Energy and solvent consumption, waste generation, and disposal are the main associated factors that present major concerns. For the first time, we are proposing a quantitative tool, the index of Greenness Assessment of Printed Pharmaceuticals (iGAPP), that evaluates the greenness of the different 3DP technologies used in the pharmaceutical industry. The tool provides a colour-coded pictogram and a numerical score indicating the overall greenness of the employed printing method. Validation was performed by constructing the greenness profile of selected formulations produced using the different 3DP techniques. This tool is simple to use and indicates the greenness level of the procedures involved, thereby creating an opportunity to modify the processes for more sustainable practices.

Assessment of the Extrusion Process and Printability of Suspension-Type Drug-Loaded AffinisolTM Filaments for 3D Printing

Three-dimensional (3D) printing technology enables the design of new drug delivery systems for personalised medicine. Polymers that can be molten are needed to obtain extruded filaments for Fused Deposition Modelling (FDM), one of the most frequently employed techniques for 3D printing. The aim of this work was to evaluate the extrusion process and the physical appearance of filaments made of a hydrophilic polymer and a non-molten model drug. Metformin was used as model drug and Affinisol™ 15LV as the main carrier. Drug-loaded filaments were obtained by using a single-screw extruder and, subsequently, their printability was tested. Blends containing up to a 60% and 50% drug load with 5% and 7.5% of auxiliary excipients, respectively, were successfully extruded. Between the obtained filaments, those containing up to 50% of the drug were suitable for use in FDM 3D printing. The studied parameters, including residence time, flow speed, brittleness, and fractal dimension, reflect a critical point in the extrusion process at between 30-40% drug load. This finding could be essential for understanding the behaviour of filaments containing a non-molten component.

Oral delivery of therapeutic peptides and proteins: Technology landscape of lipid-based nanocarriers

The oral administration of therapeutic peptides and proteins is favoured from a patient and commercial point of view. In order to reach the systemic circulation after oral administration, these drugs have to overcome numerous barriers including the enzymatic, sulfhydryl, mucus and epithelial barrier. The development of oral formulations for therapeutic peptides and proteins is therefore necessary. Among the most promising formulation approaches are lipid-based nanocarriers such as oil-in-water nanoemulsions, self-emulsifying drug delivery systems (SEDDS), solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC), liposomes and micelles. As the lipophilic character of therapeutic peptides and proteins can be tremendously increased such as by the formation of hydrophobic ion pairs (HIP) with hydrophobic counter ions, they can be incorporated in the lipophilic phase of these carriers. Since gastrointestinal (GI) peptidases as well as sulfhydryl compounds such as glutathione and dietary proteins are too hydrophilic to enter the lipophilic phase of these carriers, the incorporated therapeutic peptide or protein is protected towards enzymatic degradation as well as unintended thiol/disulfide exchange reactions. Stability of lipid-based nanocarriers towards lipases can be provided by the use to excipients that are not or just poorly degraded by these enzymes. Nanocarriers with a size <200 nm and a mucoinert surface such as PEG or zwitterionic surfaces exhibit high mucus permeating properties. Having reached the underlying absorption membrane, lipid-based nanocarriers enable paracellular and lymphatic drug uptake, induce endocytosis and transcytosis or simply fuse with the cell membrane releasing their payload into the systemic circulation. Numerous in vivo studies provide evidence for the potential of these delivery systems. Within this review we provide an overview about the different barriers for oral peptide and protein delivery, highlight the progress made on lipid-based nanocarriers in order to overcome them and discuss strengths and weaknesses of these delivery systems in comparison to other technologies.

Design, Preparation and In Vitro Evaluation of Core–Shell Fused Deposition Modelling 3D-Printed Verapamil Hydrochloride Pulsatile Tablets

The aim of the study was to investigate core–shell pulsatile tablets by combining the advantages of FDM 3D printing and traditional pharmaceutical technology, which are suitable for a patient’s individual medication and chronopathology. The tablets were designed and prepared with the commercial verapamil hydrochloride tablets as core inside and the fused deposition modelling (FDM) 3D-printed shell outside. Filaments composed of hydroxypropylmethyl cellulose (HPMC) and polyethylenglycol (PEG) 400 were prepared by hot melt extrusion (HME) and used for fabrication of the shell. Seven types of printed shells were designed for the tablets by adjusting the filament composition, geometric structure and thickness of the shell. A series of evaluations were then performed on the 3D-printed core–shell tablets, including the morphology, weight, hardness, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), in vitro drug release and CT imaging. The results showed that the tablets prepared by FDM 3D printing appeared intact without any defects. All the excipients of the tablet shells were thermally stable during the extruding and printing process. The weight, hardness and in vitro drug release of the tablets were affected by the filament composition, geometric structure and thickness of the shell. The pulsatile tablets achieved personalized lag time ranging from 4 h to 8 h in the drug release test in phosphate-buffered solution (pH 6.8). Therefore, the 3D-printed core–shell pulsatile tablets in this study presented good potential in personalized administration, thereby improving the therapeutic effects of the drug for circadian rhythm disease.

3D Printing of Pediatric Medication: The End of Bad Tasting Oral Liquids?-A Scoping Review

3D printing of pediatric-centered drug formulations can provide suitable alternatives to current treatment options, though further research is still warranted for successful clinical implementation of these innovative drug products. Extensive research has been conducted on the compliance of 3D-printed drug products to a pediatric quality target product profile. The 3D-printed tablets were of particular interest in providing superior dosing and release profile similarity compared to conventional drug manipulation and compounding methods, such as oral liquids. In the future, acceptance of 3D-printed tablets in the pediatric patient population might be better than current treatments due to improved palatability. Further research should focus on expanding clinical knowledge, providing regulatory guidance and expansion of the product range, including dosage form possibilities. Moreover, it should enable the use of diverse good manufacturing practice (GMP)-ready 3D printing techniques for the production of various drug products for the pediatric patient population.

Direct cyclodextrin-based powder extrusion 3D printing for one-step production of the BCS class II model drug niclosamide

Niclosamide (NCS) is a drug that has been used as an anthelmintic and anti-parasitic drug for about 40 years. Recently, some studies have highlighted its potential in treating various tumors, allowing a repositioning of this drug. Despite its potential, NCS is a Biopharmaceutical Classification System (BCS) Class II drug and is consequently characterized by low aqueous solubility, poor dissolution rate and reduced bioavailability, which limits its applicability. In this work, we utilize a very novel technique, direct powder extrusion (DPE) 3D printing, which overcomes the limitations of previously used techniques (fused deposition modelling, FDM) to achieve direct extrusion of powder mixtures consisting of NCS, hydroxypropyl methylcellulose (HPMC, Affinisol 15 LV), hydroxypropyl-β-cyclodextrin (HP-β-CD) and polyethylene glycol (PEG) 6000. For the first time, direct printing of powder blends containing HP-β-CD was conducted. For all tablets, in vitro dissolution studies showed sustained drug release over 48 h, but for tablets containing HP-β-CD, the release was faster. Solid-state characterization studies showed that during extrusion, the drug lost its crystal structure and was evenly distributed within the polymer matrix. All printed tablets have exhibited good mechanical and physical features and a stability of the drug content for up to 3 months. This innovative printing technique has demonstrated the possibility to produce personalized pharmaceutical forms directly from powders, avoiding the use of filament used by FDM.

3D printing of pharmaceutical oral solid dosage forms by fused deposition: the enhancement of printability using plasticised HPMCAS

3D printing (3DP) by fused deposition modelling (FDM) is one of the most extensively developed methods in additive manufacturing. Optimizing printability by improving feedability, nozzle extrusion, and layer deposition is crucial for manufacturing solid oral dosage forms with desirable properties. This work aimed to use HPMCAS (Affinisol^TM HPMCAS 716) to prepare filaments for FDM-3DP using hot-melt extrusion (HME). It explored and demonstrated the effect of HME-filament composition and fabrication on printability by evaluating thermal, mechanical, and thermo-rheological properties. It also showed that the HME-Polymer filament composition used in FDM-3DP manufacture of oral solid dosage forms provides a tailored drug release profile. HME (HAAKE MiniLab) and FDM-3DP (MakerBot) were used to prepare HME-filaments and printed objects, respectively. Two diverse ways of improving the mechanical properties of HME-filaments were deduced by changing the formulation to enable feeding through the roller gears of the printer nozzle. These include plasticizing the polymer and adding an insoluble structuring agent (talc) into the formulation. Experimental feedability was predicted using texture analysis results was a function of PEG concentration, and glass-transition temperature (T_g) values of HME-filaments. The effect of high HME screw speed (100 rpm) resulted in inhomogeneity of HME-filament, which resulted in inconsistency of the printer nozzle extrudate and printed layers. The variability of the glass-transition temperature (T_g) of the HME-filament supported by scanning electron microscopy (SEM) images of nozzle extrudates and the lateral wall of the printed tablet helped explain this result. The melt viscosity of HPMCAS formulations was investigated using a capillary rheometer. The high viscosity of unplasticized HPMCAS was concluded to be an additional restriction for nozzle extrusion. The plasticization of HPMCAS and the addition of talc into the formulation were shown to improve thickness consistency of printed layers (using homogeneous HME-filaments). A good correlation (R²=0.9546) between the solidification threshold (low-frequency oscillation test determined by parallel-plate rheometer) and T_g of HME-filaments was also established. Drug-loaded and placebo HPMCAS-based formulations were shown to be successfully printed, with the former providing tailored drug release profiles based on variation of internal geometry (infill).

Coupling of Fused Deposition Modeling and Inkjet Printing to Produce Drug Loaded 3D Printed Tablets

In the current study, we have coupled Fused Deposition Modelling (FDM) for the fabrication of plain polyvinyl alcohol (PVA) tablets followed by dispensing of minoxidil ethanolic solutions using inkjet printing. The use of a drop-on-solid printing approach facilitates an accurate and reproducible process while it controls the deposition of the drug amounts. For the purpose of the study, the effect of the solvent was investigated and minoxidil ink solutions of ethanol 70% v/v (P70) or absolute ethanol (P100) were applied on the plain PVA tablets. Physicochemical characterization showed that solvent miscibility with the polymer substrate plays a key role and can lead to the formation of drug crystals on the surface or drug absorption in the polymer matrix. The produced minoxidil tablets showed sustained release profiles or initial bursts strongly affected by the solvent grade used for dispensing the required dose on drug loaded 3D printed tablets. This paradigm demonstrates that the coupling of FDM and inkjet printing technologies could be used for rapid development of personalized dosage forms.

Polysaccharide 3D Printing for Drug Delivery Applications

3D printing, or additive manufacturing, has gained considerable interest due to its versatility regarding design as well as in the large choice of materials. It is a powerful tool in the field of personalized pharmaceutical treatment, particularly crucial for pediatric and geriatric patients. Polysaccharides are abundant and inexpensive natural polymers, that are already widely used in the food industry and as excipients in pharmaceutical and cosmetic formulations. Due to their intrinsic properties, such as biocompatibility, biodegradability, non-immunogenicity, etc., polysaccharides are largely investigated as matrices for drug delivery. Although an increasing number of interesting reviews on additive manufacturing and drug delivery are being published, there is a gap concerning the printing of polysaccharides. In this article, we will review recent advances in the 3D printing of polysaccharides focused on drug delivery applications. Among the large family of polysaccharides, the present review will particularly focus on cellulose and cellulose derivatives, chitosan and sodium alginate, printed by fused deposition modeling and extrusion-based printing.

Recent Progress in Hot Melt Extrusion Technology in Pharmaceutical Dosage Form Design

BACKGROUND

The Hot Melt Extrusion (HME) technique has shown tremendous potential in transforming highly hydrophobic crystalline drug substances into amorphous solids without using solvents. This review explores in detail the general considerations involved in the process of HME, its applications and advances.

OBJECTIVE

The present review examines the physicochemical properties of polymers pertinent to the HME process. Theoretical approaches for the screening of polymers are highlighted as a part of successful HME processed drug products. The critical quality attributes associated with the process of HME are also discussed in this review. HME plays a significant role in the dosage form design, and the same has been mentioned with suitable examples. The role of HME in developing several sustained release formulations, films, and implants is described along with the research carried out in a similar domain.

METHODS

The method includes the collection of data from different search engines like PubMed, ScienceDirect, and SciFinder to get coverage of relevant literature for accumulating appropriate information regarding HME, its importance in pharmaceutical product development, and advanced applications.

RESULTS

HME is known to have advanced pharmaceutical applications in the domains related to 3D printing, nanotechnology, and PAT technology. HME-based technologies explored using Design-of- Experiments also lead to the systematic development of pharmaceutical formulations.

CONCLUSION

HME remains an adaptable and differentiated technique for overall formulation development.

A 3D-Printed Polymer-Lipid-Hybrid Tablet towards the Development of Bespoke SMEDDS Formulations

3D printing is a rapidly growing area of interest within pharmaceutical science thanks to its versatility in creating different dose form geometries and drug doses to enable the personalisation of medicines. Research in this area has been dominated by polymer-based materials; however, for poorly water-soluble lipophilic drugs, lipid formulations present advantages in improving bioavailability. This study progresses the area of 3D-printed solid lipid formulations by providing a 3D-printed dissolvable polymer scaffold to compartmentalise solid lipid formulations within a single dosage form. This allows the versatility of different drugs in different lipid formulations, loaded into different compartments to generate wide versatility in drug release, and specific control over release geometry to tune release rates. Application to a range of drug molecules was demonstrated by incorporating the model lipophilic drugs; halofantrine, lumefantrine and clofazimine into the multicompartmental scaffolded tablets. Fenofibrate was used as the model drug in the single compartment scaffolded tablets for comparison with previous studies. The formulation-laden scaffolds were characterised using X-ray CT and dispersion of the formulation was studied using nephelometry, while release of a range of poorly water-soluble drugs into different gastrointestinal media was studied using HPLC. The studies show that dispersion and drug release are predictably dependent on the exposed surface area-to-volume ratio (SA:V) and independent of the drug. At the extremes of SA:V studied here, within 20 min of dissolution time, formulations with an SA:V of 0.8 had dispersed to between 90 and 110%, and completely released the drug, where as an SA:V of 0 yielded 0% dispersion and drug release. Therefore, this study presents opportunities to develop new dose forms with advantages in a polypharmacy context.

Influence of Print Settings on the Critical Quality Attributes of Extrusion-Based 3D-Printed Caplets: A Quality-by-Design Approach

Extrusion-based 3D-printing is an easy-to-use, cheap manufacturing technique that could be used to produce tailored precision medicines. The technique has an almost unlimited versatility since a multitude of print parameters can easily be adapted. Unfortunately, little is known of the effect of these print parameters on the critical quality attributes of the resulting printlets. In this study, practical guidelines and means to adapt certain parameters in order to achieve the desired outcome (e.g., acceptable visual quality and flexible dosing) are stipulated for medical 3D-printing using a design-of-experiments approach. The current study aims at elucidating the effect of five print parameters (infill, overlap, number of shells, layer height and layer pattern) on the mechanical properties, dimensions, weight, porosity and dissolution characteristics of a fixed-size caplet consisting of Eudragit EPO (69.3%), Polyox WSR N10 (29.7%) and zolpidem hemitartrate (1%). In terms of the mechanical properties, 3D-printed caplets possessed anisotropy where the vertical compression strength and Brinell hardness exceeded the diametral strength. In general, all 3D-printed caplets possessed acceptable mechanical strength except for a small region of the knowledge space. Dimensional analysis revealed small, statistical significant differences between different runs, although the clinical relevance of this variation is likely negligible. The weight or dose of a caplet can be varied mainly using the infill and overlap and, to a lesser extent, via the layer height and number of shells. The impact on porosity was complicated as this was influenced by many factors and their interactions. Infill was the only statistically relevant factor influencing the dissolution rate of the current formulation. This study unravels the importance of the print parameter overlap, which is a regularly neglected parameter. We also discovered that small dose variations while maintaining the same dissolution profile were possible via modifying the overlap or number of shells. However, large dose variations without affecting the dissolution behaviour could only be accomplished by size modifications of the printlet.

Three-Dimensional Printed Design of Antibiotic-Releasing Esophageal Patches for Antimicrobial Activity Prevention

Pharyngoesophageal defects can cause exposure to various bacterial flora and severe inflammation. We fabricated a biodegradable polycaprolactone (PCL) patch composed of both thin film and three-dimensional (3D) printed lattice, and then investigated the efficacy of pharyngoesophageal reconstruction by using 3D printed antibiotic-releasing PCL patches that inhibited early inflammation by sustained tetracycline (TCN) release from both thin PCL films and printed rods implanted in esophageal partial defects. PCL was 3D printed in lattice form on a presolution casted PCL thin film at ∼100 μm resolution. TCN was loaded onto the PCL-printed patches by 3D printing a mixture of TCN and PCL particles melted at 100°C. TCN exhibited sustained release in vitro for over 1 month. After loading TCN, the patches showed decreased tensile strength and Young's modulus, and less than 20% TCN was slowly released from the 2.5% TCN-loaded PCL patches over 150 days. Cytotoxicity tests of extract solutions from patch samples demonstrated excellent in vitro cell compatibility. Antibiotic-releasing PCL patches were then transplanted into partial esophageal defects in rats. Microcomputed tomography analysis revealed no leak of orally injected contrast agent in the entire esophagus. Tissue remodeling was examined through histological responses of M1 and M2 macrophages. In particular, the 1% and 3% TCN patch groups exhibited significant muscle layer regeneration by desmin immunostaining. Further histological and immunofluorescence analyses revealed that the 1% and 3% TCN patch groups exhibited the best esophageal regeneration according to reepithelialization, neovascularization, and elastin texture around the implanted sites. Our antibiotic-releasing patch successfully consolidates the regenerative potential of esophageal muscle and mucosa and the antibacterial activity of TCN for 3D esophageal reconstruction. Impact statement Anastomosis site leakage and necrosis after pharyngoesophageal transplantation inevitably causes mortality because the mediastinum and neck compartments become contaminated. Herein, we present antibiotic-releasing pharyngoesophageal patch that prevents saliva leakage and has an antimicrobial effect. We have demonstrated antibiotic release profile and mechanical properties for esophageal transplantation. Upon esophageal transplantation of antibiotic-releasing polycaprolactone patches, antimicrobial effects and muscle regeneration around the graft sites were clearly identified in the group containing 1% and 3% of tetracycline. The esophageal graft led to the remarkable recovery throughout reepithelialization, neovascularization, and elastin texture of around the implanted sites. We believe that current system is capable of various applications that require antibacterial in vivo.

Fused deposition modelling 3D printing proof-of-concept study for personalised inner ear therapy

OBJECTIVES

There is a requirement within ear therapeutics for a delivery system capable of safely delivering controlled doses to the inner ear. However, the anatomy and sensitivity of the inner ear make current delivery systems problematic and often ineffective. Therefore, a new delivery system is required to overcome these issues and provide a more efficacious system in the treatment of inner ear disease. This study assesses the potential of 3D printing (3DP) as a fabrication method for an implantable drug delivery system (DDS) to the inner ear.

KEY FINDINGS

Three implantable designs of varying geometry were produced with fused deposition modelling (FDM) 3DP, each loaded with 0.25%, 0.5% and 1% levofloxacin; filaments prepared by hot-melt extrusion. Each implant was effective in providing sustained, therapeutic release of levofloxacin for at least 4 days and as such would be effective in therapeutic treatment of many common inner ear diseases, such as otitis media or Ménière's disease.

CONCLUSIONS

This proof-of-concept research was successful in utilising FDM as a fabrication method for a DDS capable of providing prolonged release directly to the inner ear and highlights the viability of 3DP in the fabrication of an inner ear DDS.

Hydrophilic Excipient-Independent Drug Release from SLA-Printed Pellets

Three-dimensional (3D) printing technology, specifically stereolithography (SLA) technology, has recently created exciting possibilities for the design and fabrication of sophisticated dosages for oral administration, paving a practical way to precisely manufacture customized pharmaceutical dosages with both personalized properties and sustained drug release behavior. However, the sustained drug release achieved in prior studies largely relies on the presence of hydrophilic excipients in the printing formulation, which unfortunately impedes the printability and formability of the corresponding printing formulations. The current study developed and prepared mini-sized oral pellets using the SLA technique and successfully accomplished a hydrophilic excipient-independent drug release behavior. With ibuprofen as the model drug, the customized photopolymerizable printing formulation included polyethylene glycol diacrylate (PEGDA) as a monomer and diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) as a photoinitiator. The produced mini-sized pellets were thoroughly investigated for various factors, including their printability, physical properties, microscopic features, drug content, and drug-release profiles. The drug release profiles from the printed pellets that were larger size (3 mm and 6 mm) followed the Ritger–Peppas model, demonstrating that the release was influenced by both the diffusion of the dissolved drug and by the erosion of the hydrophilic excipients (PEG400). The profiles from the smaller printed pellets (1 mm and 2 mm) followed first release kinetics, not only illustrating that the release was impacted only by drug diffusion, but also indicating that there is a size boundary between the dependent and independent hydrophilic excipients. These results could create practical benefits to the pharmaceutical industry in terms of the design and development personalized dosages using the SLA printing technique with controllable drug release by manipulating size alone.

An updated review on application of 3D printing in fabricating pharmaceutical dosage forms

The concept of "one size fits all" followed by the conventional healthcare system has drawbacks in providing precise pharmacotherapy due to variation in the pharmacokinetics of different patients leading to serious consequences such as side effects. In this regard, digital-based three-dimensional printing (3DP), which refers to fabricating 3D printed pharmaceutical dosage forms with variable geometry in a layer-by-layer fashion, has become one of the most powerful and innovative tools in fabricating "personalized medicine" to cater to the need of therapeutic benefits for patients to the maximum extent. This is achieved due to the tremendous potential of 3DP in tailoring various drug delivery systems (DDS) in terms of size, shape, drug loading, and drug release. In addition, 3DP has a huge impact on special populations including pediatrics, geriatrics, and pregnant women with unique or frequently changing medical needs. The areas covered in the present article are as follows: (i) the difference between traditional and 3DP manufacturing tool, (ii) the basic processing steps involved in 3DP, (iii) common 3DP methods with their pros and cons, (iv) various DDS fabricated by 3DP till date with discussing few research studies in each class of DDS, (v) the drug loading principles into 3D printed dosage forms, and (vi) regulatory compliance.

Impact of Drug Loading Method on Drug Release from 3D-Printed Tablets Made from Filaments Fabricated by Hot-Melt Extrusion and Impregnation Processes

The purpose of this study was to investigate the impact of the drug loading method on drug release from 3D-printed tablets. Filaments comprising a poorly water-soluble model drug, indomethacin (IND), and a polymer, polyvinyl alcohol (PVA), were prepared by hot-melt extrusion (HME) and compared with IND-loaded filaments prepared with an impregnation (IMP) process. The 3D-printed tablets were fabricated using a fused deposition modeling 3D printer. The filaments and 3D printed tablets were evaluated for their physicochemical properties, swelling and matrix erosion behaviors, drug content, and drug release. Physicochemical investigations revealed no drug–excipient interaction or degradation. IND-loaded PVA filaments produced by IMP had a low drug content and a rapid drug release. Filaments produced by HME with a lower drug content released the drug faster than those with a higher drug content. The drug content and drug release of 3D-printed tablets containing IND were similar to those of the filament results. Particularly, drug release was faster in 3D-printed tablets produced with filaments with lower drug content (both by IMP and HME). The drug release of 3D-printed tablets produced from HME filaments with higher drug content was extended to 24 h due to a swelling-erosion process. This study confirmed that the drug loading method has a substantial influence on drug content, which in turn has a significant effect on drug release. The results suggest that increasing the drug content in filaments might delay drug release from 3D-printed tablets, which may be used for developing dosage forms suited for personalized medicine.

Performance and paroxetine stability in tablets manufactured by fused deposition modelling-based 3D printing

OBJECTIVES

The objective of this study was to develop a method for the preparation and characterization of paroxetine (PRX) tablets, obtained by coupling hot-melt extrusion and fused deposition modelling (FDM)-based three-dimensional printing (3DP) technology. The impact of the printing process parameters on the drug stability and on the tablets performance was assessed.

METHODS

Tablets were obtained by FDM of hot-melt extruded PRX-loaded filaments. Physicochemical, thermal, spectroscopic, diffractometric analysis and in-vitro dissolution tests of the intermediate products and the finished dosage forms were performed.

KEY FINDINGS

The characterization of printed tablets evidenced mass and dimensions uniformity, and consistency of drug content and dissolution profile. The formation of amorphous solid dispersions and interaction of formulation components throughout the manufacturing process were demonstrated. Layer thickness, printing temperature, printing and travelling speeds, and infill were the most impacting process parameters on both the physicochemical properties and the in-vitro performance of the 3D-printed tablets.

CONCLUSIONS

PRX tablets, meeting compendial limits, were manufactured by 3DP, envisaging their clinical use as individually designed dosage forms. The assessment of the impact of processing parameters on the printed tablets provided insights, which will ultimately allow streamlining of the 3D process set-up for quicker and easier production of patient-centric medicines.

Intervention of 3D printing in health care: transformation for sustainable development

INTRODUCTION

Three-dimensional (3D) technology is the practice of dropping material layer-by-layer in the construction of the desired object. The application of the 3D printing technique has been observed in miscellaneous domains. Personalized medicine becomes the most demanding trend in the health-care segment. Several advancements have been observed in the progress of 3D printing. However, the availability of finished products in the marketplace is very less. There is an utmost requirement to improve the knowledge and skills in the sustainable development of pharmaceutical and medical products by selecting suitable techniques and materials.

AREAS COVERED

This article covers the fundamental process of 3D printing, types, pharmaceutical-medical application, benefits, and challenges.

EXPERT OPINION

This technology is capable of designing the complex geometry of an organ. It is feasible to produce drug products by incorporating multiple drugs in various compartments in such a fashion that these drugs can release from the compartment at a predetermined rate. Additionally, this 3D process has the potential to revolutionize personalized therapy to different age-groups through design flexibility and accurate dosing. In the upcoming years, the potential application of this technology can be seen in a clinical setting where patients will get individualized medicine as per their needs.

Predicting Drug Release from 3D Printed Oral Medicines Based on the Surface Area to Volume Ratio of Tablet Geometry

3D printing offers the advantage of being able to modify dosage form geometry, which can be exploited to modify release characteristics. In this study, we investigated the influence of the surface area to volume ratio (SA/V) to change and predict release profiles of 3D printed dosage forms. Geometries with varying SA/V and dosages were designed and printed, and drug dissolution was investigated. Three drug substances were used: pramipexole, levodopa (both BCS I) and praziquantel (BCS II). Two polymers were chosen as matrix formers: polyvinyl alcohol (water-soluble) and ethylene vinyl acetate (inert). Drug release was characterized using the mean dissolution time (MDT) and established equations that describe complete dissolution curves were applied. Predictions were validated with previously un-printed dosage forms. Based on an identified MDT-SA/V correlation, the MDT can be predicted with a deviation of ≤5 min for a given SA/V. Using correlations of fit parameters and SA/V, RMSEP values of 0.6-2.8% and 1.6-3.4% were obtained for the BCS I formulations and RMSEP values of 1.0-3.8% were obtained for the BCS II formulation, indicating accurate prediction over a wide range of dissolution profiles. With this approach, MDT and release profiles of dosage forms with a given SA/V can be precisely predicted without performing dissolution tests and vice versa, the required SA/V can be predicted for a desired release profile.

3D Printing and Dissolution Testing of Novel Capsule Shells for Use in Delivering Acetaminophen

Individualized drug delivery improves drug efficacy and safety for patients. To implement individualized drug delivery, patient-specific tailored dosages produced on a small scale are needed. However, current pharmaceutical manufacturing is not suitable for personalized dosage forms. Although convenient to deliver various drugs, current gelatin capsules using animal collagen protein have many limitations, such as releasing drugs too fast and incompatibility with some diets. In contrast, 3D printed capsules have great potential to advance individualized treatments. In this paper, we 3D printed and tested non-animal-based capsule shells for the delivery of acetaminophen. Capsule shells were composed of poly(vinyl) alcohol (PVA) and PVA blends with 5-25% hydroxypropyl methylcellulose (HPMC). Dissolution of acetaminophen when delivered in -hese capsule shells was tested using a USP dissolution test apparatus 2 (paddle type) at gastric pH. The novel shells were compared to each other and to commercially available hard gelatin capsules. Dissolution results show that acetaminophen when delivered in 3D printed capsules was slower than when delivered by gelatin capsules. Increasing the percentage of HPMC in the blend further delayed its release and dissolution. This delay could potentially increase the efficacy and reduce the side effects of acetaminophen. These shells also offer a non-animal-based alternative to gelatin capsules. Furthermore, 3D printing of capsule shells with specific polymer blends may be useful for patient-specific therapy in compounding pharmacies across the country.

Drug Amorphous Solid Dispersions Based on Poly(vinyl Alcohol): Evaluating the Effect of Poly(propylene Succinate) as Plasticizer

Although significant actions have been taken towards the utilization of poly(vinyl alcohol) (PVA) in the preparation of drug amorphous solid dispersions (ASDs) using fusion-based techniques (such as melt-quench cooling and hot-melt extrusion), several drawbacks regarding its rather high melting temperature and its thermal degradation profile make the use of the polymer extremely challenging. This is especially important when the active pharmaceutical ingredient (API) has a lower melting temperature (than PVA) or when it is thermally labile. In this vein, a previous study showed that newly synthesized polyester-based plasticizers may improve the processability and the thermal properties of PVA. However, the effects of such polyester-based plasticizers on the drug’s physicochemical and pharmaco-technical properties are yet unknown. Hence, the aim of the present study is to extend our previous findings and evaluate the use of poly(propylene succinate) (PPSu, i.e., the most promising plasticizer in regard to PVA) in the preparation of drug-loaded PVA-based ASDs. Dronedarone (DRN), a poorly water-soluble API, was selected as a model drug, and drug ASDs (using either neat PVA or PVA-PPSu) were prepared using the melt-mixing/quench cooling approach at low melting temperatures (i.e., 170 °C). DSC and pXRD analysis showed that a portion of the API remained crystalline in the ASDs prepared only with the use of neat PVA, while the samples having PPSu as a plasticizer were completely amorphous. Further evaluation with ATR-FTIR spectroscopy revealed the formation of significant intermolecular interactions between the API and the PVA-PPSu matrix, which could explain the system’s physical stability during storage. Finally, dissolution studies, conducted under nonsink conditions, revealed that the use of PVA-PPSu is able to maintain DRN’s sustained supersaturation for up to 8 h.

Solid self emulsifying drug delivery system: Superior mode for oral delivery of hydrophobic cargos

A significant proportion of recently approved drug molecules possess poor aqueous solubility which further restrains their desired bioavailability. Poor aqueous solubility of these drugs poses significant hurdles in development of novel drug delivery systems and achieving target response. Self-emulsifying drug delivery systems (SEDDS) emerged as an insightful approach for delivering highly hydrophobic entities to enhance their bioavailability. Conventional SEDDS were developed in a liquid form which owned numerous shortcomings like low stability and drug loading efficiency, fewer choices of dosage forms and irreversible precipitation of drug or excipients. To address these curbs solid-SEDDS (S-SEDDS) was introduced as an efficient strategy that combined advantages of solid dosage forms such as increased stability, portability and patient compliance along with substantial improvement in the bioavailability. S-SEDDS are isotropic mixtures of oil, surfactant, solvent and co-solvents generated by solidification of liquid or semisolid self-emulsifying ingredients onto powders. The present review highlights components of S-SEDDS, their peculiarities to be considered while designing solid dosage forms and various methods of fabrication. Lastly, key challenges faced during development, applications and future directions for the research in this area are thoroughly summarized.

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.

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.

Machine learning predicts 3D printing performance of over 900 drug delivery systems

Three-dimensional printing (3DP) is a transformative technology that is advancing pharmaceutical research by producing personalized drug products. However, advances made via 3DP have been slow due to the lengthy trial-and-error approach in optimization. Artificial intelligence (AI) is a technology that could revolutionize pharmaceutical 3DP through analyzing large datasets. Herein, literature-mined data for developing AI machine learning (ML) models was used to predict key aspects of the 3DP formulation pipeline and in vitro dissolution properties. A total of 968 formulations were mined and assessed from 114 articles. The ML techniques explored were able to learn and provide accuracies as high as 93% for values in the filament hot melt extrusion process. In addition, ML algorithms were able to use data from the composition of the formulations with additional input features to predict the drug release of 3D printed medicines. The best prediction was obtained by an artificial neural network that was able to predict drug release times of a formulation with a mean error of ±24.29 min. In addition, the most important variables were revealed, which could be leveraged in formulation development. Thus, it was concluded that ML proved to be a suitable approach to modelling the 3D printing workflow.

Influence of Drug Load on the Printability and Solid-State Properties of 3D-Printed Naproxen-Based Amorphous Solid Dispersion

Fused deposition modelling-based 3D printing of pharmaceutical products is facing challenges like brittleness and printability of the drug-loaded hot-melt extruded filament feedstock and stabilization of the solid-state form of the drug in the final product. The aim of this study was to investigate the influence of the drug load on printability and physical stability. The poor glass former naproxen (NAP) was hot-melt extruded with Kollidon^® VA 64 at 10–30% w/w drug load. The extrudates (filaments) were characterised using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). It was confirmed that an amorphous solid dispersion was formed. A temperature profile was developed based on the results from TGA, DSC, and DMA and temperatures used for 3D printing were selected from the profile. The 3D-printed tablets were characterised using DSC, X-ray computer microtomography (XµCT), and X-ray powder diffraction (XRPD). From the DSC and XRPD analysis, it was found that the drug in the 3D-printed tablets (20 and 30% NAP) was amorphous and remained amorphous after 23 weeks of storage (room temperature (RT), 37% relative humidity (RH)). This shows that adjusting the drug ratio can modulate the brittleness and improve printability without compromising the physical stability of the amorphous solid dispersion.

3D-Printing of Drug-Eluting Implants: An Overview of the Current Developments Described in the Literature

The usage of 3D-printing for drug-eluting implants combines the advantages of a targeted local drug therapy over longer periods of time at the precise location of the disease with a manufacturing technique that easily allows modifications of the implant shape to comply with the individual needs of each patient. Research until now has been focused on several aspects of this topic such as 3D-printing with different materials or printing techniques to achieve implants with different shapes, mechanical properties or release profiles. This review is intended to provide an overview of the developments currently described in the literature. The topic is very multifaceted and several of the investigated aspects are not related to just one type of application. Consequently, this overview deals with the topic of 3D-printed drug-eluting implants in the application fields of stents and catheters, gynecological devices, devices for bone treatment and surgical screws, antitumoral devices and surgical meshes, as well as other devices with either simple or complex geometry. Overall, the current findings highlight the great potential of the manufacturing of drug-eluting implants via 3D-printing technology for advanced individualized medicine despite remaining challenges such as the regulatory approval of individualized implants.

Emerging 3D printing technologies for drug delivery devices: Current status and future perspective

The 'one-size-fits-all' approach followed by conventional drug delivery platforms often restricts its application in pharmaceutical industry, due to the incapability of adapting to individual pharmacokinetic traits. Driven by the development of additive manufacturing (AM) technology, three-dimensional (3D) printed drug delivery medical devices have gained increasing popularity, which offers key advantages over traditional drug delivery systems. The major benefits include the ability to fabricate 3D structures with customizable design and intricate architecture, and most importantly, ease of personalized medication. Furthermore, the emergence of multi-material printing and four-dimensional (4D) printing integrates the benefits of multiple functional materials, and thus provide widespread opportunities for the advancement of personalized drug delivery devices. Despite the remarkable progress made by AM techniques, concerns related to regulatory issues, scalability and cost-effectiveness remain major hurdles. Herein, we provide an overview on the latest accomplishments in 3D printed drug delivery devices as well as major challenges and future perspectives for AM enabled dosage forms and drug delivery systems.

D-Sorbitol Physical Properties Effects on Filaments Used by 3D Printing Process for Personalized Medicine

Fused filament fabrication (FFF) is a process used to manufacture oral forms adapted to the needs of patients. Polyethylene oxide (PEO) filaments were produced by hot melt extrusion (HME) to obtain a filament suitable for the production of amiodarone hydrochloride oral forms by FFF 3D printing. In order to produce personalized oral forms adapted to the patient characteristics, filaments used by FFF must be controlled in terms of mass homogeneity along filament. This work highlights the relation between filament mass homogeneity and its diameter. This is why the impact of filler excipients physical properties was studied. It has been showed that the particle’s size distribution of the filler can modify the filament diameter variability which has had an impact on the mass of oral forms produced by FFF. Through this work it was shown that D-Sorbitol from Carlo Erba allows to obtain a diameter variability of less than 2% due to its unique particle’s size distribution. Using the filament produced by HME and an innovating calibration method based on the filament length, it has been possible to carry out three dosages of 125 mg, 750 mg and 1000 mg by 3D printing with acceptable mass uniformity.

A Sensorized Soft Pneumatic Actuator Fabricated with Extrusion-Based Additive Manufacturing

Soft pneumatic actuators with a channel network (pneu-net) based on thermoplastic elastomers are compatible with fused deposition modeling (FDM). However, conventional filament-based fused deposition modeling (FDM) printers are not well suited for thermoplastic elastomers with a shore hardness (Sh < 70A). Therefore, in this study, a pellet-based FDM printer was used to print pneumatic actuators with a shore hardness of Sh18A. Additionally, the method allowed the in situ integration of soft piezoresistive sensing elements during the fabrication. The integrated piezoresistive elements were based on conductive composites made of three different styrene-ethylene-butylene-styrene (SEBS) thermoplastic elastomers, each with a carbon black (CB) filler with a ratio of 1:1. The best sensor behavior was achieved by the SEBS material with a shore hardness of Sh50A. The dynamic and quasi-static sensor behavior were investigated on SEBS strips with integrated piezoresistive sensor composite material, and the results were compared with TPU strips from a previous study. Finally, the piezoresistive composite was used for the FDM printing of soft pneumatic actuators with a shore hardness of 18 A. It is worth mentioning that 3 h were needed for the fabrication of the soft pneumatic actuator with an integrated strain sensing element. In comparison to classical mold casting method, this is faster, since curing post-processing is not required and will help the industrialization of pneumatic actuator-based soft robotics.

Effects of porosity on drug release kinetics of swellable and erodible porous pharmaceutical solid dosage forms fabricated by hot melt droplet deposition 3D printing

3D printing has the unique ability to produce porous pharmaceutical solid dosage forms on-demand. Although using porosity to alter drug release kinetics has been proposed in the literature, the effects of porosity on the swellable and erodible porous solid dosage forms have not been explored. This study used a model formulation containing hypromellose acetate succinate (HPMCAS), polyethylene oxide (PEO) and paracetamol and a newly developed hot melt droplet deposition 3D printing method, Arburg plastic free-forming (APF), to examine the porosity effects on in vitro drug release. This is the first study reporting the use of APF on 3D printing porous pharmaceutical tablets. With the unique pellet feeding mechanism of APF, it is important to explore its potential applications in pharmaceutical additive manufacturing. The pores were created by altering the infill percentages (%) of the APF printing between 20 and 100% to generate porous tablets. The printing quality of these porous tablets was examined. The APF printed formulation swelled in pH 1.2 HCl and eroded in pH 6.8 PBS. During the dissolution at pH 1.2, the swelling of the printing pathway led to the gradual decreases in the open pore area and complete closure of pores for the tablets with high infills. In pH 6.8 buffer media, the direct correlation between drug release rate and infills was observed for the tablets printed with infill at and less than 60%. The results revealed that drug release kinetics were controlled by the complex interplay of the porosity and dynamic changes of the tablets caused by swelling and erosion. It also implied the potential impact of fluid hydrodynamics on the in vitro data collection and interpretation of porous solids.

Coupling hot melt extrusion and fused deposition modeling: Critical properties for successful performance

Interest in 3D printing for pharmaceutical applications has increased in recent years. Compared to other 3D printing techniques, hot melt extrusion (HME)-based fused deposition modeling (FDM) 3D printing has been the most extensively investigated for patient-focused dosage. HME technology can be coupled with FDM 3D printing as a continuous manufacturing process. However, the crucial pharmaceutical polymers, formulation and process parameters must be investigated to establish HME-coupled FDM 3D printing. These advancements will lead the way towards developing continuous drug delivery systems for personalized therapy. This brief overview classifies pharmaceutical additive manufacturing, Hot Melt Extrusion, and Fused Deposition Modeling 3D printing techniques with a focus on coupling HME and FDM 3D printing processes. It also provides insights on the critical material properties, process and equipment parameters and limitations of successful HME-coupled FDM systems.

Polyvinyl Alcohol-Based 3D Printed Tablets: Novel Insight into the Influence of Polymer Particle Size on Filament Preparation and Drug Release Performance

Three-dimensional printing (3DP) by fused deposition modeling (FDM) has gained momentum as a promising pharmaceutical manufacturing method due to encouraging forward-looking perspectives in personalized medicine preparation. The current challenges the technology has for applicability in the fabrication of solid dosage forms include the limited range of suitable pharmaceutical grade thermoplastic materials. Hence, it is important to investigate the implications of variable properties of the polymeric carrier on the preparation steps and the final output, as versatile products could be obtained by using the same material. In this study, we highlighted the influence of polyvinyl alcohol (PVA) particle size on the residence time of the mixtures in the extruder during the drug-loaded filament preparation step and the consequent impact on drug release from the 3D printed dosage form. We enhanced filament printability by exploiting the plasticizing potential of the active pharmaceutical ingredient (API) and we explored a channeled tablet model as a design strategy for dissolution facilitating purposes. Our findings disclosed a new perspective regarding material considerations for the preparation of PVA-based solid dosage forms by coupling hot melt extrusion (HME) and FDM-3DP.

Practicality of 3D Printed Personalized Medicines in Therapeutics

Technological advances in science over the past century have paved the way for remedial treatment outcomes in various diseases. Pharmacogenomic predispositions, the emergence of multidrug resistance, medication and formulation errors contribute significantly to patient mortality. The concept of "personalized" or "precision" medicines provides a window to addressing these issues and hence reducing mortality. The emergence of three-dimensional printing of medicines over the past decades has generated interests in therapeutics and dispensing, whereby the provisions of personalized medicines can be built within the framework of producing medicines at dispensaries or pharmacies. This plan is a good replacement of the fit-for-all modality in conventional therapeutics, where clinicians are constrained to prescribe pre-formulated dose units available on the market. However, three-dimension printing of personalized medicines faces several hurdles, but these are not insurmountable. In this review, we explore the relevance of personalized medicines in therapeutics and how three-dimensional printing makes a good fit in current gaps within conventional therapeutics in order to secure an effective implementation of personalized medicines. We also explore the deployment of three-dimensional printing of personalized medicines based on practical, legal and regulatory provisions.

Production of Reproducible Filament Batches for the Fabrication of 3D Printed Oral Forms

Patients need medications at a dosage suited to their physiological characteristics. Three-dimensional printing (3DP) technology by fused-filament fabrication (FFF) is a solution for manufacturing medication on demand. The aim of this work was to identify important parameters for the production of reproducible filament batches used by 3DP for oral formulations. Amiodarone hydrochloride, an antiarrhythmic and insoluble drug, was chosen as a model drug because of dosage adaptation need in children. Polyethylene oxide (PEO) filaments containing amiodarone hydrochloride were produced by hot-melt extrusion (HME). Different formulation storage conditions were investigated. For all formulations, the physical form of the drug following HME and fused-deposition modeling (FDM) 3D-printing processes were assessed using thermal analysis and X-ray powder diffraction (XRPD). Filament mechanical properties, linear mass density and surface roughness, were investigated by, respectively, 3-point bending, weighing, and scanning electron microscopy (SEM). Analysis results showed that the formulation storage condition before HME-modified filament linear mass density and, therefore, the oral forms masses from a batch to another. To obtain constant filament apparent density, it has been shown that a constant and reproducible drying condition is required to produce oral forms with constant mass.

Development of FDM 3D-printed tablets with rapid drug release, high drug-polymer miscibility and reduced printing temperature by applying the acid-base supersolubilization (ABS) principle

Some of the major issues with the development of FDM 3D printed tablets are slow drug release, lack of drug-polymer miscibility, high processing temperature, and poor printability. In this investigation, these issues were addressed by using a novel physicochemical principle called acid-base supersolubilization (ABS) previously developed in our laboratory. The aqueous solubility of a basic drug, haloperidol, was increased to ~300 mg/g of solution by adding glutaric acid, and, upon drying, the concentrated solutions produced amorphous materials. Similar amorphous systems could also be produced by heating haloperidol-glutaric acid mixtures. Filaments for 3D printing were prepared by melt extrusion of formulations containing 15% w/w haloperidol and 10.5% glutaric acid (1:2 M ratio) along with 74.5% polymers, such as Kollidon® VA64 alone or its mixtures with Affinisol™ 15cP. Filaments could be extruded and printed at low temperatures of 115 and 120 °C, respectively. Haloperidol was fully miscible in the formulations because of the acid-base interaction and formed amorphous systems even at higher drug loads. Although filaments of haloperidol-Kollidon® VA64 mixtures by themselves cannot be printed, the printability of formulation improved such that those containing glutaric acid were printable. Drug release rates from the formulations at pH 2 and 6.8 were rapid and complete.

Quality-by-design in hot melt extrusion based amorphous solid dispersions: An industrial perspective on product development

An industrially feasible approach to overcome the solubility and bioavailability limitations of poorly soluble active pharmaceutical ingredients is the development of amorphous solid dispersions (ASDs) using hot-melt extrusion (HME) technique. The application of Quality by Design (QbD) had a profound impact on the development of HME-based ASDs. The formulation and process optimization of ASDs manufactured via HME techniques require an understanding of critical quality attributes, critical material attributes, critical process parameters, risk assessment tools, and experimental designs. The knowledge gained from each of these QbD elements helps ensure the consistency of product quality. The selection and implementation of appropriate Design of Experiments (DoE) methodology to screen and optimize the formulation and process variables remain a major challenge. This review provides a comprehensive overview on QbD concepts in HME-based ASDs with an emphasis on DoE methodologies. Further, the information provided in this review can assist researchers in selecting a suitable design with optimal experimental conditions. Specifically, this review has focused on the prediction of drug-polymer miscibility, the elements and sequence of QbD, and various screening and optimization designs, to provide insights into the formulation and process variables that are encountered routinely in the production of HME-based ASDs.

Tailoring immediate release FDM 3D printed tablets using a quality by design (QbD) approach

The aims of this work were to produce immediate release printed tablets using fused deposition modelling (FDM) technique and to systematically explore the effects of different compositions on drug release by Quality by Design approach. Screening studies of various drug loadings and excipients were conducted by hot melt extrusion and FDM printing to set up the appropriate limit of each independent factor (critical material attribute, CMA) in Design of Experiment. This study demonstrated that the use of polymeric mixture containing different theophylline loadings (10, 30 and 60% w/w) in combination with multiple pharmaceutical polymers (hydroxy propyl cellulose (HPC), Eudragit® EPO, Kollidon® VA 64) and disintegrant (sodium starch glycolate) were successfully hot melt-extruded and FDM printed with no plasticizer. Rheological measurement was performed to understand the critical process parameters (CPP) while the mechanical property of extrudable and printable filaments was investigated by 3-point test for the formulation development. Surprisingly, HPC were found to be superior as a flexibility modifier in all printable filaments. A range of pharmaceutical characterizations were examined to ensure the critical quality attributes (CQA). Characteristic dissolution profiles were obtained. D-optimal mixture design of 17 formulations suggested that theophylline release was considerably affected by the combined action of different excipients and could predict the optimum formulation with the required quality target product profile (QTPP) in pharmacopoeia (85% release at 30 min). Therefore, this can be a useful platform to develop immediate release products for a specific group of patients commercially.

Compact Model for 3D Printer Energy Estimation and Practical Energy-Saving Strategy

3D printing is emerging as a technology for future production due to its support for human life. Increasingly more printed products include many applications. Developers and companies have expressed their ambition to develop the next generation to bring 3D printers to most families. However, energy efficiency is a big challenge for such devices. In this research, we investigated the power of components given by measurements on commercial 3D printers. We then built a compact model to estimate the energy of 3D printers and proposed an energy-saving strategy, primarily focused on the heating process. We separated thermal plates into two independent temperature sections to cut wasted energy costs when printing specially shaped objects and small prints. In order to reduce power dissipation, the printing process needs to be installed at high ambient temperatures. Experimental results show that our method reduces 23% of total power consumption in comparison to the current commercial device.

3D-printed tablets using a single-step hot-melt pneumatic process for poorly soluble drugs

Main purpose was to evaluate the applicability of a 3D-printer equipped with a hot-melt pneumatic dispenser as a single-step process to prepare tablet dosage forms. Dutasteride, a poorly water-soluble drug, was selected as a model drug. Soluplus®, Kollidon® VA 64, Eudragit® E PO, and hydroxypropyl cellulose (HPC) were premixed as bulking agents prior to printing. Differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA) were utilized to evaluate the physicochemical properties of the 3D-printed tablets. Moreover, different geometries were designed to correlate the surface area/volume (SA/V) of the tablets with respect to their release profiles. As a result, printed dutasteride was confirmed to be in an amorphous state and not recrystallized even after the accelerated storage stability. Out of the four bulking agents, Kollidon® VA 64, enhanced the dissolution of the printed dutasteride, reaching above 80% within 15 min. These results suggest that the hot-melt pneumatic dispenser was efficient in converting the solid state into an amorphous state, which significantly enhanced the dissolution. On the other hand, the tube-shaped 3D-printed tablet exhibited the fastest drug dissolution profile, which had the highest SA/V ratio in comparison to the cube, hemisphere, and pyramid shapes. These results confirm the dependency of the drug dissolution rate not only on its crystallinity but also on the surface area of the 3D-printed tablet. Therefore, a 3D-printer equipped with a hot-melt pneumatic dispenser possesses useful applicability in enhancing drug dissolution, especially for poorly water-soluble drugs, in a single-step process.