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

Emerging 3D printing technologies for solid oral dosage forms: Processes, materials and analytical tools for real-time assessment

Three-dimensional (3D) printing is an emerging technology with the potential to increase manufacturing flexibility and enable personalized drug delivery. 3D printing may form tablets using digitally controlled layer-by-layer material deposition, permitting the tailoring of solid oral dosage geometry and facile modifications of drug release profiles without requiring extensive alterations to the pharmaceutical formulation and process. The challenge to assure the quality of drugs still lies in monitoring and controlling critical steps in the 3D printing process. Optimizing an 3D printing process requires a comprehensive understanding of the critical process parameters, material attributes and their impact on the performance of 3D-printed tablets. This review focuses on recent advances in 3D printing technologies for solid oral dosage forms, emphasizing critical process parameters and material attributes that may be considered for optimizing printing processes and enhancing the quality of printed tablets. Additionally, this review explores real-time analytical tools and the crucial considerations for ensuring the performance of building materials, printing processes, and manufactured solid drug products. This review contributes to the ongoing discourse on harnessing the potential of 3D printing in the pharmaceutical field while emphasizing the imperative need for quality assurance throughout additive manufacturing processes.

Selective laser sintering for printing bilayer tablets

In this study Selective Laser Sintering (SLS) was used to produce bilayer tablets containing rosuvastatin and acetylsalicylic acid. Initially, monolithic tablets of each drug were manufactured using different laser intensities in order to identify their impact on the tablet's dissolution, friability and hardness. After the optimization, the final bilayer tablet was fabricated using a new method, that allowed the printing using different powder blends. For that, a 3D-printed casing was employed to maintain the compartments of the tablet in the correct position during the printing process. The results demonstrated that the increased laser intensities led to denser inner cores, enhanced hardness, decreased friability, and slower drug release. Moreover, the new method was able to produce bilayer tablets completely aligned, showing a minor impact on dissolution when the two compartments were printed together in a single tablet. The work demonstrated the feasibility of using SLS in the production of multi-material drug delivery systems.

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

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

Droplet-based 3D bioprinting for drug delivery and screening

Recently, the conventional criterion of "one-size-fits-all" is not qualified for each individual patient, requiring precision medicine for enhanced therapeutic effects. Besides, drug screening is a high-cost and time-consuming process which requires innovative approaches to facilitate drug development rate. Benefiting from consistent technical advances in 3D bioprinting techniques, droplet-based 3D bioprinting techniques have been broadly utilized in pharmaceutics due to the noncontact printing mechanism and precise control on the deposition position of droplets. More specifically, cell-free/cell-laden bioinks which are deposited for the fabrication of drug carriers/3D tissue constructs have been broadly utilized for precise drug delivery and high throughput drug screening, respectively. This review summarizes the mechanism of various droplet-based 3D bioprinting techniques and the most up-to-date applications in drug delivery and screening and discusses the potential improvements of droplet-based 3D bioprinting techniques from both technical and material aspects. Through technical innovations, materials development, and the assistance from artificial intelligence, the formation process of drug carriers will be more stable and accurately controlled guaranteeing precise drug delivery. Meanwhile, the shape fidelity and uniformity of the printed tissue models will be significantly improved ensuring drug screening efficiency and efficacy.

Application of 3D printing on the design and development of pharmaceutical oral dosage forms

3D printing technologies confer an unparalleled degree of control over the material distribution on the structures they produce, which has led them to become an extremely attractive research topic in pharmaceutical dosage form development, especially for the design of personalized treatments. With fine tuning in material selection and careful design, these technologies allow to tailor not only the amount of drug administered but the biopharmaceutical behaviour of the dosage forms as well. While fused deposition modelling (FDM) is still the most studied 3D printing technology in this area, others are gaining more relevance, which has led to many new and exciting dosage forms developed during 2022 and 2023. Considering that these technologies, in time, will join the current manufacturing methods and with the ever-increasing knowledge on this topic, our review aims to explore the advantages and limitations of 3D printing technologies employed in the design and development of pharmaceutical oral dosage forms, giving special focus to the most important aspects governing the resulting drug release profiles.

Paediatric clinical study of 3D printed personalised medicines for rare metabolic disorders

Rare diseases are infrequent, but together they affect up to 6-10 % of the world's population, mainly children. Patients require precise doses and strict adherence to avoid metabolic or cardiac failure in some cases, which cannot be addressed in a reliable way using pharmaceutical compounding. 3D printing (3DP) is a disruptive technology that allows the real-time personalization of the dose and the modulation of the dosage form to adapt the medicine to the therapeutic needs of each patient. 3D printed chewable medicines containing amino acids (citrulline, isoleucine, valine, and isoleucine and valine combinations) were prepared in a hospital setting, and the efficacy and acceptability were evaluated in comparison to conventional compounded medicines in six children. The inclusion of new flavours (lemon, vanilla and peach) to obtain more information on patient preferences and the implementation of a mobile app to obtain patient feedback in real-time was also used. The 3D printed medicines controlled amino acid levels within target levels as well as the conventional medicines. The deviation of citrulline levels was narrower and closer within the target concentration with the chewable formulations. According to participants' responses, the chewable formulations were well accepted and can improve adherence and quality of life. For the first time, 3DP enabled two actives to be combined in the same formulation, reducing the number of administrations. This study demonstrated the benefits of preparing 3D printed personalized treatments for children diagnosed with rare metabolic disorders using a novel technology in real clinical practice.

Incorporating surfactants into PCL microneedles for sustained release of a hydrophilic model drug

Polymeric microneedles (MNs) are widely used for sustained drug release due to their distinct advantages over other types of MNs. Poly-ε-caprolactone (PCL) stands out as a biodegradable and biocompatible hydrophobic polymer commonly employed in drug delivery applications. This study explores the impact of surfactants on the encapsulation and release rate of a model hydrophilic drug, minoxidil (MXD), from PCL MNs. Three nonionic surfactants, Tween 80, Span 60, and polyethylene glycol (PEG), were integrated into PCL MNs at varying concentrations. Compared to the other types of surfactants, PEG-containing PCL MNs exhibit enhanced insertion capabilities into a skin-simulant parafilm model and increased mechanical strength, suggesting facile penetration into the stratum corneum. Furthermore, MXD-PEG MNs show the highest encapsulation efficiency and are further characterized using FTIR, DSC and XRD. Their mechanical strength against different static forces was measured. The MNs exhibit a sustained release pattern over 20 days. Eventually, MXD-PEG MNs were subjected to penetration testing using chicken skin and required minimal insertion forces with no observed MN failure during experimentation even after compression with the maximum force applied (32 N per patch). Taken together, the present work demonstrates the feasibility of incorporating nonionic surfactants like PEG into the tips of hydrophobic PCL MNs for sustained delivery of a model hydrophilic drug. This formulation strategy can be used to improve patient compliance by allowing self-administration and achieving prolonged drug release.

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.

Polyvinyl Alcohol, a Versatile Excipient for Pharmaceutical 3D Printing

Three-dimensional (3D) printing in the pharmaceutical field allows rapid manufacturing of a diverse range of pharmaceutical dosage forms, including personalized items. The application of this technology in dosage form manufacturing requires the judicious selection of excipients because the selected materials must be appropriate to the working principle of each technique. Most techniques rely on the use of polymers as the main material. Among the pharmaceutically approved polymers, polyvinyl alcohol (PVA) is one of the most used, especially for fused deposition modeling (FDM) technology. This review summarizes the physical and chemical properties of pharmaceutical-grade PVA and its applications in the manufacturing of dosage forms, with a particular focus on those fabricated through FDM. The work provides evidence on the diversity of dosage forms created using this polymer, highlighting how formulation and processing difficulties may be overcome to get the dosage forms with a suitable design and release profile.

Influence of the Volatility of Solvent on the Reproducibility of Droplet Formation in Pharmaceutical Inkjet Printing

Drop-on-demand (DOD) inkjet printing enables exact dispensing and positioning of single droplets in the picoliter range. In this study, we investigate the long-term reproducibility of droplet formation of piezoelectric inkjet printed drug solutions using solvents with different volatilities. We found inkjet printability of EtOH/ASA drug solutions is limited, as there is a rapid forming of drug deposits on the nozzle of the printhead because of fast solvent evaporation. Droplet formation of c = 100 g/L EtOH/ASA solution was affected after only a few seconds by little drug deposits, whereas for c = 10 g/L EtOH/ASA solution, a negative affection was observed only after t = 15 min, while prominent drug deposits form at the printhead tip. Due to the creeping effect, the crystallizing structures of ASA spread around the nozzle but do not clog it necessarily. When there is a negative affection, the droplet trajectory is affected the most, while the droplet volume and droplet velocity are influenced less. In contrast, no formation of drug deposits could be observed for highly concentrated, low volatile DMSO-based drug solution of c = 100 g/L even after a dispensing time of t = 30 min. Therefore, low volatile solvents are preferable to highly volatile solvents to ensure a reproducible droplet formation in long-term inkjet printing of highly concentrated drug solutions. Highly volatile solvents require relatively low drug concentrations and frequent printhead cleaning. The findings of this study are especially relevant when high droplet positioning precision is desired, e.g., drug loading of microreservoirs or drug-coating of microneedle devices.

Dose Titration of Solid Dosage Forms via FDM 3D-Printed Mini-Tablets

The robustness of 3D-printed mini-tablets as a platform to administer milligram dosages, intended for age-specific therapy, without the need of tablet splitting while maintaining similar release profiles, was investigated. Griseofulvin, as a model poorly water-soluble drug, and hydroxypropyl cellulose along with Kollicoat Protect as polymers were used to prepare filaments at 1-20% drug concentrations via hot-melt extrusion (HME). Higher drug concentrations served for testing the feasibility of a reduced number of mini-tablets to be administered. A reliable dose titration in the range 0.19-3.91 mg at a high accuracy (R2 of 0.999) was achieved through composite unit (multi-unit) mini-tablets. All mini-tablets produced had excellent content uniformity and their label claim values were within the acceptable range, proving that HME processing followed by 3D printing promotes content uniformity even for mini-tablets containing low drug doses (0.19 mg). Remarkably, the proposed approach allowed achieving similar drug release profiles via composite unit mini-tablets as well as single mini-tablets at high drug concentrations. In contrast, split tablets demonstrated different release behaviors, attributed to their size and shape differences. Overall, the distinct advantages of mini-tablets to provide dose flexibility while maintaining similar release profiles was demonstrated.

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

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