Gastroretentive Technologies in Tandem with Controlled-Release Strategies: A Potent Answer to Oral Drug Bioavailability and Patient Compliance Implications

Chitosan: An overview of biological activities, derivatives, properties, and current advancements in biomedical applications

The second and most often utilized natural polymer is chitosan (CS), a naturally existing amino polysaccharide that is produced by deacetylating chitin. Numerous applications have been the subject of in-depth investigation due to its non-hazardous, biologically compatible, and biodegradable qualities. Chitosan's characteristics, such as mucoadhesion, improved permeability, controlled release of drugs, in situ gelation process, and antibacterial activity, depend on its amino (-NH2) and hydroxyl groups (-OH). This study examines the latest findings in chitosan research, including its characteristics, derivatives, preliminary research, toxic effects, pharmaceutical kinetics and chitosan nanoparticles (CS-NPs) based for non-parenteral delivery of drugs. Chitosan and its derivatives have a wide range of physical and chemical properties that make them highly promising for use in the medicinal and pharmaceutical industries. The characteristics and biological activities of chitosan and its derivative-based nanomaterials for the delivery of drugs, therapeutic gene transfer, delivery of vaccine, engineering tissues, evaluations, and other applications in medicine are highlighted in detail in the current review. Together with the techniques for binding medications to nanoparticles, the application of the nanoparticles was also dictated by their physical properties that were classified and specified. The most recent research investigations on delivery of drugs chitosan nanoparticle-based medication delivery methods applied topically, through the skin, and through the eyes were considered.

Advanced polymers and recent advancements on gastroretentive drug delivery system; a comprehensive review

Oral route of drug administration is typically the initial option for drug administration because it is both practical and affordable. However, major drawback of this route includes the release of drug at a specified place thus reduces the bioavailability. This could be overcome by utilising the gastroretentive drug delivery system (GRRDS). Prolonged stomach retention improves bioavailability and increases solubility for medicines that are unable to dissolve in high pH environments. Many recent advancements in the floating, bio adhesive, magnetic, expandable, raft forming and ion exchange systems have been made that had led towards advanced form of drug delivery. From the past few years, floating drug delivery system has been most commonly utilised for the delivery of drug in a delayed manner. Various polymers have been utilised for manufacturing of these systems, including alginates, chitosan, pectin, carrageenan's, xanthan gum, hydroxypropyl cellulose, carbomer, polyethylene oxide and sodium carboxy methyl cellulose. Chitosan, pectin and xanthan gum have been found to be most commonly used polymers in the manufacturing of drug inclusion complex for gastroretentive drug delivery. This study aimed to define various types and advanced polymers as well as also highlights recent advances and future perspectives of gastroretentive drug delivery system.

In situ triggered, floating delivery systems of capsaicin for prolonged gastroprotection

Capsaicin (CAP) has been implicated as a gastroprotective agent in the treatment of peptic ulcers. However, its oral administration is hampered by its poor aqueous solubility and caustic effect at high administered doses. To address these limitations, we describe the development of gastric floating, sustained release electrospun films loaded with CAP. The nanofiber films were formulated using the polymers Eudragit RL/RS and sodium bicarbonate (SB) as the effervescent agent. The films were tested for their physicochemical properties, and film buoyancy and in vitro release of CAP were assessed in simulated gastric fluid. The cytocompatibility and anti-inflammatory properties of the films were evaluated in lipopolysaccharide (LPS)-stimulated Caco-2 cells. The amorphous films showed improved wettability, a short floating lag time (<1 s) and a total floating time of over 24 h accompanied by sustained CAP release for up to 24 h. CAP-loaded films demonstrated biocompatibility with Caco-2 cells and potential cytoprotective effects by attenuating inflammatory cytokine and reactive oxygen species (ROS) production in LPS-stimulated Caco-2 cells. The gastric floating electrospun films could serve as a platform for sustained and stomach-specific drug delivery applications.

Resveratrol-loaded octenyl succinic anhydride modified starch emulsions and hydroxypropyl methylcellulose (HPMC) microparticles: Cytotoxicity and antioxidant bioactivity assessment after in vitro digestion

Hydroxypropyl methylcellulose (HPMC)-based microparticles and modified starch emulsions (OSA-MS) were loaded with resveratrol and characterized regarding their physicochemical and thermal properties. Both delivery systems were subject to an in vitro gastrointestinal digestion to assess the bioaccessibility of resveratrol. In addition, cell-based studies were conducted after in vitro digestion and cytotoxicity and oxidative stress were assessed. HPMC-based microparticles displayed higher average sizes (d) and lower polydispersity index (PDI) (d = 948 nm, PDI < 0.2) when compared to OSA-MS-based emulsions (d = 217 nm, PDI < 0.3). Both proved to protect resveratrol under digestive conditions, leading to an increase in bioaccessibility. Resveratrol-loaded HPMC-microparticles showed a higher bioaccessibility (56.7 %) than resveratrol-loaded emulsions (19.7 %). Digested samples were tested in differentiated co-cultures of Caco-2 and HT29-MTX, aiming at assessing cytotoxicity and oxidative stress, and a lack of cytotoxicity was observed for all samples. Results displayed an increasing antioxidant activity, with 1.6-fold and 1.4-fold increases over the antioxidant activity of free resveratrol, for HPMC-microparticles and OSA-MS nanoemulsions, respectively. Our results offer insight into physiological relevancy due to assessment post-digestion and highlight the protection that the use of micro-nano delivery systems can confer to resveratrol and their potential to be used as functional food ingredients capable of providing antioxidant benefits upon consumption.

Development of a multi-component gastroretentive expandable drug delivery system (GREDDS) for personalized administration of metformin

OBJECTIVES

Efficacy and compliance of type II diabetes treatment would greatly benefit from dosage forms providing controlled release of metformin in the upper gastrointestinal tract. In this respect, the feasibility of a new system ensuring stomach-retention and personalized release of this drug at its absorption window for multiple days was investigated.

METHODS

The system proposed comprised of a drug-containing core and a viscoelastic umbrella-like skeleton, which were manufactured by melt-casting and 3D printing. Prototypes, alone or upon assembly and insertion into commercially-available capsules, were characterized for key parameters: thermo-mechanical properties, accelerated stability, degradation, drug release, deployment performance, and resistance to simulated gastric contractions.

RESULTS

Each part of the system was successfully manufactured using purposely-selected materials and the performance of final prototypes matched the desired one. This included: i) easy folding of the skeleton against the core in the collapsed administered shape, ii) rapid recovery of the cumbersome configuration at the target site, even upon storage, and iii) prolonged release of metformin.

CONCLUSIONS

Composition, geometry, and performance of the system developed in this work were deemed acceptable for stomach-retention and prolonged as well as customizable release of metformin in its absorption window, laying promising bases for further development steps.

Improved gastric residence time of famotidine by raft-forming drug delivery system using DOE

OBJECTIVE

This study investigated the raft-forming suspension of famotidine as an anti-reflux formulation to improve the oral bioavailability of narrow absorption window drugs by enhancing gastric residence time (GRT) and preventing gastro-esophageal reflux disease (GERD).

METHOD

Various combinations of raft-forming agents, such as Tragacanth gum (TG), guar gum (GG), and xanthan gum (XG), were evaluated alongside sodium alginate (SA) to develop an effective raft. Preformulation studies and preliminary screening were conducted to identify the most suitable raft-forming agent, and GG was chosen due to its mucilaginous properties. The formulation was optimized using a 32 full factorial design, with the quantities of GG and SA as independent factors and apparent viscosity and in-vitro drug release (%) as dependent factors. The in vivo floating behavior study was performed for optimized and stabilized formulation.

RESULTS

Among the tested batches, F6 was selected as the optimized formulation. It exhibited desirable characteristics such as adequate raft weight for extended floating in gastric fluid, improved apparent viscosity, and a significant percentage of drug release at 12 h. A mathematical model was applied to the in-vitro data to gain insights into the drug release mechanism of the formulation. The stability of the suspension was assessed under accelerated conditions, and it demonstrated satisfactory stability. The formulation remains floating in the Rabbit stomach for more than 12 h.

CONCLUSION

It concludes that the developed formulation has enhanced bioavailability in the combination of GG and SA. The floating layer of the raft prevents acid reflux, and the famotidine is retained for an extended period of time in the gastric region, preventing excess acid secretion. The developed formulations are effective for stomach ulcers and GERD, with the effect of reducing acid secretion by H2 receptor antagonists.

Oral liposomal delivery of an activatable budesonide prodrug reduces colitis in experimental mice

Inflammatory bowel disease (IBD) is one of the most common intestinal disorders, with increasing global incidence and prevalence. Numerous therapeutic drugs are available but require intravenous administration and are associated with high toxicity and insufficient patient compliance. Here, an oral liposome that entraps the activatable corticosteroid anti-inflammatory budesonide was developed for efficacious and safe IBD therapy. The prodrug was produced via the ligation of budesonide with linoleic acid linked by a hydrolytic ester bond, which was further constrained into lipid constituents to form colloidal stable nanoliposomes (termed budsomes). Chemical modification with linoleic acid augmented the compatibility and miscibility of the resulting prodrug in lipid bilayers to provide protection from the harsh environment of the gastrointestinal tract, while liposomal nanoformulation enables preferential accumulation to inflamed vasculature. Hence, when delivered orally, budsomes exhibited high stability with low drug release in the stomach in the presence of ultra-acidic pH but released active budesonide after accumulation in inflamed intestinal tissues. Notably, oral administration of budsomes demonstrated favorable anti-colitis effect with only ∼7% mouse body weight loss, whereas at least ∼16% weight loss was observed in other treatment groups. Overall, budsomes exhibited higher therapeutic efficiency than free budesonide treatment and potently induced remission of acute colitis without any adverse side effects. These data suggest a new and reliable approach for improving the efficacy of budesonide. Our in vivo preclinical data demonstrate the safety and increased efficacy of the budsome platform for IBD treatment, further supporting clinical evaluation of this orally efficacious budesonide therapeutic.

Bilosomes and Biloparticles for the Delivery of Lipophilic Drugs: A Preliminary Study

In this study, bile acid-based vesicles and nanoparticles (i.e., bilosomes and biloparticles) are studied to improve the water solubility of lipophilic drugs. Ursodeoxycholic acid, sodium cholate, sodium taurocholate and budesonide were used as bile acids and model drugs, respectively. Bilosomes and biloparticles were prepared following standard protocols with minor changes, after a preformulation study. The obtained systems showed good encapsulation efficiency and dimensional stability. Particularly, for biloparticles, the increase in encapsulation efficiency followed the order ursodeoxycholic acid < sodium cholate < sodium taurocholate. The in vitro release of budesonide from both bilosytems was performed by means of dialysis using either a nylon membrane or a portion of Wistar rat small intestine and two receiving solutions (i.e., simulated gastric and intestinal fluids). Both in gastric and intestinal fluid, budesonide was released from bilosystems more slowly than the reference solution, while biloparticles showed a significant improvement in the passage of budesonide into aqueous solution. Immunofluorescence experiments indicated that ursodeoxycholic acid bilosomes containing budesonide are effective in reducing the inflammatory response induced by glucose oxidase stimuli and counteract ox-inflammatory damage within intestinal cells.

Oral Drug Delivery Systems Applied to Launched Products: Value for the Patients and Industrial Considerations

Drug delivery systems (DDS) control the amount, rate, and site of administration of drug substances in the body as well as their release and ADME (absorption, distribution, metabolism, excretion). Among the various types of DDS, amount-controlled DDS for solubilization and absorption increase the bioavailability. Time- and amount-controlled DDS are controlled release formulations classified as (1) membrane-type, (2) matrix-type, (3) osmotic-type, and (4) ion-exchange type. Timed-release formulations also control the time and amount of release and the absorption of drugs. Site- and amount-controlled DDS are characterized by colonic delivery and intestinal lymph-targeting to improve release and ADME of drug substances. Finally, site-, time-, and amount-controlled DDS are gastroretentive formulations and local delivery in the oral cavity to improve site retention, release, and ADME of drugs. DDS can enhance efficacy, reduce adverse effects, and optimize the dosing frequency of various drug products to increase patient value. This review focuses on patient value and industrial considerations of launched oral DDS. We provide a technological overview of candidate and marketed DDS, as well as the pros/cons of the technologies for industrialization with consideration to excipients, manufacturing, and storage stability. Moreover, to demonstrate the usefulness of the technology and support the selection and development of the best technologies for patients, we also describe patient value from clinical studies and analyses, particularly with regard to increased new medical options, higher efficacy, reduced adverse effects, reduced number of doses and clinic visits, easier administration, higher quality of life, greater adherence, and satisfaction.

PLGA-based microspheres loaded with metformin hydrochloride: Modified double emulsion method preparation, optimization, characterization, and in vitro evaluation

The modified solvent removal method was used to encapsulate metformin hydrochloride (MH) within poly(lactic-co-glycolic acid) (PLGA) microspheres. The study investigated the effect of varying polymer concentrations on the loading and release of the drug from the microspheres. The encapsulation process involved using a double emulsion method, resulting in microspheres with particle diameters ranging from approximately 4.4μm to 2.7μm. The study achieved high encapsulation efficiencies, ranging from 81% to 90%, with drug loadings ranging from 18% to 11%. The release of the drug from the microspheres followed a biphasic pattern over 24 days, with nearly complete release by the end of the study period. Fourier transform infrared spectroscopy (FTIR) analysis indicated that there were no notable differences between PLGA and MH-loaded microspheres, suggesting minimal interactions between MH and PLGA. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques were used to investigate the state of the MH within the microspheres. The results suggested that the MH was dispersed at a molecular level within the spheres and existed in an amorphous state. This amorphous state of the drug may explain the slow and prolonged release observed in the study.

Controlled release of MT-1207 using a novel gastroretentive bilayer system comprised of hydrophilic and hydrophobic polymers

In the present study, novel gastroretentive bilayer tablets were developed that are promising for the once-a-day oral delivery of the drug candidate MT-1207. The gastroretentive layer consisted of a combination of hydrophilic and hydrophobic polymers, namely polyethylene oxide and Kollidon® SR. A factorial experiment was conducted, and the results revealed a non-effervescent gastroretentive layer that, unlike most gastroretentive layers reported in the literature, was easy to prepare, and provided immediate tablet buoyancy (mean floating lag time of 1.5 s) that lasted over 24 h in fasted state simulated gastric fluid (FaSSGF) pH 1.6, irrespective of the drug layer, thereby allowing a 24-hour sustained release of MT-1207 from the drug layer of the tablets. Furthermore, during in vitro buoyancy testing of the optimised bilayer tablets in media of different pH values (1.0, 3.0, 6.0), the significant difference (one-way ANOVA, p < 0.001) between the respective total floating times indicated that stomach pH effects on tablet buoyancy are important to be considered during the development of non-effervescent gastroretentive formulations and the choice of dosing regimen. To the best of our knowledge, this has not been reported before, and it should probably be factored in when designing dosing regimens. Finally, a pharmacokinetic study in Beagle dogs indicated a successful in vivo 24-hour sustained release of MT-1207 from the optimised gastroretentive bilayer tablet formulations with the drug plasma concentration remaining above the estimated minimum effective concentration of 1 ng/mL at the 24-hour timepoint and also demonstrated the gastroretentive capabilities of the hydrophilic and hydrophobic polymer combination. The optimised formulations will be forwarded to clinical development.

Advances in Biomedical Applications of Solution Blow Spinning

In recent years, Solution Blow Spinning (SBS) has emerged as a new technology for the production of polymeric, nanocomposite, and ceramic materials in the form of nano and microfibers, with similar features to those achieved by other procedures. The advantages of SBS over other spinning methods are the fast generation of fibers and the simplicity of the experimental setup that opens up the possibility of their on-site production. While producing a large number of nanofibers in a short time is a crucial factor in large-scale manufacturing, in situ generation, for example, in the form of sprayable, multifunctional dressings, capable of releasing embedded active agents on wounded tissue, or their use in operating rooms to prevent hemostasis during surgical interventions, open a wide range of possibilities. The interest in this spinning technology is evident from the growing number of patents issued and articles published over the last few years. Our focus in this review is on the biomedicine-oriented applications of SBS for the production of nanofibers based on the collection of the most relevant scientific papers published to date. Drug delivery, 3D culturing, regenerative medicine, and fabrication of biosensors are some of the areas in which SBS has been explored, most frequently at the proof-of-concept level. The promising results obtained demonstrate the potential of this technology in the biomedical and pharmaceutical fields.

Organ-Retentive Osmotically Driven System (ORODS): A Novel Expandable Platform for in Situ Drug Delivery

Drug delivery systems capable of being retained within hollow organs allow the entire drug dose to be delivered locally to the disease site or to absorption windows for improved systemic bioavailability. A novel Organ-Retentive Osmotically Driven System (ORODS) was here proposed, obtained by assembling drug-containing units having prolonged release kinetics with osmotic units used as increasing volume compartments. Particularly, prototypes having H-shape design were conceived, manufactured and evaluated. Such devices were assembled by manually inserting a tube made of regenerated cellulose (osmotic unit) into the holes of two perforated hydrophilic tableted matrices containing paracetamol as a tracer drug. The osmotic unit was obtained by folding and gluing a plain regenerated cellulose membrane and loading sodium chloride inside. When immersed in aqueous fluids, this compartment expanded to approximately 80% of its maximum volume within 30 min of testing, and a plateau was maintained for about 6 h. Subsequently, it slowly shrank to approximately 20% of the maximum volume in 24 h, which would allow for physiological emptying of the device from hollow organs. While expanding, the osmotic unit acquired stiffness. Drug release from H-shaped ORODSs conveyed in hard-gelatin capsules was shown to be prolonged for more than 24 h.

Preparation, Characterization and Evaluation of Flavonolignan Silymarin Effervescent Floating Matrix Tablets for Enhanced Oral Bioavailability

The convenient and highly compliant route for the delivery of active pharmaceutical ingredients is the tablet. A versatile platform of tablets is available for the delivery of therapeutic agents to the gastrointestinal tract. This study aimed to prepare gastro retentive drug delivery floating tablets of silymarin to improve its oral bioavailability and solubility. Hydroxypropyl methylcellulose (HPMCK4M and HPMCK15), Carbopol 934p and sodium bicarbonate were used as a matrix, floating enhancer and gas generating agent, respectively. The prepared tablets were evaluated for physicochemical parameters such as hardness, weight variation, friability, floating properties (floating lag time, total floating time), drug content, stability study, in vitro drug release, in vivo floating behavior and in vivo pharmacokinetics. The drug–polymer interaction was studied by Differential Scanning Calorimetry (DSC) thermal analysis and Fourier transform infrared (FTIR). The floating lag time of the formulation was within the prescribed limit (<2 min). The formulation showed good matrix integrity and retarded the release of drug for >12 h. The dissolution can be described by zero-order kinetics (r2 = 0.979), with anomalous diffusion as the release mechanism (n = 0.65). An in vivo pharmacokinetic study showed that Cmax and AUC were increased by up to two times in comparison with the conventional dosage form. An in vivo imaging study showed that the tablet was present in the stomach for 12 h. It can be concluded from this study that the combined matrix system containing hydrophobic and hydrophilic polymers min imized the burst release of the drug from the tablet and achieved a drug release by zero-order kinetics, which is practically difficult with only a hydrophilic matrix. An in vivo pharmacokinetic study elaborated that the bioavailability and solubility of silymarin were improved with an increased mean residence time.

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.

Hydrocaffeic acid-chitosan coating of gastric patch provides long-acting mucoadhesive delivery of model chemotherapeutic agent

The development of a long-acting orally administered dosage form is a challenge. Here, we report development of a multi-layered mucoadhesive gastric patch that could deliver entrapped chemotherapeutic agent for eight days after oral administration. The multi-layered patch was designed to contain core layer, mucoadhesive layer and backing layer. The core layer contained the model chemotherapeutic agent, regorafenib. The mucoadhesive layer made of chitosan-hydrocaffeic acid conjugate showed greatest mucoadhesion strength of 18.1 ± 0.78 kPa in freshly excised rat gastric mucosa. The backing layer made of hydrophobic polycaprolactone-polydimethylsiloxane composite showed the contact angle of 120 ± 4.7° after placement of water drop. The entrapped regorafenib predominantly released from the mucoadhesive-side of the patch into simulated gastric fluid and showed a zero-order release profile. The patches were found to be stable for desired characteristics for up to 3 months in long term storage conditions. The pharmacokinetic studies in rat model revealed constant plasma concentration of regorafenib sustained for 8 days after oral administration of gastric patch. The gastric tissue where the patch adhered for 8 days did not show any significant histological changes compared with the normal gastric tissue. The oral administration of single dose of regorafenib-loaded gastric patch in FaDu cell xenografted tumor bearing athymic nude mice has shown significant (P < 0.05) reduction in the tumor volume over 7 days compared to the control group. Taken together, the multi-layered mucoadhesive gastric patch can be developed as a long-acting oral drug delivery system.

Clarithromycin and Pantoprazole Gastro-Retentive Floating Bilayer Tablet for the Treatment of Helicobacter Pylori: Formulation and Characterization

Bilayer/multilayer tablets have been introduced to formulate incompatible components for compound preparations, but they are now more commonly used to tailor drug release. This research aimed to formulate a novel gastro-retentive tablet to deliver a combination of a fixed dose of two drugs to eliminate Helicobacter pylori (H. pylori) in the gastrointestinal tract. The bilayer tablets were prepared by means of the direct compression technique. The controlled-release bilayer tablets were prepared using various hydrophilic swellable polymers (sodium alginate, chitosan, and HPMC-K15M) alone and in combination to investigate the percent of swelling behavior and average drug release. The weight of the controlled-release floating layer was 500 mg, whereas the weight of the floating tablets of pantoprazole was 100 mg. To develop the most-effective formulation, the effects of the experimental components on the floating lag time, the total floating time, T 50%, and the amount of drug release were investigated. The drugs' and excipients' compatibilities were evaluated using ATR-FTIR and DSC. Pre-compression and post-compression testing were carried out for the prepared tablets, and they were subjected to in vitro characterization studies. The pantoprazole layer of the prepared tablet demonstrated drug release (95%) in 2 h, whereas clarithromycin demonstrated sustained drug release (83%) for up to 24 h (F7). The present study concluded that the combination of sodium alginate, chitosan, and HPMC polymers (1:1:1) resulted in a gastro-retentive and controlled-release drug delivery system of the drug combination. Thus, the formulation of the floating bilayer tablets successfully resulted in a biphasic drug release. Moreover, the formulation (F7) offered the combination of two drugs in a single-tablet formulation containing various polymers (sodium alginate, chitosan, and HPMC polymers) as the best treatment option for local infections such as gastric ulcers.

Model-Informed drug development of gastroretentive release systems for sildenafil citrate

Gastroretentive drug delivery systems (GRDDS) are modified-release dosage forms designed to prolong their residence time in the upper gastrointestinal tract, where some drugs are preferentially absorbed, and increase the drug bioavailability. This work aimed the development of a novel GRDDS containing 60 mg of sildenafil citrate, and the evaluation of the feasibility of the proposed formulation for use in the treatment of pulmonary arterial hypertension (PAH), for once a day administration, by using in silico pharmacokinetic (PK) modeling and simulations using GastroPlus^TM. The Model-Informed Drug Development (MIDD) approach was used in formulation design and pharmacokinetic exposure prospecting. A 2² factorial design with a central point was used for optimization of the formulation, which was produced by direct compression and characterized by some tests, including buoyancy test, assay, impurities, and in vitro dissolution. A compartmental PK model was built using the GatroPlus^TM software for virtual bioequivalence of the proposed formulations in comparison with the defined target release profile provided by an immediate release (IR) tablet formulation containing 20 mg of sildenafil administered three times a day (TID). The results of the factorial design showed a direct correlation between the dissolution rate and the amount of hydroxypropyl methyl cellulose (HPMC) in the formulations. By comparing the PK parameters predicted by the virtual bioequivalence, the formulations F1, F2, F3 and F5 failed on bioequivalence. The F4 showed bioequivalence to the reference and was considered the viable formulation to substitute the IR. Thus, GRDDS could be a promising alternative for controlling the release of drugs with a pH-dependent solubility and narrow absorption window, specifically in the gastric environment, and an interesting way to reduce dose frequency and increase the drug bioavailability. The MIDD approach increases the level of information about the pharmaceutical product and guide the drug development for more assertive ways.

Expandable Drug Delivery Systems Based on Shape Memory Polymers: Impact of Film Coating on Mechanical Properties and Release and Recovery Performance

Retentive drug delivery systems (DDSs) are intended for prolonged residence and release inside hollow muscular organs, to achieve either local or systemic therapeutic goals. Recently, formulations based on shape memory polymers (SMPs) have gained attention in view of their special ability to recover a shape with greater spatial encumbrance at the target organ (e.g., urinary bladder or stomach), triggered by contact with biological fluids at body temperature. In this work, poly(vinyl alcohol) (PVA), a pharmaceutical-grade SMP previously shown to be an interesting 4D printing candidate, was employed to fabricate expandable organ-retentive prototypes by hot melt extrusion. With the aim of improving the mechanical resistance of the expandable DDS and slowing down relevant drug release, the application of insoluble permeable coatings based on either Eudragit^® RS/RL or Eudragit^® NE was evaluated using simple I-shaped specimens. The impact of the composition and thickness of the coating on the shape memory, swelling, and release behavior as well as on the mechanical properties of these specimens was thoroughly investigated and the effectiveness of the proposed strategy was demonstrated by the results obtained.

Polymeric Excipients in the Technology of Floating Drug Delivery Systems

The combination of targeted transport and improvement of the release profile of the active pharmaceutical ingredient (API) is a current trend in the development of oral medicinal products (MP). A well-known way to implement this concept is to obtain floating gastroretentive delivery systems that provide a long stay of the dosage form (DF) on the surface of the stomach contents. The nomenclature of excipients (Es) of a polymeric nature used in the technology of obtaining floating drug delivery systems (FDDS) is discussed. Based on the data presented in research papers, the most widely used groups of polymers, their properties, and their purpose in various technological approaches to achieving buoyancy have been determined. In addition, ways to modify the release of APIs in these systems and the Es used for this are described. The current trends in the use of polymers in the technology of floating dosage forms (FDF) and generalized conclusions about the prospects of this direction are outlined.

Progress of Electrospun Nanofibrous Carriers for Modifications to Drug Release Profiles

Electrospinning is an advanced technology for the preparation of drug-carrying nanofibers that has demonstrated great advantages in the biomedical field. Electrospun nanofiber membranes are widely used in the field of drug administration due to their advantages such as their large specific surface area and similarity to the extracellular matrix. Different electrospinning technologies can be used to prepare nanofibers of different structures, such as those with a monolithic structure, a core-shell structure, a Janus structure, or a porous structure. It is also possible to prepare nanofibers with different controlled-release functions, such as sustained release, delayed release, biphasic release, and targeted release. This paper elaborates on the preparation of drug-loaded nanofibers using various electrospinning technologies and concludes the mechanisms behind the controlled release of drugs.

Formulation of metoclopramide HCl gastroretentive film and in vitro- in silico prediction using Gastroplus® PBPK software

The new trends in pharmaceutical studies focus on targeting drug delivery and computer software that help in the body environment simulation, such as Gastroplus® software. The interest of this study is to prepare a gastroretentive film of metoclopramide HCl (MTC) that was followed by applying the in silico approach to estimate the in vivo prepared formulations. The films were prepared from HPMC E5 and sodium alginate polymers as primary polymers with the aid of secondary polymers. The sodium alginate high proportions films showed instant and long floating duration reaching 24 h but with variable folding endurance. Moreover, sodium alginate films with their secondary polymers carbopol and HPMC E5 slowed the release of MTC. The floating and slow-release patterns assessed the gastroretentive properties of sodium alginate films and were further examined by a mucoadhesive study that guaranteed mucosal adhesion, and the film's FESEM images showed similar top morphology, but different side view structures. Last, the pharmacokinetic profile of selected films that approached the gastroretentive properties was in silico predicted depending on in vitro release study and floating duration employing the physiological-based pharmacokinetic model in Gastroplus® software. The model determines this prediction found successfully of intravenous and immediate oral release tablets (10 and 30 mg) of MTC. The simulation showed a high amount of MTC retained for long periods in the stomach to Sod.Alginate-3, Sod.Alginate-8, and Sod.Alginate-10 films (films of secondary polymers carbopol and HPMC E5) aid in reaching the optimum site of absorption jejunum 1 due to the slow MTC release.

Microencapsulation of Ionic Liquid by Interfacial Self-Assembly of Metal-Phenolic Network for Efficient Gastric Absorption of Oral Drug Delivery

Improving bioavailability of orally delivered drugs is still challenging, as conventional drug delivery systems suffer from non-specific drug delivery in the gastrointestinal (GI) tract and limited drug absorption efficiency. Gastric drug delivery is even more difficult due to the harsh microenvironment, short retention time, and physiologic barriers in the stomach. Here, an oral drug delivery microcapsule system was developed for gastric drug delivery, which consists of ionic liquid (IL) as the inner carrier and metal-phenolic network (MPN) as the microcapsule shell. The IL@MPN microcapsules are prepared by interfacial self-assembly of Fe^III and quercetin at the interface of hydrophobic IL ([EMIM][NTf₂]) and water. The formation of MPN shell could improve the stability of IL droplets in water and endow the system with pH-response drug release properties, while the encapsulated IL core could efficiently load the drug and enhance the drug tissue permeability. The IL@MPN microcapsules showed enhanced drug absorption in the stomach after oral administration in a rat model, where the microcapsules are disassembled in gastric acid, and the released IL could reduce the viscosity of mucus gel and increase the drug transport rate across endothelial cells. This work presents a simple yet efficient strategy for oral drug delivery to the stomach. Given the diversity and versatility of both MPN and IL, the proposed self-assembled microcapsules could expand the toolbox of drug delivery systems with enhanced oral drug bioavailability.

Administration strategies and smart devices for drug release in specific sites of the upper GI tract

Targeting the release of drugs in specific sites of the upper GI tract would meet local therapeutic goals, improve the bioavailability of specific drugs and help overcoming compliance-related limitations, especially in chronic illnesses of great social/economic impact and involving polytherapies (e.g. Parkinson's and Alzeimer's disease, tubercolosis, malaria, HIV, HCV). It has been traditionally pursued using gastroretentive (GR) systems, i.e. low-density, high-density, magnetic, adhesive and expandable devices. More recently, the interest towards oral administration of biologics has prompted the development of novel drug delivery systems (DDSs) provided with needles and able to inject different formulations in the mucosa of the upper GI tract and particularly of esophagus, stomach or small intestine. Besides comprehensive literature analysis, DDSs identified as smart devices in view of their high degree of complexity in terms of design, working mechanism, materials employed and manufacturing steps were discussed making use of graphic tools.

Gastroretentive Sustained-Release Tablets Combined with a Solid Self-Micro-Emulsifying Drug Delivery System Adsorbed onto Fujicalin®

Gastroretentive drug delivery systems (GRDDS) get retained in the stomach for a long time, thus facilitating the absorption of drugs in the upper gastrointestinal tract. However, drugs that are difficult to dissolve or unstable in an acidic environment are not suitable for GRDDS. The current study designs GRDDS combined with a self-micro-emulsifying drug delivery system (SMEDDS) for drugs with solubility or stability problems in the stomach. The model drug fenofibrate was formulated into the optimized liquid SMEDDS composed of 50 w/w% Capryol^® PGMC, 40 w/w% Kolliphor^® RH40, and 10 w/w% Transcutol^® HP and solidified through adsorption on several porous adsorbents. In a dissolution medium at pH 1.2, the powdered SMEDDS using Fujicalin^® dissolved quickly and achieved higher drug dissolution than other adsorbents. Based on these results, a gastroretentive bilayer tablet consisting of a drug release layer and a swelling layer was designed. The drug release layer was formulated with the powdered SMEDDS and hydroxypropyl methylcellulose (HPMC) as a release modifier. HPMC was also added to the swelling layer as a water-swellable polymer. The dissolution rate depended on the viscosity of the HPMC in the drug release layer. The time for 90% drug release was extended from 3.7 to 12.0 h by increasing the viscosity grade of HPMC from 0.1 to 100 K. Moreover, the tablet swelled and maintained a size comparable to a human pylorus diameter or more for at least 24 h. This GRDDS could apply to a broader range of drug candidates.

Assessing the Synergistic Activity of Clarithromycin and Therapeutic Oils Encapsulated in Sodium Alginate Based Floating Microbeads

We developed alginate-based floating microbeads of clarithromycin with therapeutic oils for the possible eradication of Helicobacter pylori (H. pylori) infections by enhancing the residence time of the carrier at the site of infection. In pursuit of this endeavor, the alginate was blended with hydroxy propyl methyl cellulose (HPMC) as an interpenetrating polymer to develop beads by ionotropic gelation using calcium carbonate as a gas generating agent. The developed microbeads remained buoyant under gastric conditions for 24 h. These microbeads initially swelled and afterwards decreased in size, possibly due to the erosion of the polymer. Furthermore, swelling was also affected by the type of encapsulated oil, i.e., swelling decreased with increasing concentrations of eucalyptus oil and increased with increasing concentrations of oleic acid. Antibacterial assays of the formulations showed significant antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli); these assays also showed synergistic activity between clarithromycin and therapeutic oils as evident from the higher zone of inhibition of the microbeads as compared to the pure drug and oils. Scanning electron microscopy (SEM) images revealed a smoother surface for oleic acid containing the formulation as compared to eucalyptus oil containing the formulation. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) revealed the development of a stable formulation, while Fourier transform infrared spectrophotometry (FTIR) studies did not reveal any interaction between the polymers and the active ingredients. Optimized formulations (CLM3 and CLM6) were designed to release the drug in a controlled manner in gastric media by Fickian diffusion. Conclusively, the developed microbeads are a promising carrier to overcome the narrow therapeutic index and low bioavailability of clarithromycin, while the presence of therapeutic oils will produce synergistic effects with the drug to eradicate infection effectively.

The Development of Innovative Dosage Forms of the Fixed-Dose Combination of Active Pharmaceutical Ingredients

The development of innovative forms of combination drugs is closely related to the invention of the multilayer tablet press, polymers for pharmaceutical applications, the hot-melt extrusion process, and 3D printing in the pharmaceutical industry. However, combining multiple drugs within the same dosage form can bring many physicochemical and pharmacodynamic interactions. More and more new forms of fixed-dose combinations (FDCs) have been developed due to work to overcome the incompatibility of active substances or to obtain different drug release profiles in the same dosage form. This review provides discussions of the application of various innovation formulation technologies of FDC drugs such as bilayer system, multilayer tablet, active film coating, hot-melt extrusion, and 3D printing, taking into account the characteristics of the key ingredients in the FDC formulation and presenting technological problems and challenges related to the development of combination drugs. Moreover, the article summarizes the range of dosage forms that have been made using these technologies over the past 30 years.

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.

Development of starch/chitosan expandable films as a gastroretentive carrier for ginger extract-loaded solid dispersion

Gastroretentive expandable films were developed to provide controlled release of ginger extract (GE) for treatment of gastric diseases. The dosage form consisted of ginger extract solid dispersion (GE-SD) loaded in a starch/chitosan composite film, which was subsequently folded and inserted into a hard gelatin capsule. GE-SD was prepared by solvent evaporation using an optimum weight ratio of 1:1 for GE and PVP K30. Expandable films containing GE-SD were prepared by solvent casting combinations of chitosan and either rice-, glutinous rice - or pregelatinized maize starch with glycerin incorporated as a plasticizer. The optimized film formulation prepared from glutinous rice starch, exhibited tensile strength of 5.4 N/cm² and high expansion in simulated gastric fluid (SGF), resulting in a 2.8-fold increase in area. The films resulted in sustained release of up to 90% of the content of 6-gingerol during 8 h exposure to SGF. Furthermore, the 6-gingerol released from the film displayed dose-dependent cytotoxic activity against AGS human gastric adenocarcinoma cells and anti-inflammatory activity by inhibiting the production of nitric oxide (NO) in LPS-stimulated RAW264.7 cells.