The strawberry-derived permeation enhancer pelargonidin enables oral protein delivery

Nanostructure-Mediated Transport of Therapeutics through Epithelial Barriers

The ability to precisely treat human disease is facilitated by the sophisticated design of pharmacologic agents. Nanotechnology has emerged as a valuable approach to creating vehicles that can specifically target organ systems, effectively traverse epithelial barriers, and protect agents from premature degradation. In this review, we discuss the molecular basis for epithelial barrier function, focusing on tight junctions, and describe different pathways that drugs can use to cross barrier-forming tissue, including the paracellular route and transcytosis. Unique features of drug delivery applied to different organ systems are addressed: transdermal, ocular, pulmonary, and oral delivery. We also discuss how design elements of different nanoscale systems, such as composition and nanostructured architecture, can be used to specifically enhance transepithelial delivery. The ability to tailor nanoscale drug delivery vehicles to leverage epithelial barrier biology is an emerging theme in the pursuit of facilitating the efficacious delivery of pharmacologic agents.

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.

Proof-of-concept studies with a computationally designed Mpro inhibitor as a synergistic combination regimen alternative to Paxlovid

As the SARS-CoV-2 virus continues to spread and mutate, it remains important to focus not only on preventing spread through vaccination but also on treating infection with direct-acting antivirals (DAA). The approval of Paxlovid, a SARS-CoV-2 main protease (Mpro) DAA, has been significant for treatment of patients. A limitation of this DAA, however, is that the antiviral component, nirmatrelvir, is rapidly metabolized and requires inclusion of a CYP450 3A4 metabolic inhibitor, ritonavir, to boost levels of the active drug. Serious drug-drug interactions can occur with Paxlovid for patients who are also taking other medications metabolized by CYP4503A4, particularly transplant or otherwise immunocompromised patients who are most at risk for SARS-CoV-2 infection and the development of severe symptoms. Developing an alternative antiviral with improved pharmacological properties is critical for treatment of these patients. By using a computational and structure-guided approach, we were able to optimize a 100 to 250 μM screening hit to a potent nanomolar inhibitor and lead compound, Mpro61. In this study, we further evaluate Mpro61 as a lead compound, starting with examination of its mode of binding to SARS-CoV-2 Mpro. In vitro pharmacological profiling established a lack of off-target effects, particularly CYP450 3A4 inhibition, as well as potential for synergy with the currently approved alternate antiviral, molnupiravir. Development and subsequent testing of a capsule formulation for oral dosing of Mpro61 in B6-K18-hACE2 mice demonstrated favorable pharmacological properties, efficacy, and synergy with molnupiravir, and complete recovery from subsequent challenge by SARS-CoV-2, establishing Mpro61 as a promising potential preclinical candidate.

Recent advances in oral insulin delivery technologies

With the rise in diabetes mellitus cases worldwide, oral delivery of insulin is preferred over subcutaneous insulin administration due to its good patient compliance and non-invasiveness, simplicity, and versatility. However, oral insulin delivery is hampered by various gastrointestinal barriers that result in low drug bioavailability and insufficient therapeutic efficiency. Numerous strategies have been developed to overcome these barriers and increase the bioavailability of oral insulin. Yet, no commercial oral insulin product is available to address all clinical hurdles because of various substantial obstacles related to the structural organization and physiological function of the gastrointestinal tract. Herein, we discussed the significant physiological barriers (including chemical, enzymatic, and physical barriers) that hinder the transportation and absorption of orally delivered insulin. Then, we showcased recent significant and innovative advances in oral insulin delivery technologies. Finally, we concluded the review with remarks on future perspectives on oral insulin delivery technologies and potential challenges for forthcoming clinical translation of oral insulin delivery technologies.

Structured soft particulate matters for delivery of bioactive compounds in foods and functioning in the colon

The present review discusses challenges, perspectives, and current needs of delivering bioactive compounds (BCs) using soft particulate matters (SPMs) for gut health. SPMs can entrap BCs for incorporation in foods, preserve their bioactivities during processing, storage, and gastrointestinal digestion, and deliver BCs to functioning sites in the colon. To enable these functions, physical, chemical, and biological properties of BCs are integrated in designing various types of SPMs to overcome environmental factors reducing the bioavailability and bioactivity of BCs. The design principles are applied using food grade molecules with the desired properties to produce SPMs by additionally considering the cost, sustainability, and scalability of manufacturing processes. Lastly, to make delivery systems practical, impacts of SPMs on food quality are to be evaluated case by case, and health benefits of functional foods incorporated with delivery systems are to be confirmed and must outweigh the cost of preparing SPMs.

Revealing the interaction between peptide drugs and permeation enhancers in the presence of intestinal bile salts

Permeability enhancer-based formulations offer a promising approach to enhance the oral bioavailability of peptides. We used all-atom molecular dynamics simulations to investigate the interaction between two permeability enhancers (sodium caprate, and SNAC), and four different peptides (octreotide, hexarelin, degarelix, and insulin), in the presence of taurocholate, an intestinal bile salt. The permeability enhancers exhibited distinct effects on peptide release based on their properties, promoting hydrophobic peptide release while inhibiting water-soluble peptide release. Lowering peptide concentrations in the simulations reduced peptide-peptide interactions but increased their interactions with the enhancers and taurocholates. Introducing peptides randomly with enhancer and taurocholate molecules yielded dynamic molecular aggregation, and reduced peptide-peptide interactions and hydrogen bond formation compared to peptide-only systems. The simulations provided insights into molecular-level interactions, highlighting the specific contacts between peptide residues responsible for aggregation, and the interactions between peptide residues and permeability enhancers/taurocholates that are crucial within the mixed colloids. Therefore, our results can provide insights into how modifications of these critical contacts can be made to alter drug release profiles from peptide-only or mixed peptide-PE-taurocholate aggregates. To further probe the molecular nature of permeability enhancers and peptide interactions, we also analyzed insulin secondary structures using Fourier transform infrared spectroscopy. The presence of SNAC led to an increase in β-sheet formation in insulin. In contrast, both in the absence and presence of caprate, α-helices, and random structures dominated. These molecular-level insights can guide the design of improved permeability enhancer-based dosage forms, allowing for precise control of peptide release profiles near the intended absorption site.

Sweet Cherry Extract as Permeation Enhancer of Tyrosine Kinase Inhibitors: A Promising Prospective for Future Oral Anticancer Therapies

Although patients would rather oral therapies to injections, the gastrointestinal tract's low permeability makes this method limiting for most compounds, including anticancer drugs. Due to their low bioavailability, oral antitumor therapies suffer from significant variability in pharmacokinetics and efficacy. The improvement of their pharmacokinetic profiles can be achieved by a new approach: the use of natural extracts enriched with polyphenolic compounds that act as intestinal permeability enhancers. Here, we propose a safe sweet cherry extract capable of enhancing oral absorption. The extract was characterized by the HPLC-UV/MS method, evaluated for in vitro antioxidant activity, safety on the Caco-2 cell line, and as a potential permeation enhancer. The sweet cherry extract showed a high antioxidant capacity (ABTS and DPPH assays were 211.74 and 48.65 µmol of Trolox equivalent/g dried extract, respectively), high content of polyphenols (8.44 mg of gallic acid per gram of dry extract), and anthocyanins (1.80 mg of cyanidin-3-glucoside equivalent per g of dry extract), reassuring safety profile (cell viability never lower than 98%), and a significant and fully reversible ability to alter the integrity of the Caco-2 monolayer (+81.5% of Lucifer yellow permeability after 2 h). Furthermore, the ability of the sweet cherry extract to improve the permeability (Papp) and modify the efflux ratio (ER) of reference compounds (atenolol, propranolol, and dasatinib) and selected pyrazolo[3,4-d]pyrimidine derivatives was investigated. The obtained results show a significant increase in apparent permeability across the Caco-2 monolayer (tripled and quadrupled in most cases), and an interesting decrease in efflux ratio when compounds were co-incubated with sweet cherry extract.

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.

Storming the gate: New approaches for targeting the dynamic tight junction for improved drug delivery

As biologics used in the clinic outpace the number of new small molecule drugs, an important challenge for their efficacy and widespread use has emerged, namely tissue penetrance. Macromolecular drugs - bulky, high-molecular weight, hydrophilic agents - exhibit low permeability across biological barriers. Epithelial and endothelial layers, for example within the gastrointestinal tract or at the blood-brain barrier, present the most significant obstacle to drug transport. Within epithelium, two subcellular structures are responsible for limiting absorption: cell membranes and intercellular tight junctions. Previously considered impenetrable to macromolecular drugs, tight junctions control paracellular flux and dictate drug transport between cells. Recent work, however, has shown tight junctions to be dynamic, anisotropic structures that can be targeted for delivery. This review aims to summarize new approaches for targeting tight junctions, both directly and indirectly, and to highlight how manipulation of tight junction interactions may help usher in a new era of precision drug delivery.

Affordable oral proinsulin bioencapsulated in plant cells regulates blood sugar levels similar to natural insulin

Diabetes Mellitus is a silent epidemic affecting >500 million, which claimed 6.7 million lives in 2021, a projected increase of >670% in <20 years old in the next two decades but insulin is unaffordable for the large majority of the globe. Therefore, we engineered proinsulin in plant cells to facilitate oral delivery. Stability of the proinsulin gene and expression in subsequent generations, after removal of the antibiotic-resistance gene, was confirmed using PCR, Southern and western blots. Proinsulin expression was high (up to 12 mg/g DW or 47.5% of total leaf protein), stable up to one year after storage of freeze-dried plant cells at ambient temperature and met FDA regulatory requirements of uniformity, moisture content and bioburden. GM1 receptor binding, required for uptake via gut epithelial cells was confirmed by pentameric assembly of CTB-Proinsulin. IP insulin injections (without C peptide) in STZ mice rapidly decreased blood glucose level leading to transient hypoglycemia, followed by hepatic glucose compensation. On the other hand, other than the 15-min lag period of oral proinsulin (transit time required to reach the gut), the kinetics of blood sugar regulation of oral CTB-Proinsulin in STZ mice was very similar to naturally secreted insulin in healthy mice (both contain C-peptide), without rapid decrease or hypoglycemia. Elimination of expensive fermentation, purification and cold storage/transportation should reduce cost and increase other health benefits of plant fibers. The recent approval of plant cell delivery of therapeutic proteins by FDA and approval of CTB-ACE2 for phase I/II human clinical studies augur well for advancing oral proinsulin to the clinic.

Overcoming barriers to patient adherence: the case for developing innovative drug delivery systems

Poor medication adherence is a pervasive issue with considerable health and socioeconomic consequences. Although the underlying reasons are generally understood, traditional intervention strategies rooted in patient-centric education and empowerment have proved to be prohibitively complex and/or ineffective. Formulating a pharmaceutical in a drug delivery system (DDS) is a promising alternative that can directly mitigate many common impediments to adherence, including frequent dosing, adverse effects and a delayed onset of action. Existing DDSs have already positively influenced patient acceptability and improved rates of adherence across various disease and intervention types. The next generation of systems have the potential to instate an even more radical paradigm shift by, for example, permitting oral delivery of biomacromolecules, allowing for autonomous dose regulation and enabling several doses to be mimicked with a single administration. Their success, however, is contingent on their ability to address the problems that have made DDSs unsuccessful in the past.

Preparation, Drug Distribution, and In Vivo Evaluation of the Safety of Protein Corona Liposomes for Liraglutide Delivery

The development of oral drug delivery systems is challenging, and issues related to the mucus layer and low intestinal epithelial permeability have not yet been surmounted. The purpose of this study was to develop a promising formulation that is more adapted to in vivo absorption and to facilitate the administration of oral liraglutide. Cationic liposomes (CLs) linked to AT-1002 were prepared using a double-emulsion method, and BSA was adsorbed on the surface of the AT-CLs, resulting in protein corona cationic liposomes with AT-1002 (Pc-AT-CLs). The preparation method was determined by investigating various process parameters. The particle size, potential, and encapsulation efficiency (EE%) of the Pc-AT-CLs were 202.9 ± 12.4 nm, 1.76 ± 4.87 mV, and 84.63 ± 5.05%, respectively. The transmission electron microscopy (TEM) imaging revealed a nearly spherical structure of the Pc-AT-CLs, with a recognizable coating. The circular dichroism experiments confirmed that the complex preparation process did not affect the secondary structure of liraglutide. With the addition of BSA and AT-1002, the mucosal accumulation of the Pc-AT-CLs was nearly two times lower than that of the AT-CLs, and the degree of enteric metaplasia was 1.35 times higher than that of the PcCLs. The duration of the intestinal absorption of the Pc-AT-CLs was longer, offering remarkable biological safety.