Development of a gastroretentive delivery system for acyclovir by 3D printing technology and its in vivo pharmacokinetic evaluation in Beagle dogs

3D printing of partially-coated floating systems for controlled release of drugs into the stomach

This work focused on the development of a retentive drug delivery system (DDS) able to float in the gastric fluids and to ensure prolonged release of drugs over a pre-defined period of time, being then safely emptied from the stomach. To this end, the design step played a pivotal role. The device was thus devised to be composed of a polyvinyl alcohol-based matrix with a tapered geometry, which was partially coated with an insoluble layer of thermoplastic elastomer. This way, release of allopurinol (ALP), used as model drug, could occur only from the uncoated surfaces, while the peculiar geometry of the hydrophilic swellable/erodible matrix was intended to balance the increase in the diffusional path over time with a wider release area. In addition, the coating featured air pockets, whose volume was sized to compensate for the weight force of the DDS once immersed in gastric fluids, thus ensuring its long-lasting buoyancy. By easing the entrance of gastric fluids when the matrix is completely exhausted, such air pockets would also favor sinking and removal of the DDS from the pylorus. Given the multi-layered geometry of the final floating device, including hard-to-fabricate details (e.g. uncoated surfaces, voids), fused deposition modeling 3D printing was identified as the technique of choice for its effectiveness in manufacturing complex shapes. Various formulations were tested for fabricating both the inner matrix and the outer coating, assessing their thermo-mechanical properties, printability and release behavior. The gastro-retentive system demonstrated prolonged buoyancy (> 12 h) and a wide portfolio of ALP release performances, differing in rate and duration, which would make it a promising platform for personalized delivery of drugs in the upper gastrointestinal tract.

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.

Current trends in 3D printed gastroretentive floating drug delivery systems: A comprehensive review

Gastrointestinal (GI) environment is influenced by several factors (gender, genetics, sex, disease state, food) leading to oral drug absorption variability or to low bioavailability. In this scenario, gastroretentive drug delivery systems (GRDDS) have been developed in order to solve absorption problems, to lead to a more effective local therapy or to allow sustained drug release during a longer time period than the typical oral sustained release dosage forms. Among all GRDDS, floating systems seem to provide a promising and practical approach for achieving a long intra-gastric residence time and sustained release profile. In the last years, a novel technique is being used to manufacture this kind of systems: three-dimensional (3D) printing technology. This technique provides a versatile and easy process to manufacture personalized drug delivery systems. This work presents a systematic review of the main 3D printing based designs proposed up to date to manufacture floating systems. We have also summarized the most important parameters involved in buoyancy and sustained release of the systems, in order to facilitate the scale up of this technology to industrial level. Finally, a section discussing about the influence of materials in drug release, their biocompatibility and safety considerations have been included.

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

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

Design and fabrication of 3D-printed gastric floating tablets of captopril: effect of geometry and thermal crosslinking of polymer on floating behavior and drug release

The present study aims to investigate the potential of the 3D printing technique to design gastroretentive floating tablets (GFTs) for modifying the drug release profile of an immediate-release tablet. A 3D-printed floating shell enclosing a captopril tablet was designed having varying number of drug-release windows. The impact of geometrical changes in the design of delivery system and thermal cross-linking of polymers were evaluated to observe the influence on floating ability and drug release. Water uptake, water insolubilization, Differential Scanning Calorimetry (DSC), and Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR) were performed to assess the degree of thermal cross-linking of polyvinyl alcohol (PVA) filament. The 3D-printed GFT9 was considered the optimized gastric floating tablet that exhibited >12 h of total floating time with zero floating lag time and successfully accomplished modified-drug release by exhibiting >80% of drug release in 8 h. The zero-order release model, with an r2 value of 0.9923, best fitted the drug release kinetic data of the GFT9, which followed a super case II drug transport mechanism with an n value of 0.95. The optimized gastric floating device (GFT9) also exhibited the highest MDT values (238.55), representing slow drug release from the system due to thermal crosslinking and the presence of a single drug-releasing window in the device.

3D-printed dosage forms for oral administration: a review

Oral administration is the most commonly used form of treatment due to its advantages, including high patient compliance, convenient administration, and minimal preparation required. However, the traditional preparation process of oral solid preparation has many defects. Although continuous manufacturing line that combined all the unit operations has been developed and preliminarily applied in the pharmaceutical industry, most of the currently used manufacturing processes are still complicated and discontinuous. As a result, these complex production steps will lead to low production efficiency and high quality control risk of the final product. Additionally, the large-scale production mode is inappropriate for the personalized medicines, which commonly is customized with small amount. Several attractive techniques, such as hot-melt extrusion, fluidized bed pelletizing and spray drying, could effectively shorten the process flow, but still, they have inherent limitations that are challenging to address. As a novel manufacturing technique, 3D printing could greatly reduce or eliminate these disadvantages mentioned above, and could realize a desirable continuous production for small-scale personalized manufacturing. In recent years, due to the participation of 3D printing, the development of printed drugs has progressed by leaps and bounds, especially in the design of oral drug dosage forms. This review attempts to summarize the new development of 3D printing technology in oral preparation and also discusses their advantages and disadvantages as well as potential applications.

Enhanced gastric residence time of acyclovir by floating raft formulation using box-behnken design

This research paper reports enhancing Acyclovir's gastric residence time by implementing a raft-forming drug delivery system. Because acyclovir is a narrow absorption window drug, it has a poor bioavailability of 10-20 % and a short half-life (t1/2) of 2.5 h. The guar gum and GMS-based floating raft formulation retain the drug in the stomach for an extended period by enhancing GRT. The Box-Behnken design is used to optimize the amount of guar gum, glyceryl monostearate, and calcium carbonate and to study how they affect the in vitro gelation time, viscosity, and in vitro drug release. The ratio of drug and excipients in guar gum (1:0.5), GMS (1:1.25) based FRF suspension containing sodium citrate (0.25 %), carbopol (0.1 %), and calcium carbonate (1:1.5). Seventeen runs were developed through the Box-Behnken design to study all the optimal interactions between variables and responses through a polynomial equation. The optimized formulation is then characterized using various physicochemical tests such as rheological analysis, in vitro drug release, kinetic drug release, and in vitro permeation studies. The in vitro gelation time, viscosity, and in vitro drug release time of optimized FRF are 12 s, 1090 cps, and 88 % at 24 h, respectively. The flux and permeability coefficient of the optimized batch have a higher value indicating higher permeability of acyclovir. The FRF follows non-fickian diffusion as a drug release mechanism. The results show that the raft-forming drug delivery system significantly enhances the absorption of Acyclovir by prolonging drug release and also improving its gastric residence time in the stomach. This research contributes to the field of drug delivery systems by providing a novel approach for improving the therapeutic efficacy of acyclovir and potentially other drugs with similar characteristics.

3D printing combined with biopredictive dissolution and PBPK/PD modeling optimization and personalization of pharmacotherapy: Are we there yet?

Precision medicine requires selecting the appropriate dosage regimen for a patient using the right drug, at the right time. Model-Informed Precision Dosing (MIPD) is a concept suggesting utilization of model-based prediction methods for optimizing the treatment benefit-harm balance, based on individual characteristics of the patient, disease, treatment method, and other factors. Here, we discuss a theoretical workflow comprising several elements, beginning from the physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD) models, through 3D printed tablets with the model proposed dose, information range and flow, and the patient themselves. We also describe each of these elements, and the connection between them, highlighting challenges and potential obstacles.

Fused Deposition Modelling 3D-Printed Gastro-Retentive Floating Device for Propranolol Hcl Tablets

Three-dimensional printing has revolutionized drug manufacturing and has provided a solution to the limitations associated with the conventional manufacturing method by designing complex drug delivery systems with customized drug release profiles for personalized therapies. The present investigation aims to design a gastric floating tablet with prolonged gastric floating time and sustained drug release profile. In the present study, a gastro retentive floating device (GRFD) was designed and fabricated using a fused deposition modelling (FDM)-based 3D printing technique. This device acts as a multifunctional dosage form exhibiting prolonged gastric retention time and sustained drug release profile with improved oral bioavailability in the upper gastrointestinal tract. Commercial polyvinyl alcohol (PVA) and polylactic acid (PLA) filaments were used to design GRFD, which was comprised of dual compartments. The outer sealed compartment acts as an air-filled chamber that imparts buoyancy to the device and the inner compartment is filled with a commercial propranolol hydrochloride immediate-release tablet. The device is designed as a round-shaped shell with a central opening of varying size (1 mm, 2 mm, 3 mm, and 4 mm), which acts as a drug release window. Scanning electron microscope (SEM) images were used to determine morphological characterization. The in vitro buoyancy and drug release were evaluated using the USP type II dissolution apparatus. All the designed GRFDs exhibit good floating ability and sustained drug release profiles. GRFDs fabricated using PLA filament show maximum buoyancy (>24 h) and sustained drug release for up to 10 h. The floating ability and drug release from the developed devices were governed by the drug release window opening size and the filament material affinity towards the gastric fluid. The designed GRFDs show great prospects in modifying the drug release characteristics and could be applied to any conventional immediate-release product.

Design, preparation, and in vitro evaluation of gastroretentive floating matrix tablet of mitiglinide

The present research is focused on developing floating matrix tablets of mitiglinide to prolong its gastric residence time for better absorption. Gastroretentive tablets were prepared using a direct compression technique with hydroxypropyl methylcellulose K15M (HPMC K15M) and sodium alginate as matrix-forming polymers and sodium bicarbonate as the gas-forming agent. A 32 full factorial design was adopted to optimize the flotation and release profile of the drug. The concentration of HPMC K15M and sodium alginate were taken as the independent variables, and the floating lag time, time required for 50% drug release, and time required for 90% drug release were taken as dependent variables. The compatibility between drug and excipients was assessed by Fourier transform infrared (FTIR) spectroscopy. The prepared tablets were evaluated for different parameters such as hardness, friability, drug content, floating time, in vitro dissolution, and stability. Dissolution data were analyzed using various kinetic models to ascertain the mechanism of drug release. Finally, a radiographic study was conducted to estimate the retention time of the optimized floating matrix tablets of mitiglinide inside the body. The results revealed that all the physical properties of the developed formulations were within standard limits. The formulation M3, with the maximum amount of both independent variables, was considered to be the optimized formulation based on the desirability value. In addition, the optimized M3 formulation showed stability for over 6 months, as evidenced by insignificant changes in lag time, drug release pattern, and other physical properties. Furthermore, radiographic examination indicated that the tablets remained afloat in gastric fluid for up to 12 h in the rabbit’s stomach. In conclusion, the developed floating matrix tablet of mitiglinide could be regarded as a promising formulation that could release the drug in the stomach at a controlled rate and, hence, offer better management of type II diabetes.

Hydrophilic High Drug-Loaded 3D Printed Gastroretentive System with Robust Release Kinetics

Three-dimensional printing (3DP) technology enables an important improvement in the design of new drug delivery systems, such as gastroretentive floating tablets. These systems show a better temporal and spatial control of the drug release and can be customized based on individual therapeutic needs. The aim of this work was to prepare 3DP gastroretentive floating tablets designed to provide a controlled release of the API. Metformin was used as a non-molten model drug and hydroxypropylmethyl cellulose with null or negligible toxicity was the main carrier. High drug loads were assayed. Another objective was to maintain the release kinetics as robust as possible when varying drug doses from one patient to another. Floating tablets using 10–50% w/w drug-loaded filaments were obtained by Fused Deposition Modelling (FDM) 3DP. The sealing layers of our design allowed successful buoyancy of the systems and sustained drug release for more than 8 h. Moreover, the effect of different variables on the drug release behaviour was studied. It should be highlighted that the robustness of the release kinetics was affected by varying the internal mesh size, and therefore the drug load. This could represent a step forward in the personalization of the treatments, a key advantage of 3DP technology in the pharmaceutical field.

Fabrication of Gastro-Floating Famotidine Tablets: Hydroxypropyl Methylcellulose-Based Semisolid Extrusion 3D Printing

Semisolid extrusion (SSE) three-dimensional (3D) printing uses drug-loaded paste for the printing process, which is capable of constructing intricate 3D structures. This research presents a unique method for fabricating gastro-floating tablets (GFT) using SSE. Paste-loaded famotidine with a matrix made of hydroxypropyl methylcellulose (HPMC) were prepared. Nine 3D printed tablets were developed with different HPMC concentrations and infill percentages and evaluated to determine their physicochemical properties, content uniformity, dissolution, and floating duration. The crystallinity of the drug remained unchanged throughout the process. Dissolution profiles demonstrated the correlation between the HPMC concentration/infill percentage and drug release behavior over 10 h. All the fabricated GFTs could float for 10 h and the Korsmeyer-Peppas model described the dissolution kinetics as combination of non-Fickian or anomalous transport mechanisms. The results of this study provided insight into the predictability of SSE 3D printability, which uses hydro-alcoholic gel-API blend materials for GFTs by controlling traditional pharmaceutical excipients and infill percentages. SSE 3D printing could be an effective blueprint for producing controlled-release GFTs, with the additional benefits of simplicity and versatility over conventional methods.

Efficacy of a multidose acyclovir protocol against cyprinid herpesvirus 3 infection in koi (Cyprinus carpio)

OBJECTIVE

To evaluate the effect of a multidose acyclovir protocol on koi herpesvirus (KHV) viral load and mortality in a cohabitation challenge.

ANIMALS

180 koi fish.

PROCEDURES

Forty fish (shedders) were immersed in a 0.5 KHV plaque-forming units/mL static bath for 8 hours. Mock shedders were treated similarly but exposed to cell culture media. KHV shedders were then transferred into 8 tanks (5 shedders per tank) containing 10 naïve fish (cohabitants) each. Fish in the acyclovir group (AT) received a 10 mg/kg acyclovir intracoelomic injection 1, 3, and 6 days after the first confirmed KHV mortality. Positive controls (PC) were treated similarly but received sterile saline injections. Negative controls (NC) were exposed to mock shedders. Morbidity and mortality were evaluated daily for 50 days post-challenge. Quantitative PCR was used to determine viral load in the gill biopsies of shedders and cohabitants collected at days 19 (T1), 22 (T2), 25 (T3), 34 (T4), and 50 (T5) post-challenge.

RESULTS

Survival curves analyzed by the Gehan-Breslow-Wilcoxon method revealed a delayed onset of mortalities and a significantly lower KHV load at T2 and T3 detected in AT cohabitant fish (P = .042) compared to PC group. However, there were no significant differences in overall mortality or viral loads at T5.

CLINICAL RELEVANCE

The acyclovir protocol used in this study did not control viral infection or mortality at the end of the 50-day trial. Shorter intervals between injections could improve outcomes, but the additional stress inflicted by handling should be considered. Exploring other therapeutic alternatives and doses is warranted.

Effect of Hydrophilic Polymers on the Release Rate and Pharmacokinetics of Acyclovir Tablets Obtained by Wet Granulation: In Vitro and In Vivo Assays

This study aims to evaluate the feasibility of producing acyclovir-containing modified release matrix tablets by a wet granulation method based on the type and concentration of two pharmaceutical-grade hydrophilic matrix polymers (i.e., hydroxypropyl methylcellulose (HPMC), carbomers, and their combinations) commonly used in biomedical applications. The mechanical properties of the tablets and in vitro and in vivo performance were studied. The physicochemical properties of the raw materials and corresponding physical mixtures were characterized by differential scanning calorimetry, showing that the hydrophilic polymers did not influence the physicochemical properties of the drug. The wet granulation process improved the flow and compression properties of the obtained granules. This method enabled the preparation of the matrix tablets of acyclovir with appropriate mechanical properties concerning hardness and friability. The drug release kinetics was governed by the type and concentration of the hydrophilic polymers composing the matrices. The study has proven that HPMC-composed tablets were superior in modified drug release properties compared to carbomer- and HPMC/carbomer-based tablets. Mathematical analysis of the release profiles, determined in a medium adjusted to pH 1.2 followed by pH 7.4, revealed that the drug released from the hydrophilic tablets followed non-Fickian first-order kinetics. An optimal HPMC-based formulation submitted to accelerated stability studies (40 °C, 75% RH) was stable for three months. A complete cross-over bioavailability study of the selected acyclovir-loaded sustained release tablets and marketed immediate-release tablets were compared in six healthy male volunteers. The extent of drug absorption from the sustained release tablets was significantly greater than that from immediate-release pills, which may improve the drug's antiviral properties attributed to the lower elimination rate and enhanced acyclovir half-life.

3D-printing of the polymer/insect-repellent system poly(l-lactic acid)/ethyl butylacetylaminopropionate (PLLA/IR3535)

The polymer/solvent system poly(l-lactic acid)/ethyl butylacetylaminopropionate (PLLA/IR3535) is regarded as an insect-repellent-delivery system, serving, e.g., for fighting mosquito-borne tropical diseases. In such systems the solid polymer hosts the liquid repellent, with the latter slowly released to the environment, expelling mosquitoes. As a new approach, exceeding prior work about application of different technologies to obtain such devices, in this work, samples of the polymer/repellent system PLLA/IR3535 were prepared by 3D-printing. The experiments showed that it is possible to print 3D-parts containing up to 25 m% repellent, with an only minor loss of repellent during the printing process. For samples containing low amount of repellent, crystallization of PLLA was suppressed due to the rather fast cooling step and the low bed temperature of around 25 °C, being lower than the glass transition temperature of the homogeneous polymer/repellent strands. At higher repellent concentration, due to the lowering of the glass transition temperature to near or even below ambient temperature, the crystallinity slowly increased during storage after printing. For all samples, regardless of the initial repellent concentration, the repellent-release rate increases with temperature, and at ambient temperature the release-time constant is in the order of 10 days. The study successfully proved the applicability of the technology of extrusion-based 3D-printing for the preparation of polymer parts with a specific shape/design containing mosquito-repellent at a concentration which raises the expectation to be used as a repellent delivery-device.

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

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

Feasibility of Enhancing Skin Permeability of Acyclovir through Sterile Topical Lyophilized Wafer on Self-Dissolving Microneedle-Treated Skin

Acyclovir is an antiviral drug that is frequently prescribed for the herpes virus. However, the drug requires frequent dosing due to limited bioavailability (10–26.7%). The rationale of the present study was to develop a self-dissolving microneedle system for local and systemic delivery of acyclovir using a topical lyophilized wafer on microneedle-treated skin to provide the drug at the site of infection. The microneedles prepared with hydroxypropyl methylcellulose (HPMC) (8% w/w) or HPMC (8% w/w)-polyvinyl pyrrolidone (PVP) (30% w/w) penetrated excised rat skin, showing sufficient mechanical strength and rapid polymer dissolution. The topical wafer was prepared with acyclovir (40% w/w; equivalent to 200 mg of drug), gelatin (10% w/w), mannitol (5% w/w), and sodium chloride (5% w/w). The uniform distribution of acyclovir within the wafer in an amorphous form was confirmed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). No polymer–drug interaction was evident in the lyophilized wafer as per Fourier transform infrared spectroscopy (FTIR) analysis. The wafer showed a sufficiently porous structure for rapid hydration as per scanning electron microscopy (SEM) analysis. During ex-vivo analysis, the skin was pre-treated with a self-dissolving microneedle array for 5 minutes, and the wafer was placed on this microporated-skin. Topical wafer provided ∼7–11 times higher skin concentration than the ID₉₉ reported with a lower lag-time. Based on in-vivo testing, ∼2.58 µg/ml of Cmax was achieved in rabbit plasma during 24 hours’ study. Our findings suggest that the self-dissolving microneedle-assisted topical wafer, proposed for the first time, would be efficacious against the infection residing in the skin layer and for systemic therapy.

Development of Composite, Reinforced, Highly Drug-Loaded Pharmaceutical Printlets Manufactured by Selective Laser Sintering-In Search of Relevant Excipients for Pharmaceutical 3D Printing

3D printing by selective laser sintering (SLS) of high-dose drug delivery systems using pure brittle crystalline active pharmaceutical ingredients (API) is possible but impractical. Currently used pharmaceutical grade excipients, including polymers, are primarily designed for powder compression, ensuring good mechanical properties. Using these excipients for SLS usually leads to poor mechanical properties of printed tablets (printlets). Composite printlets consisting of sintered carbon-stained polyamide (PA12) and metronidazole (Met) were manufactured by SLS to overcome the issue. The printlets were characterized using DSC and IR spectroscopy together with an assessment of mechanical properties. Functional properties of the printlets, i.e., drug release in USP3 and USP4 apparatus together with flotation assessment, were evaluated. The printlets contained 80 to 90% of Met (therapeutic dose ca. 600 mg), had hardness above 40 N (comparable with compressed tablets) and were of good quality with internal porous structure, which assured flotation. The thermal stability of the composite material and the identity of its constituents were confirmed. Elastic PA12 mesh maintained the shape and structure of the printlets during drug dissolution and flotation. Laser speed and the addition of an osmotic agent in low content influenced drug release virtually not changing composition of the printlet; time to release 80% of Met varied from 0.5 to 5 h. Composite printlets consisting of elastic insoluble PA12 mesh filled with high content of crystalline Met were manufactured by 3D SLS printing. Dissolution modification by the addition of an osmotic agent was demonstrated. The study shows the need to define the requirements for excipients dedicated to 3D printing and to search for appropriate materials for this purpose.

Metronidazole Based Floating Bioadhesive Drug Delivery System for Potential Eradication of H. pylori: Preparation and In Vitro Characterization

Metronidazole has the potential to produce local stomach specific action in order to treat Helicobacter pylori induced peptic ulcer disease. The current project executes the development of osmotically controlled bioadhesive metronidazole loaded effervescent floating tablets with optimized floating and swelling behavior. Direct compression technique was used to prepare the tablets. The designed formulations exhibited physico-chemical properties within acceptable optimum limits as per pharmacopeial requirements. The results of tablet floating studies revealed that all formulations, except F1 and F5, had good buoyancy characteristics (TFT > 12 h except F2 and F8 with TFT of 6 h). Formulation F2 containing guar gum in higher concentration with carbopol and formulation F8 containing guar gum in 50% decreased concentration in combination with HPMC and carbopol had enhanced FLT appreciably, with least TFT as compared to formulations F3, F4, and F6 (ANOVA; p ≤ 0.05). Formulation batches of F3, F4, and F6 exhibited appreciable FLT as well as TFT and were optimized formulations. Out of the above mentioned optimized batches, F4 and F6 formulations showed low FLT (4 and 5 s respectively). The results of the swelling study indicated a proportionate increase in the swelling index with increase in time. A significantly higher swelling ratio was found with formulation F6 and F4 compared with that of F7 and F8 (ANOVA; p ≤ 0.05). Additionally, the impact of pH change, agitational intensity, as well as increasing concentration of NaCl was investigated on drug release. It was observed that agitational intensity had no effect on drug release rate while increasing concentration of NaCl produced an increased drug release from the dosage form as compared to the drug release exhibited by the formulations in the absence of NaCl. Overall, this project could have valuable contribution in the fabrication of metronidazole loaded effervescent floating tablets. Gastro-retentive systems are expected to enhance local stomach specific action of anti H. pylori agents based on their buoyancy and swelling behavior.

FDM 3D-Printed Sustained-Release Gastric-Floating Verapamil Hydrochloride Formulations with Cylinder, Capsule and Hemisphere Shapes, and Low Infill Percentage

The aim of this work was to design and fabricate fused deposition modeling (FDM) 3D-printed sustained-release gastric-floating formulations with different shapes (cylinder, capsule and hemisphere) and infill percentages (0% and 15%), and to investigate the influence of shape and infill percentage on the properties of the printed formulations. Drug-loaded filaments containing HPMC, Soluplus^® and verapamil hydrochloride were prepared via hot-melt extrusion (HME) and then used to print the following gastric-floating formulations: cylinder-15, capsule-0, capsule-15, hemisphere-0 and hemisphere-15. The morphology of the filaments and the printed formulations were observed by scanning electron microscopy (SEM). The physical state of the drugs in the filaments and the printed formulations were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The printed formulations were evaluated in vitro, including the weight variation, hardness, floating time, drug content and drug release. The results showed that the drug-loaded filament prepared was successful in printing the gastric floating formulations. Verapamil hydrochloride was proved thermally stable during HME and FDM, and in an amorphous state in the filament and the printed formulations. The shape and infill percentage of the printed formulations effected the hardness, floating time and in vitro drug release.

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

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

Preparation of Acyclovir-Containing Solid Foam by Ultrasonic Batch Technology

In recent years, the application of solid foams has become widespread. Solid foams are not only used in the aerospace field but also in everyday life. Although foams are promising dosage forms in the pharmaceutical industry, their usage is not prevalent due to decreased stability of the solid foam structure. These special dosage forms can result in increased bioavailability of drugs. Low-density floating formulations can also increase the gastric residence time of drugs; therefore, drug release will be sustained. Our aim was to produce a stable floating formula by foaming. Matrix components, PEG 4000 and stearic acid type 50, were selected with the criteria of low gastric irritation, a melting range below 70 °C, and well-known use in oral drug formulations. This matrix was melted at 54 °C in order to produce a dispersion of active substance and was foamed by different gases at atmospheric pressure using an ultrasonic homogenizer. The density of the molded solid foam was studied by the pycnometer method, and its structure was investigated by SEM and micro-CT. The prolonged drug release and mucoadhesive properties were proved in a pH 1.2 buffer. According to our experiments, a stable foam could be produced by rapid homogenization (less than 1 min) without any surfactant material.

3D Printing of Thermo-Sensitive Drugs

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

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

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.

3D Printed Intragastric Floating and Sustained-Release Tablets with Air Chambers

This work aimed to use hot-melt extrusion (HME) and dual fused deposition modeling (FDM) 3D printing technology to develop a novel intragastric floating and sustained-release drug delivery system. The intragastric floating and sustained-release tablet was engineered by employing hydroxypropyl methylcellulose (Affinisol^TM HPMC HME 15LV) for a drug-loaded core and polylactic acid (PLA) for an insoluble shell with an air chamber. Filaments for the drug-loaded core were compounded using a single-screw hot melt extruder. 3DMAX software was utilized to design a core with a complementary shell which consisted of a hollow chamber at the top and a drug-release window with different sizes (radius in 1.5, 2.5, 3, 3.5, 4.5 mm) at the bottom. Pharmaceutical characterization, solid dispersion evaluation, and drug release behavior were studied. The model drug in all formulations kept stable, and part of the drug in the extruded filaments and 3D printed tablets became amorphous. The introduction of an air chamber reduced the tablet density to below 0.9 g/cm³ and the 3D printed tablets floated immediately and continuously during the drug release process. The presence of the insoluble shell greatly prolonged the drug release time, and the drug release rate was positively correlated with the area of the release window. In addition, compared with shellless tablets, the 3D printed tablets with air chambers (radius in 4.5 mm) showed closer zero-order drug release for 24 h and released drug by diffusion-erosion combined mechanism. The developed intragastric floating and sustained-release tablets with air chambers could be applied to various drugs and provided a new way for the development of personalized drug delivery systems.

Controlling drug release with additive manufacturing-based solutions

3D printing is an innovative manufacturing technology with great potential to revolutionise solid dosage forms. Novel features of 3D printing technology confer advantage over conventional solid dosage form manufacturing technologies, including rapid prototyping and an unparalleled capability to fabricate complex geometries with spatially separated conformations. Such a novel technology could transform the pharmaceutical industry, enabling the production of highly personalised dosage forms with well-defined release profiles. In this work, we review the current state of the art of using additive manufacturing for predicting and understanding drug release from 3D printed novel structures. Furthermore, we describe a wide spectrum of 3D printing technologies, materials, procedure, and processing parameters used to fabricate fundamentally different matrices with different drug releases. The different methods to manipulate drug release patterns including the surface area-to-mass ratio, infill pattern, geometry, and composition, are critically evaluated. Moreover, the drug release mechanisms and models that could aid exploiting the release profile are also covered. Finally, this review also covers the design opportunities alongside the technical and regulatory challenges that these rapidly evolving technologies present.

Design and Optimization of 3D-Printed Gastroretentive Floating Devices by Central Composite Design

This study aimed to optimize the size of capsule-shaped 3D-printed devices (CPD) using an experimental design by the response surface methodology to provide a gastroretentive drug delivery system (GRDDS) with optimal floating time. The CPD was fabricated using a fused deposition modeling (FDM) 3D printer. The central composite design was employed for the optimization of the devices. The morphology of the CPD was observed using a digital microscope and scanning electron microscope (SEM). The in vitro floating time and drug release were evaluated using a USP dissolution apparatus II. Appropriate total floating time (TFT) of the devices (more than 3 h) was obtained with the device's body, cap, and bottom thickness of 1.2, 1.8, and 2.9 mm, respectively. The release kinetics of the drug from the devices fitted well with zero-order kinetics. In conclusion, the optimization of CPD for GRDDS using the experimental design provided the devices with desirable floating time and ideal drug release characteristics.

Process Optimization for the Continuous Production of a Gastroretentive Dosage Form Based on Melt Foaming

Several drugs have poor oral bioavailability due to low or incomplete absorption which is affected by various effects as pH, motility of GI, and enzyme activity. The gastroretentive drug delivery systems are able to deal with these problems by prolonging the gastric residence time, while increasing the therapeutic efficacy of drugs. Previously, we developed a novel technology to foam hot and molten dispersions on atmospheric pressure by a batch-type in-house apparatus. Our aim was to upgrade this technology by a new continuous lab-scale apparatus and confirm that our formulations are gastroretentive. At first, we designed and built the apparatus and continuous production was optimized using a Box-Behnken experimental design. Then, we formulated barium sulfate-loaded samples with the optimal production parameters, which was suitable for in vivo imaging analysis. In vitro study proved the low density, namely 507 mg/cm3, and the microCT record showed high porosity with 40 μm average size of bubbles in the molten suspension. The BaSO4-loaded samples showed hard structure at room temperature and during the wetting test, the complete wetting was detected after 120 min. During the in vivo study, the X-ray taken showed the retention of the formulation in the rat stomach after 2 h. We can conclude that with our device low-density floating formulations were prepared with prolonged gastric residence time. This study provides a promising platform for marketed active ingredients with low bioavailability.

3D printing of four-in-one oral polypill with multiple release profiles for personalized delivery of caffeine and vitamin B analogues

Personalized supplementation has found recent momentum with an estimated global market size of USD 1.6 billion in 2019 and an expected CAGR of 8.5% between 2020 and 2028. Alongside this rising trend, a simple, accurate, inexpensive and flexible method to produce personalized dosage forms of a wide variety of supplements would be beneficial to both the industry players and individual consumers. Here, we present a 3D printing method to fabricate a four-in-one oral polypill with multiple release profiles for personalized delivery of caffeine and vitamin B analogues. The 3D printable formulations were fabricated and optimized from existing FDA GRAS excipients based on their viscosity, shear thinning properties, recovery of paste and mechanical strength. In the polypill, vitamin B analogues and caffeine were used as the model dietary ingredients. We performed a standard 2 stage USP in vitro dissolution test of the polypill, and demonstrated that vitamin B1, B3 and B6 could be immediately released within 30 min, while caffeine could be slowly released over a period of 4 h. This demonstrated the ability dietary supplement containing different ingredients with varying release profiles, all within a single polypill. Throughout the formulation and 3D printing process, there were no detectable changes to the dietary ingredients nor any interactions with the excipients. This method serves as an intriguing complement to traditional manufacturing of oral tablets, especially when flexibility in design, dose, volume and release profiles of each dietary ingredient is required, as exemplified in personalized supplementation.

3DP Printing of Oral Solid Formulations: A Systematic Review

Three-dimensional (3D) printing is a recent technology, which gives the possibility to manufacture personalised dosage forms and it has a broad range of applications. One of the most developed, it is the manufacture of oral solid dosage and the four 3DP techniques which have been more used for their manufacture are FDM, inkjet 3DP, SLA and SLS. This systematic review is carried out to statistically analyze the current 3DP techniques employed in manufacturing oral solid formulations and assess the recent trends of this new technology. The work has been organised into four steps, (1) screening of the articles, definition of the inclusion and exclusion criteria and classification of the articles in the two main groups (included/excluded); (2) quantification and characterisation of the included articles; (3) evaluation of the validity of data and data extraction process; (4) data analysis, discussion, and conclusion to define which technique offers the best properties to be applied in the manufacture of oral solid formulations. It has been observed that with SLS 3DP technique, all the characterisation tests required by the BP (drug content, drug dissolution profile, hardness, friability, disintegration time and uniformity of weight) have been performed in the majority of articles, except for the friability test. However, it is not possible to define which of the four 3DP techniques is the most suitable for the manufacture of oral solid formulations, because the selection is affected by different parameters, such as the type of formulation, the physical-mechanical properties to achieve. Moreover, each technique has its specific advantages and disadvantages, such as for FDM the biggest challenge is the degradation of the drug, due to high printing temperature process or for SLA is the toxicity of the carcinogenic risk of the photopolymerising material.

Synthesis, Characterization and Safety Evaluation of Sericin-Based Hydrogels for Controlled Delivery of Acyclovir

Conventional formulations of antiviral drug acyclovir have various limitations such as low bioavailability. The current study was aimed at developing polymeric matrices for the controlled delivery of acyclovir using sericin as polymer and acrylic acid (AA) as a monomer. The free radical polymerization technique was used for hydrogel formulation. Briefly, sericin was chemically cross-linked with acrylic acid. N′-N′-methylene bis-acrylamide (MBA) and ammonium persulfate (APS) were used as cross-linker and initiator, respectively. FTIR spectra showed that acyclovir was successfully loaded into sericin hydrogel. SEM micrographs revealed that the outer surface was solid-like and smooth. According to DSC thermograms, the developed polymeric network was thermally stable. Amorphous nature of acyclovir was observed in XRD. The pH of medium and reactants’ concentration affected swelling dynamics and acyclovir release pattern. In addition, drug release occurred through a diffusion-controlled process. Sericin hydrogel suspension was well tolerable up to 3800 mg/kg of rabbits’ body weight. Haematology and serum chemistry results were well within the range signifying normal liver and kidney functions. Similarly, histopathology slides of the rabbit’s vital organs were also in normal condition without causing any histopathological change. It was concluded from the findings that sericin-co-AA polymeric matrices are ideal for the pH-dependent delivery of acyclovir.

Fused Deposition Modeling (FDM), the new asset for the production of tailored medicines

Over the last few years, conventional medicine has been increasingly moving towards precision medicine. Today, the production of oral pharmaceutical forms tailored to patients is not achievable by traditional industrial means. A promising solution to customize oral drug delivery has been found in the utilization of 3D Printing and in particular Fused Deposition Modeling (FDM). Thus, the aim of this systematic literature review is to provide a synthesis on the production of pharmaceutical solid oral forms using FDM technology. In total, 72 relevant articles have been identified via two well-known scientific databases (PubMed and ScienceDirect). Overall, three different FDM methods have been reported: "Impregnation-FDM", "Hot Melt Extrusion coupled with FDM" and "Print-fill", which yielded to the formulation of thermoplastic polymers used as main component, five families of other excipients playing different functional roles and 47 active ingredients. Solutions are underway to overcome the high printing temperatures, which was the initial brake on to use thermosensitive ingredients with this technology. Also, the moisture sensitivity shown by a large number of prints in preliminary storage studies is highlighted. FDM seems to be especially fitted for the treatment of rare diseases, and particular populations requiring tailored doses or release kinetics. For future use of FDM in clinical trials, an implication of health regulatory agencies would be necessary. Hence, further efforts would likely be oriented to the use of a quality approach such as "Quality by Design" which could facilitate its approval by the authorities, and also be an aid to the development of this technology for manufacturers.

Design and Assessment of a Polyurethane Carrier Used for the Transmembrane Transfer of Acyclovir

THE Herpes simplex viruses (HSV-1, HSV-2) are responsible for a wide variety of conditions, from cutaneous-mucosal to central nervous system (CNS) infections and occasional infections of the visceral organs, some of them with a lethal end. Acyclovir is often used intravenously, orally, or locally to treat herpetic infections but it must be administered with caution to patients with kidney disease and to children of early age. The main objectives of this study were to synthesize and evaluate new polyurethane nanoparticles that might be used as proper transmembrane carriers for acyclovir. Polyurethane particles were obtained by a polyaddition process: a mixture of two aliphatic diisocyanates used as organic phase was added to a mixture of butanediol and polyethylene glycol used as aqueous phase. Two different samples (with and without acyclovir, respectively) were synthesized and characterized by UV-Vis spectra in order to assess the encapsulation efficacy and the release profile, FT-IR, DSC, SEM, and SANS for structural characterization, as well as skin irritation tests. Nearly homogeneous samples with particle sizes between 78 and 91 nm have been prepared and characterized revealing a medium tendency to form clusters and a high resistance to heat up to 300 °C. The release profile of these nanoparticles is characteristic to a drug delivery system with a late discharge of the loaded active agents. Very slight increases in the level of transepidermal water loss and erythema were found in a 15-day evaluation on human skin. The results suggest the synthesis of a non-irritative carrier with a high encapsulation efficacy that can be successfully used for the transmembrane transfer of acyclovir.

3D Printed Tacrolimus Rectal Formulations Ameliorate Colitis in an Experimental Animal Model of Inflammatory Bowel Disease

The aim of this study was to fabricate novel self-supporting tacrolimus suppositories using semisolid extrusion 3-dimensional printing (3DP) and to investigate their efficacy in an experimental model of inflammatory bowel disease. Blends of Gelucire 44/14 and coconut oil were employed as lipid excipients to obtain suppository formulations with self-emulsifying properties, which were then tested in a TNBS (2,4,6-trinitrobenzenesulfonic acid) induced rat colitis model. Disease activity was monitored using PET/CT medical imaging; maximum standardized uptake values (SUVmax), a measure of tissue radiotracer accumulation rate, together with body weight changes and histological assessments, were used as inflammatory indices to monitor treatment efficacy. Following tacrolimus treatment, a significant reduction in SUVmax was observed on days 7 and 10 in the rat colon sections compared to non-treated animals. Histological analysis using Nancy index confirmed disease remission. Moreover, statistical analysis showed a positive correlation (R2 = 71.48%) between SUVmax values and weight changes over time. Overall, this study demonstrates the effectiveness of 3D printed tacrolimus suppositories to ameliorate colitis and highlights the utility of non-invasive PET/CT imaging to evaluate new therapies in the preclinical area.

Hot Melt Extrusion and its Application in 3D Printing of Pharmaceuticals

Hot Melt Extrusion (HME) is a continuous pharmaceutical manufacturing process that has been extensively investigated for solubility improvement and taste masking of active pharmaceutical ingredients. Recently, it is being explored for its application in 3D printing. 3D printing of pharmaceuticals allows flexibility of dosage form design, customization of dosage form for personalized therapy and the possibility of complex designs with the inclusion of multiple actives in a single unit dosage form. Fused Deposition Modeling (FDM) is a 3D printing technique with a variety of applications in pharmaceutical dosage form development. FDM process requires a polymer filament as the starting material that can be obtained by hot melt extrusion. Recent reports suggest enormous applications of a combination of hot melt extrusion and FDM technology in 3D printing of pharmaceuticals and need to be investigated further. This review in detail describes the HME process, along with its application in 3D printing. The review also summarizes the published reports on the application of HME coupled with 3D printing technology in drug delivery.

Hot melt extrusion paired fused deposition modeling 3D printing to develop hydroxypropyl cellulose based floating tablets of cinnarizine

Three-dimensional printing could serve as a platform to fabricate individualized medicines and complex-structured solid dosage forms. Herein, hot melt extrusion was coupled with 3D printing to develop a unique gastro retentive dosage form to personalize treatment of cinnarizine or other narrow absorption window drugs. The mechanical strength of the extruded strands was optimized for printing by combining two polymers, hydroxypropyl cellulose and vinylpyrrolidone vinyl acetate copolymer. The unit dose, floating force, and release profile were controlled by the printing parameters and object design. The tablets floated immediately within the FaSSGF, and floating force was relatively constant up to 12 h. Drug release followed zero-order kinetics and could be controlled from 6 h to ≥ 12 h. Input variables had a good correlation (R > 0.95) with unit dose, floating force, and dissolution profile (p < 0.05). Authors successfully proposed and tested a new paradigm of individualized medicine fabrication to meet individual patient needs.

PEGylated Lipid Polymeric Nanoparticle-Encapsulated Acyclovir for In Vitro Controlled Release and Ex Vivo Gut Sac Permeation

Currently, pharmaceutical research is directed wide range for developing new drugs for oral administration to target disease. Acyclovir formulation is having common issues of short half-life and poor permeability, causing messy treatment which results in patient incompliance. The present study formulates a lipid polymeric hybrid nanoparticles for antiviral acyclovir (ACV) agent with Phospholipon® 90G (lecithin), chitosan, and polyethylene glycol (PEG) to improve controlled release of the drugs. The study focused on the encapsulation of the ACV in lipid polymeric particle and their sustained delivery. The formulation developed for the self-assembly of chitosan and lecithin to form a shell encapsulating acyclovir, followed by PEGylation. Optimisation was performed via Box-Behnken Design (BBD), forming nanoparticles with size of 187.7 ± 3.75 nm, 83.81 ± 1.93% drug-entrapped efficiency (EE), and + 37.7 ± 1.16 mV zeta potential. Scanning electron microscopy and transmission electron microscopy images displayed spherical nanoparticles formation. Encapsulation of ACV and complexity with other physical parameters are confirmed through analysis using Fourier transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffraction. Nanoparticle produced was capable of achieving 24-h sustained release in vitro on gastric and intestinal environments. Ex vivo study proved the improvement of acyclovir's apparent permeability from 2 × 10-6 to 6.46 × 10-6 cm s-1. Acyclovir new formulation was achieved to be stable up to 60 days for controlled release of the drugs. Graphical abstract.

In-Depth Study into Polymeric Materials in Low-Density Gastroretentive Formulations

The extensive use of oral dosage forms for the treatment of diseases may be linked to deficient pharmacokinetic properties. In some cases the drug is barely soluble; in others, the rapid transit of the formulation through the gastrointestinal tract (GIT) makes it difficult to achieve therapeutic levels in the organism; moreover, some drugs must act locally due to a gastric pathology, but the time they remain in the stomach is short. The use of formulations capable of improving all these parameters, as well as increasing the resident time in the stomach, has been the target of numerous research works, with low-density systems being the most promising and widely explored, however, there is further scope to improve these systems. There are a vast variety of polymeric materials used in low-density gastroretentive systems and a number of methods to improve the bioavailability of the drugs. This works aims to expedite the development of breakthrough approaches by providing an in-depth understanding of the polymeric materials currently used, both natural and synthetic, their properties, advantages, and drawbacks.

3D-Printed Gastroretentive Sustained Release Drug Delivery System by Applying Design of Experiment Approach

This study aimed to develop a novel oral drug delivery system for gastroretentive sustained drug release by using a capsular device. A capsular device that can control drug release rates from the inner immediate release (IR) tablet while floating in the gastric fluid was fabricated and printed by a fused deposition modeling 3D printer. A commercial IR tablet of baclofen was inserted into the capsular device. The structure of the capsular device was optimized by applying a design of experiment approach to achieve sustained release of a drug while maintaining sufficient buoyancy. The 2-level factorial design was used to identify the optimal sustained release with three control factors: size, number, and height of drug-releasing holes of the capsular device. The drug delivery system was buoyant for more than 24 h and the average time to reach 80% dissolution (T₈₀) was 1.7–6.7 h by varying the control factors. The effects of the different control factors on the response factor, T₈₀, were predicted by using the equation of best fit. Finally, drug delivery systems with predetermined release rates were prepared with a mean prediction error ≤ 15.3%. This approach holds great promise to develop various controlled release drug delivery systems.

Linseed hydrogel based floating drug delivery system for fluoroquinolone antibiotics: Design, in vitro drug release and in vivo real-time floating detection

Herein, we designed a novel gastroretentive drug delivery system as floating matrix tablets based on a polysaccharide material from linseeds (Linum usitatissimum L.) for fluoroquinolone antibiotics. A number of formulations were designed with a combination of linseed hydrogel (LSH) and different excipients to obtain a desired sustained release profile of moxifloxacin. The drug release study was performed basically at pH 1.2. However, the tablet may pass through the stomach to intestine due to certain reasons then it also offered sustained drug release at intestinal pH 4.5, 6.8 and 7.4, as well. Results indicated that sustained moxifloxacin release was directly proportional to the concentration of LSH and the release of drug followed non-Fickian diffusion. SEM of the tablets indicated porous nature of LSH with elongated channels which contributed to the swelling of the tablet and then facilitated the discharge of moxifloxacin from the core of the tablet. In vivo X-ray study was performed to assess disintegration and real-time floating of tablet that confirmed its presence for 6 h in the stomach. These findings indicated that LSH can be used to develop novel gastroretentive sustained release drug delivery systems with the double advantage of sustained drug release at all pH of GIT.

Design and Fabrication of Three-Dimensional Printed Scaffolds for Cancer Precision Medicine

Three-dimensional (3D)-engineered scaffolds have been widely investigated as drug delivery systems (DDS) or cancer models with the aim to develop effective cancer therapies. The in vitro and in vivo models developed via 3D printing (3DP) and tissue engineering concepts have significantly contributed to our understanding of cell-cell and cell-extracellular matrix interactions in the cancer microenvironment. Moreover, 3D tumor models were used to study the therapeutic efficiency of anticancer drugs. The present study aims to provide an overview of applying the 3DP and tissue engineering concepts for cancer studies with suggestions for future research directions. The 3DP technologies being used for the fabrication of personalized DDS have been highlighted and the potential technical approaches and challenges associated with the fused deposition modeling, the inkjet-powder bed, and stereolithography as the most promising 3DP techniques for drug delivery purposes are briefly described. Then, the advances, challenges, and future perspectives in tissue-engineered cancer models for precision medicine are discussed. Overall, future advances in this arena depend on the continuous integration of knowledge from cancer biology, biofabrication techniques, multiomics and patient data, and medical needs to develop effective treatments ultimately leading to improved clinical outcomes. Impact statement Three-dimensional printing (3DP) enables the fabrication of personalized medicines and drug delivery systems. The convergence of 3DP, tissue engineering concepts, and cancer biology could significantly improve our understanding of cancer biology and contribute to the development of new cancer therapies.