Physical methods for enhancing drug absorption from the gastrointestinal tract

Mussel Foot Protein Membrane-Enclosed Crystalline Drug with Zero-Order Release Kinetics for Long-Acting Therapy

Injectable formulations with sustained and steady release capabilities are critically required to treat diseases requiring temporary or lifelong continuous therapy, especially for drugs with a short half-life. Additionally, achieving a sufficiently high drug loading in a single dose remains a persistent challenge. Herein, by mimicking the formation principles of mussel adhesive plaques, we have developed membrane-enclosed crystalline systems of insulin and progesterone as model macro- and small-molecular crystalline drugs. The system exhibits a substantial drug loading capacity (>90 %). It exhibits sustained and zero-order release kinetics, thereby facilitating the establishment of a subcutaneous reservoir containing a substantial drug load, enabling progressive and continuous release of the drug into the body. One single injection of membrane-enclosed insulin crystal can maintain normoglycemia in diabetic mice for up to 7 days. Meanwhile, membrane-coated progesterone crystals can sustain drug release in rats for over 7 days. The protein membrane can be cleared from the injection sites in 35 days. This system can serve as a versatile platform for the sustained release of various crystalline pharmaceuticals and the treatment of distinct diseases.

Macrophage-hitchhiked, effervescence-induced nanoemulsions for enhanced oral chemotherapy and immunotherapy: Impact on absorption route

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal cancer. Paclitaxel (PTX), typically administered intravenously (IV) as chemotherapy, shows promise for triggering immunogenic cell death (ICD) and may serve as a potential immunotherapy. This study introduces an oral PTX delivery method using an enteric-coated gelatin capsule containing capric acid oil and an effervescent agent, optionally with decylamine-conjugated β-glucans (DA-βGlus). Upon dissolving in the small intestine, the capsule undergoes an effervescence reaction that produces emulsified oil droplets (ODs) by bile salts, forming either Bared/ODs/PTX or DA-βGlus/ODs/PTX, with the latter featuring surface-attached DA-βGlus. The study evaluates the oral absorption, pharmacokinetics, and therapeutic efficacy of these formulations, comparing them to IV administration. IV PTX causes rapid spikes in plasma concentration, quick metabolism, and elimination, which can be unsafe. In contrast, the oral delivery system maintains consistent drug levels in the bloodstream for longer periods, improving overall effectiveness. Bared/ODs/PTX follows conventional fat absorption pathways, limiting tumor targeting. On the other hand, DA-βGlus/ODs/PTX uses DA-βGlus to enhance specificity for tumors through endogenous macrophage-mediated transport, effectively acting as "cellular tumor-seeking vehicles". This method reduces tumor stroma fibrosis, delivers PTX precisely, induces apoptosis, triggers PTX-induced ICD, and enhances cytotoxic T cell responses, augmenting targeted anti-PDAC strategies.

Longan-inspired chitosan-pectin core-shell hydrogel beads for oral delivery of biodrugs to enhance osteoporosis therapy

Osteoporosis, a common disorder, is characterized by a systemic reduction in bone mass and structural integrity, resulting in brittle bones. Reducing bone loss and enhancing bone density through oral administration of biopharmaceuticals provides significant advantages, including convenience and non-invasiveness for patients. However, challenges such as poor absorption and enzymatic degradation necessitate the development of innovative drug delivery systems. This research introduces a core-shell hydrogel system inspired by the natural architecture of Longan fruit, constructed from pectin and chitosan biopolymers, designed to create biocapsules and sustain the release of biodrugs. In this system, salmon calcitonin (sCT) was encapsulated within mesoporous silica nanoparticles (MSNs) and incorporated into the core of the beads. The synthesis of the core-shell hydrogel beads was carefully regulated by adjusting the immersion time and concentration of the crosslinker. The hydrogel beads demonstrated durability, with the pectin shell effectively preventing rapid degradation in the stomach, while the chitosan layer enhanced adhesion to the intestinal walls, safeguarded sCT, and enabled sustained drug release over an extended period of up to 30 h. Furthermore, biocompatibility tests indicated minimal cytotoxicity and hemolysis. Cellular uptake assays demonstrated that the core-shell beads effectively encapsulated sCT and ensured its prolonged release to CT-26 cells. This study presents a promising platform for oral sCT delivery, offering enhanced efficacy, patient compliance, and a potential replacement for injection-based therapies.

Studies on the changes in rectal permeability and intestinal microbiota with developmental age in young rats

Introduction

The gut contains a diverse array of commensal microorganisms, forming a vital biological barrier within the intestine that contributes to the overall intestinal mucosal barrier. However, research on the rectal barrier during early development remains limited. This study aims to investigate the relationship between intestinal microbiota and rectal barrier function in young rats.

Methods

We evaluated the rectal barrier structure and function in rats at 2-, 4-, and 10-week-old. Methodology included histological analysis, Muc2 expression quantification, immunofluorescence localization of tight junction proteins (ZO-1, Occludin, Claudins), blood glucose monitoring after rectal insulin administration, and 16S rDNA sequencing of rectal microbiota. Spearman correlation analysis was used to explore mechanisms linking age-dependent changes in rectal permeability to microbiota dynamics.

Results

Physiological rectal permeability was significantly higher in 2-week-old rats compared to 4- and 10-week-old rats (p < 0.01), although systemic biomarkers (LPS, D-LA, and LBP) showed no significant differences. The rectal microbiota exhibited marked age-dependent shifts in composition, α/β-diversity, and metabolic pathways, with increased abundance of beneficial taxa (e.g., Muribaculaceae, Akkermansia) in older rats. Correlation analysis revealed strong associations between reduced permeability, elevated Occludin expression, and microbiota maturation (R = 0.65, p < 0.001).

Conclusion

This study demonstrates that age-dependent maturation of the rectal barrier is closely linked to microbiota composition and tight junction protein expression, providing insights into developmental mechanisms and potential strategies for pediatric rectal drug delivery.

Optimized suction patch design for enhanced transbuccal macromolecular drug delivery

Peptides represent a rapidly expanding class of drugs with broad therapeutic potential. However, due to their large molecular weight and susceptibility to degradation in the gastrointestinal tract, most peptide drugs are administered via subcutaneous injections. Despite extensive research, a painless broad delivery platform for these drugs is still lacking. Recently, an octopus-inspired buccal patch has shown promise in addressing this challenge by leveraging a synergistic combination of mechanical stretching and permeation enhancers. In this study, the patch and the loaded formulation were optimized to improve ease of use, scalability, and efficacy. Through assessments of mechanical properties, finite element simulations, and ex vivo experiments, we evaluated the effects of patch design and material, as well as the drug matrix composition and the formulation preparation methods on the delivery performance. A patch with a > 9-fold larger effective surface area, produced via mold casting of medical-grade silicone (shore hardness 50) and loaded with a lyophilized drug matrix, emerged as the most promising system. In beagle dogs, 30-min application of this patch resulted in a 14.6 % bioavailability for teriparatide (4118 g mol-1), while bioavailability of semaglutide (4114 g mol-1) was 9.6 times higher than that of the commercial tablet. This work showcases how systematic optimization of this technology can improve and simplify the buccal administration of macromolecular drugs, facilitating the clinical translation of this non-invasive dosage form.

In Silico Identification of Putative Allosteric Pockets and Inhibitors for the KRASG13D-SOS1 Complex in Cancer Therapy

RAS mutations occur in about 30% of human cancers, leading to enhanced RAS signaling and tumor growth. KRAS is the most commonly mutated oncogene in human tumors, especially lung, pancreatic, and colorectal cancers. Direct targeting of KRAS is difficult due to its highly conserved sequence; but, its complex with the guanine nucleotide exchange factor Son of Sevenless (SOS) 1 promises an attractive target for inhibiting RAS-mediated signaling. Here, we first revealed putative allosteric binding sites of the SOS1, KRASG12C-SOS1 complex, and the ternary KRASG13D-SOS1 complex structures using two network-based models, the essential site scanning analysis and the residue interaction network model. The results enabled us to identify two new putative allosteric pockets for the ternary KRASG13D-SOS1 complex. These were then screened together with the known ligand binding site against the natural compounds in the InterBioScreen (IBS) database using the Glide software package developed by Schrödinger, Inc. The docking poses of seven hit compounds were assessed using 400 ns long molecular dynamics (MD) simulations with two independent replicas using Desmond, coupled with thermal MM-GBSA calculations for the estimation of the binding free energy values. The structural skeleton of the seven proposed compounds consists of different functional groups and heterocyclic rings that possess anti-cancer activity and exhibit persistent interactions with key residues in binding pockets throughout the MD simulations. STOCK1N-09823 was determined as the most promising hit that promoted the disruption of the interactions R73 (chain A)/N879 and R73 (chain A)/Y884, which are key for SOS1-mediated KRAS activation.

Single-dose oral administration of drug-loaded magnetic 3D-printed microbullets for eradication of Helicobacter pylori

Infections of Helicobacter pylori (H. pylori) affect 42.1 % of the Chinese population and 43.1 % of the world population. H. pylori inhabits the mucous sublayer at the pylorus, leading to gastric ulcers, gastritis, and even cancer. Oral antibiotics are usually used to treat H. pylori infections, whereas traditional quadruple therapy has side effects including headaches, nausea, diarrhea, intestinal dysbacteriosis, antibiotic resistance, and repeat infections. Here, a drug-loaded magnetic microbullet was designed to realize long-term retention in the stomach for one-shot treatment for H. pylori infections. It comprises a hollow cylinder wherein eight microneedles homogenously distribute at the top and several round pores located at the bottom. It was three-dimensional (3D)-printed by stereolithography. A clarithromycin (CAM) ground mixture (CGM) was prepared to improve solubility. Enough CGM powders were filled into the cylinder, covered by a small round magnet, and sealed to form a CAM-loaded magnetic microbullet (CMMB). CAM continually released from CMMBs for >24 h. With outside magnetic guidance, an oral CMMB targeted the pylorus site and the microneedles immediately headed into the mucosa followed by long-term local drug release. The in vitro and in vivo safety of CMMBs was confirmed, where their swelling rates were low, and the oral CMMB was finally completely evacuated. An oral CMMB was administered to H. pylori-infected mice and maintained in the stomach for 36 h with magnetic guidance, and the successful eradication of H. pylori was confirmed after single-dose administration. Oral CMMBs are a convenient medication for the eradication of H. pylori.

Advances in Oral Biomacromolecule Therapies for Metabolic Diseases

Metabolic diseases like obesity and diabetes are on the rise, and therapies with biomacromolecules (such as proteins, peptides, antibodies, and oligonucleotides) play a crucial role in their treatment. However, these drugs are traditionally injected. For patients with chronic diseases (e.g., metabolic diseases), long-term injections are accompanied by inconvenience and low compliance. Oral administration is preferred, but the delivery of biomacromolecules is challenging due to gastrointestinal barriers. In this article, we introduce the available biomacromolecule drugs for the treatment of metabolic diseases. The gastrointestinal barriers to oral drug delivery and strategies to overcome these barriers are also explored. We then discuss strategies for alleviating metabolic defects, including glucose metabolism, lipid metabolism, and energy metabolism, with oral biomacromolecules such as insulin, glucagon-like peptide-1 receptor agonists, proprotein convertase subtilisin/kexin type 9 inhibitors, fibroblast growth factor 21 analogues, and peptide YY analogues.

Core-shell hydrogel with synergistic super absorption and long-term acid resistance stability: a novel gastric retention drug delivery carrier

Traditional natural polysaccharide-based hydrogels, when used as drug carriers, often struggle to maintain long-term stability in the extremely harsh gastric environment. This results in unstable drug release and significant challenges in bioavailability. To address this issue, this study utilized inexpensive and safe natural polysaccharides-chitosan (CS) and high methoxyl pectin (HM)-as raw materials. Dynamic chemical bonds and anion-cation electrostatic interactions were employed to successfully prepare a super absorbent gel bead substrate (CS-HM), which serves as the "core" structure. Subsequently, another low-density hydrophilic polysaccharide, sodium carboxymethyl cellulose (CMCNa), was used to coat and crosslink the outer layer of the core, increasing the number of ionic groups. This enhancement raises the osmotic pressure inside the gel network, improving its absorption capacity. At the same time, the core-shell structure provides an energy dissipation mechanism, allowing the material to remain more stable in a strong acid environment. Due to its super absorption, high modulus, and continuous floating release properties, CS-HM@CMCNa-as a new type of acid-resistant super absorbent core-shell material-possesses the key characteristics required for gastric retention sustained-release systems. It is expected to become an ideal drug carrier for the treatment of clinical chronic diseases.

Efficacy and in vitro pharmacological assessment of novel N-hydroxypyridinediones as hepatitis B virus ribonuclease H inhibitors

We previously reported N-hydroxypyridinedione (HPD) compounds with mid-nanomolar efficacy and selectivity indexes around 300 against hepatitis B virus (HBV) replication. However, they lack pharmacological evaluation. Here, we report in vitro anti-HBV efficacy, cytotoxicity, and pharmacological characterization of 29 novel HPDs within seven subgroups. The best two compounds had EC50s of 61 and 190 nM and selectivity indexes of 526 and 1,071. Compounds with one halogen on the major R group were most effective and compounds with large ether R groups were most cytotoxic. Compounds were not cytotoxic in primary human hepatocytes. All compounds were freely soluble in pHs reflecting plasma (7.4) and the gastrointestinal tract (5 and 6.5). Almost all highly soluble compounds were passively permeable at pH 5.0 and 7.4. Only 2 of 11 compounds tested were likely to be effluxed by p-glycoprotein. The most potent HPDs inhibited HBV replication over human ribonuclease H1 activity by 10-fold. Four of 19 compounds inhibited CYP2D6 >50%, but their CYP2D6 IC50s were >8× higher than their anti-HBV EC50. No compound substantially inhibited CYP3A4. Thirteen of 15 compounds had human microsomal half-lives >30 min with medium to low rates of intrinsic clearance. Eleven of 12 compounds bound plasma proteins by ≥80%; however, effects against HBV replication for only one would likely be physiologically relevant. These results identify two lead candidate HPDs with pharmacological characteristics resembling commercially available drugs that are suitable for in vivo pharmacological and efficacy studies.

4D printing of biodegradable intestinal drug delivery devices with shape-memory effect

Expanding devices designed to physically facilitate the permeation of drugs across the gastrointestinal mucosa are gaining attention for the oral delivery of therapeutic macromolecules. The ideal system should be biodegradable with latex-like properties, allowing it to withstand gut movement without breaking prematurely and preventing intestinal obstruction or damage. A highly foldable and elastic device is desirable because it can fit into commercial capsules by being compressed into confined spaces. However, this compression has limits due to the device's tendency to spring back to its original shape driven by stored elastic energy after deformation. This challenge can be addressed by using shape-memory polymers. In this work, we report a photo-crosslinkable resin suitable for 3D printing by digital light processing that yields an elastomer with latex-like properties, shape-recovery at body temperature, and degradation within 6 h under simulated intestinal conditions. Thermal shape-memory was conferred by adding stearyl(acrylate) to poly(β-aminoester)-based inks, achieving high elasticity (>700 %) and strength (>7.5 MPa), along with strain-hardening properties.

Absorption of food-derived peptides: Mechanisms, influencing factors, and enhancement strategies

Food-derived peptides (FPs) are bioactive molecules produced from dietary proteins through enzymatic hydrolysis or fermentation. These peptides exhibit various biological activities. However, their efficacy largely depends on bioavailability, the ability to cross absorption barriers, and reach target sites within the body. This review addresses key issues in FP absorption, including barriers, pathways, influencing factors, and strategies to enhance absorption. The biochemical and physical barriers to FP absorption include pH variations, enzymes, unstirred water layer, mucus layer, and intestinal epithelial cells. FPs enter the bloodstream via four main pathways: carrier-mediated transport, endocytosis, paracellular, and passive diffusion. The barrier-crossing efficiency depends on the structural properties and state of FPs and coexisting substances. Absorption efficiency can be significantly improved with permeability enhancers, nano-delivery systems, and chemical modifications. These insights provide a scientific basis and practical guidance for optimizing the bioactivity and health benefits of food-derived peptides.

Gastrointestinal Permeation Enhancers Beyond Sodium Caprate and SNAC - What is Coming Next?

Oral peptide delivery is trending again. Among the possible reasons are the recent approvals of two oral peptide formulations, which represent a huge stride in the field. For the first time, gastrointestinal (GI) permeation enhancers (PEs) are leveraged to overcome the main limitation of oral peptide delivery-low permeability through the intestinal epithelium. Despite some success, the application of current PEs, such as salcaprozate sodium (SNAC), sodium caprylate (C8), and sodium caprate (C10), is generally resulting in relatively low oral bioavailabilities (BAs)-even for carefully selected therapeutics. With several hundred peptide-based drugs presently in the pipeline, there is a huge unmet need for more effective PEs. Aiming to provide useful insights for the development of novel PEs, this review summarizes the biological hurdles to oral peptide delivery with special emphasis on the epithelial barrier. It describes the concepts and action modes of PEs and mentions possible new targets. It further states the benchmark that is set by current PEs, while critically assessing and evaluating emerging PEs regarding translatability, safety, and efficacy. Additionally, examples of novel PEs under preclinical and clinical evaluation and future directions are discussed.

An in situ bioadhesive foam as a large intestinal delivery platform for antibody fragment to treat inflammatory bowel disease

Biologics have been widely used as injectables in the treatment of inflammatory bowel disease (IBD). Different local treatment attempts have been developed in recent years. However, maintaining systemic levels of biologics is still crucial for achieving colitis remission. An equilibrium between systemic and local concentrations of biologics is therefore essential for treatment of colitis. Current formulations struggle to create optimal balance between drug concentrations in plasma and the colonic wall. Addressing this challenge, we developed a rectally delivered in situ foam that generates CO2via a reaction between potassium bicarbonate (PB) and citric acid (CA) without the aid of an external device. An anti-TNF-α antibody fragment (Fab) was loaded into the foam formulation, which promoted prolonged colon retention and improved Fab distribution up to proximal colon following rectal administration to mice. In addition, we observed increased plasma Fab concentrations in mice receiving the rectal Fab foam compared to a Fab solution. In a non-everted rat gut ex vivo model, a single exposure to the CO2-containing foam improved macromolecule transepithelial flux across colonic tissue by over ten-fold. Foam efficacy for Fab was investigated in a range of colitis mouse models, from acute to chronic. This non-invasive formulation platform demonstrates potential to overcome existing limitations in delivering biologics to inflamed colonic tissue.

Harnessing the Power of Stimuli-Responsive Nanoparticles as an Effective Therapeutic Drug Delivery System

The quest for effective and reliable methods of delivering medications, with the aim of improving delivery of therapeutic agent to the intended location, has presented a demanding yet captivating field in biomedical research. The concept of smart drug delivery systems is an evolving therapeutic approach, serving as a model for directing drugs to specific targets or sites. These systems have been developed to specifically target and regulate the administration of therapeutic substances in a diverse array of chronic conditions, including periodontitis, diabetes, cardiac diseases, inflammatory bowel diseases, rheumatoid arthritis, and different cancers. Nevertheless, numerous comprehensive clinical trials are still required to ascertain both the immediate and enduring impacts of such nanosystems on human subjects. This review delves into the benefits of different drug delivery vehicles, aiming to enhance comprehension of their applicability in addressing present medical requirements. Additionally, it touches upon the current applications of these stimuli-reactive nanosystems in biomedicine and outlines future development prospects.

Oral peptide therapeutics for diabetes treatment: State-of-the-art and future perspectives

Diabetes, characterized by hyperglycemia, is a major cause of death and disability worldwide. Peptides, such as insulin and glucagon-like peptide-1 (GLP-1) analogs, have shown promise as treatments for diabetes due to their ability to mimic or enhance insulin's actions in the body. Compared to subcutaneous injection, oral administration of anti-diabetic peptides is a preferred approach. However, biological barriers significantly reduce the efficacy of oral peptide therapeutics. Recent advancements in drug delivery systems and formulation techniques have greatly improved the oral delivery of peptide therapeutics and their efficacy in treating diabetes. This review will highlight (1) the benefits of oral anti-diabetic peptide therapeutics; (2) the biological barriers for oral peptide delivery, including pH and enzyme degradation, intestinal mucosa barrier, and biodistribution barrier; (3) the delivery platforms to overcome these biological barriers. Additionally, the review will discuss the prospects in this field. The information provided in this review will serve as a valuable guide for future developments in oral anti-diabetic peptide therapeutics.

Identification and assessment of the 1,6-dihydroxy-pyridin-2-one moiety as privileged scaffold for HBV ribonuclease H inhibition

The Hepatitis B Virus (HBV) ribonuclease H (RNase H) although promising remains an unexploited therapeutic target. HBV RNase H inhibition causes premature termination of viral minus-polarity DNA strands, prevents the synthesis of the viral positive-polarity DNA strand, and causes accumulation of RNA:DNA heteroduplexes within viral capsids. As part of our ongoing research to develop more potent anti-HBV RNase H inhibitors, we designed, synthesized and analyzed a library of 18 novel compounds (17 N-hydroyxpyridinedione (HPD) imine derivatives and 1 barbituric acid analogue) as potential leads for HBV treatment development. In cell assays, fourteen HPDs showed significant anti-HBV activity with EC50s from 1.1 to 2.5 μM and selectivity indices (SI) of up to 58. Three of them exhibited more than 3-fold improvement in the SI over the best previous HPD imine (SI = 13). To gain insight to the interaction between the tested compounds and the active site of HBV RNase H, docking experiments were undertaken. In almost all binding poses, the novel HPDs coordinated both active site Mg2+ ions via their oxygen trident. Furthermore, the novel HPDs displayed high cell permeability and solubility as well as good drug-like properties. These results reveal that HPD imines can be significantly active and selective HBV inhibitors, and that the HPD scaffold merits further development towards anti-HBV agents.

Flexible Coatings Facilitate pH-Targeted Drug Release via Self-Unfolding Foils: Applications for Oral Drug Delivery

Ingestible self-configurable proximity-enabling devices have been developed as a non-invasive platform to improve the bioavailability of drug compounds via swellable or self-unfolding devices. Self-unfolding foils support unidirectional drug release in close proximity to the intestinal epithelium, the main drug absorption site following oral administration. The foils are loaded with a solid-state formulation containing the active pharmaceutical ingredient and then coated and rolled into enteric capsules. The coated lid must remain intact to ensure drug protection in the rolled state until targeted release in the small intestine after capsule disintegration. Despite promising results in previous studies, the deposition of an enteric top coating that remains intact after rolling is still challenging. In this study, we compare different mixtures of enteric polymers and a plasticizer, PEG 6000, as potential coating materials. We evaluate mechanical properties as well as drug protection and targeted release in gastric and intestinal media, respectively. Commercially available Eudragit® FL30D-55 appears to be the most suitable material due to its high strain at failure and integrity after capsule fitting. In vitro studies of coated foils in gastric and intestinal media confirm successful pH-triggered drug release. This indicates the potential advantage of the selected material in the development of self-unfolding foils for oral drug delivery.

Magnetic and/or Radiopaque Functionalization of Self-Unfolding Foils for Improved Applicability within Oral Drug Delivery

Various types of microfabricated devices have been proposed for overcoming the gastrointestinal (GI) challenges associated with oral administration of pharmaceutical compounds. However, unidirectional drug release in very close forced proximity to the intestinal wall still appears to be an unresolved issue for many of these microdevices, which typically show low drug absorption and thereby low bioavailabilities. This work explores how recently developed and promising self-unfolding foils (SUFs) can be magnetically and/or radiopaquely (M/R-) functionalized, by the addition of BaSO4 or Fe3O4 nanoparticles, for improving their applicability within oral drug delivery. Through surface characterization, mechanical testing, and X-ray imaging, the (M/R-)SUFs are generally inspected and their overall properties compared. Furthermore, R-SUFs are being used in an in vivo rat X-ray imaging study, whereas in situ rat testing of MR-SUFs are attempted together with an investigation of their general magnetic properties. Unfolding of the R-SUF, and its very close forced proximity to the small intestine, is very easily observed 2 h post-administration by applying both computed tomography scanning and planar X-ray imaging. In addition, MR-SUFs show a great magnetic response in water, which suggests the possibility for controlled motion and retention in the GI tract. However, the magnetic response does not seem strong enough for in situ rat testing, but most likely a strong magnetization of the MR-SUFs using for example an impulse magnetizer can be made for increasing the magnetic response. All of the results presented herein are highly relevant and applicable for future usage of (M/R-)SUFs, as well as similar devices, in pre-clinical studies and potential clinical trials.

In vitro evaluation of tropolone absorption, metabolism, and clearance

Tropolone compounds can inhibit hepatitis B virus (HBV) replication at sub-micromolar levels and are synergistic upon co-treatment with nucleos(t)ide analog drugs. However, only a few compounds within this chemotype have been screened for their pharmacological properties. Here, we chose 36 structurally diverse tropolones from six subclasses to characterize their in vitro pharmacological parameters. All compounds were more soluble in pHs that reflect the gastrointestinal tract (pH 5 and 6.5) than plasma (pH 7.4). Those compounds that had solubility limits >100 μM were tested in a passive permeability assay, and there was no general trend in the compounds' passive permeability at any pH. Twenty-nine compounds with the best absorption parameters were tested in HEK293 cells to assess potential cytotoxicity; measured toxicities were similar to those in the hepatic HepDES19 cells used for screening (R2 = 0.55). Sixteen representative compounds were tested against five major CYP450 isoforms and there was no substantial inhibition by any compound against any of the enzymes tested (<50%). The t1/2 values of 15 compounds were determined in the microsome stability assay and 12 compounds were evaluated in plasma protein binding assays to assess factors affecting their rate of clearance. All compounds with detectable analyte peaks had t1/2 > 30 min, and while 4 of 12 had statistically significant decreased potency in conditions with increased albumin concentrations, only one compound's potency was biologically significant. These data indicate that the tropolones have pharmacological characteristics that reflect approved drugs and inform future structure activity relationships during drug design.

Overcoming biological barriers by virus-like drug particles for drug delivery

Virus-like particles (VLPs) have natural structural antigens similar to those found in viruses, making them valuable in vaccine immunization. Furthermore, VLPs have demonstrated significant potential in drug delivery, and emerged as promising vectors for transporting chemical drug, genetic drug, peptide/protein, and even nanoparticle drug. With virus-like permeability and strong retention, they can effectively target specific organs, tissues or cells, facilitating efficient intracellular drug release. Further modifications allow VLPs to transfer across various physiological barriers, thus acting the purpose of efficient drug delivery and accurate therapy. This article provides an overview of VLPs, covering their structural classifications, deliverable drugs, potential physiological barriers in drug delivery, strategies for overcoming these barriers, and future prospects.

Recent Developments in Metallic Degradable Micromotors for Biomedical and Environmental Remediation Applications

Synthetic micromotor has gained substantial attention in biomedicine and environmental remediation. Metal-based degradable micromotor composed of magnesium (Mg), zinc (Zn), and iron (Fe) have promise due to their nontoxic fuel-free propulsion, favorable biocompatibility, and safe excretion of degradation products Recent advances in degradable metallic micromotor have shown their fast movement in complex biological media, efficient cargo delivery and favorable biocompatibility. A noteworthy number of degradable metal-based micromotors employ bubble propulsion, utilizing water as fuel to generate hydrogen bubbles. This novel feature has projected degradable metallic micromotors for active in vivo drug delivery applications. In addition, understanding the degradation mechanism of these micromotors is also a key parameter for their design and performance. Its propulsion efficiency and life span govern the overall performance of a degradable metallic micromotor. Here we review the design and recent advancements of metallic degradable micromotors. Furthermore, we describe the controlled degradation, efficient in vivo drug delivery, and built-in acid neutralization capabilities of degradable micromotors with versatile biomedical applications. Moreover, we discuss micromotors' efficacy in detecting and destroying environmental pollutants. Finally, we address the limitations and future research directions of degradable metallic micromotors.

Smart pills and drug delivery devices enabling next generation oral dosage forms

Oral dosage forms are the preferred solution for systemic treatment and prevention of disease conditions. However, traditional dosage forms face challenges regarding treatment adherence and delivery of biologics. Oral therapies that require frequent administrations face difficulties with patient compliance. In addition, only a few peptide- and protein-based drugs have been commercialized for oral administration so far, presenting a bioavailability that is generally low. Therefore, research and development on novel formulation strategies for oral drug delivery has bloomed massively in the last decade to overcome these challenges. On the one hand, approaches based on lumen-release of drugs such as 3D-printed capsules and prolonged gastric residence dosage forms have been explored to offer personalized medicine to the patient and reduce frequent dosing of small drug compounds that are currently in the market as powdered tablet or capsules. On the other hand, strategies based on mucus interfacing such as gastrointestinal patches, or even epithelium injections have been investigated in order to enhance the permeability of biologic macromolecules, which are mostly commercialized in the form of subcutaneous injections. Despite the fact that these methods are at an early development stage, promising results have been revealed in terms of personalized medicine and improved bioavailability. In this review, we offer a critical overview of novel ingestible millimeter-sized devices and technologies for oral drug delivery that are currently used in the clinic as well as those that could emerge on the market in a not too distant future.

Boosting systemic absorption of peptides with a bioinspired buccal-stretching patch

Biopharmaceuticals, including proteins and peptides, have revolutionized the treatment of a wide range of diseases, from diabetes and cardiovascular disorders to virus infections and cancer. Despite their efficacy, most of these macromolecular drugs require parenteral administration because of their high molecular weight and relative instability. Over the past 40 years, only a few oral peptide drugs have entered clinical trials, even when formulated with substantial amounts of permeation enhancers. To overcome the epithelial barrier, devices that inject drugs directly into the gastrointestinal mucosa have been proposed recently. However, the robustness and safety of those complex systems are yet to be assessed. In this study, we introduced an innovative technology to boost drug absorption by synergistically combining noninvasive stretching of the buccal mucosa with permeation enhancers. Inspired by the unique structural features of octopus suckers, a self-applicable suction patch was engineered, enabling strong adhesion to and effective mechanical deformation of the mucosal tissue. In dogs, this suction patch achieved bioavailability up to two orders of magnitude higher than those of the commercial tablet formulation of desmopressin, a peptide drug known for its poor oral absorption. Moreover, systemic exposure comparable to that of the approved oral semaglutide tablet was achieved without further optimization. Last, a first-in-human study involving 40 healthy participants confirmed the dosage form's acceptability, thereby supporting the clinical translatability of this simple yet effective platform technology.

Current Understanding of Sodium N-(8-[2-Hydroxylbenzoyl] Amino) Caprylate (SNAC) as an Absorption Enhancer: The Oral Semaglutide Experience

Oral administration of peptide therapeutics faces challenges because of the distinct environment of the gastrointestinal tract. An oral formulation of semaglutide, a glucagon-like peptide 1 receptor agonist, was approved by the U.S. Food and Drug Administration in 2019 as a peptide therapy for the treatment of type 2 diabetes. Oral semaglutide uses sodium N-(8-[2-hydroxybenzoyl] amino) caprylate (SNAC) technology to enhance the absorption of semaglutide in the stomach and protect it from degradation by gastric enzymes. This article presents a summary of studies investigating SNAC technology as an absorption enhancer for a number of molecules and, in particular, explores how SNAC, once coformulated with oral semaglutide, facilitates increased absorption and bioavailability. Practical advice and dispensing information for pharmacists is also provided.

Challenges and opportunities in delivering oral peptides and proteins

INTRODUCTION

Rapid advances in bioengineering enable the use of complex proteins as therapeutic agents to treat diseases. Compared with conventional small molecule drugs, proteins have multiple advantages, including high bioactivity and specificity with low toxicity. Developing oral dosage forms with active proteins is a route to improve patient compliance and significantly reduce production costs. However, the gastrointestinal environment remains a challenge to this delivery path due to enzymatic degradation, low permeability, and weak absorption, leading to reduced delivery efficiency and poor clinical outcomes.

AREAS COVERED

This review describes the barriers to oral delivery of peptides and complex proteins, current oral delivery strategies utilized and the opportunities and challenges ahead to try and circumvent these barriers. Oral protein drugs on the market and clinical trials provide insights and approaches for advancing delivery strategies.

EXPERT OPINION

Although most current studies on oral protein delivery rely on in vitro and in vivo animal data, the safety and limitations of the approach in humans remain uncertain. The shortage of clinical data limits the development of new or alternative strategies. Therefore, designing appropriate oral delivery strategies remains a significant challenge and requires new ideas, innovative design strategies and novel model systems.

Untethered shape-changing devices in the gastrointestinal tract

INTRODUCTION

Advances in microfabrication, automation, and computer engineering seek to revolutionize small-scale devices and machines. Emerging trends in medicine point to smart devices that emulate the motility, biosensing abilities, and intelligence of cells and pathogens that inhabit the human body. Two important characteristics of smart medical devices are the capability to be deployed in small conduits, which necessitates being untethered, and the capacity to perform mechanized functions, which requires autonomous shape-changing.

AREAS COVERED

We motivate the need for untethered shape-changing devices in the gastrointestinal tract for drug delivery, diagnosis, and targeted treatment. We survey existing structures and devices designed and utilized across length scales from the macro to the sub-millimeter. These devices range from triggerable pre-stressed thin film microgrippers and spring-loaded devices to shape-memory and differentially swelling structures.

EXPERT OPINION

Recent studies demonstrate that when fully enabled, tether-free and shape-changing devices, especially at sub-mm scales, could significantly advance the diagnosis and treatment of GI diseases ranging from cancer and inflammatory bowel disease (IBD) to irritable bowel syndrome (IBS) by improving treatment efficacy, reducing costs, and increasing medication compliance. We discuss the challenges and possibilities associated with ensuring safe, reliable, and autonomous operation of these smart devices.

Protamine-mediated efficient transcellular and transmucosal delivery of proteins

Proteins and peptides often require frequent needle-based administrations. Here, we report a non-parenteral delivery method for proteins through physical mixing with protamine, an FDA-approved peptide. Protamine was shown to promote tubulation and rearrangement of cellular actin, leading to enhanced intracellular delivery of proteins compared to poly(arginine)₈ (R8). While the R8-mediated delivery resulted in significant lysosomal accumulation of the cargo, protamine directed the proteins to the nuclei with little lysosomal uptake. Intranasal delivery of insulin mixed with protamine effectively reduced blood glucose levels in diabetic mice 0.5 h after administration and the effect lasted for ∼6 h, comparable to subcutaneously injected insulin at the same dose. In mice, protamine was shown to overcome mucosal and epithelial barriers and modulate adherens junctions, promoting insulin penetration to the lamina propria layer for systemic absorption.

Mesoporous silica nanoparticles with chiral pattern topological structure function as “antiskid tires” on the intestinal mucosa to facilitate oral drugs delivery

The weak adhesion between nanocarriers and the intestinal mucosa was one of the main reasons caused the failure in oral delivery. Inspired by the "antiskid tires" with complex chiral patterns, mesoporous silica nanoparticles AT-R@CMSN exhibiting geometrical chiral structure were designed to improve the surface/interface roughness in nanoscale, and employed as the hosting system for insoluble drugs nimesulide (NMS) and ibuprofen (IBU). Once performing the delivery tasks, AT-R@CMSN with rigid skeleton protected the loaded drug and reduced the irritation of drug on gastrointestinal tract (GIT), while their porous structure deprived drug crystal and improved drug release. More importantly, AT-R@CMSN functioned as "antiskid tire" to produce higher friction on intestinal mucosa and substantively influenced multiple biological processes, including "contact", "adhesion", "retention", "permeation" and "uptake", compared to the achiral S@MSN, thereby improving the oral adsorption effectiveness of such drug delivery systems. By engineering AT-R@CMSN to overcome the stability, solubility and permeability bottlenecks of drugs, orally administered NMS or IBU loaded AT-R@CMSN could achieve higher relative bioavailability (705.95% and 444.42%, respectively) and stronger anti-inflammation effect. In addition, AT-R@CMSN displayed favorable biocompatibility and biodegradability. Undoubtedly, the present finding helped to understand the oral adsorption process of nanocarriers, and provided novel insights into the rational design of nanocarriers.

Oral nano-formulation improves pancreatic islets dysfunction via lymphatic transport for antidiabetic treatment

Type 2 diabetes mellitus (T2DM) therapy is facing the challenges of long-term medication and gradual destruction of pancreatic islet β-cells. Therefore, it is timely to develop oral prolonged action formulations to improve compliance, while restoring β-cells survival and function. Herein, we designed a simple nanoparticle with enhanced oral absorption and pancreas accumulation property, which combined apical sodium-dependent bile acid transporter-mediated intestinal uptake and lymphatic transportation. In this system, taurocholic acid (TCA) modified poly(lactic-co-glycolic acid) (PLGA) was employed to achieve pancreas location, hydroxychloroquine (HCQ) was loaded to execute therapeutic efficacy, and 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) was introduced as stabilizer together with synergist (PLGA-TCA/DLPC/HCQ). In vitro and in vivo results have proven that PLGA-TCA/DLPC/HCQ reversed the pancreatic islets damage and dysfunction, thus impeding hyperglycemia progression and restoring systemic glucose homeostasis via only once administration every day. In terms of mechanism PLGA-TCA/DLPC/HCQ ameliorated oxidative stress, remodeled the inflammatory pancreas microenvironment, and activated PI3K/AKT signaling pathway without obvious toxicity. This strategy not only provides an oral delivery platform for increasing absorption and pancreas targetability but also opens a new avenue for thorough T2DM treatment.

Magnetically Driven Muco-Inert Janus Nanovehicles for Enhanced Mucus Penetration and Cellular Uptake

One of the main challenges of transmucosal drug delivery is that of enabling particles and molecules to move across the mucosal barrier of the mucosal epithelial surface. Inspired by nanovehicles and mucus-penetrating nanoparticles, a magnetically driven, mucus-inert Janus-type nanovehicle (Janus-MMSN-pCB) was fabricated by coating the zwitterionic polymer poly(carboxybetaine methacrylate) (pCB) on the mesoporous silica nanorod, which was grown on one side of superparamagnetic Fe3O4 nanoparticle using the sol–gel method. X-ray diffraction, transmission electron microscopy, vibrating sample magnetometry, and Fourier infrared spectroscopy were used to characterize the structure and morphology of the nanovehicles, proving the success of each synthesis step. The in vitro cell viability assessment of these composites using Calu-3 cell lines indicates that the nanovehicles are biocompatible in nature. Furthermore, the multiparticle tracking, Transwell® system, and cell imaging experimental results demonstrate that both the modification of pCB and the application of a magnetic field effectively accelerated the diffusion of the nanovehicles in the mucus and improved the endocytosis through Calu-3. The favorable cell uptake performance of Janus-MMSN-pCB in mucus systems with/without magnetic driving proves its potential role in the diagnosis, treatment, and imaging of mucosal-related diseases.

RoboCap: Robotic mucus-clearing capsule for enhanced drug delivery in the gastrointestinal tract

Oral drug delivery of proteins is limited by the degradative environment of the gastrointestinal tract and poor absorption, requiring parenteral administration of these drugs. Luminal mucus represents the initial steric and dynamic barrier to absorption. To overcome this barrier, we report the development of the RoboCap, an orally ingestible, robotic drug delivery capsule that locally clears the mucus layer, enhances luminal mixing, and topically deposits the drug payload in the small intestine to enhance drug absorption. RoboCap's mucus-clearing and churning movements are facilitated by an internal motor and by surface features that interact with small intestinal plicae circulares, villi, and mucus. Vancomycin (1.4 kilodaltons of glycopeptide) and insulin (5.8 kilodaltons of peptide) delivery mediated by RoboCap resulted in enhanced bioavailability 20- to 40-fold greater in ex vivo and in vivo swine models when compared with standard oral delivery (P < 0.05). Further, insulin delivery via the RoboCap resulted in therapeutic hypoglycemia, supporting its potential to facilitate oral delivery of drugs that are normally precluded by absorption limitations.

Poly (maleic anhydride-alt-1-octadecene)-based bioadhesive nanovehicles improve oral bioavailability of poor water-soluble gefitinib

The poor water solubility and inadequate oral bioavailability of gefitinib (Gef) remains a critical issue to achieve the therapeutic outcomes. Herein, we designed a poly (maleic anhydride-alt-1-octadecene) (PMA/C18) based lipid nanovehicle (PLN) to improve the intestinal absorption and oral bioavailability of poorly water-soluble Gef. PLN was nanometer-sized particles, and Gef was dispersed in the PLN formulation as amorphous or molecular state. At 4 h of oral administration, the tissue concentration of Gef in duodenum, jejunum and ileum was profoundly enhanced 3.37-, 8.94- and 8.09-fold by PLN when comparing to the counterpart lipid nanovehicle. Moreover, the oral bioavailability of Gef was significantly enhanced 2.48-fold by the PLN formulation when comparing to the free drug suspension. Therefore, this study provides an encouraging bioadhesive delivery platform to improve the oral delivery of poorly water-soluble drugs.

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.

An insight into gastrointestinal macromolecule delivery using physical oral devices

Oral delivery is preferred over other routes of drug administration by both patients and physicians. The bioavailability of some therapeutics that are delivered via the oral route is restricted due to the protease- and bacteria-rich environment in the gastrointestinal tract, and by the pH variability along the delivery route. Given these harsh environments, the oral delivery of therapeutic macromolecules is complicated and remains challenging. Various formulation approaches, including the use of permeation enhancers and nanosized carriers, as well as chemical alteration of the drug structure, have been studied as ways to improve the oral absorption of macromolecular drugs. Nevertheless, the bioavailability of marketed oral peptide medicines is often relatively poor. This review highlights the most recent and promising physical methods for improving the oral bioavailability of macromolecules such as peptides. These methods include microneedle injections, high-speed stream injectors, magnetic drug targeting, expandable hydrogels, and iontophoresis. We highlight the potential and challenges of these new technologies, which may impact the future approaches used by pharmaceutical companies to create more efficient and safer orally administered macromolecules. Teaser: Despite substantial effort, the oral delivery of macromolecules remains challenging due to their low bioavailability. This review discusses the potential, challenges, and safety concerns associated with new technologies and devices for oral macromolecule delivery.