Non-invasive delivery strategies for biologics

Tailor-Made Fluorinated Ionic Liquids for Protein Delivery

Nowadays, pharmaceutical companies are facing several challenges with the development and approval of new biological products. The unique properties of several fluorinated ionic liquids (FILs), such as their high surfactant power in aqueous solutions, their chemical and biological stability, and low toxicity, favor their application in the pharmaceutical industry. Furthermore, the numerous combinations between cations and anions, in the FILs design, enlarge the possibilities to construct a successful delivery system. Several FILs also proved to not affect the activity, stability, and secondary structure of the therapeutic protein lysozyme. This work aims to study the aggregation behavior of distinct FILs in the protein suitable medium, in the presence or absence of lysozyme. Besides, different incubation conditions were tested to guarantee the optimal enzymatic activity of the protein at more stable delivery systems. Following the optimization of the incubation conditions, the quantification of the encapsulated lysozyme was performed to evaluate the encapsulation efficiency of each FIL-based system. The release of the protein was tested applying variables such as time, temperature, and ultrasound frequency. The experimental results suggest that the aggregation behavior of FILs is not significantly influenced by the protein and/or protein buffer and supports their application for the design of delivery systems with high encapsulation efficiencies, maintaining the biological activity of either encapsulated and released protein.

Preparation and Evaluation of 6-Maleimidohexanoic Acid Grafted Chitosan Nanoparticles as a Novel Carrier for Intranasal Protein Delivery

In this study, 6-maleimidohexanoic acid grafted chitosan nanoparticles (MHA-CS NPs) were prepared and evaluated the efficiency of intranasal protein delivery as compared with well-known chitosan nanoparticles (CS NPs). Fluorescein isothiocyanate labelled with bovine serum albumin (FITC-BSA) was used as a model protein. The results indicated that both CS NPs and MHA-CS NPs were positively charged NPs before and after protein loading. The condition for optimal protein loading was 1:6 mass ratio of protein/NPs at 1 h incubation period. The optimal formulations of CS NPs and MHA-CS NPs were evaluated on porcine mucosa as ex vivo. The mucoadhesive and permeation properties of FITC-BSA loaded MHA-CS NPs showed a greater than FITC-BSA loaded CS NPs and FITC-BSA solution, respectively. These ex vivo studies present the potential of MHA-CS NPs as a novel carrier for intranasal protein delivery that will be a candidate for in vivo study.

A single molecular descriptor to predict solution behavior of therapeutic antibodies

Despite the therapeutic success of monoclonal antibodies (mAbs), early identification of developable mAb drug candidates with optimal manufacturability, stability, and delivery attributes remains elusive. Poor solution behavior, which manifests as high solution viscosity or opalescence, profoundly affects the developability of mAb drugs. Using a diverse dataset of 59 mAbs, including 43 approved products, and an array of molecular descriptors spanning colloidal, conformational, charge-based, hydrodynamic, and hydrophobic properties, we show that poor solution behavior is prevalent (>30%) in mAbs and is singularly predicted (>90%) by the diffusion interaction parameter (k _D), a dilute-solution measure of colloidal self-interaction. No other descriptor, individually or in combination, was found to be as effective as k _D. We also show that well-behaved mAbs, a substantial subset of which bear high positive charge and pI, present no disadvantages with respect to pharmacokinetics in humans. Here, we provide a systematic framework with quantitative thresholds for selecting well-behaved therapeutic mAbs during drug discovery.

Spray Drying for the Preparation of Nanoparticle-Based Drug Formulations as Dry Powders for Inhalation

Nanoparticle-based therapeutics have been used in pulmonary formulations to enhance delivery of poorly water-soluble drugs, protect drugs against degradation and achieve modified release and drug targeting. This review focuses on the use of spray drying as a solidification technique to produce microparticles containing nanoparticles (i.e., nanoparticle (NP) agglomerates) with suitable properties as dry powders for inhalation. The review covers the general aspects of pulmonary drug delivery with emphasis on nanoparticle-based dry powders for inhalation and the principles of spray drying as a method for the conversion of nanosuspensions to microparticles. The production and therapeutic applications of the following types of NP agglomerates are presented: nanoporous microparticles, nanocrystalline agglomerates, lipid-based and polymeric formulations. The use of alternative spray-drying techniques, namely nano spray drying, and supercritical CO2-assisted spray drying is also discussed as a way to produce inhalable NP agglomerates.

Noninvasive transdermal delivery of liposomes by weak electric current

Noninvasive transdermal drug delivery (NTDD) offers an exciting new method of administration relative to conventional routes, but is associated with some challenges. Liposomes are capable of encapsulating transdermally-unfavorable drugs. However, the horny layer of skin is a significant barrier that limits efficient transdermal delivery of liposomes. Iontophoresis using weak electric current (WEC) represents a NTDD technology. WEC treatment of liposomes applied to the skin surface improves transdermal penetration of encapsulated drugs by cooperative effects. In this review, we provide an overview of the application of WEC/liposomes for transdermal delivery of macromolecules and low molecular weight drugs. We compare the transdermal delivery and therapeutic efficiency of the combined system with conventional routes of administration and their individual use. We discuss a novel perspective on the mechanism of WEC-mediated transdermal delivery of liposomes, which suggests that WEC activates the intracellular signaling pathway for transdermal permeation and induces unique endocytosis in skin cells.

Using First Principles to Link Silicone Oil/Formulation Interfacial Tension With Syringe Functionality in Pre-Filled Syringes Systems

Numerous interactions can arise at the interface between the glass barrel/silicone oil coating/aqueous formulation in pre-filled syringes that can affect the functionality of the medical device. In this study, the Young-Dupré equation was applied at these interfaces to correlate the interfacial tension between the silicone oil coating and aqueous formulation to the functionality of the syringe. It was shown that lower silicone oil/drug product formulation interfacial tension led to an increase in the glide force of the syringe. The relationship between glide force profiles and silicone oil thickness after injection was also investigated and the data revealed that the silicone oil was removed at the end of the syringe barrel when the formulation contains polysorbate 80.

Generic high-capacity protein capture and release by pH control

Techniques for immobilization and release of proteins are of general interest but challenging to develop. Here we show a new method for high-capacity (several μg cm^-2) immobilization of proteins in polyelectrolyte brushes by multivalent hydrogen bonds. Upon increasing pH, the proteins are fully released with preserved structure and activity.

Bioinspired oral delivery of gut microbiota by self-coating with biofilms

Transplanting beneficial bacteria to the gut microbiome can positively modulate the bacterial composition and remains of great interest in prevention and treatment. However, environmental assaults and rapid transit times in the gastrointestinal (GI) tract result in low oral bioavailability and limited intestinal colonization. Here, we describe a bioinspired strategy of self-coating with biofilms that endows the transplanted gut microbiota with superior resistance and adhesion capacity. Using clinical Bacillus subtilis as a model probiotic bacterium, biofilm-coated probiotics demonstrate substantially improved GI tract tolerance and mucoadhesion in mice and swine. In particular, coated probiotics exhibit a 125-fold higher oral bioavailability and a 17 times greater intestinal colonization than uncoated bacteria in the porcine model. With notable ability to survive and reside in the GI tract, coated bacteria further show a significantly enhanced decolonization effect in mice colonized with Staphylococcus aureus. Self-coating with biofilms suggests a robust platform for oral doses of gut microbiota.

Biodegradable β-Cyclodextrin Conjugated Gelatin Methacryloyl Microneedle for Delivery of Water-Insoluble Drug

Transdermal delivery of water-insoluble drugs via hydrogel-based microneedle (MN) arrays is crucial for improving their therapeutic efficacies. However, direct loading of water-insoluble drug into hydrophilic matrices remains challenging. Here, a biodegradable MN array patch that is fabricated from naturally derived polymer conjugates of gelatin methacryloyl and β-cyclodextrin (GelMA-β-CD) is reported. When curcumin, an unstable and water-insoluble anticancer drug, is loaded as a model drug, its stability and solubility are improved due to the formation of an inclusion complex. The polymer-drug complex GelMA-β-CD/CUR can be formulated into MN arrays with sufficient mechanical strength for skin penetration and tunable drug release profile. Anticancer efficacy of released curcumin is observed in three-dimensional B16F10 melanoma models. The GelMA-β-CD/CUR MN exhibits relatively higher therapeutic efficacy through more localized and deeper penetrated manner compared with a control nontransdermal patch. In vivo studies also verify biocompatibility and degradability of the GelMA-β-CD MN arrays patch.

Systemic delivery of peptides by the oral route: Formulation and medicinal chemistry approaches

In its 33 years, ADDR has published regularly on the po5tential of oral delivery of biologics especially peptides and proteins. In the intervening period, analysis of the preclinical and clinical trial failures of many purported platform technologies has led to reflection on the true status of the field and reigning in of expectations. Oral formulations of semaglutide, octreotide, and salmon calcitonin have completed Phase III trials, with oral semaglutide being approved by the FDA in 2019. The progress made with oral peptide formulations based on traditional permeation enhancers is against a background of low and variable oral bioavailability values of ~1%, leading to a current perception that only potent peptides with a viable cost of synthesis can be realistically considered. Desirable features of candidates should include a large therapeutic index, some stability in the GI tract, a long elimination half-life, and a relatively low clearance rate. Administration in nanoparticle formats have largely disappointed, with few prototypes reaching clinical trials: insufficient particle loading, lack of controlled release, low epithelial particle uptake, and lack of scalable synthesis being the main reasons for discontinuation. Disruptive technologies based on engineered devices promise improvements, but scale-up and toxicology aspects are issues to address. In parallel, medicinal chemists are synthesizing stable hydrophobic macrocyclic candidate peptides of lower molecular weight and with potential for greater oral bioavailability than linear peptides, but perhaps without the same requirement for elaborate drug delivery systems. In summary, while there have been advances in understanding the limitations of peptides for oral delivery, low membrane permeability, metabolism, and high clearance rates continue to hamper progress.

Extending the small-molecule similarity principle to all levels of biology with the Chemical Checker

Small molecules are usually compared by their chemical structure, but there is no unified analytic framework for representing and comparing their biological activity. We present the Chemical Checker (CC), which provides processed, harmonized and integrated bioactivity data on ~800,000 small molecules. The CC divides data into five levels of increasing complexity, from the chemical properties of compounds to their clinical outcomes. In between, it includes targets, off-targets, networks and cell-level information, such as omics data, growth inhibition and morphology. Bioactivity data are expressed in a vector format, extending the concept of chemical similarity to similarity between bioactivity signatures. We show how CC signatures can aid drug discovery tasks, including target identification and library characterization. We also demonstrate the discovery of compounds that reverse and mimic biological signatures of disease models and genetic perturbations in cases that could not be addressed using chemical information alone. Overall, the CC signatures facilitate the conversion of bioactivity data to a format that is readily amenable to machine learning methods.

Orally ingestible medical devices for gut engineering

Orally ingestible medical devices provide significant advancement for diagnosis and treatment of gastrointestinal (GI) tract-related conditions. From micro- to macroscale devices, with designs ranging from very simple to complex, these medical devices can be used for site-directed drug delivery in the GI tract, real-time imaging and sensing of gut biomarkers. Equipped with uni-direction release, or self-propulsion, or origami design, these microdevices are breaking the barriers associated with drug delivery, including biologics, across the GI tract. Further, on-board microelectronics allow imaging and sensing of gut tissue and biomarkers, providing a more comprehensive understanding of underlying pathophysiological conditions. We provide an overview of recent advances in orally ingestible medical devices towards drug delivery, imaging and sensing. Challenges associated with gut microenvironment, together with various activation/actuation modalities of medical devices for micromanipulation of the gut are discussed. We have critically examined the relationship between materials–device design–pharmacological responses with respect to existing regulatory guidelines and provided a clear roadmap for the future.

Formulation technologies and advances for oral delivery of novel nitroimidazoles and antimicrobial peptides

Antibiotic resistance has become a global crisis, driving the exploration for novel antibiotics and novel treatment approaches. Among these research efforts two classes of antibiotics, bicyclic nitroimidazoles and antimicrobial peptides, have recently shown promise as novel antimicrobial agents with the possibility to treat multi-drug resistant infections. However, they suffer from the issue of poor oral bioavailability due to disparate factors: low solubility in the case of nitroimidazoles (BCS class II drugs), and low permeability in the case of peptides (BCS class III drugs). Moreover, antimicrobial peptides present another challenge as they are susceptible to chemical and enzymatic degradation, which can present an additional pharmacokinetic hurdle for their oral bioavailability. Formulation technologies offer a potential means for improving the oral bioavailability of poorly permeable and poorly soluble drugs, but there are still drawbacks and limitations associated with this approach. This review discusses in depth the challenges associated with oral delivery of nitroimidazoles and antimicrobial peptides and the formulation technologies that have been used to overcome these problems, including an assessment of the drawbacks and limitations associated with the technologies that have been applied. Furthermore, the potential for supercritical fluid technology to overcome the shortcomings associated with conventional drug formulation methods is reviewed.

Rapidly dissolving microneedle patch for synergistic gene and photothermal therapy of subcutaneous tumor

The synergistic combination of gene therapy and photothermal therapy (PTT) has been widely investigated as a promising strategy for cancer treatment. To deliver genes and photothermal agents simultaneously and accurately to a tumor site, a microneedle (MN) patch co-loaded with p53 DNA and IR820 was fabricated by a two-step casting method. Hyaluronic acid was chosen as a matrix and p53 DNA and IR820 were mainly loaded into the tips to enhance utilization and reduce waste. The MN patch could efficiently penetrate the stratum corneum, and dissolve rapidly to release p53 DNA and IR820 in the subcutaneous tumor site. Due to the efficient photothermal efficacy of IR820, the temperature of the tumor site where the MN patch was applied increased by 14.7 °C under near-infrared light irradiation. The MN patch showed excellent antitumor effects in vivo owing to the synergistic effect of gene therapy and PTT. Consequently, the p53 DNA/IR820 MN patch may be a promising synergistic strategy for subcutaneous tumor treatments.

Influence of molecular weight on transdermal delivery of model macromolecules using hydrogel-forming microneedles: potential to enhance the administration of novel low molecular weight biotherapeutics

With a view to improve the current monoclonal antibody-based therapies dominating the pharmaceutical market, low molecular weight (MW) protein-based macromolecules, such as recombinant antibody fragments, typically within the range of 10-70 kDa, have been developed. Previously, our group successfully delivered Avastin®, a monoclonal antibody (mAb) across the skin using hydrogel-forming microneedles (MN). However, it is thought that this delivery system can be further enhanced using novel, lower MW biomolecules. To address this perception, in the current study, FITC-dextran of different MWs (10, 70 and 150 kDa) was used to model the transdermal delivery of low MW biotherapeutics and mAbs with MWs of approximately 150 kDa. Conversely, fluorescein sodium was the compound selected to model hydrophilic, low MW drugs. As expected, fluorescein sodium produced the greatest cumulative permeation (637.4 ± 42.69 μg). The amounts of FITC-dextran 10 kDa and 150 kDa which permeated across neonatal porcine skin in vitro were 462.17 ± 65.85 μg and 213.54 ± 15.19 μg after 24 h, respectively. The results collated here suggest that the delivery of emerging novel biotherapeutics, via'super swelling' hydrogel-forming MNs, have the potential to result in greater permeation across human skin, compared to the delivery of mAbs delivered via the same route.

Flame-Made Calcium Phosphate Nanoparticles with High Drug Loading for Delivery of Biologics

Nanoparticles exhibit potential as drug carriers in biomedicine due to their high surface-to-volume ratio that allows for facile drug loading. Nanosized drug delivery systems have been proposed for the delivery of biologics facilitating their transport across epithelial layers and maintaining their stability against proteolytic degradation. Here, we capitalize on a nanomanufacturing process famous for its scalability and reproducibility, flame spray pyrolysis, and produce calcium phosphate (CaP) nanoparticles with tailored properties. The as-prepared nanoparticles are loaded with bovine serum albumin (model protein) and bradykinin (model peptide) by physisorption and the physicochemical parameters influencing their loading capacity are investigated. Furthermore, we implement the developed protocol by formulating CaP nanoparticles loaded with the LL-37 antimicrobial peptide, which is a biological drug currently involved in clinical trials. High loading values along with high reproducibility are achieved. Moreover, it is shown that CaP nanoparticles protect LL-37 from proteolysis in vitro. We also demonstrate that LL-37 retains its antimicrobial activity against Escherichia coli and Streptococcus pneumoniae when loaded on nanoparticles in vitro. Therefore, we highlight the potential of nanocarriers for optimization of the therapeutic profile of existing and emerging biological drugs.

Electrothermal patches driving the transdermal delivery of insulin

Transdermal patches have become a widely used approach for painless delivery of drugs. One major current limitation of these systems remains the restricted skin permeation of proteins and peptides as exemplified by insulin, necessitating different considerations for their successful transdermal delivery. We present a novel patch design based on the integration of nano-engineered heating elements on polyimide substrates for electrothermal transdermal therapy. The results reveal that tuning of the electrical resistivity of an array of gold nanoholes, patterned on polyimide, facilitates a fast-responding electrothermal skin patch, while post-coating with reduced graphene oxide offers capabilities for drug encapsulation, like insulin. Application of insulin-loaded patches to the skin of mice resulted in blood glucose regulation within minutes. While demonstrated for insulin, the skin patches might be well adapted to other low and high molecular weight therapeutic drugs, enabling on-demand electrothermal transdermal delivery.

Design and Characterizations of Inhalable Poly(lactic-co-glycolic acid) Microspheres Prepared by the Fine Droplet Drying Process for a Sustained Effect of Salmon Calcitonin

The present study aimed to develop inhalable poly (lactic-co-glycolic acid) (PLGA)-based microparticles of salmon calcitonin (sCT) for sustained pharmacological action by the fine droplet drying (FDD) process, a novel powderization technique employing printing technologies. PLGA was selected as a biodegradable carrier polymer for sustained-release particles of sCT (sCT/SR), and physicochemical characterizations of sCT/SR were conducted. To estimate the in vivo efficacy of the sCT/SR respirable powder (sCT/SR-RP), plasma calcium levels were measured after intratracheal administration in rats. The particle size of sCT/SR was 3.6 µm, and the SPAN factor, one of the parameters to present the uniformity of particle size distribution, was calculated to be 0.65. In the evaluation of the conformational structure of sCT, no significant changes were observed in sCT/SR even after the FDD process. The drug release from sCT/SR showed a biphasic pattern with an initial burst and slow diffusion in simulated lung fluid. sCT/SR-RP showed fine inhalation performance, as evidenced by a fine particle fraction value of 28% in the cascade impactor analysis. After the insufflation of sCT samples (40 µg-sCT/kg) in rats, sCT/SR-RP could enhance and prolong the hypocalcemic action of sCT possibly due to the sustained release and pulmonary absorption of sCT. From these observations, the strategic application of the FDD process could be efficacious to provide PLGA-based inhalable formulations of sCT, as well as other therapeutic peptides, to enhance their biopharmaceutical potentials.

Polymeric Films for the Encapsulation, Storage, and Tunable Release of Therapeutic Microbes

Microbe-based therapeutics (MBTs) are an emerging therapeutic modality for treating gastrointestinal infections and inflammatory bowel diseases. Current formulations for oral delivery of MBTs use capsules to achieve safe gastric transit, but oral formulations that control the spatiotemporal concentration of MBTs are yet to be developed, despite well-established connections between all therapeutics and their location, concentration, and distribution at sites of action. The development of a multi-functional polymer-based encapsulation system to formulate MBTs for enhanced storage and delivery through formulation of a model MBT, Lactobacillus casei ATCC393, is reported here. This approach enables the additive inclusion of excipients and polymers to grant specific functions, toward the development of a modular MBT platform. Through addition of established excipients, the formulation provides long-term storage of the encapsulated MBT. By adding higher molecular weight polymers, the release kinetics of the encapsulated MBTs can be modified. The inclusion of a mucoadhesive polymer significantly increases the adhesion force between the formulation and the intestinal tissue. Together, mucoadhesive and sustained release properties can be used to modulate the spatiotemporal concentration of MBTs. The formulation is compatible with standard oral capsules, thus maintaining existing clinical advantages of oral capsules while providing new functions from film encapsulation.

Systematic Review of Device Parameters and Design of Studies Bridging Biologic-Device Combination Products Using Prefilled Syringes and Autoinjectors

Biologic-device combination products using prefilled syringes (PFSs) and autoinjectors (AIs) are popular for biological products administered subcutaneously. Pharmacokinetic (PK) comparability studies commonly provide the scientific data to support introduction of AI presentations via bridging with PFS. A survey of biological products approved by FDA's Center for Drug Evaluation and Research identified 17 biologics license applications (BLAs) with both PFS and AI presentations for subcutaneous (SC) administration, including 16 approved on February 1, 2018, and one with AI presentation under review. A systematic review on the device parameters and the PK comparability studies bridging the two presentations was conducted. Subsequently, whether device parameters or the PK study design may have influenced the PK comparability study results was evaluated. The reported device parameters for AI and PFS are generally consistent across BLAs, whereas the approach to assess PK comparability varied, including the study design. Most PK comparability studies met bioequivalence (BE) criteria. Upon inspection of the studies that did not meet BE criteria, injection depth of AI and the injection site for either AI or PFS were identified as potential influencing factors to the outcome of PK comparability study. This study represents an initial attempt to identify the potential influencing factors on device bridging, including the characteristics of the device and the clinical pharmacology study. These findings may inform the combination product development strategy, specifically design considerations for device and PK comparability studies.

Flash Fabrication of Orally Targeted Nanocomplexes for Improved Transport of Salmon Calcitonin across the Intestine

Salmon calcitonin (sCT) is a potent calcium-regulating peptide hormone and widely applied for the treatment of some bone diseases clinically. However, the therapeutic usefulness of sCT is hindered by the frequent injection required, owing to its short plasma half-life and therapeutic need for a high dose. Oral delivery is a popular modality of administration for patients because of its convenience to self-administration and high patient compliance, while orally administered sCT remains a great challenge currently due to the existence of multiple barriers in the gastrointestinal (GI) tract. Here, we introduced an orally targeted delivery system to increase the transport of sCT across the intestine through both the paracellular permeation route and the bile acid pathway. In this system, sCT-based glycol chitosan-taurocholic acid conjugate (GC-T)/dextran sulfate (DS) ternary nanocomplexes (NC-T) were produced by a flash nanocomplexation (FNC) process in a kinetically controlled mode. The optimized NC-T exhibited well-controlled properties with a uniform and sub-60 nm hydrodynamic diameter, high batch-to-batch reproducibility, good physical or chemical stability, as well as sustained drug release behaviors. The studies revealed that NC-T could effectively improve the intestinal uptake and permeability, owing to its surface functionalization with the taurocholic acid ligand. In the rat model, orally administered NC-T showed an obvious hypocalcemia effect and a relative oral bioavailability of 10.9%. An in vivo assay also demonstrated that NC-T induced no observable side effect after long-term oral administration. As a result, the orally targeted nanocomplex might be a promising candidate for improving the oral transport of therapeutic peptides.

Particle diffusion in extracellular hydrogels

Hyaluronic acid is an abundant polyelectrolyte in the human body that forms extracellular hydrogels in connective tissues. It is essential for regulating tissue biomechanics and cell-cell communication, yet hyaluronan overexpression is associated with pathological situations such as cancer and multiple sclerosis. Due to its enormous molecular weight (in the range of millions of Daltons), accumulation of hyaluronan hinders transport of macromolecules including nutrients and growth factors through tissues and also hampers drug delivery. However, the exact contribution of hyaluronan to tissue penetrability is poorly understood due to the complex structure and molecular composition of tissues. Here we reconstitute biomimetic hyaluronan gels and systematically investigate the effects of gel composition and crosslinking on the diffusion of microscopic tracer particles. We combine ensemble-averaged measurements via differential dynamic microscopy with single-particle tracking. We show that the particle diffusivity depends on the particle size relative to the network pore size and also on the stress relaxation dynamics of the network. We furthermore show that addition of collagen, the other major biopolymer in tissues, causes the emergence of caged particle dynamics. Our findings are useful for understanding macromolecular transport in tissues and for designing biomimetic extracellular matrix hydrogels for drug delivery and tissue regeneration.

Silica-Coated Nanoparticles with a Core of Zinc, l-Arginine, and a Peptide Designed for Oral Delivery

Nanoparticle constructs for oral peptide delivery at a minimum must protect and present the peptide at the small intestinal epithelium in order to achieve oral bioavailability. In a reproducible, scalable, surfactant-free process, a core was formed with insulin in ratios with two established excipients and stabilizers, zinc chloride and l-arginine. Cross-linking was achieved with silica, which formed an outer shell. The process was reproducible across several batches, and physicochemical characterization of a single batch was confirmed in two independent laboratories. The silica-coated nanoparticles (SiNPs) entrapped insulin with high entrapment efficiency, preserved its structure, and released it at a pH value present in the small intestine. The SiNP delivered insulin to the circulation and reduced plasma glucose in a rat jejunal instillation model. The delivery mechanism required residual l-arginine in the particle to act as a permeation enhancer for SiNP-released insulin in the jejunum. The synthetic process was varied in terms of ratios of zinc chloride and l-arginine in the core to entrap the glucagon-like peptide 1 analogue, exenatide, and bovine serum albumin. SiNP-delivered exenatide was also bioactive in mice to some extent following oral gavage. The process is the basis for a platform for oral peptide and protein delivery.

Hydrogel-Based Controlled Drug Delivery for Cancer Treatment: A Review

As an emerging drug carrier, hydrogels have been widely used for tumor drug delivery. A hydrogel drug carrier can cause less severe side effects than systemic chemotherapy and can achieve sustained delivery of a drug at tumor sites. In addition, hydrogels have excellent biocompatibility and biodegradability and lower toxicity than nanoparticle carriers. Smart hydrogels can respond to stimuli in the environment (e.g., heat, pH, light, and ultrasound), enabling in situ gelation and controlled drug release, which greatly enhance the convenience and efficiency of drug delivery. Here, we summarize the different sizes of hydrogels used for cancer treatment and their related delivery routes, discuss the design strategies for stimuli-responsive hydrogels, and review the research concerning smart hydrogels reported in the past few years.

An improved synthesis of poly(amidoamine)s for complexation with self-amplifying RNA and effective transfection

Aza-Michael addition to synthesise poly(amidoamines) was optimised to minimise appearance of bimodal molecular weight distributions caused by a radical-branching side-reaction. This significantly improved cellular delivery of a model self-amplifying RNA vaccine.

Physical stability of dry powder inhaler formulations

Introduction: Dry powder inhalers (DPIs) are popular for pulmonary drug delivery. Various techniques have been employed to produce inhalation drug particles and improve the delivery efficiency of DPI formulations. Physical stability of these DPI formulations is critical to ensure the delivery of a reproducible dose to the airways over the shelf-life.Areas covered: This review focuses on the impact of solid-state stability on aerosolization performance of DPI drug particles manufactured by powder production approaches and particle-engineering techniques. It also highlights the different analytical tools that can be used to characterize the physical instability originating from production and storage.Expert opinion: A majority of the DPI literature focuses on the effects of physico-chemical properties such as size, morphology, and density on aerosolization. While little has been reported on the physical stability, particularly the stability of engineered drug particles for use in DPIs. Literature data have shown that different particle-engineering methods and storage conditions may cause physical instability of dry powders for inhalation and can significantly change the aerosol performance. A systematic examination of physical instability mechanisms in DPI formulations is necessary during formulation development in order to select the optimum formulation with satisfactory stability. In addition, the use of appropriate characterization tools is critical to detect and understand physical instability during the development of DPI formulations.

Preparation and characterisation of PHT-loaded chitosan lecithin nanoparticles for intranasal drug delivery to the brain

The use of nanoparticles (NPs) for intranasal (IN) drug delivery to the brain represents a hopeful strategy to enhance brain targeting of anti-epileptic drugs.

SHBG141-161 Domain-Peptide Stimulates GPRC6A-Mediated Response in Leydig and β-Langerhans cell lines

GPRC6A is acknowledged as a major regulator of energy metabolism and male fertility through the action of undercarboxylated osteocalcin (ucOCN), representing a possible therapeutic target. We recently showed that the sex hormone-binding globulin (SHBG) binds to GPRC6A through the likely involvement of the 141-161 domain. To confirm this model, here we investigated the possible binding and agonist activity of SHBG(141-161) domain-peptide (SHBG_141-161) on GPRC6A. The binding of SHBG_141-161 to GPRC6A and downstream dissociation from G_αi(GDP) protein was computationally modelled. SHBG_141-161 was obtained by solid-phase synthesis, characterized by circular dichroism (CD) and the receptor binding was assessed by displacement of ucOCN on HEK-293 cells transfected with GPRC6A gene. Agonist activity of SHBG_141-161 was assessed on Leydig MA-10 and Langerhans β-TC6 cell lines through the GPRC6A-mediated release of testosterone (T) and insulin. SHBG_141-161 was predicted to bind to GPRC6A and to reduce the affinity for G_αi(GDP) at computational level. Conformational properties and binding to GPRC6A of the synthetic SHBG_141-161 were confirmed by CD and displacement experiments. SHBG_141-161 stimulated cell secretion of T and insulin, with dose dependency from 10^-13 to 10^-11M for T release (respectively P = 0,041 10^-13M; P = 0,032 10^-12M; P = 0,008 10^-11M vs basal) and for 10^-12 to 10^-10M for insulin (respectively P = 0,041 10^-12M; P = 0,007 10^-11M; P = 0,047 10^-10M; P = 0,045 vs basal). Blockade with anti GPRC6A IgG abolished the response to SHBG_141-161, suggesting agonist specificity. SHBG_141-161 showed stimulating activity on GPRC6A, representing a template peptide with possible therapeutic use for metabolic and endocrine disorders.

Advances in oral peptide therapeutics

Protein and peptide therapeutics require parenteral administration, which can be a deterrent to medication adherence. For this reason, there have been extensive efforts to develop alternative delivery strategies, particularly for peptides such as insulin that are used to treat endocrine disorders. Oral delivery is especially desirable, but it faces substantial barriers related to the structural organization and physiological function of the gastrointestinal tract. This article highlights strategies designed to overcome these barriers, including permeation enhancers, inhibitors of gut enzymes, and mucus-penetrating and cell-penetrating peptides. It then focuses on the experience with oral peptides that have reached clinical trials, including insulin, calcitonin, parathyroid hormone and vasopressin, with an emphasis on the advances that have recently led to the landmark approval of an oral formulation of the glucagon-like peptide 1 receptor agonist semaglutide for the treatment of type 2 diabetes.

Therapies for rare diseases: therapeutic modalities, progress and challenges ahead

Most rare diseases still lack approved treatments despite major advances in research providing the tools to understand their molecular basis, as well as legislation providing regulatory and economic incentives to catalyse the development of specific therapies. Addressing this translational gap is a multifaceted challenge, for which a key aspect is the selection of the optimal therapeutic modality for translating advances in rare disease knowledge into potential medicines, known as orphan drugs. With this in mind, we discuss here the technological basis and rare disease applicability of the main therapeutic modalities, including small molecules, monoclonal antibodies, protein replacement therapies, oligonucleotides and gene and cell therapies, as well as drug repurposing. For each modality, we consider its strengths and limitations as a platform for rare disease therapy development and describe clinical progress so far in developing drugs based on it. We also discuss selected overarching topics in the development of therapies for rare diseases, such as approval statistics, engagement of patients in the process, regulatory pathways and digital tools.

Machine learning for target discovery in drug development

The discovery of macromolecular targets for bioactive agents is currently a bottleneck for the informed design of chemical probes and drug leads. Typically, activity profiling against genetically manipulated cell lines or chemical proteomics is pursued to shed light on their biology and deconvolute drug-target networks. By taking advantage of the ever-growing wealth of publicly available bioactivity data, learning algorithms now provide an attractive means to generate statistically motivated research hypotheses and thereby prioritize biochemical screens. Here, we highlight recent successes in machine intelligence for target identification and discuss challenges and opportunities for drug discovery.

Effect of Surface Charges on Oral Absorption of Intact Solid Lipid Nanoparticles

Surface charge is a crucial factor that determines the in vivo behaviors of drug nanocarriers following administration via different routes. However, there is still a lack of comprehensive knowledge of how surface charges affect the in vivo behaviors of particles, especially for oral delivery. In this study, solid lipid nanoparticles (SLNs), as model drug nanocarriers, are modified to bear either anionic, cationic, or net neutral surface charges. The effect of surface charges on oral absorption of intact SLNs was investigated by tracking the in vivo transport of the particles. The fluorescent bioimaging strategy exploits the aggregation-caused quenching property to discriminate the particles. Both in vitro and in vivo lipolysis studies confirm slowed-down lipolysis by anionic charges in comparison with both unmodified and net neutral SLNs but accelerated degradation by cationic charges. The scanning of ex vivo tissues and organs reveals limited absorption of unmodified SLNs into the circulation. Nevertheless, all three types of surface charge modifications are able to enhance the oral absorption of intact SLNs with the fastest and highest absorption observed for net neutral SLNs, possibly owing to promoted mucus penetration. Anionic SLNs, though repulsed by the mucus layer, show the second highest absorption owing to enhanced lymphatic transport. The efficacy of cationic charge modification is less significant due to entrapment and retention in mucus layers as well as increased lability to lipolysis. In conclusion, surface charges may serve as initiators to guide the in vivo behaviors and enhance the oral absorption of intact SLNs.

A luminal unfolding microneedle injector for oral delivery of macromolecules

Insulin and other injectable biologic drugs have transformed the treatment of patients suffering from diabetes^1,2, yet patients and healthcare providers often prefer to use and prescribe less effective orally dosed medications^3-5. Compared with subcutaneously administered drugs, oral formulations create less patient discomfort⁴, show greater chemical stability at high temperatures⁶, and do not generate biohazardous needle waste⁷. An oral dosage form for biologic medications is ideal; however, macromolecule drugs are not readily absorbed into the bloodstream through the gastrointestinal tract⁸. We developed an ingestible capsule, termed the luminal unfolding microneedle injector, which allows for the oral delivery of biologic drugs by rapidly propelling dissolvable drug-loaded microneedles into intestinal tissue using a set of unfolding arms. During ex vivo human and in vivo swine studies, the device consistently delivered the microneedles to the tissue without causing complete thickness perforations. Using insulin as a model drug, we showed that, when actuated, the luminal unfolding microneedle injector provided a faster pharmacokinetic uptake profile and a systemic uptake >10% of that of a subcutaneous injection over a 4-h sampling period. With the ability to load a multitude of microneedle formulations, the device can serve as a platform to orally deliver therapeutic doses of macromolecule drugs.

In vivo clearance of nanoparticles by transcytosis across alveolar epithelial cells

Nanoparticles in polluted air or aerosolized drug nanoparticles predominantly settle in the alveolar lung. Here, we describe a novel, highly effective pathway for the particles to cross the alveolar epithelium and reach the lymph and bloodstream. Amorphous silica nanoparticles, suspended in perfluorocarbon, were instilled into the lungs of mice for intravital microscopy. Particles formed agglomerates that settled on the alveolar wall, half of which were removed from the lung within 30 minutes. TEM histology showed agglomerates in stages of crossing the alveolar epithelium, in large compartments inside the epithelial cells and crossing the basal membrane into the interstitium. This pathway is consistent with published kinetic studies in rats and mice, using a host of (negatively) charged and polar nanoparticles.

Polymer-Based Nanoparticle Strategies for Insulin Delivery

Diabetes mellitus (DM) is a chronic metabolic illness estimated to have affected 451 million individuals to date, with this number expected to significantly rise in the coming years. There are two main classes of this disease, namely type 1 diabetes (T1D) and type 2 diabetes (T2D). Insulin therapy is pivotal in the management of diabetes, with diabetic individuals taking multiple daily insulin injections. However, the mode of administration has numerous drawbacks, resulting in poor patient compliance. In order to optimize insulin therapy, novel drug delivery systems (DDSes) have been suggested, and alternative routes of administration have been investigated. A novel aspect in the field of drug delivery was brought about by the coalescence of polymeric science and nanotechnology. In addition to polymeric nanoparticles (PNPs), insulin DDSes can incorporate the use of nanoplatforms/carriers. A combination of these systems can bring about novel formulations and lead to significant improvements in the drug delivery system (DDS) with regard to therapeutic efficacy, bioavailability, increased half-life, improved transport through physical and chemical barriers, and controlled drug delivery. This review will discuss how recent developments in polymer chemistry and nanotechnology have been employed in a multitude of platforms as well as in administration routes for the safe and efficient delivery of insulin for the treatment of DM.

Striving Towards the Perfect In Vitro Oral Drug Absorption Model

Oral drug delivery systems have multiple goals, assessing and enabling intestinal absorption at efficacious doses being one of them. Here we highlight the in vitro advances in modeling drug absorption, which more faithfully reflect human intestinal physiology and reduce the reliance on animal models.

Slowing down lipolysis significantly enhances the oral absorption of intact solid lipid nanoparticles

Only a limited amount of orally administered lipid nanoparticles are absorbed as intact particles due to lipolysis by lipases in the gastrointestinal tract. It is hypothesized that by counteracting lipolysis, more particles will survive gastrointestinal digestion and be absorbed as intact particles. In this study, incorporation of a lipase inhibitor orlistat (OLST), as well as polyethylene glycol (PEG) coating, is employed to slow down the lipolysis using solid lipid nanoparticles (SLNs) as model particles. To explore the in vivo behaviors of the particles, near-infrared fluorescent probes with absolute aggregation-caused quenching (ACQ) properties are used to label and track the unmodified, PEG-coated and OLST-loaded SLNs. The in vitro lipolysis study indicates very fast first-order degradation of unmodified SLNs and significantly decreased degradation of OLST-SLNs. Live imaging reveals the same trend of slowed-down lipolysis in vivo which correlates well with the in vitro lipolysis. The scanning of ex vivo gastrointestinal segments confirms the considerably prolonged residence time of OLST-SLNs, mirroring the significantly decreased lipolysis rate. The observation of fluorescence in the blood, though very weak, and in the liver speaks of the oral absorption of intact SLNs. The substantially higher hepatic levels of OLST-SLNs than unmodified SLNs should be attributed to the significantly enhanced survival rate because both particles exhibit similar cellular recognition as well as similar physicochemical properties except for the survival rate. Similarly, slowing down lipolysis also contributes to the significantly enhanced cumulative lymphatic transport of OLST-SLNs (7.56% vs. 1.27% for the unmodified SLNs). The PEG coating slows down the lipolysis rate as well but not to the degree as done by OLST. As a result, the gastrointestinal residence time of PEG-SLNs has been moderately prolonged and the hepatic levels moderately increased. The weakened cellular recognition of PEG-SLNs implies that the enhanced oral absorption is solely ascribed to the slowed-down lipolysis and enhanced mucus penetration. In conclusion, the oral absorption of intact SLNs can be significantly enhanced by slowing down lipolysis, especially by OLST, showing potential as carriers for the oral delivery of labile biomacromolecules.

Small molecules for modulating the localisation of the water channel aquaporin-2-disease relevance and perspectives for targeting local cAMP signalling

The tight spatial and temporal organisation of cyclic adenosine monophosphate (cAMP) signalling plays a key role in arginine-vasopressin (AVP)-mediated water reabsorption in renal collecting duct principal cells and in a plethora of other processes such as in the control of cardiac myocyte contractility. This review critically discusses in vitro- and cell-based screening strategies for the identification of small molecules that interfere with AVP/cAMP signalling in renal principal cells; it features phenotypic screening and approaches for targeting protein-protein interactions of A-kinase anchoring proteins (AKAPs), which organise local cAMP signalling hubs. The discovery of novel chemical entities for the modulation of local cAMP will not only provide tools for elucidating molecular mechanisms underlying cAMP signalling. Novel chemical entities can also serve as starting points for the development of novel drugs for the treatment of human diseases. Examples illustrate how screening for small molecules can pave the way to novel approaches for the treatment of certain forms of diabetes insipidus, a disease caused by defects in AVP-mediated water reabsorption.

Delivery of Nanoparticles across the Intestinal Epithelium via the Transferrin Transport Pathway

The aim of this study was to probe whether the transferrin (Tf) transport pathway can be exploited for intestinal delivery of nanoparticles. Tf was adsorbed on 100 nm model polystyrene nanoparticles (NP), followed by size characterisation of these systems. Cell uptake of Tf and Tf-adsorbed NP was investigated in intestinal epithelial Caco-2 cells cultured on multi-well plates and as differentiated polarised monolayers. Tf-NP demonstrated a remarkably higher cell uptake compared to unmodified NP in both non-polarised (5-fold) and polarised cell monolayers (16-fold difference). Application of soluble Tf significantly attenuated the uptake of Tf-NP. Notably, Tf-NP displayed remarkably higher rate (23-fold) of epithelial transport across Caco-2 monolayers compared to unmodified NP. This study therefore strongly suggests that the Tf transport pathway should be considered as a candidate biological transport route for orally-administered nanomedicines and drugs with poor oral bioavailability.