3D-Printing with precise layer-wise dose adjustments for paediatric use via pressure-assisted microsyringe printing

3D printed dispersible efavirenz tablets: A strategy for nasogastric administration in children

Enteral feeding tubes (EFTs) can be placed in children diagnosed with HIV which need nutritional support due to malnutrition. EFTs are the main route for medication administration in these patients, bringing up concerns about off label use of medicines, dose inaccuracy and tube clogging. Here we report for the first time the use of selective laser sintering (SLS) 3D printing to develop efavirenz (EFZ) dispersible printlets for patients with HIV that require EFT administration. Water soluble polymers Parteck® MXP and Kollidon® VA64 were used to obtain both 500 mg (P500 and K500) and 1000 mg printlets (P1000 and K1000) containing 200 mg of EFZ each. The use of SLS 3D printing obtained porous dosage forms with high drug content (20 % and 40 % w/w) and drug amorphization using both polymers. P500, K500 and K1000 printlets reached disintegration in under 230 s in 20 mL of water (25 ± 1 °C), whilst P1000 only partially disintegrated, possibly due to saturation of the polymer in the medium. As a result, the development of dispersible EFZ printlets using hydrophilic polymers can be explored as a potential strategy for drug delivery through EFTs in paediatrics with HIV, paving the way towards the exploration of more rapidly disintegrating polymers and excipients for SLS 3D printing.

Quality by Design Considerations for Drop-on-Demand Point-of-Care Pharmaceutical Manufacturing of Precision Medicine

Distributed and point-of-care (POC) manufacturing facilities enable an agile pharmaceutical production paradigm that can respond to localized needs, providing personalized and precision medicine. These capabilities are critical for narrow therapeutic index drugs and pediatric or geriatric dosing, among other specialized needs. Advanced additive manufacturing, three-dimensional (3D) printing, and drop-on-demand (DoD) dispensing technologies have begun to expand into pharmaceutical production. We employed a quality by design (QbD) approach to identify critical quality attributes (CQAs), critical material attributes (CMAs), and critical process parameters (CPPs) of a POC pharmaceutical manufacturing paradigm. This theoretical framework encompasses the production of active pharmaceutical ingredient (API) "inks" at a centralized facility, which are distributed to POC sites for DoD dispensing into/onto delivery vehicles (e.g., orodispersible films, capsules, single liquid dose vials). Focusing on the POC dispensing/dosing processes, QbD considerations and cause-and-effect analyses identified the dispensed API quantity and solid-state form (CQAs), as well as the nozzle diameter, system pressure channel, and number of drops dispensed (CPPs) for detailed investigation. Final assay quantification and content uniformity CQAs were measured from demonstrative levothyroxine sodium single-dose liquid vials of glycerin/water, meeting the standard acceptance values. Each POC facility is unlikely to maintain full quality control laboratory capabilities, requiring the development of appropriate atline or inline methods to ensure quality control. We developed control strategies, including atline ultraviolet-visible (UV-vis) verification of the API ink prior to dispensing, inline drop counting during dispensing, intermediate atline-dispensed volume checks, and offline batch confirmation by liquid chromatography-tandem mass spectrometry (LC-MS/MS) following production.

Influence of design parameters on sustained drug release properties of 3D-printed theophylline tablets

The application of three-dimensional printing (3DP) in the pharmaceutical industry brings a broad spectrum of benefits to patients by addressing individual needs and improve treatment success. This study investigates the sustained release properties of 3DP tablets containing Theophylline (TPH), which is commonly used to treat respiratory diseases and recently having a comeback due to its potential in the treatment of conditions like Covid-19. Since TPH is a narrow therapeutic window (NTW) drug with serious side effects in the event of overdose, the release properties must be observed particularly closely. We employed a state-of-the-art single screw extrusion 3D printer, which is fed with granules containing the drug. By employing a Taguchi orthogonal array design of experiments (DOE), tablet design parameters and factor related process stability were sought to be evaluated fundamentally. Following this, examinations regarding tailored TPH dosages were undertaken and a relationship between the real printed dose of selected tablet designs and their sustained drug release was established. The release profiles were analyzed using different mathematical model fits and compared in terms of mean dissolution times (MDT). Finally, in-vivo/in-vitro correlation (IVIVC) and physiologically based pharmacokinetic (PBPK) modeling showed that a paradigm patient group could be covered with the dosage forms produced.

3D printing processes in precise drug delivery for personalized medicine

With the advent of personalized medicine, the drug delivery system will be changed significantly. The development of personalized medicine needs the support of many technologies, among which three-dimensional printing (3DP) technology is a novel formulation-preparing process that creates 3D objects by depositing printing materials layer-by-layer based on the computer-aided design method. Compared with traditional pharmaceutical processes, 3DP produces complex drug combinations, personalized dosage, and flexible shape and structure of dosage forms (DFs) on demand. In the future, personalized 3DP drugs may supplement and even replace their traditional counterpart. We systematically introduce the applications of 3DP technologies in the pharmaceutical industry and summarize the virtues and shortcomings of each technique. The release behaviors and control mechanisms of the pharmaceutical DFs with desired structures are also analyzed. Finally, the benefits, challenges, and prospects of 3DP technology to the pharmaceutical industry are discussed.

Pediatric Formulations Developed by Extrusion-Based 3D Printing: From Past Discoveries to Future Prospects

Three-dimensional printing (3DP) technology in pharmaceutical areas is leading to a significant change in controlled drug delivery and pharmaceutical product development. Pharmaceutical industries and academics are becoming increasingly interested in this innovative technology due to its inherent inexpensiveness and rapid prototyping. The 3DP process could be established in the pharmaceutical industry to replace conventional large-scale manufacturing processes, particularly useful for personalizing pediatric drugs. For instance, shape, size, dosage, drug release and multi-drug combinations can be tailored according to the patient's needs. Pediatric drug development has a significant global impact due to the growing needs for accessible age-appropriate pediatric medicines and for acceptable drug products to ensure adherence to the prescribed treatment. Three-dimensional printing offers several significant advantages for clinical pharmaceutical drug development, such as the ability to personalize medicines, speed up drug manufacturing timelines and provide on-demand drugs in hospitals and pharmacies. The aim of this article is to highlight the benefits of extrusion-based 3D printing technology. The future potential of 3DP in pharmaceuticals has been widely shown in the last few years. This article summarizes the discoveries about pediatric pharmaceutical formulations which have been developed with extrusion-based technologies.

Eucalypt Extracts Prepared by a No-Waste Method and Their 3D-Printed Dosage Forms Show Antimicrobial and Anti-Inflammatory Activity

The pharmaceutical industry usually utilizes either hydrophobic or hydrophilic substances extracted from raw plant materials to prepare a final product. However, the waste products from the plant material still contain biologically active components with the opposite solubility. The aim of this study was to enhance the comprehensive usability of plant materials by developing a new no-waste extraction method for eucalypt leaves and by investigating the phytochemical and pharmacological properties of eucalypt extracts and their 3D-printed dosage forms. The present extraction method enabled us to prepare both hydrophobic soft extracts and hydrophilic (aqueous) dry extracts. We identified a total of 28 terpenes in the hydrophobic soft extract. In the hydrophilic dry extract, a total of 57 substances were identified, and 26 of them were successfully isolated. The eucalypt extracts studied showed significant antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis, Candida albicans, Corynebacterium diphtheriae gravis, and Corynebacterium diphtheriae mitis. The anti-inflammatory activity of the dry extract was studied using a formalin-induced-edema model in mice. The maximum anti-exudative effect of the dry extract was 61.5% at a dose of 20 mg/kg. Composite gels of polyethylene oxide (PEO) and eucalypt extract were developed, and the key process parameters for semi-solid extrusion (SSE) 3D printing of such gels were verified. The SSE 3D-printed preparations of novel synergistically acting eucalypt extracts could have uses in antimicrobial and anti-inflammatory medicinal applications.

3D printing in vaginal drug delivery: a revolution in pharmaceutical manufacturing

INTRODUCTION

The Food and Drug Administration's approval of the first three-dimensional (3D) printed tablet, Spritam®, led to a burgeoning interest in using 3D printing to fabricate numerous drug delivery systems for different routes of administration. The high degree of manufacturing flexibility achieved through 3D printing facilitates the preparation of dosage forms with many actives with complex and tailored release profiles that can address individual patient needs.

AREAS COVERED

This comprehensive review provides an in-depth look into the several 3D printing technologies currently utilized in pharmaceutical research. Additionally, the review delves into vaginal anatomy and physiology, 3D-printed drug delivery systems for vaginal applications, the latest research studies, and the challenges of 3D printing technology and future possibilities.

EXPERT OPINION

3D printing technology can produce drug-delivery devices or implants optimized for vaginal applications, including vaginal rings, intra-vaginal inserts, or biodegradable microdevices loaded with drugs, all custom-tailored to deliver specific medications with controlled release profiles. However, though the potential of 3D printing in vaginal drug delivery is promising, there are still challenges and regulatory hurdles to overcome before these technologies can be widely adopted and approved for clinical use. Extensive research and testing are necessary to ensure safety, effectiveness, and biocompatibility.

Potentially Harmful Excipients: State of the Art for Oral Liquid Forms Used in Neonatology and Pediatrics Units

The pediatric population exhibits an important age-dependent heterogeneity in pharmacokinetics and pharmacodynamics parameters, resulting in differences in drug efficacy and toxicity compared to the adult population, particularly for neonates. Toxicity and efficacy divergences have been studied for active molecules, but the impact on the pharmacological parameters of excipients remains less well known. To fill this lack of knowledge, several initiatives have been started to gather information on the specific toxicity of excipients, such as the KIDS list or the STEP database. In order to contribute to this much-needed action, in this work, a compilation of the 219 formulations of oral liquid forms prescribed in pediatrics and neonatology units was established based on the summary of product characteristics. Then, for excipients found in more than 10% of the analyzed formulations, a review of their toxicity data was carried out using the STEP database. Finally, for a selection of 10 frequently used liquid forms, the amounts of excipients administered daily were calculated based on the recommended posology in the Summary of Product Characteristics (SPC) and compared with the recommended daily limits proposed by the European Medicine Agency. Pediatrics-adapted formulations are still rare, and it is not always possible to find safe alternatives to drugs containing excipients of interest.

Towards personalized drug delivery via semi-solid extrusion: Exploring poly(vinyl alcohol-co-vinyl acetate) copolymers for hydrochlorothiazide-loaded films

The increasing need for personalized drug delivery requires developing systems with tailorable properties. The copolymer poly(vinyl alcohol-co-vinyl acetate) (PVA/PVAc) allows for adjusting the monomer ratio. This study explored the effect of vinyl alcohol (VA) and vinyl acetate (VAc) monomer ratio on the properties of hydrochlorothiazide (HCT) films. Five copolymers with different VA/VAc ratios were selected and characterized. Semi-solid extrusion was employed as a method for the preparation of HCT-PVA/PVAc films to address the challenges of HCT´s low water solubility, high melting point, and low permeability. All copolymers were suitable for semi-solid extrusion, however, the mechanical properties of films with higher VA proportions were more suitable. The drug was found to be homogeneously distributed on a micrometer level throughout the prepared films. It was found that using different monomer ratios in the copolymer allows for drug release tuning - higher VA proportions showed an increased rate of drug release. Experiments through HT29-MTX cell monolayers revealed differences in HCT permeability between the different formulations. In addition, no cytotoxicity was observed for the tested formulations. The results highlight the effect of monomer ratio on film properties, providing valuable guidance for formulators in selecting PVA/PVAc copolymers for achieving desired high-quality films. In addition, varying the monomer ratio allows tuning of the film properties, and can be applied for personalization, with flexible-dose adjustment and design of appealing shapes of the pharmaceutics, not least attractive for pediatric drug delivery.

Synergistic stabilization of emulsion gel by nanoparticles and surfactant enables 3D printing of lipid-rich solid oral dosage forms

Pharmaceutical formulation of oral dosage forms is continuously challenged by the low solubility of new drug candidates. Pickering emulsions, emulsions stabilized with solid particles, are a promising alternative to surfactants for developing long-term stable emulsions that can be tailored for controlled release of lipophilic drugs. In this work, a non-emulsifying lipid-based formulation (LBF) loaded with fenofibrate was formulated into an oil-in-water (O/W) emulsion synergistically stabilized by stearic acid and silica (SiO2) nanoparticles. The emulsion had a droplet size of 341 nm with SiO2 particles partially covering the oil-water interface. In vitro lipid digestion was faster for the emulsion compared to the corresponding LBF due to the larger total surface area available for digestion. Cellulose biopolymers were added to the emulsion to produce a gel for semi-solid extrusion (SSE) 3D printing into tablets. The emulsion gel showed suitable rheological attributes for SSE, with a trend of higher viscosity, yield stress, and storage modulus (G'), compared to a conventional self-emulsifying lipid-based emulsion gel. The developed emulsion gel allows for a non-emulsifying LBF to be transformed into solid dosage forms for rapid lipid digestion and drug release of a poorly water-soluble drug in the small intestine.

Quality attributes for printable emulsion gels and 3D-printed tablets: Towards production of personalized dosage forms

3D-printing technology offers a flexible manufacturing platform with the potential to address the need of personalized dosage forms. However, quality aspects of such small-scale, on-demand production of pharmaceutical products intended for personalization is still limited. The aim of this study was therefore to study critical quality control attributes of lipid tablets produced by semi-solid extrusion (SSE) 3D printing from emulsion gels incorporating a poorly water-soluble drug. Quality attributes for both the printable emulsion gel and the printed dosage forms were assessed. The emulsion gel was shown to be printable with accurate dosing for at least one month of storage at 4 °C. Tablets were 3D printed in different sizes and a correlation, R2 value of 0.99, was found between the weight and the drug content. The 3D-printed tablets complied with the mass and drug content uniformity requirements described in the European Pharmacopoeia.. Solid-state characterization of the tablets during short-term storage revealed no signs of crystallinity of the drug. Lastly, the lipid digestion and drug release were unchanged after short-term storage of the tablets. This study demonstrates the potential of SSE 3D printing for personalized dosing of a lipid-based formulation strategy and discusses central quality attributes for the printable formulation and the 3D-printed dosage form.

Manufacturing pharmaceutical mini-tablets for pediatric patients using drop-on-demand printing

The pharmaceutical industry has traditionally manufactured medicines in a limited range of dose strengths, with an emphasis on addressing the needs of the largest patient subgroups. This has disadvantaged smaller patient subsets, such as children, who often cannot find drug products in dosage levels suitable for their requirements. In recent years, development of pharmaceutical mini-tablets has emerged as an attractive solution to this problem. These are small-size dosages that offer attractive features such as flexible and personalized drug dosing, ease of swallowing, and tailored drug release, making them an excellent choice for administering medicines to children. This study presents a novel technique for manufacturing pharmaceutical mini-tablets, using a drop-on-demand (DoD) printing system. In this method, a DoD system is used to generate precise droplets of a melt-based formulation, which are then captured and solidified in an inert solvent bath to produce individual mini-tablets. The study also evaluates the performance of this technique for various formulations, and quantifies two critical quality attributes (CQAs) of the resulting mini-tablets: content uniformity and dissolution behavior. The findings demonstrate that the manufactured mini-tablets can meet regulatory specifications for both CQAs, and that their release profiles can be customized by modifying the excipients used. The study also discusses promising areas of application and limitations of this technique.

Characterization and Validation of a New 3D Printing Ink for Reducing Therapeutic Gap in Pediatrics through Individualized Medicines

3D printing technology can be used to develop individualized medicines in hospitals and pharmacies, allowing a high degree of personalization and the possibility to adjust the dose of the API based on the quantity of material extruded. The main goal of incorporating this technology is to have a stock of API-load print cartridges that could be used at different storage times and for different patients. However, it is necessary to study the extrudability, stability, and buildability of these print cartridges during storage time. A paste-like formulation containing hydrochlorothiazide as a model drug was prepared and distributed in five print cartridges, each of which was studied for different storage times (0 h-72 h) and conditions, for repeated use on different days. For each print cartridge, an extrudability analysis was performed, and subsequently, 100 unit forms of 10 mg hydrochlorothiazide were printed. Finally, various dosage units containing different doses were printed, taking into account the optimized printing parameters based on the results of the extrudability analysis carried out previously. An appropriate methodology for the rapid development of appropriate SSE 3DP inks for pediatrics was established and evaluated. The extrudability analysis and several parameters allowed the detection of changes in the mechanical behavior of the printing inks, the pressure interval of the steady flow, and the selection of the volume of ink to be extruded to obtain each of the required doses. The print cartridges were stable for up to 72 h after processing, and orodispersible printlets containing 6 mg to 24 mg of hydrochlorothiazide can be produced using the same print cartridge and during the same printing process with guaranteed content and chemical stability. The proposed workflow for the development of new printing inks containing APIs will allow the optimization of feedstock material and human resources in pharmacy or hospital pharmacy services, thus speeding up their development and reducing costs.

Advancing non-destructive analysis of 3D printed medicines

Pharmaceutical 3D printing (3DP) has attracted significant interest over the past decade for its ability to produce personalised medicines on demand. However, current quality control (QC) requirements for traditional large-scale pharmaceutical manufacturing are irreconcilable with the production offered by 3DP. The US Food and Drug Administration (FDA) and the UK Medicines and Healthcare Products Regulatory Agency (MHRA) have recently published documents supporting the implementation of 3DP for point-of-care (PoC) manufacturing along with regulatory hurdles. The importance of process analytical technology (PAT) and non-destructive analytical tools in translating pharmaceutical 3DP has experienced a surge in recognition. This review seeks to highlight the most recent research on non-destructive pharmaceutical 3DP analysis, while also proposing plausible QC systems that complement the pharmaceutical 3DP workflow. In closing, outstanding challenges in integrating these analytical tools into pharmaceutical 3DP workflows are discussed.

Selective laser sintering additive manufacturing of dosage forms: Effect of powder formulation and process parameters on the physical properties of printed tablets

Large batches of placebo and drug-loaded solid dosage forms were successfully fabricated using selective laser sintering (SLS) 3D printing in this study. The tablet batches were prepared using either copovidone (N-vinyl-2-pyrrolidone and vinyl acetate, PVP/VA) or polyvinyl alcohol (PVA) and activated carbon (AC) as radiation absorbent, which was added to improve the sintering of the polymer. The physical properties of the dosage forms were evaluated at different pigment concentrations (i.e., 0.5 and 1.0 wt%) and at different laser energy inputs. The mass, hardness, and friability of the tablets were found to be tunable and structures with greater mass and mechanical strength were obtained with increasing carbon concentration and energy input. Amorphization of the active pharmaceutical ingredient in the drug-loaded batches, containing 10 wt% naproxen and 1 wt% AC, was achieved in-situ during printing. Thus, amorphous solid dispersions were prepared in a single-step process and produced tablets with mass losses below 1 wt%. These findings show how the properties of dosage forms can be tuned by careful selection of the process parameters and the powder formulation. SLS 3D printing can therefore be considered to be an interesting and promising technique for the fabrication of personalized medicines.

Recent Advances in the Applications of Additive Manufacturing (3D Printing) in Drug Delivery: A Comprehensive Review

There has been a tremendous increase in the investigations of three-dimensional (3D) printing for biomedical and pharmaceutical applications, and drug delivery in particular, ever since the US FDA approved the first 3D printed medicine, SPRITAM® (levetiracetam) in 2015. Three-dimensional printing, also known as additive manufacturing, involves various manufacturing techniques like fused-deposition modeling, 3D inkjet, stereolithography, direct powder extrusion, and selective laser sintering, among other 3D printing techniques, which are based on the digitally controlled layer-by-layer deposition of materials to form various geometries of printlets. In contrast to conventional manufacturing methods, 3D printing technologies provide the unique and important opportunity for the fabrication of personalized dosage forms, which is an important aspect in addressing diverse patient medical needs. There is however the need to speed up the use of 3D printing in the biopharmaceutical industry and clinical settings, and this can be made possible through the integration of modern technologies like artificial intelligence, machine learning, and Internet of Things, into additive manufacturing. This will lead to less human involvement and expertise, independent, streamlined, and intelligent production of personalized medicines. Four-dimensional (4D) printing is another important additive manufacturing technique similar to 3D printing, but adds a 4th dimension defined as time, to the printing. This paper aims to give a detailed review of the applications and principles of operation of various 3D printing technologies in drug delivery, and the materials used in 3D printing, and highlight the challenges and opportunities of additive manufacturing, while introducing the concept of 4D printing and its pharmaceutical applications.

Direct cyclodextrin based powder extrusion 3D printing of budesonide loaded mini-tablets for the treatment of eosinophilic colitis in paediatric patients

The purpose of this study was to combine direct powder extrusion (DPE) 3D printing and fluid bed coating techniques to create a budesonide (BD) loaded solid oral formulations for the treatment of eosinophilic colitis (EC) in paediatric patients. The preferred medication for EC treatment is BD, which has drawbacks due to its poor water solubility and low absorption. Additionally, since commercially available medications for EC treatment are created and approved for adult patients, administering them to children sometimes requires an off-label use and an impromptu handling, which can result in therapeutic ineffectiveness. The DPE 3D approach was investigated to create Mini-Tablets (MTs) to suit the swallowing, palatability, and dose flexibility control requirements needed by paediatric patients. Additionally, DPE 3D and the inclusion of hydroxypropyl-β-cyclodextrin in the initial powder mixture allowed for an improvement in the solubility and rate of BD dissolution in aqueous medium. Then, to accomplish a site-specific drug release at the intestinal level, MTs were coated with a layer of Eudragit FS 30D, an enteric polymer responsive at pH > 7.0 values. In vitro release experiments showed that film-coated MTs were suitable in terms of size and dose, enabling potential therapeutic customization and targeted delivery of BD to the colon.

Additive manufacturing technologies with emphasis on stereolithography 3D printing in pharmaceutical and medical applications: A review

Three-dimensional (3D) printing or Additive Manufacturing (AM) technology is an innovative tool with great potential and diverse applications in various fields. As 3D printing has been burgeoning in recent times, a tremendous transformation can be envisaged in medical care, especially the manufacturing procedures leading to personalized medicine. Stereolithography (SLA), a vat-photopolymerization technique, that uses a laser beam, is known for its ability to fabricate complex 3D structures ranging from micron-size needles to life-size organs, because of its high resolution, precision, accuracy, and speed. This review presents a glimpse of varied 3D printing techniques, mainly expounding SLA in terms of the materials used, the orientation of printing, and the working mechanisms. The previous works that focused on developing pharmaceutical dosage forms, drug-eluting devices, and tissue scaffolds are presented in this paper, followed by the challenges associated with SLA from an industrial and regulatory perspective. Due to its excellent advantages, this technology could transform the conventional "one dose fits all" concept to bring digitalized patient-centric medication into reality.

Novel Approach to Pharmaceutical 3D-Printing Omitting the Need for Filament-Investigation of Materials, Process, and Product Characteristics

The utilized 3D printhead employs an innovative hot-melt extrusion (HME) design approach being fed by drug-loaded polymer granules and making filament strands obsolete. Oscillatory rheology is a key tool for understanding the behavior of a polymer melt in extrusion processes. In this study, small amplitude shear oscillatory (SAOS) rheology was applied to investigate formulations of model antihypertensive drug Metoprolol Succinate (MSN) in two carrier polymers for pharmaceutical three-dimensional printing (3DP). For a standardized printing process, the feeding polymers viscosity results were correlated to their printability and a better understanding of the 3DP extrudability of a pharmaceutical formulation was developed. It was found that the printing temperature is of fundamental importance, although it is limited by process parameters and the decomposition of the active pharmaceutical ingredients (API). Material characterization including differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA) of the formulations were performed to evaluate component miscibility and ensure thermal durability. To assure the development of a printing process eligible for approval, all print runs were investigated for uniformity of mass and uniformity of dosage in accordance with the European Pharmacopoeia (Ph. Eur.).

Orally Dispersible Dosage Forms for Paediatric Use: Current Knowledge and Development of Nanostructure-Based Formulations

The paediatric population has always suffered from a lack of medicines tailored to their needs, especially in terms of accurate dosage, stability and acceptability. Orodispersible dosage forms have gone through a resurrection as an alternative to liquid formulations or fractioned solid formulations, although they are still subject to several inconveniences, among which the unpleasant taste and the low oral bioavailability of the API are the most significant hurdles in the way of achieving an optimal drug product. Nanostructures can address these inconveniences through their size and variety, owing to the plethora of materials that can be used in their manufacturing. Through the formation and functionalisation of nanostructures, followed by their inclusion in orodispersible dosage forms, safe, stable and acceptable medicines intended for paediatric use can be developed.

Immediate release 3D printed oral dosage forms: How different polymers have been explored to reach suitable drug release behaviour

Three-dimensional (3D) printing has been gaining attention as a new technological approach to obtain immediate release (IR) dosage forms. The versatility conferred by 3D printing techniques arises from the suitability of using different polymeric materials in the production of solids with different porosities, geometries, sizes, and infill patterns. The appropriate choice of polymer can facilitate in reaching IR specifications and afford other specific properties to 3D printed solid dosage forms. This review aims to provide an overview of the polymers that have been employed in the development of IR 3D printed dosage forms, mainly considering their in vitro drug release behaviour. The physicochemical and mechanical properties of the IR 3D printed dosage forms will also be discussed, together with the manufacturing process strategies. Up to now, methacrylic polymers, cellulosic polymers, vinyl derivatives, glycols and different polymeric blends have been explored to produce IR 3D printed dosage forms. Their effects on drug release profiles are critically discussed here, giving a complete overview to drive formulators towards a rational choice of polymeric material and thus contributing to future studies in 3D printing of pharmaceuticals.

Quality control evaluation of paediatric chocolate-based dosage forms: 3D printing vs mold-casting method

Pharmaceutical compounding is a core activity in the preparation of patient-specific dosage forms. In the current study we aimed to investigate whether 3D printing could be employed for the preparation of pediatric-friendly personalized dosage forms that fulfil the acceptance criteria specified in the pharmacopoeias for conventional dosage forms. We then compared the 3D printed dosage forms with the same formulations prepared with mold-casting, a method frequently applied during pharmaceutical compounding. The molded dosage forms failed to pass most of the quality control tests, including the mass uniformity and content uniformity tests, as well as dose accuracy, contrary to the 3D printed, which not only passed all tests but also enabled precision overdose adjustment. Hence, 3D printing of chocolate-based dosage forms may effectively serve as an acceptable alternative method to mold casting in compounding patient-specific medication at the point-of-care.

Modified Release Kinetics in Dual Filament 3D Printed Individualized Oral Dosage Forms

On demand production of totally customizable combinative preparations is a central goal of a patient-centric pharmaceutical supply chain. Additive manufacturing techniques like fused deposition modeling (FDM) could be key technologies towards such individualized dosage forms. As so far only a limited number of studies on 3D printed combinative preparations applying FDM have been reported, a core-shell dosage form was the focus of the present study. Dosage forms with an initial and a sustained release part with theophylline as model API were successfully produced applying a dual nozzle FDM 3D printer. Investigations identified microstructural defects at the interface between the two formulations by means of µCT analysis. Dissolution testing proved the achievement of the intended release profile. In combination with additionally characterized release profile of single material prints of different shapes, the combinative release profiles could be predicted by developing model equations and taking into account the geometric composition. As these model approaches can accordingly facilitate the prediction of API release from 3D printed combinative preparations with only data from single material release. This is a first step towards a truly individualized and reliable patient-centric pharmaceutical supply via 3D printing.

Development of sustained-release drug-loaded intravesical inserts via semi-solid micro-extrusion 3D-printing for bladder targeting

Discontinued treatment and non-adherence are oftentimes weaknesses of common first-line drug therapy against bladder conditions due to their negative side-effects. To overcome these limitations and increase patients' quality of life, intravesical therapies are continuously being explored. 3D-printing offers the possibility of freely tailoring drug delivery systems to manufacture indwelling devices that may administer drugs locally over an extended time and avoiding frequently repeated administrations while minimizing systemic side-effects. In the present work, pressure-assisted micro syringe printing has been used to develop flexible drug-loaded inserts applicable via common urinary catheter that can remain up to several weeks inside the urinary bladder. Three APIs (lidocaine hydrochloride, trospium chloride (TrCl) and hydrochlorothiazide (HCT)) with different properties and solubilities were investigated for their applicability together with two different pharmaceutical polymers (biodegradable polycaprolactone (PCL) and non-degradable ethylene vinyl acetate copolymer (EVA)). The fastest release was thereby observed for the PCL-TrCl combination and the slowest for EVA-HCT depending on the API's solubility in the dissolution medium and formation of API clusters within the matrix. It was further demonstrated that the dissolution profile could be modified by adapting drug loads between 5 and 15 % or the geometry of the printed inserts indicating the possibility of tailoring release profiles.

Additive Manufacturing Strategies for Personalized Drug Delivery Systems and Medical Devices: Fused Filament Fabrication and Semi Solid Extrusion

Novel additive manufacturing (AM) techniques and particularly 3D printing (3DP) have achieved a decade of success in pharmaceutical and biomedical fields. Highly innovative personalized therapeutical solutions may be designed and manufactured through a layer-by-layer approach starting from a digital model realized according to the needs of a specific patient or a patient group. The combination of patient-tailored drug dose, dosage, or diagnostic form (shape and size) and drug release adjustment has the potential to ensure the optimal patient therapy. Among the different 3D printing techniques, extrusion-based technologies, such as fused filament fabrication (FFF) and semi solid extrusion (SSE), are the most investigated for their high versatility, precision, feasibility, and cheapness. This review provides an overview on different 3DP techniques to produce personalized drug delivery systems and medical devices, highlighting, for each method, the critical printing process parameters, the main starting materials, as well as advantages and limitations. Furthermore, the recent developments of fused filament fabrication and semi solid extrusion 3DP are discussed. In this regard, the current state of the art, based on a detailed literature survey of the different 3D products printed via extrusion-based techniques, envisioning future directions in the clinical applications and diffusion of such systems, is summarized.

3D Printed Mini-Floating-Polypill for Parkinson's Disease: Combination of Levodopa, Benserazide, and Pramipexole in Various Dosing for Personalized Therapy

Therapy for Parkinson’s disease is quite challenging. Numerous drugs are available for symptomatic treatment, and levodopa (LD), in combination with a dopa decarboxylase inhibitor (e.g., benserazide (BZ)), has been the drug of choice for years. As the disease progresses, therapy must be supplemented with a dopamine agonist (e.g., pramipexole (PDM)). Side effects increase, as do the required dose and dosing intervals. For these specific requirements of drug therapy, the 3D printing method fused deposition modelling (FDM) was applied in this study for personalized therapy. Hot melt extrusion was utilized to produce two different compositions into filaments: PDM and polyvinyl alcohol for rapid drug release and a fixed combination of LD/BZ (4:1) in an ethylene-vinyl acetate copolymer matrix for prolonged drug release. Since LD is absorbed in the upper gastrointestinal tract, a formulation that floats in gastric fluid was desired to prolong API absorption. Using the FDM 3D printing process, different polypill geometries were printed from both filaments, with variable dosages. Dosage forms with 15−180 mg LD could be printed, showing similar release rates (f2 > 50). In addition, a mini drug delivery dosage form was printed that released 75% LD/BZ within 750 min and could be used as a gastric retentive drug delivery system due to the floating properties of the composition. The floating mini-polypill was designed to accommodate patients’ swallowing difficulties and to allow for individualized dosing with an API release over a longer period of time.

Development and evaluation of a 3D printing protocol to produce zolpidem-containing printlets, as compounding preparation, by the pressurized-assisted microsyringes technique

Insomnia is a chronic disorder with a mean prevalence ranged from 6% to 15% worldwide. The usual pharmacologic treatment for insomnia has been benzodiazepines and barbiturates. More recently, z-drugs were introduced in the therapeutic arsenal to maximize benefits and minimize treatment damage. Zolpidem tartrate, whose primary indication is for sleep initiation problems, is conventionally used at a recommended dose of 5 mg for women as well as elderly patients (<65 years-old) and 10 mg for non-elderly men. However, it was demonstrated that the dose of zolpidem should be adjusted according to the gender, age, condition of the patient and the presence of polypharmacy to decrease the occurrence of adverse events. Faced with the therapeutic limitations inherent to marketed products, magistral preparations offer medical and legal alternatives to mass treatment. The use of a semi-automatic technique, with standardized protocol, such as 3D printing should be advantageously implemented as an alternative to standard compounding procedures. In this work, the pressure-assisted microsyringes method was selected as it allows the tridimensional printing, and so the customization of the dose, by easily extruding a viscous semi-liquid material, called "slurry", through a syringe at room temperature. It has been demonstrated that this methodology allows obtaining printlets that responded to the zolpidem-containing tablets monograph of the US pharmacopoeia Edition 42. The compounding preparations proposed in this work therefore have the same criteria of requirements as a commercial form.

‘Tablet-in-Syringe’: A Novel Dosing Mechanism for Dysphagic Patients Containing Fast-Disintegrating Tablets Fabricated Using Semisolid Extrusion 3D Printing

With the ability to fabricate personalized dosage forms and considerably shorter manufacturing time, semisolid extrusion (SSE) 3D printing has rapidly grown in popularity in recent years as a novel, versatile manufacturing method that powers a wide range of applications in the pharmaceutical field. In this work, the feasibility of using SSE 3D printing to fabricate fast-disintegrating tablets (FDTs) that are pre-filled in dosing syringes was evaluated. The novel design approach, ‘tablet-in-syringe’, was aimed to ease the oral drug administration and improve the dosing accuracy for dysphagic patients. The effect of varying polymer (hydroxypropyl methylcellulose E15) concentrations and printing parameters (e.g., extrusion rate) on dimensional accuracy, physicochemical properties, disintegration time, and content uniformity of 3D-printed FDTs was studied. An overall comparison of results demonstrated that the best FDT formulation among those developed was with a polymer:drug ratio (w/w) of 1:30, printed at extrusion rate of 3.5 μL/s. The diameter of printed filaments of this formulation was observed to be similar to the nozzle diameter (22G), proving that good printing accuracy was achieved. This FDTs also had the fastest disintegration time (0.81 ± 0.14 min) and a drug (phenytoin sodium, as the model drug) content uniformity that met pharmacopeial specifications. Although the flow characteristics of the dissolved formulation still need improvement, our findings suggested that the novel ‘tablet-in-syringe’ could potentially be considered as a promising fast-disintegrating drug delivery system that can be personalized and manufactured at—or close to—the point of care for dysphagic patients using SSE.

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.

Dose-independent drug release from 3D printed oral medicines for patient-specific dosing to improve therapy safety

Fused deposition modelling (FDM) 3D printing provides the ability to address individual patients' therapeutic needs without having to change the formulation every time. This is particularly interesting for dosing and release modelling. In this study, a geometry model was developed that can represent variable dosages while keeping the surface area to volume (SA/V) ratio alike, so the drug release profiles remain similar. The model was tested on three different formulations. Two BCS I active pharmaceutical ingredients (API), pramipexole and levodopa, and one BCS II API, praziquantel, were used. Polyvinyl alcohol (PVA, water soluble) and a combination of vinylpyrrolidone-vinyl acetate copolymer (PVP-VA, water soluble) and ethylene-vinyl acetate (EVA, water insoluble) were used as the polymer matrix. The curves were compared using the similarity factor (f₂ value) and mean dissolution time (MDT). Using a hollow cylinder-based (HCb) geometry model, a dose-independent drug release could be realized. For the PVA formulations, an 8-fold dose change could be obtained and for the EVA-PVP-VA formulation a factor of 5.5 could be achieved, with f₂ > 50. Due to the layer structure of the printed objects, very fine dose variation of 0.13 mg per layer is possible within these models. This allows variable dosing in small steps with only one basis formulation.

Manipulations and age-appropriateness of oral medications in pediatric oncology patients in Sweden: Need for personalized dosage forms

Due to the lack of age-appropriate formulations for children, healthcare professionals and caregivers frequently manipulate dosage forms to facilitate oral administration and obtain the required dose. In this study, we investigated drug manipulation and age-appropriateness of oral medications for pediatric oncology patients with the aim of identifying the therapeutic needs for personalized dosage forms. An observational study at a pediatric oncology ward, combined with analysis of the age-appropriateness of the oral medications, was performed. Nurses frequently manipulated solid dosage forms to administer them via enteral feeding tubes. Of the active pharmaceutical ingredients (APIs) assessed for age-appropriateness, 74% (29 of 39) were identified to need personalization, either because of lack of child-friendly dosage form, suitable dosage strength, or both. Most APIs, due to limited solubility, were sensitive to formulation changes, such as drug manipulation. This study demonstrates problems and therapeutic needs regarding oral dosage forms in treatment of children with cancer. Expertise in formulation design, new manufacturing technologies, and patient-centered information are needed to address age-appropriate formulations for children.

Mini-Tablets: A Valid Strategy to Combine Efficacy and Safety in Pediatrics

In the treatment of pediatric diseases, mass-produced dosage forms are often not suitable for children. Commercially available medicines are commonly manipulated and mixed with food by caregivers at home, or extemporaneous medications are routinely compounded in the hospital pharmacies to treat hospitalized children. Despite considerable efforts by regulatory agencies, the pediatric population is still exposed to questionable and potentially harmful practices. When designing medicines for children, the ability to fine-tune the dosage while ensuring the safety of the ingredients is of paramount importance. For these purposes solid formulations may represent a valid alternative to liquid formulations for their simpler formula and more stability, and, to overcome the problem of swelling ability, mini-tablets could be a practicable option. This review deals with the different approaches that may be applied to develop mini-tablets intended for pediatrics with a focus on the safety of excipients. Alongside the conventional method of compression, 3D printing appeared particularly appealing, as it allows to reduce the number of ingredients and to avoid both the mixing of powders and intermediate steps such as granulation. Therefore, this technique could be well adaptable to the daily galenic preparations of a hospital pharmacy, thus leading to a reduction of the common practice of off-label preparations.

Fabricating scalable, personalized wound dressings with customizable drug loadings via 3D printing

In recent times, 3D printing has been gaining traction as a fabrication platform for customizable drug dosages as a form of personalized medicine. While this has been recently demonstrated as oral dosages, there is potential to provide the same customizability and personalization as topical applications for wound healing. In this paper, the application of 3D printing to fabricate hydrogel wound dressings with customizable architectures and drug dosages was investigated. Chitosan methacrylate was synthesized and mixed with Lidocaine Hydrochloride and Levofloxacin respectively along with a photoinitiator before being used to print wound dressings of various designs. These designs were then investigated for their effect on drug release rates and profiles. Our results show the ability of 3D printing to customize drug dosages and drug release rates through co-loading different drugs at various positions and varying the thickness of drug-free layers over drug-loaded layers in the wound dressing respectively. Two scale-up approaches were also investigated for their effects on drug release rates from the wound dressing. The influence that each wound dressing design has on the release profile of drugs was also shown by fitting them with drug release kinetic models. This study thus shows the feasibility of utilizing 3D printing to fabricate wound dressings with customizable shapes, drug dosage and drug release rates that can be tuned according to the patient's requirements.

Connected healthcare: Improving patient care using digital health technologies

Now more than ever, traditional healthcare models are being overhauled with digital technologies of Healthcare 4.0 increasingly adopted. Worldwide, digital devices are improving every stage of the patient care pathway. For one, sensors are being used to monitor patient metrics 24/7, permitting swift diagnosis and interventions. At the treatment stage, 3D printers are under investigation for the concept of personalised medicine by allowing patients access to on-demand, customisable therapeutics. Robots are also being explored for treatment, by empowering precision surgery, rehabilitation, or targeted drug delivery. Within medical logistics, drones are being leveraged to deliver critical treatments to remote areas, collect samples, and even provide emergency aid. To enable seamless integration within healthcare, the Internet of Things technology is being exploited to form closed-loop systems that remotely communicate with one another. This review outlines the most promising healthcare technologies and devices, their strengths, drawbacks, and opportunities for clinical adoption.

Polymers in pharmaceutical additive manufacturing: A balancing act between printability and product performance

Materials and manufacturing processes share a common purpose of enabling the pharmaceutical product to perform as intended. This review on the role of polymeric materials in additive manufacturing of oral dosage forms, focuses on the interface between the polymer and key stages of the additive manufacturing process, which determine printability. By systematically clarifying and comparing polymer functional roles and properties for a variety of AM technologies, together with current and emerging techniques to characterize these properties, suggestions are provided to stimulate the use of readily available and sometimes underutilized pharmaceutical polymers in additive manufacturing. We point to emerging characterization techniques and digital tools, which can be harnessed to manage existing trade-offs between the role of polymers in printer compatibility versus product performance. In a rapidly evolving technological space, this serves to trigger the continued development of 3D printers to suit a broader variety of polymers for widespread applications of pharmaceutical additive manufacturing.

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.

Mucosal drug delivery and 3D printing technologies: A focus on special patient populations

In the last decade, additive manufacturing (AM) technologies have revolutionized how healthcare provision is envisioned. The rapid evolution of these technologies has already created a momentum in the effort to address unmet personalized needs in large patient groups, especially those belonging to sensitive subgroup populations (e.g., paediatric, geriatric, visually impaired). At the same time, AM technologies have become a salient ally to overcome defined health challenges in drug formulation development by addressing not only the requirement of personalized therapy, but also problems related to lowering non-specific drug distribution and the risk of adverse reactions, enhancing drug absorption and bioavailability, as well as ease of administration and patient compliance. To this end, mucoadhesive drug delivery systems fabricated with the support of AM technologies provide competitive advantages over conventional dosage forms, aiming to entice innovation in drug formulation with special focus on sensitive patient populations.

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

OBJECTIVES

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

METHODS

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

KEY FINDINGS

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

CONCLUSIONS

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

Exploration and Preparation of Patient-specific Ciprofloxacin Implants Drug Delivery System Via 3D Printing Technologies

A suitable drug-loaded implant delivery system that can effectively release antibacterial drug in the postoperative lesion area and help repair bone infection is very significant in the clinical treatment of bone defect. The work was aimed to investigate the feasibility of applying three-dimensional (3D) printing technology to prepare drug-loaded implants for bone repair. Semi-solid extrusion (SSE) and Fuse deposition modeling® (FDM) technologies were implemented and ciprofloxacin (CIP) was chosen as the model drug. All of the implants exhibited a smooth surface, good mechanical properties and satisfactory structural integrity as well as accurate dimensional size. In vitro drug release showed that the implants made by 3D printing technologies slowed down the initial drug burst effect and expressed a long-term sustained release behavior, compared with the implants prepared with traditional method. In addition, the patient-specific macrostructure implants, consisting of interconnected and different shapes pores, were created using unique lay down patterns. As a result, the weakest burst release effect and the sustained drug release were achieved in the patient-specific implants with linear pattern. These results clearly stated that 3D printing technology offers a viable approach to prepare control-releasing implants with patient-specific macro-porosity and presents novel strategies for treating bone infections.

Opportunities and challenges of three-dimensional printing technology in pharmaceutical formulation development

Three-dimensional printing is a technology that prints the products layer-by-layer, in which materials are deposited according to the digital model designed by computer aided design (CAD) software. This technology has competitive advantages regarding product design complexity, product personalization, and on-demand manufacturing. The emergence of 3D technology provides innovative strategies and new ways to develop novel drug delivery systems. This review summarizes the application of 3D printing technologies in the pharmaceutical field, with an emphasis on the advantages of 3D printing technologies for achieving rapid drug delivery, personalized drug delivery, compound drug delivery and customized drug delivery. In addition, this article illustrates the limitations and challenges of 3D printing technologies in the field of pharmaceutical formulation development.

Disrupting 3D printing of medicines with machine learning

3D printing (3DP) is a progressive technology capable of transforming pharmaceutical development. However, despite its promising advantages, its transition into clinical settings remains slow. To make the vital leap to mainstream clinical practice and improve patient care, 3DP must harness modern technologies. Machine learning (ML), an influential branch of artificial intelligence, may be a key partner for 3DP. Together, 3DP and ML can utilise intelligence based on human learning to accelerate drug product development, ensure stringent quality control (QC), and inspire innovative dosage-form design. With ML's capabilities, streamlined 3DP drug delivery could mark the next era of personalised medicine. This review details how ML can be applied to elevate the 3DP of pharmaceuticals and importantly, how it can expedite 3DP's integration into mainstream healthcare.

A micro-extrusion 3D printing platform for fabrication of orodispersible printlets for pediatric use

3D printed pharmaceuticals offers the potential to manufacture personalized medicines for patients. Such technology is of particular benefit to pediatric populations from the offer of increased patient compliance and dose flexibility. With a bench-to-patient approach, this study established and optimized the critical parameters of the semi-solid micro-extrusion 3D printing process to guarantee the quality attributes of the final dosage form. Pediatrics orodispersible printlets of hydrochlorothiazide were manufactured through the modification of printing parameters, as well as printing surfaces materials. The printlets were characterized and the dimensions were measured using a digital caliper and computer vision algorithm. This study identified that the printing surface material and the first printing layer are critical parameters for high-resolution printlets. Following the optimization of 3D printing parameters, high quality orodispersible printlets loaded with hydrochlorothiazide - specifically tailored for pediatric patient's dosage forms - were obtained (4.62 mm × 1.90 mm). Mass and content uniformity assays demonstrated that the printlets satisfied the requirements for orodispersible printlets set by the European Pharmacopoeia. As such, in order to transition from laboratory research towards the treatment of patients, distinguishing accurate 3D printing parameters is necessary for the manufacture of medicines with key quality attributes that follow Pharmacopoeia requirements.

Polymeric drug delivery systems by additive manufacturing

Additive manufacturing (AM) is gaining interests in drug delivery applications, offering innovative opportunities for the design and development of systems with complex geometry and programmed controlled release profile. In addition, polymer-based drug delivery systems can improve drug safety, efficacy, patient compliance, and are the key materials in AM. Therefore, combining AM and polymers can be beneficial to overcome the existing limitations in the development of controlled release drug delivery systems. Considering these advantages, here we are focusing on the recent developments in the field of polymeric drug delivery systems prepared by AM. This review provides a comprehensive overview on a holistic polymer-AM perspective for drug delivery systems with discussion on the materials, properties, design and fabrication techniques and the mechanisms used to achieve a controlled release system. The current challenges and future perspectives for personalized medicine and clinical use of these systems are also briefly discussed.

3D printed furosemide and sildenafil tablets: Innovative production and quality control

Three-dimensional (3D) printing of pharmaceuticals has the potential to revolutionise personalised medicine but is as yet largely unexplored. A proof-of-concept study of a novel heated, piston-driven semi-solid extrusion 3D printer was performed by producing furosemide and sildenafil tablets for paediatric patients. The average weight of the tablets was 141.1 mg (RSD 1.26%). The acceptance values of the content uniformity were 4.2-10.6 (concentration RSD 0.41-0.63%), 4.8-8.9 (concentration RSD 0.76-0.97%) and 6.6-9.2 (concentration RSD 0.94-1.44%) for furosemide 2 mg, 10 mg and sildenafil 4 mg, respectively. The dissolution rate limiting step was the dissolving and eroding of the tablet matrix and showed an immediate release. The tablets complied to the requirements of the European Pharmacopoeia (EP) for uniformity of mass (EP 2.9.5), content uniformity (EP 2.9.40) and conventional release (EP 2.9.3). While they complied, not all of these quality tests for tablets might be suitable for 3D printed tablets due to the layering of the tablets and the small batch production. To assess adequate layer adhesion adjusted friability (EP 2.9.7) and resistance to crushing (EP 2.9.8) tests are proposed.

Versatility on demand - The case for semi-solid micro-extrusion in pharmaceutics

Since additive manufacturing of pharmaceuticals has been introduced as viable method to produce individualized drug delivery systems with complex geometries and release profiles, semi-solid micro-extrusion has shown to be uniquely beneficial. Easy incorporation of actives, room-temperature processability and avoidance of cross-contamination by using disposables are some of the advantages that led many researchers to focus their work on this technology in the last few years. First acceptability and in-vivo studies have brought it closer towards implementation in decentralized settings. This review covers recently established process models in light of viscosity and printability discussions to help develop high quality printed medicines. Quality defining formulation and process parameters to characterize the various developed dosage forms are presented before critically discussing the role of semi-solid micro-extrusion in the future of personalized drug delivery systems. Remaining challenges regarding regulatory guidance and quality assurance that pose the last hurdle for large scale and commercial manufacturing are addressed.