A Step Toward Development of Printable Dosage Forms for Poorly Soluble Drugs

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.

Inkjet Printing of Pharmaceuticals

Inkjet printing (IJP) is an additive manufacturing process that selectively deposits ink materials, layer-by-layer, to create 3D objects or 2D patterns with precise control over their structure and composition. This technology has emerged as an attractive and versatile approach to address the ever-evolving demands of personalized medicine in the healthcare industry. Although originally developed for nonhealthcare applications, IJP harnesses the potential of pharma-inks, which are meticulously formulated inks containing drugs and pharmaceutical excipients. Delving into the formulation and components of pharma-inks, the key to precise and adaptable material deposition enabled by IJP is unraveled. The review extends its focus to substrate materials, including paper, films, foams, lenses, and 3D-printed materials, showcasing their diverse advantages, while exploring a wide spectrum of therapeutic applications. Additionally, the potential benefits of hardware and software improvements, along with artificial intelligence integration, are discussed to enhance IJP's precision and efficiency. Embracing these advancements, IJP holds immense potential to reshape traditional medicine manufacturing processes, ushering in an era of medical precision. However, further exploration and optimization are needed to fully utilize IJP's healthcare capabilities. As researchers push the boundaries of IJP, the vision of patient-specific treatment is on the horizon of becoming a tangible reality.

Two-dimensional printing of nanoparticles as a promising therapeutic method for personalized drug administration

The necessity for personalized patient treatment has drastically increased since the contribution of genes to the differences in physiological and metabolic state of individuals have been exposed. Different approaches have been considered so far in order to satisfy all of the diversities in patient needs, yet none of them have been fully implemented thus far. In this framework, various types of 2D printing technologies have been identified to offer some potential solutions for personalized medication, which development is increasing rapidly. Accurate drug-on-demand deposition, the possibility of consuming multiple drug substances in one product and adjusting individual drug concentration are just some of the few benefits over existing bulk pharmaceuticals manufacture, which printing technologies brings. With inclusion of nanotechnology by printing nanoparticles from its dispersions some further opportunities such as controlled and stimuli-responsive drug release or targeted and dose depending on drug delivery were highlighted. Yet, there are still some challenges to be solved before such products can reach the pharmaceutical market. In those terms mostly chemical, physical as well as microbiological stability concerns should be answered, with which 2D printing technology could meet the treatment needs of every individual and fulfill some existing drawbacks of large-scale batch production of pharmaceuticals we possess today.

Development of Simvastatin-Loaded Particles Using Spray Drying Method for Ex Tempore Preparation of Cartridges for 2D Printing Technology

In this work, a spray drying method was developed to produce drug/polymer (simvastatin/polycaprolactone) microparticles that have the potential to be used as a pre-formulation for ex tempore preparation of 2D printing cartridges. An experimental model was designed with the process parameters set to predict the smallest particle size required for successful 2D printing. Three different types of particles (lactose, nanocellulose/lactose, calcium silicate) were produced, and the average size of the dry particles varied depending on the sampling location (cyclone, collection vessel). The encapsulation efficiency of simvastatin was highest with nanocellulose/lactose from the collection vessel. The one-month stability of simvastatin in the particles showed low content, but the addition of ascorbic acid as an antioxidant increased the chemical stability of the drug. Interestingly, the addition of antioxidants decreased the stability of simvastatin in the calcium silicate particles from the collection vessel. Dispersion of the particles in three different propylene glycol and water mixtures (10/90, 50/50, and 90/10% (v/v)), representing a printable ink medium with three different viscosity and surface tension properties, showed that nanocellulose/lactose was the most suitable antiadhesive in terms of dispersed particle size (˂1 µm). After one month of storage, the dispersed particles remained in the same size range without undesirable particle agglomeration.

3D printing of amorphous solid dispersions: A comparison of fused deposition modeling and drop-on-powder printing

Nowadays, a high number of pipeline drugs are poorly soluble and require solubility enhancement by e.g., manufacturing of amorphous solid dispersion. Pharmaceutical 3D printing has great potential in producing amorphous solid oral dosage forms. However, 3D printing techniques differ greatly in terms of processing as well as tablet properties. In this study, an amorphous formulation, which had been printed via Fused Deposition Modeling and drop-on-powder printing, also known as binder jetting, was characterized in terms of solid-state properties and physical stability. Solid state assessment was performed by differential scanning calorimetry, powder X-ray diffraction and polarized microscopy. The supersaturation performance of the amorphous solid dispersion was assessed via non-sink dissolution. We further evaluated both 3D printing techniques regarding their processability as well as tablet uniformity in terms of dimension, mass and content. Challenges and limitations of each 3D printing technique were discussed. Both techniques are feasible for the production of amorphous formulations. Results indicated that Fused Deposition Modeling is better suited for production, as the recrystallization tendency was lower. Still, filament production and printing presented a major challenge. Drop-on-powder printing can be a viable alternative for the production of amorphous tablets, when a formulation is not printable by Fused Deposition Modeling.

Development of 3D Printed Multi-Layered Orodispersible Films with Porous Structure Applicable as a Substrate for Inkjet Printing

The direct tailoring of the size, composition, or number of layers belongs to the advantages of 3D printing employment in producing orodispersible films (ODFs) compared to the frequently utilized solvent casting method. This study aimed to produce porous ODFs as a substrate for medicated ink deposited by a 2D printer. The innovative semi-solid extrusion 3D printing method was employed to produce multilayered ODFs, where the bottom layer assures the mechanical properties. In contrast, the top layer provides a porous structure for ink entrapment. Hydroxypropyl methylcellulose and polyvinyl alcohol were utilized as film-forming polymers, glycerol as a plasticizer, and sodium starch glycolate as a disintegrant in the bottom matrix. Several porogen agents (Aeroperl^® 300, Fujisil^®, Syloid^® 244 FP, Syloid^® XDP 3050, Neusilin^® S2, Neusilin^® US2, and Neusilin^® UFL2) acted as porosity enhancers in the two types of top layer. ODFs with satisfactory disintegration time were prepared. The correlation between the porogen content and the mechanical properties was proved. A porous ODF structure was detected in most samples and linked to the porogen content. SSE 3D printing represents a promising preparation method for the production of porous ODFs as substrates for subsequent drug deposition by 2D printing, avoiding the difficulties arising in casting or printing medicated ODFs directly.

Drop-on-powder 3D printing of amorphous high dose oral dosage forms: Process development, opportunities and printing limitations

Drop-on-powder 3D printing is able to produce highly drug loaded solid oral dosage forms. However, this technique is mainly limited to well soluble drugs. The majority of pipeline compounds is poorly soluble, though, and requires solubility enhancement, e.g., via formation of amorphous solid dispersions. This study presents a detailed and systematic development approach for the production of tablets containing high amounts of a poorly soluble, amorphized drug via drop-on-powder 3D printing (also known as binder jetting). Amorphization of the compound was achieved via hot-melt extrusion using the exemplary system of the model compound ketoconazole and copovidone as matrix polymer at drug loadings of 20% and 40%. The milled extrudate was used as powder for printing and the influence of inks and different ink-to-powder ratios on recrystallization of ketoconazole was investigated in a material-saving small-scale screening. Crystallinity assessment was performed using differential scanning calorimetry and polarized light microscopy to identify even small traces of crystallinity. Printing of tablets showed that the performed small-scale screening was capable to identify printing parameters for the development of amorphous and mechanically stable tablets via drop-on-powder printing. A stability study demonstrated physically stable tablets over twelve weeks at accelerated storage conditions.

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

Polymers in Technologies of Additive and Inkjet Printing of Dosage Formulations

Technologies for obtaining dosage formulations (DF) for personalized therapy are currently being developed in the field of inkjet (2D) and 3D printing, which allows for the creation of DF using various methods, depending on the properties of pharmaceutical substances and the desired therapeutic effect. By combining these types of printing with smart polymers and special technological approaches, so-called 4D printed dosage formulations are obtained. This article discusses the main technological aspects and used excipients of a polymeric nature for obtaining 2D, 3D, 4D printed dosage formulations. Based on the literature data, the most widely used polymers, their properties, and application features are determined, and the technological characteristics of inkjet and additive 3D printing are shown. Conclusions are drawn about the key areas of development and the difficulties that arise in the search and implementation in the production of new materials and technologies for obtaining those dosage formulations.

Development of Nanosuspension Formulations Compatible with Inkjet Printing for the Convenient and Precise Dispensing of Poorly Soluble Drugs

The pharmaceutical industry has been challenged by the increasing number of poorly soluble drug candidates, resulting in significant issues with obtaining sufficient absorption and bioavailability, risk of exposure variability, and difficulties in achieving a safe therapeutic index. Additionally, the rapid and precise dispensing of specific drug dosages is an important aspect that can enable personalized medicines for the patient. Herein, we report on the development of inkjet printing as a method for delivering precise quantities of poorly soluble drug molecules using commercially available equipment. Despite challenges due to low solubility making it difficult to prepare liquid solutions, stable suspensions of drug nanoparticles with the appropriate viscosity were successfully printed and dispensed onto a thin film suitable for delivery. The drug nanoparticles remained intact and could be reconstituted after printing, demonstrating that they remained stable and retained their advantageous particle size. This demonstrates that inkjet printing can be a practical and convenient approach for dispensing poorly soluble drug molecules when formulated as nanosuspensions.

Multi-material 3D printing of programmable and stretchable oromucosal patches for delivery of saquinavir

Oromucosal patches for drug delivery allow fast onset of action and ability to circumvent hepatic first pass metabolism of drugs. While conventional fabrication methods such as solvent casting or hot melt extrusion are ideal for scalable production of low-cost delivery patches, these methods chiefly allow for simple, homogenous patch designs. As alternative, a multi-material direct-ink-write 3D printing for rapid fabrication of complex oromucosal patches with unique design features was demonstrated in the present study. Specifically, three print-materials: an acidic saquinavir-loaded hydroxypropyl methylcellulose ink, an alkaline effervescent sodium carbonate-loaded ink, and a methyl cellulose backing material were combined in various designs. The CO₂ content and pH of the microenvironment were controlled by adjusting the number of alkaline layers in the patch. Additionally, the rigid and brittle patches were converted to compliant and stretchable patches by implementing mesh-like designs. Our results illustrate how 3D printing can be used for rapid design and fabrication of multifunctional or customized oromucosal patches with tailored dosages and changed drug permeation.

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

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

Data-Enriched Edible Pharmaceuticals (DEEP) with Bespoke Design, Dose and Drug Release

Data-enriched edible pharmaceuticals (DEEP) is an approach to obtain personalized medicine, in terms of flexible and precise drug doses, while at the same time containing data, embedded in quick response (QR) codes at a single dosage unit level. The aim of this study was to fabricate DEEP with a patient-tailored dose, modify drug release and design to meet patients' preferences. It also aimed to investigate physical stability in terms of the readability of QR code patterns of DEEP during storage. Cannabinoids, namely, cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC), were used as the model active pharmaceutical ingredients (APIs). Three different substrates and two colorants for the ink were tested for their suitability to fabricate DEEP by desktop inkjet printing. Flexible doses and customizable designs of DEEP were obtained by manipulating the digital design of the QR code, particularly, by exploring different pattern types, embedded images and the physical size of the QR code pattern. Modification of the release of both APIs from DEEP was achieved by applying a hydroxypropyl cellulose (HPC) polymer coating. The appearance and readability of uncoated and polymer-coated DEEP did not change on storage in cold and dry conditions; however, the HPC polymer layer was insufficient in preserving the readability of the QR code pattern in the extreme storage condition (40 °C and 75% relative humidity). To sum up, the DEEP concept provides opportunities for the personalization of medicines, considering also patients' preferences.

Printing Methods in the Production of Orodispersible Films

Orodispersible film (ODF) formulations are promising and progressive drug delivery systems that are widely accepted by subjects across all the age groups. They are traditionally fabricated using the most popular yet conventional method called solvent casting method. The most modern and evolving method is based on printing technologies and such printed products are generally termed as printed orodispersible films (POFs). This modern technology is well suited to fabricate ODFs across different settings (laboratory or industrial) in general and in a pharmacy setting in particular. The present review provides an overview of various printing methods employed in fabricating POFs. Particularly, it provides insight about preparing POFs using inkjet, flexographic, and three-dimensional printing (3DP) or additive manufacturing techniques like filament deposition modeling, hot-melt ram extrusion 3DP, and semisolid extrusion 3DP methods. Additionally, the review is focused on patenting trends in POFs using ESPACENET, a European Patent Office search database. Finally, the review captures future market potential of 3DP in general and ODFs market potential in particular.

[2D-3D printing in hospital pharmacies, what roles and challenges?]

The additive technology or 2D and 3D printing are increasingly used in various industrial fields, from aeronautics to mechanics but also in the fields of health such as dentistry or for bone reconstructions. These techniques have been studied for about fifteen years by the academic community in the pharmaceutical field (medical device and drug), and recently they have started to be applied to produce drugs in industry and in hospitals. Indeed, the Food and Drug Administration approved in August 2015 the marketing of the first drug printed by additive technique, then in 2018 the first clinical trial using 3D printed drugs was carried out in Great Britain by a hospital pharmacy. 2D-3D printing is presented as one of the tools of a more personalized medicine, the techniques of additive printing allowing the production of tabs containing several drugs in one tab (polypills) and the development of custom modified-releases drugs. This approach could allow better acceptance of the finished product and secure manufacturing. The objective of this work is to highlight relevant printing technologies for implementation in hospital pharmacies, and to see how these technologies could lead to a change in pharmaceutical practices, to improve patient care.

Application of Extrusion-Based 3D Printed Dosage Forms in the Treatment of Chronic Diseases

Chronic disease management has been a significant burden in many countries. As most treatment options involve long-term pharmacotherapy, patient compliance has been a challenge, as patients have to remember taking medications on time at the prescribed dose for each disease state. Patients are often required to split the dosage unit, which may lead to under- or over-dose and dose-related adverse effects. However, 3D printing technologies have been used for fabricating personalized medications and multiple drugs in a single dose unit (polypills), which might greatly reduce treatment monitoring, dosing errors, and follow-ups with the health care providers. Extrusion-based 3D printing is the most used technology to fabricate polypills and to customize the dose, dosage form, and release kinetics, which might potentially reduce the risk of patient non-compliance. Although extrusion-based 3D printing has existed for some time, interest in its potential to fabricate dosage forms for treating chronic diseases is still in its infancy. This review focuses on the various extrusion-based 3D printing technologies such as fused deposition modeling, pressure-assisted microsyringe, and direct powder extrusion 3D printing in the preparation of customizable, multi-drug dosage forms for treating chronic diseases.

Inkjet Bioprinting of Biomaterials

The inkjet technique has the capability of generating droplets in the picoliter volume range, firing thousands of times in a few seconds and printing in the noncontact manner. Since its emergence, inkjet technology has been widely utilized in the publishing industry for printing of text and pictures. As the technology developed, its applications have been expanded from two-dimensional (2D) to three-dimensional (3D) and even used to fabricate components of electronic devices. At the end of the twentieth century, researchers were aware of the potential value of this technology in life sciences and tissue engineering because its picoliter-level printing unit is suitable for depositing biological components. Currently inkjet technology has been becoming a practical tool in modern medicine serving for drug development, scaffold building, and cell depositing. In this article, we first review the history, principles and different methods of developing this technology. Next, we focus on the recent achievements of inkjet printing in the biological field. Inkjet bioprinting of generic biomaterials, biomacromolecules, DNAs, and cells and their major applications are introduced in order of increasing complexity. The current limitations/challenges and corresponding solutions of this technology are also discussed. A new concept, biopixels, is put forward with a combination of the key characteristics of inkjet printing and basic biological units to bring a comprehensive view on inkjet-based bioprinting. Finally, a roadmap of the entire 3D bioprinting is depicted at the end of this review article, clearly demonstrating the past, present, and future of 3D bioprinting and our current progress in this field.

Inkjet printing of a thermolabile model drug onto FDM-printed substrates: formulation and evaluation

OBJECTIVE

The inkjet printing (IP) and fused deposition modeling (FDM) technologies have emerged in the pharmaceutical field as novel and personalized formulation approaches. Specific manufacturing factors must be considered in each adopted methodology, i.e. the development of suitable substrates for IP and the incorporation of highly thermostable active pharmaceutical compounds (APIs) for FDM. In this study, IP and FDM printing technologies were investigated for the fabrication of hydroxypropyl methylcellulose-based mucoadhesive films for the buccal delivery of a thermolabile model drug. Significance: This proof-of-concept approach was expected to provide an alternative formulation methodology for personalized mucoadhesive buccal films.

METHODS

Mucoadhesive substrates were prepared by FDM and were subjected to sequential IP of an ibuprofen-loaded liquid ink. The interactions between these processes and the performance of the films were evaluated by various analytical and spectroscopic techniques, as well as by in vitro and ex vivo studies.

RESULTS

The model drug was efficiently deposited by sequential IP passes onto the FDM-printed substrates. Significant variations were revealed on the morphological, physicochemical and mechanical properties of the prepared films, and linked to the number of IP passes. The mechanism of drug release, the mucoadhesion and the permeation of the drug through the buccal epithelium were evaluated, in view of the extent of ink deposition onto the buccal films, as well as the distribution of the API.

CONCLUSIONS

The presented methodology provided a proof-of-concept formulation approach for the development of personalized mucoadhesive films.

Fabrication of Mucoadhesive Buccal Films for Local Administration of Ketoprofen and Lidocaine Hydrochloride by Combining Fused Deposition Modeling and Inkjet Printing

In the area of developing oromucosal drug delivery systems, mucoadhesive buccal films are the most promising formulations for either systemic or local drug delivery. The current study presents the fabrication of buccal films, by combining fused deposition modeling (FDM) and inkjet printing. Hydroxypropyl methylcellulose-based films were fabricated via FDM, containing the non-steroidal anti-inflammatory drug ketoprofen. Unidirectional release properties were achieved, by incorporating an ethyl cellulose-based backing layer. The local anesthetic lidocaine hydrochloride, combined with the permeation enhancer l-menthol, was deposited onto the film by inkjet printing. Physicochemical analysis showed alterations in the characteristics of the films, and the mucoadhesive and mechanical properties were effectively modified, due to the ink deposition on the substrates. The in vitro release data of the active pharmaceutical compounds, as well as the permeation profiles across ex vivo porcine buccal mucosa and filter-grown TR146 cells of human buccal origin, were associated with the presence of the permeation enhancer and the backing layer. The lack of any toxicity of the fabricated films was demonstrated by the MTT viability assay. This proof-of-concept study provides an alternative formulation approach of mucoadhesive buccal films, intended for the treatment of local oromucosal diseases or systemic drug delivery.

Fabrication of Muco-Adhesive Oral Films by the 3D Printing of Hydroxypropyl Methylcellulose-Based Catechin-Loaded Formulations

Pharmaceutical applications of three dimensional (3D) printing technology are increasing following the approval of 3D-printed tablets by the U.S. Food and Drug Administration. Semi-solid extrusion-type 3D printers are used to 3D print hydrogel- and paste-based materials. We previously developed tablet formulations for semi-solid extrusion-type 3D bioprinters. In the present study, we extended our study to the preparation of muco-adhesive oral film formulations to 3D bioprint mouth ulcer pharmaceuticals. We focused on hydroxypropyl methylcellulose (HPMC)-based catechin (model drug)-loaded hydrogel formulations and found that the viscosity of a hydrogel formulation is dependent on the HPMC concentration, and that viscosity is important for facile 3D printing. HPMC-based films were prepared using two different drying methods (air drying and freeze drying). The films exhibited different drug dissolution profiles, and increasing the amount of HPMC in the film delayed drug dissolution. The fabrication of HPMC-based catechin-loaded films with different shapes provides a model of individualized, on-demand pharmaceuticals. Our results support the flexible application of 3D bioprinters (semi-solid extrusion-type 3D printers) for preparing film formulations.

FDM-printed pH-responsive capsules for the oral delivery of a model macromolecular dye

To this day, the oral delivery of biomacromolecules remains a major developmentally-oriented challenge. A combinatorial approach was followed at this study, to formulate an efficient carrier for the in vitro delivery of a model macromolecule, fluorescein isothiocyanate-dextran 4 kDa (FD4). The model macromolecule was formulated in a self-assembling peptide hydrogel (ac-(RADA)₄-CONH₂), prior to deposition in a hydroxypropyl methylcellulose-phthalate (HPMCP)-based 3D-printed capsule. Loading of FD4 was investigated for potential alterations on the structural (AFM) and gelling properties of the peptide carrier. Thermal analysis and morphological properties of the 3D-printed capsules were assessed by TGA, DSC and microscopy studies. For the peptide hydrogel, similar release profiles of FD4 were recorded in simulated gastric fluid pH 1.2 and phosphate buffer saline pH 7.4, indicating the need for a structural barrier, to protect the peptide carrier from the acidic environment of the stomach. The pH responsive character of the HPMCP-based capsule was evidenced in the release profiles of FD4 in a sequence of release media, i.e. simulated gastric fluid pH 1.2, simulated intestinal fluid pH 6.8 and phosphate buffer saline pH 7.4. The results supported the combinatorial formulation approach as a promising system for the efficient oral delivery of biomacromolecules.

3D Printing Technology in Customized Drug Delivery System: Current State of the Art, Prospective and the Challenges

BACKGROUND

3D printing/Additive Manufacturing seems a pragmatic approach to realize the quest for a truly customized and personalized drug delivery. 3DP technology, with innovations in pharmaceutical development and an interdisciplinary approach to finding newer Drug Delivery Systems can usher a new era of treatments to various diseases. The true potential of this is yet to be realized, and the US-FDA is focusing on the regulatory science of 3D printed medical devices to help patients access this technology safely and effectively. The approval of the first 3D printed prescription medicine by FDA is a promising step in the translation of more research in this area.

METHODS

A web-search on PubMed, ScienceDirect, and Nature was performed with the keywords Customized 3D printing and Drug delivery, publications dealing with the aspects of drug delivery using 3D printing for personalized or customized delivery were further considered and analyzed and discussed.

RESULTS

We present the advantages offered by 3DP over conventional methods of formulation development and discuss the current state of 3DP in pharmaceutics and how it can be used to develop a truly customized drug delivery system, various 3DP technologies including Stereolithography (SLA), Selective Laser Sintering (SLS), Fused Deposition Modelling (FDM), Pressure Assisted Microsyringe (PAM) that have been used to develop pharmaceutical products have been discussed along with their limitations and also the regulatory considerations to help formulation scientists envisaging research in this area with the necessary information.

CONCLUSION

3D printing has the potential to fabricate a customized drug delivery system. Presence of many drug formulation and the devices are already in the regulatory approval process indicating its success.

3D Printing Methods for Pharmaceutical Manufacturing: Opportunity and Challenges

BACKGROUND

A recently FDA approved 3D printed drug is paving a path for new pharmaceutical manufacturing era. The 3D printing is a novel approach of producing 3D pharmaceuticals from digital designs, in a layer-by-layer fashion. However, traditional manufacturing of drug products is being carried out from decades with well-established manufacturing processes and with well approved regulatory guidelines but these processes are too obsolete in concern of process aptitude and manufacturing flexibility. On the other hand, 3D printing provides a competitive flexibility in terms of personalized drug dosage forms with complex geometries that will be made on-demand with desired drug release kinetics, hence providing the formulator a substantial provision of improvising the safety and efficacy of the drugs. Furthermore, this novel 3D technology allows tailoring of composite tissue scaffolds and sample models for characterization that closely mimic in-vivo simulations. Nevertheless, certain limitations are there in terms of regulatory aspects hindering the launch of 3DP products in the market.

METHODS

Exhaustive search were made on Google Scholar and PubMed databases concerning 3-D printing methods, drug delivery applications, and past to present evolution of personalized medicine.

RESULTS

Although a high magnitude of progress have been made on 3-D printing techniques in a short span of time, still inkjet, nozzle-based deposition, stereolithography and selective laser sintering techniques are the most popular ones. Their application is adapted in the fabrication of tablets, implants, polypills and nanoparticles.

CONCLUSION

3D printing is revolutionizing the pharma expectations towards customized medicines but still there is a need to explore the aspects of cost, flexibility and bioequivalence. The present review provides a comprehensive account of various 3D printing technologies and highlights the opportunities and key challenges of 3D printing relevant to pharmaceuticals.

Towards Printed Pediatric Medicines in Hospital Pharmacies: Comparison of 2D and 3D-Printed Orodispersible Warfarin Films with Conventional Oral Powders in Unit Dose Sachets

To date, the lack of age-appropriate medicines for many indications results in dose manipulation of commercially available dosage forms, commonly resulting in inaccurate doses. Various printing technologies have recently been explored in the pharmaceutical field due to the flexible and precise nature of the techniques. The aim of this study was, therefore, to compare the currently used method to produce patient-tailored warfarin doses at HUS Pharmacy in Finland with two innovative printing techniques. Dosage forms of various strengths (0.1, 0.5, 1, and 2 mg) were prepared utilizing semisolid extrusion 3D printing, inkjet printing and the established compounding procedure for oral powders in unit dose sachets (OPSs). Orodispersible films (ODFs) drug-loaded with warfarin were prepared by means of printing using hydroxypropylcellulose as a film-forming agent. The OPSs consisted of commercially available warfarin tablets and lactose monohydrate as a filler. The ODFs resulted in thin and flexible films showing acceptable ODF properties. Moreover, the printed ODFs displayed improved drug content compared to the established OPSs. All dosage forms were found to be stable over the one-month stability study and suitable for administration through a naso-gastric tube, thus, enabling administration to all possible patient groups in a hospital ward. This work demonstrates the potential of utilizing printing technologies for the production of on-demand patient-specific doses and further discusses the advantages and limitations of each method.

Comparison of Linear and 4-Arm Star Poly(vinyl pyrrolidone) for Aqueous Binder Jetting Additive Manufacturing of Personalized Dosage Tablets

Fabrication of personalized dosage oral pharmaceuticals using additive manufacturing (AM) provides patients with customizable, locally manufactured, and cost-efficient tablets, while reducing the probability of side effects. Binder jetting AM has potential for fabrication of customized dosage tablets, but the resulting products lack in strength due to solely relying on the binder to produce structural integrity. The selection of polymeric binders is also limited due to viscosity restraints, which limits molecular weight and concentration. To investigate and ameliorate these limitations, this article reports a comprehensive study of linear and 4-arm star poly(vinyl pyrrolidone) (PVP) over a range of molecular weights as polymeric binders for binder jetting AM and their effect on physical tablet properties. Formulation of varying molecular weights and concentrations of linear and 4-arm star PVP in deionized water and subsequent jetting revealed relationships between the critical overlap concentrations (C*) and jettability on binder jetting systems with thermal inkjet printheads. After printing with a commercially available ZCorp Spectrum Z510 printer with an HP11 printhead with a lactose and powdered sugar powder bed, subsequent measurement of compressive strength, compressive modulus, and porosity revealed structure-property relationships between molecular weight, polymer concentration, and linear and 4-arm star architectures with physical properties of binder jetted tablets. This study elucidated that the dominating factor to increase compressive strength of a tablet is dependent on the weight percent of the polymer in the binder, which filled interstitial voids between powder particles. Because 4-arm star polymers have lower solution viscosities compared to linear analogues at the same molecular weights, they were jettable at higher concentrations, thus producing the strongest tablets at a compressive strength of 1.2 MPa. Finally, the inclusion of an active pharmaceutical ingredient (API), acetaminophen, revealed maintenance of the tablet physical properties across 5-50 total wt % API in each tablet.

Three-dimensional printing for drug delivery devices: a state-of-the-art survey

Over the last several decades, 3D printing technology, which encompasses many different fabrication techniques, had emerged as a promising tool in many fields of production, including the pharmaceutical industry. Specifically, 3D printing may be advantageous for drug delivery systems, systems aiming to improve the pharmacokinetics of drugs. These advantages include the ease of designing complex shapes, printing of drugs on demand, tailoring dosage to the specific needs of the patient and enhancing the bioavailability of drugs. This paper reviews the most recent advancements in this field, presenting both the abilities and limitations of several promising 3D printing methods.

SOFTs - Structured orodispersible film templates

Orodispersible films (ODFs) have a high potential to accelerate the individualized medication. The films can be produced as drug-free templates and subsequently printed with an API (active pharmaceutical ingredient) solution or suspension according to the needs of the patient. While the printing technology already enables a precise dosing of fluids, there is still a high need of suitable, edible templates with elevated loading capacity. The structured orodispersible film templates (SOFTs) developed in this study should overcome this void. The SOFTs are pervaded with pores to realize a high API load into the film structure and possess a closed bottom side to prevent the printed fluids to pass through the film. They consist of a water-soluble cellulose derivative and are produced with the solvent casting method. This study focused on the influence of the formulation of the film casting mass on the film properties, like porosity and disintegration time due to changed pore sizes and numbers. Due to the porous film structure a mass load of up to 6.1 mg cm^-2 could be realized already in SOFTs, but, higher loads are feasible. The mechanical film properties could further be improved by additional matrix material in the suspension formulation, also inhibiting particle agglomeration and aggregation during the drying process, and positively influencing the dissolution behavior of the applied nanoparticles. An application of a protection layer on top of the loaded SOFTs improves the handling safety by inhibiting contact to the API and it prevents a removal of the particles from the film surface.

Investigating the application of FDM 3D printing pattern in preparation of patient-tailored dosage forms

Aim: The aim of this work was to investigate the effect of printing pattern on physical attributes and dissolution of fused deposition modeling 3D printed caplets. Methods: Hydrochlorothiazide-loaded polyvinyl alcohol filaments were prepared by hot melt extrusion. Caplets printed in hexagonal (HexCap), diamond infill (DiaCap) in three different sizes using fused deposition modeling 3D printer and evaluated for hardness, disintegration and dissolution. Results: DiaCaps exhibited higher hardness than HexCaps. Disintegration time for HexCaps was <20 mins. while DiaCaps took 25–40 mins. DiaCaps showed 20–30% lower release at all time points compared with HexCaps. Conclusion: Although composition, processing parameters were same, mere change in printing pattern alters disintegration and dissolution. Findings of this study can be invaluable in developing patient-tailored medicines.

Analytical aspects of printed oral dosage forms

Printing technologies, both 2D and 3D, have gained considerable interest during the last years for manufacturing of personalized dosage forms, tailored to each patient. Here we review the research work on 2D printing techniques, mainly inkjet printing, for manufacturing of film-based oral dosage forms. We describe the different printing techniques and give an overview of film-based oral dosage forms produced using them. The main part of the review focuses on the non-destructive analytical methods used for evaluation of qualitative aspects of printed dosage forms, e.g., solid-state properties, as well as for quantification of the active pharmaceutical ingredient (API) in the printed dosage forms, with an emphasis on spectroscopic methods. Finally, the authors share their view on the future of printed dosage forms.

Inkjet printing of paracetamol and indomethacin using electromagnetic technology: Rheological compatibility and polymorphic selectivity

Drop-on-demand inkjet printing is a potential enabling technology both for continuous manufacturing of pharmaceuticals and for personalized medicine, but its use is often restricted to low-viscosity solutions and nano-suspensions. In the present study, a robust electromagnetic (valvejet) inkjet technology has been successfully applied to deposit prototype dosage forms from solutions with a wide range of viscosities, and from suspensions with particle sizes exceeding 2 μm. A detailed solid-state study of paracetamol, printed from a solution ink on hydroxypropyl methylcellulose (HPMC), revealed that the morphology of the substrate and its chemical interactions can have a considerable influence on polymorphic selectivity. Paracetamol ink crystallized exclusively into form II when printed on a smooth polyethylene terephthalate substrate, and exclusively into form I when in sufficient proximity to the rough surface of the HPMC substrate to be influenced by confinement in pores and chemical interactions. The relative standard deviation in the strength of the dosage forms was <4% in all cases, for doses as low as 0.8 mg, demonstrating the accuracy and reproducibility associated with electromagnetic inkjet technology. Good adhesion of indomethacin on HPMC was achieved using a suspension ink with hydroxypropyl cellulose, but not on an alternative polyethylene terephthalate substrate, emphasising the need to tailor the binder to the substrate. Future work will focus on lower-dose drugs, for which dosing flexibility and fixed dose combinations are of particular interest.

FDM 3D printing of modified drug-delivery systems using hot melt extrusion: a new approach for individualized therapy

The production process of 3D-printed drugs offers unique advantages such as the possibility of individualizing the drug therapy and easily associating different drugs and release technologies in the same pharmaceutical unit. Fused deposition modeling, a 3D printing technique, seems especially interesting for pharmaceutical applications, due to its low cost, precise and reproducible control of the printed structures, and versatility for industrial and laboratory scale. This technique combined with another technology already adapted for the pharmaceutical industry, the hot melt extrusion, is able to incorporate various mechanisms of modified drug release. This special report aims to bring together data of the experimental progress achieved using the fused deposition modeling 3D printing combined with hot melt extrusion technique and its potential in drug delivery.

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Novel strategies for the formulation and processing of poorly water-soluble drugs

Low aqueous solubility of active pharmaceutical ingredients presents a serious challenge in the development process of new drug products. This article provides an overview on some of the current approaches for the formulation of poorly water-soluble drugs with a special focus on strategies pursued at the Center of Pharmaceutical Engineering of the TU Braunschweig. These comprise formulation in lipid-based colloidal drug delivery systems and experimental as well as computational approaches towards the efficient identification of the most suitable carrier systems. For less lipophilic substances the preparation of drug nanoparticles by milling and precipitation is investigated for instance by means of microsystem-based manufacturing techniques and with special regard to the preparation of individualized dosage forms. Another option to overcome issues with poor drug solubility is the incorporation into nanospun fibers.

Inkjet printing of antiviral PCL nanoparticles and anticancer cyclodextrin inclusion complexes on bioadhesive film for cervical administration

Personalized medicine is an important treatment approach for diseases like cancer with high intrasubject variability. In this framework, printing is one of the most promising methods since it permits dose and geometry adjustment of the final product. With this study, a combination product consisting of anticancer (paclitaxel) and antiviral (cidofovir) drugs was manufactured by inkjet printing onto adhesive film for local treatment of cervical cancers as a result of HPV infection. Furthermore, solubility problem of paclitaxel was overcome by maintaining this poorly soluble drug in a cyclodextrin inclusion complex and release of cidofovir was controlled by encapsulation in polycaprolactone nanoparticles. In vitro characterization studies of printed film formulations were performed and cell culture studies showed that drug loaded film formulation was effective on human cervical adenocarcinoma cells. Our study suggests that inkjet printing technology can be utilized in the development of antiviral/anticancer combination dosage forms for mucosal application. The drug amount in the delivery system can be accurately controlled and modified. Moreover, prolonged drug release time can be obtained. Printing of anticancer and antiviral drugs on film seem to be a potential approach for HPV-related cervical cancer treatment and a good candidate for further studies.

Application of a handheld NIR spectrometer in prediction of drug content in inkjet printed orodispersible formulations containing prednisolone and levothyroxine

Quality control tools to assess the quality of printable orodispersible formulations are yet to be defined. Four different orodispersible dosage forms containing two poorly soluble drugs, levothyroxine and prednisolone, were produced on two different edible substrates by piezoelectric inkjet printing. Square shaped units of 4cm² were printed in different resolutions to achieve an escalating drug dose by highly accurate and uniform displacement of droplets in picoliter range from the printhead onto the substrates. In addition, the stability of drug inks in a course of 24h as well as the mechanical properties and disintegration behavior of the printed units were examined. A compact handheld near-infrared (NIR) spectral device in the range of 1550-1950nm was used for quantitative estimation of the drug amount in printed formulations. The spectral data was treated with mean centering, Savitzky-Golay filtering and a third derivative approach. Principal component analysis (PCA) and orthogonal partial least squares (OPLS) regression were applied to build predictive models for quality control of the printed dosage forms. The accurate tuning of the dose in each formulation was confirmed by UV spectrophotometry for prednisolone (0.43-1.95mg with R²=0.999) and high performance liquid chromatography for levothyroxine (0.15-0.86mg with R²=0.997). It was verified that the models were capable of clustering and predicting the drug dose in the formulations with both Q² and R²Y values between 0.94-0.99.