A review on the strategies for oral delivery of proteins and peptides and their clinical perspectives

Analytical and drug delivery strategies for short peptides: From manufacturing to market

In recent times, biopharmaceuticals have gained attention because of their tremendous potential to benefit millions of patients globally by treating widespread diseases such as cancer, diabetes and many rare diseases. Short peptides (SP), also termed as oligopeptides, are one such class of biopharmaceuticals, that are majorly involved in efficient functioning of biological systems. Peptide chains that are 2-20 amino acids long are considered as oligopeptides by researchers and are some of the functionally vital compounds with widespread applications including self-assembly material for drug delivery, targeting ligands for precise/specific targeting and other biological uses. Using functionalised biomacromolecules such as short chained peptides, helps in improving pharmacokinetic properties and biodistribution profile of the drug. Apart from this, functionalised SP are being employed as cell penetrating peptides and prodrug to specifically and selectively target tumor sites. In order to minimize any unwanted interaction and adverse effects, the stability and safety of SP should be ensured throughout its development from manufacturing to market. Formulation development and characterization strategies of these potential molecules are described in the following review along with various applications and details of marketed formulations.

Anti-inflammatory peptide therapeutics and the role of sulphur containing amino acids (cysteine and methionine) in inflammation suppression: A review

BACKGROUND

Inflammation serves as our body's immune response to combat infections, pathogens, viruses, and external stimuli. Inflammation can be classified into two types: acute inflammation and chronic inflammation. Non-steroidal anti-inflammatory medications (NSAIDs) are used to treat both acute and chronic inflammatory disorders. However, these treatments have various side effects such as reduced healing efficiency, peptic ulcers, gastrointestinal toxicities, etc. METHOD: This review assesses the potential of anti-inflammatory peptides (AIPs) derived from various natural sources, such as algae, fungi, plants, animals, and marine organisms. Focusing on peptides rich in cysteines and methionine, sulphur-containing amino acids known for their role in suppression of inflammation.

RESULT

Due to their varied biological activity, ability to penetrate cells, and low cytotoxicity, bioactive peptides have garnered interest as possible therapeutic agents. The utilisation of AIPs has shown great potential in the treatment of disorders associated with inflammation. AIPs can be obtained from diverse natural sources such as algae, fungi, plants, and animals. Cysteine and methionine are sulphur-containing amino acids that aid in the elimination of free radicals, hence assisting in the treatment of inflammatory diseases.

CONCLUSION

This review specifically examines several sources of AIPs including peptides that contain numerous cysteines and methionine. In addition, the biological characteristics of these amino acids and advancements in peptide delivery are also discussed.

A Physiologically Based Pharmacokinetic (PBPK) Study to Assess the Adjuvanticity of Three Peptides in an Oral Vaccine

Following up on the first PBPK model for an oral vaccine built for alpha-tocopherol, three peptides are explored in this article to verify if they could support an oral vaccine formulation as adjuvants using the same PBPK modeling approach. A literature review was conducted to verify what peptides have been used as adjuvants in the last decades, and it was noticed that MDP derivatives have been used, with one of them even being commercially approved and used as an adjuvant when administered intravenously in oncology. The aim of this study was to build optimized models for three MDP peptides (MDP itself, MTP-PE, and murabutide) and to verify if they could act as adjuvants for an oral vaccine. Challenges faced by peptides in an oral delivery system are taken into consideration, and improvements to the formulations to achieve better results are described in a step-wise approach to reach the most-optimized model. Once simulations are performed, results are compared to determine what would be the best peptide to support as an oral adjuvant. According to our results, MTP-PE, the currently approved and commercialized peptide, could have potential to be incorporated into an oral formulation. It would be interesting to proceed with further in vivo experiments to determine the behavior of this peptide when administered orally with a proper formulation to overcome the challenges of oral delivery systems.

Transmucosal Delivery of Peptides and Proteins Through Nanofibers: Current Status and Emerging Developments

Advancements in recombinant DNA technology have made proteins and peptides available for diagnostic and therapeutic applications, but their effectiveness when taken orally leads to poor patient compliance, requiring clinical administration. Among the alternative routes, transmucosal delivery has the advantage of being noninvasive and bypassing hepato-gastrointestinal clearance. Various mucosal routes-buccal, nasal, pulmonary, rectal, and vaginal-have been explored for delivering these macromolecules. Nanofibers, due to their unique properties like high surface-area-to-volume ratio, mechanical strength, and improved encapsulation efficiency, serve as promising carriers for proteins and peptides. These nanofibers can be tailored for quick dissolution, controlled release, enhanced encapsulation, targeted delivery, and improved bioavailability, offering superior pharmaceutical and pharmacokinetic performance compared to conventional methods. This leads to reduced dosages, fewer side effects, and enhanced patient compliance. Hence, nanofibers hold tremendous potential for protein/peptide delivery, especially through mucosal routes. This review focuses on the therapeutic application of proteins and peptides, challenges faced in their conventional delivery, techniques for fabricating different types of nanofibers and, various nanofiber-based dosage forms, and factors influencing nanofiber generation. Insights pertaining to the precise selection of materials used for fabricating nanofibers and regulatory aspects have been covered. Case studies wherein the use of specific protein/peptide-loaded nanofibers and delivered via oral/vaginal/nasal mucosa for diagnostic/therapeutic use and related preclinical and clinical studies conducted have been included in this review.

Design and fabrication of customizable microneedles enabled by 3D printing for biomedical applications

Microneedles (MNs) is an emerging technology that employs needles ranging from 10 to 1000 μm in height, as a minimally invasive technique for various procedures such as therapeutics, disease monitoring and diagnostics. The commonly used method of fabrication, micromolding, has the advantage of scalability, however, micromolding is unable to achieve rapid customizability in dimensions, geometries and architectures, which are the pivotal factors determining the functionality and efficacy of the MNs. 3D printing offers a promising alternative by enabling MN fabrication with high dimensional accuracy required for precise applications, leading to improved performance. Furthermore, enabled by its customizability and one-step process, there is propitious potential for growth for 3D-printed MNs especially in the field of personalized and on-demand medical devices. This review provides an overview of considerations for the key parameters in designing MNs, an introduction on the various 3D-printing techniques for fabricating this new generation of MNs, as well as highlighting the advancements in biomedical applications facilitated by 3D-printed MNs. Lastly, we offer some insights into the future prospects of 3D-printed MNs, specifically its progress towards translation and entry into market.

Protein-Based Nanocarriers and Nanotherapeutics for Infection and Inflammation

Infectious and inflammatory diseases are one of the leading causes of death globally. The status quo has become more prominent with the onset of the coronavirus disease 2019 (COVID-19) pandemic. To combat these potential crises, proteins have been proven as highly efficacious drugs, drug targets, and biomarkers. On the other hand, advancements in nanotechnology have aided efficient and sustained drug delivery due to their nano-dimension-acquired advantages. Combining both strategies together, the protein nanoplatforms are equipped with the advantageous intrinsic properties of proteins as well as nanoformulations, eloquently changing the field of nanomedicine. Proteins can act as carriers, therapeutics, diagnostics, and theranostics in their nanoform as fusion proteins or as composites with other organic/inorganic materials. Protein-based nanoplatforms have been extensively explored to target the major infectious and inflammatory diseases of clinical concern. The current review comprehensively deliberated proteins as nanocarriers for drugs and nanotherapeutics for inflammatory and infectious agents, with special emphasis on cancer and viral diseases. A plethora of proteins from diverse organisms have aided in the synthesis of protein-based nanoformulations. The current study specifically presented the proteins of human and pathogenic origin to dwell upon the field of protein nanotechnology, emphasizing their pharmacological advantages. Further, the successful clinical translation and current bottlenecks of the protein-based nanoformulations associated with the infection-inflammation paradigm have also been discussed comprehensively. SIGNIFICANCE STATEMENT: This review discusses the plethora of promising protein-based nanocarriers and nanotherapeutics explored for infectious and inflammatory ailments, with particular emphasis on protein nanoparticles of human and pathogenic origin with reference to the advantages, ADME (absorption, distribution, metabolism, and excretion parameters), and current bottlenecks in development of protein-based nanotherapeutic interventions.

Non-Invasive Delivery of Insulin for Breaching Hindrances against Diabetes

Insulin is recognized as a crucial weapon in managing diabetes. Subcutaneous (s.c.) injections are the traditional approach for insulin administration, which usually have many limitations. Numerous alternative (non-invasive) slants through different routes have been explored by the researchers for making needle-free delivery of insulin for attaining its augmented absorption as well as bioavailability. The current review delineating numerous pros and cons of several novel approaches of non-invasive insulin delivery by overcoming many of their hurdles. Primary information on the topic was gathered by searching scholarly articles from PubMed added with extraction of data from auxiliary manuscripts. Many approaches (discussed in the article) are meant for the delivery of a safe, effective, stable, and patient friendly administration of insulin via buccal, oral, inhalational, transdermal, intranasal, ocular, vaginal and rectal routes. Few of them have proven their clinical efficacy for maintaining the glycemic levels, whereas others are under the investigational pipe line. The developed products are comprising of many advanced micro/nano composite technologies and few of them might be entering into the market in near future, thereby garnishing the hopes of millions of diabetics who are under the network of s.c. insulin injections.

Current Advancements on Oral Protein and Peptide Drug Delivery Approaches to Bioavailability: Extensive Review on Patents

Protein and peptide-based drugs have greater therapeutic efficacy and potential application and lower toxicity compared to chemical entities in long-term use within optimum concentration as they are easily biodegradable due to biological origin. While oral administration is preferable, most of these substances are currently administered intravenously or subcutaneously. This is primarily due to the breakdown and poor absorption in the GI tract. Hence, ongoing research is focused on investigating absorption enhancers, enzyme inhibitors, carrier systems, and stability enhancers as potential strategies to facilitate the oral administration of proteins and peptides. Investigations have been directed towards advancing novel technologies to address gastrointestinal (GI) barriers associated with protein and peptide medications. The current review intensifies formulation and stability approaches for oral protein & peptide drug delivery systems with all significant parameters intended for patient safety. Notably, certain innovative technologies have been patented and are currently undergoing clinical trials or have already been introduced into the market. All the approaches stated for the administration of protein and peptide drugs are critically discussed, having their current status, future directions, and recent patents published in the last decades.

Discovery of bioactive peptides as therapeutic agents for skin wound repair

Short sequences of amino acids called peptides have a wide range of biological functions and the potential to treat a number of diseases. Bioactive peptides can be derived from different sources, including marine organisms, and synthetic design, making them versatile candidates for production of therapeutic agents. Their therapeutic effects span across areas such as antimicrobial activity, cells proliferation and migration, synthesis of collagen, and more. This current review explores the fascinating realm of bioactive peptides as promising therapeutic agents for skin wound healing. This review focuses on the multifaceted biological effects of specific peptides, shedding light on their potential to revolutionize the field of dermatology and regenerative medicine. It delves into how these peptides stimulate collagen synthesis, inhibit inflammation, and accelerate tissue regeneration, ultimately contributing to the effective repair of skin wounds. The findings underscore the significant role several types of bioactive peptides can play in enhancing wound healing processes and offer promising insights for improving the quality of life for individuals with skin injuries and dermatological conditions. The versatility of peptides allows for the development of tailored treatments catering to specific wound types and patient needs. As continuing to delve deeper into the realm of bioactive peptides, there is immense potential for further exploration and innovation. Future endeavors may involve the optimization of peptide formulations, elucidation of underlying molecular and cellular mechanisms.

Oral Absorption of Middle-to-Large Molecules and Its Improvement, with a Focus on New Modality Drugs

To meet unmet medical needs, middle-to-large molecules, including peptides and oligonucleotides, have emerged as new therapeutic modalities. Owing to their middle-to-large molecular sizes, middle-to-large molecules are not suitable for oral absorption, but there are high expectations around orally bioavailable macromolecular drugs, since oral administration is the most convenient dosing route. Therefore, extensive efforts have been made to create bioavailable middle-to-large molecules or develop absorption enhancement technology, from which some successes have recently been reported. For example, Rybelsus® tablets and Mycapssa® capsules, both of which contain absorption enhancers, were approved as oral medications for type 2 diabetes and acromegaly, respectively. The oral administration of Rybelsus and Mycapssa exposes their pharmacologically active peptides with molecular weights greater than 1000, namely, semaglutide and octreotide, respectively, into systemic circulation. Although these two medications represent major achievements in the development of orally absorbable peptide formulations, the oral bioavailability of peptides after taking Rybelsus and Mycapssa is still only around 1%. In this article, we review the approaches and recent advances of orally bioavailable middle-to-large molecules and discuss challenges for improving their oral absorption.

A novel antibacterial approach of Cecropin-B peptide loaded on chitosan nanoparticles against MDR Klebsiella pneumoniae isolates

Egypt has witnessed the emergence of multidrug-resistant (MDR) Klebsiella pneumoniae, which has posed a serious healthcare challenge. The proper treatment choice for MDR-KP infections is not well determined which renders the problem more complicated, thus making the control of such infections a serious challenge for healthcare professionals. This study aims to encapsulate the cationic antimicrobial peptide; Cecropin-B (Cec-B), to increase its lifetime, drug targeting, and efficacy and study the antimicrobial effect of free and encapsulated recombinant rCec-B peptide on multidrug-resistant K. pneumoniae (MDR-KP) isolates. Fifty isolates were collected from different clinical departments at Theodore Bilharz Research Institute. Minimal inhibitory concentrations (MICs) of rCec-B against MDR-KP isolates were determined by the broth microdilution test. In addition, encapsulation of rCec-B peptide into chitosan nanoparticles and studying its bactericidal effect against MDR-KP isolates were also performed. The relative expression of efflux pump and porin coding genes (ArcrB, TolC, mtdK, and Ompk35) was detected by quantitative PCR in treated MDR-KP bacterial isolates compared to untreated isolates. Out of 60 clinical MDR isolates, 50 were MDR-KP. 60% of the isolates were XDR while 40% were MDR. rCec-B were bactericidal on 21 isolates, then these isolates were subjected to treatment using free nanocapsule in addition to the encapsulated peptide. Free capsules showed a mild cytotoxic effect on MDR-KP at the highest concentration. MIC of encapsulated rCec-B was higher than the free peptide. The expression level of genes encoding efflux and porin (ArcrB, TolC, mtdK, and Ompk35) was downregulated after treatment with encapsulated rCec-B. These findings indicate that encapsulated rCec-B is a promising candidate with potent antibacterial activities against drug-resistant K. pneumoniae.

Solidification and oral delivery of biologics to the colon- A review

The oral delivery of biologics such as therapeutic proteins, peptides and oligonucleotides for the treatment of colon related diseases has been the focus of increasing attention over the last years. However, the major disadvantage of these macromolecules is their degradation propensity in liquid state which can lead to the undesirable and complete loss of function. Therefore, to increase the stability of the biologic and reduce their degradation propensity, formulation techniques such as solidification can be performed to obtain a stable solid dosage form for oral administration. Due to their fragility, stress exerted on the biologic during solidification has to be reduced with the incorporation of stabilizing excipients into the formulation. This review focuses on the state-of-the-art solidification techniques required to obtain a solid dosage form for the oral delivery of biologics to the colon and the use of suitable excipients for adequate stabilization upon solidification. The solidifying processes discussed within this review are spray drying, freeze drying, bead coating and also other techniques such as spray freeze drying, electro spraying, vacuum- and supercritical fluid drying. Further, the colon as site of absorption in both healthy and diseased state is critically reviewed and possible oral delivery systems for biologics are discussed.

An Update on Strategies to Deliver Protein and Peptide Drugs to the Eye

In the past few decades, advancements in protein engineering, biotechnology, and structural biochemistry have resulted in the discovery of various techniques that enhanced the production yield of proteins, targetability, circulating half-life, product purity, and functionality of proteins and peptides. As a result, the utilization of proteins and peptides has increased in the treatment of many conditions, including ocular diseases. Ocular delivery of large molecules poses several challenges due to their high molecular weight, hydrophilicity, unstable nature, and poor permeation through cellular and enzymatic barriers. The use of novel strategies for delivering protein and peptides such as glycoengineering, PEGylation, Fc-fusion, chitosan nanoparticles, and liposomes have improved the efficacy, safety, and stability, which consequently expanded the therapeutic potential of proteins. This review article highlights various proteins and peptides that are useful in ocular disorders, challenges in their delivery to the eye, and strategies to enhance ocular bioavailability using novel delivery approaches. In addition, a few futuristic approaches that will assist in the ocular delivery of proteins and peptides were also discussed.

Insulin Tregopil: An Ultra-Fast Oral Recombinant Human Insulin Analog: Preclinical and Clinical Development in Diabetes Mellitus

Insulin therapy is indispensable for achieving glycemic control in all patients with type 1 diabetes mellitus and many patients with type 2 diabetes mellitus. Insulin injections are associated with negative connotations in patients owing to administration discomfort and adverse effects such as hypoglycemia and weight gain. Insulin administered orally can overcome these limitations by providing a convenient and effective mode of delivery with a potentially lower risk of hypoglycemia. Oral insulin mimics the physiologic process of insulin secretion, absorption into the portal circulation, and subsequent peripheral delivery, unlike the subcutaneous route that results in peripheral hyperinsulinemia. Insulin tregopil (IN-105), a new generation human recombinant insulin, methoxy (polyethylene glycol) hexanoyl human recombinant insulin, is developed by Biocon as an ultra-fast onset short-acting oral insulin analog. This recombinant oral insulin is a single short-chain amphiphilic oligomer modified with the covalent attachment of methoxy-triethylene-glycol-propionyl moiety at Lys-β29-amino group of the B-chain via an amide linkage. Sodium caprate, an excipient in the insulin tregopil formulation, is a permeation enhancer that increases its absorption through the gastrointestinal tract. Also, meal composition has been shown to non-significantly affect its absorption. Several global randomized, controlled clinical trials have been conducted in type 1 and type 2 diabetes patients towards the clinical development of insulin tregopil. The formulation shows post-prandial glucose control that is more effective than placebo throughout the meal period; however, compared with an active comparator insulin aspart, the post-prandial control is more effective mainly in the early post-meal period. It shows a good safety profile with a lower incidence of clinically significant hypoglycemia. This review covers the overall clinical development of insulin tregopil establishing it as an ultra-fast onset, short-acting oral insulin analog for optimizing post-prandial glucose.

Advancement from Small Peptide Pharmaceuticals to Orally Active Piperazine-2,5-dion-Based Cyclopeptides

The oral delivery of peptide pharmaceuticals has long been a fundamental challenge in drug development. A new chemical platform was designed based on branched piperazine-2,5-diones for creating orally available biologically active peptidomimetics. The platform includes a bio-carrier with "built-in" functionally active peptide fragments or bioactive molecules that are covalently attached via linkers. The developed platform allows for a small peptide to be taken with a particular biological activity and to be transformed into an orally stable compound displaying the same activity. Based on this approach, various peptidomimetics exhibiting hemostimulating, hemosuppressing, and adjuvant activity were prepared. In addition, new examples of a rare phenomenon when enantiomeric molecules demonstrate reciprocal biological activity are presented. Finally, the review summarizes the evolutionary approach of the short peptide pharmaceutical development from the immunocompetent organ separation to orally active cyclopeptides and peptidomimetics.

Recent Update on Nanoemulsion Impregnated Hydrogel: a Gleam into the Revolutionary Strategy for Diffusion-Controlled Delivery of Therapeutics

Since earlier times, dermatological remedies have been utilized to treat diseases associated with pain, irritation, and skin conditions. Compared to other routes of drug delivery, topical delivery of drugs offers several benefits. Scientists are investigating different alterations in dosage forms in addition to existing topical formulations such as ointments, gels, creams, lotions, and ointments to significantly improve the permeation of drugs and enhance the pharmacological efficacy of medications that are poorly absorbed via the skin. Conventional formulations have a plethora of problems viz. poor absorption, no target specificity, low spreadability, and inadequate bioavailability which leads the researchers toward developing novel formulations like nanoemulsions. The nanoemulsion can enhance the gradient in concentration and thermodynamic movement toward the epidermis and enhance the penetration of its constituents. However, due to its difficult application, nanoemulsion's lower viscosity limited its use in transdermal delivery. Thus, the development of nanoemulsion-based hydrogels has shown to be a successful strategy for removing obstacles from existing drug formulations. The simple application, expedient spreadability, non-stickiness, safety, and effectiveness of nanoemulsion-based hydrogel have led to substantial growth in their research in recent years. This review gives a brief idea about the prevalence of skin diseases, skin as an obstacle for drug delivery, and recent research insights to combat these obstacles. The work highlights the mechanism of drug release via nanoemulsion, hydrogels, and nanoemulsion-based hydrogels with reference to recent research on hydrophobic and hydrophilic drugs.

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.

Dual-targeted and dual-sensitive self-assembled protein nanocarrier delivering hVEGI-192 for triple-negative breast cancer

Breast cancer is a highly prevalent malignancy worldwide among women with an increasing incidence in recent years. Triple-negative breast cancer (TNBC), a specific type of breast cancer, occurs primarily in young women and exhibits large tumor size, high clinical stage, and extremely poor prognosis with a high rate of lymph node, liver, and lung metastases. TNBC is insensitive to endocrine therapy and trastuzumab treatment, and there is an urgent need for effective therapeutics and treatment guidelines. However, investigations into antiangiogenic agents for the treatment of TNBC are ongoing. In this study, we successfully engineered a self-assembled protein nanocarrier TfRBP9-hVEGI-192-ELP fusion protein (TVEFP) to deliver the therapeutic protein, human vascular endothelial growth inhibitor (hVEGI-192). This was found to be effective in inhibiting tumor angiogenesis in vivo. The protein nanocarrier effectively inhibited the progression of TNBC in vivo and showed the behavior of self-assembly, thermoresponsiveness, enzyme stimulation-responsiveness, tumor-targeting, biocompatibility, and biodegradability. Near-infrared imaging studies showed that fluorescent dye-stained TVEFP effectively aggregated at the tumor site. The TVEFP nanocarrier significantly expands the application of the therapeutic protein hVEGI-192 and improves the imaging and biotherapeutic effects in TNBC, chiefly based on anti-angiogenesis effects.

Multidimensional futuristic approaches to address the pandemics beyond COVID-19

Globally, the impact of the coronavirus disease 2019 (COVID-19) pandemic has been enormous and unrelenting with ∼6.9 million deaths and ∼765 million infections. This review mainly focuses on the recent advances and potentially novel molecular tools for viral diagnostics and therapeutics with far-reaching implications in managing the future pandemics. In addition to briefly highlighting the existing and recent methods of viral diagnostics, we propose a couple of potentially novel non-PCR-based methods for rapid, cost-effective, and single-step detection of nucleic acids of viruses using RNA mimics of green fluorescent protein (GFP) and nuclease-based approaches. We also highlight key innovations in miniaturized Lab-on-Chip (LoC) devices, which in combination with cyber-physical systems, could serve as ideal futuristic platforms for viral diagnosis and disease management. We also discuss underexplored and underutilized antiviral strategies, including ribozyme-mediated RNA-cleaving tools for targeting viral RNA, and recent advances in plant-based platforms for rapid, low-cost, and large-scale production and oral delivery of antiviral agents/vaccines. Lastly, we propose repurposing of the existing vaccines for newer applications with a major emphasis on Bacillus Calmette-Guérin (BCG)-based vaccine engineering.

Oral insulin delivery: Barriers, strategies, and formulation approaches: A comprehensive review

Diabetes Mellitus is characterized by a hyperglycemic condition which can either be caused by the destruction of the beta cells or by the resistance developed against insulin in the cells. Insulin is a peptide hormone that regulates the metabolism of carbohydrates, proteins, and fats. Type 1 Diabetes Mellitus needs the use of Insulin for efficient management. However invasive methods of administration may lead to reduced adherence by the patients. Hence there is a need for a non-invasive method of administration. Oral Insulin has several merits over the conventional method including patient compliance, and reduced cost, and it also mimics endogenous insulin and hence reaches the liver by the portal vein at a higher concentration and thereby showing improved efficiency. However oral Insulin must pass through several barriers in the gastrointestinal tract. Some strategies that could be utilized to bypass these barriers include the use of permeation enhancers, absorption enhancers, use of suitable polymers, use of suitable carriers, and other agents. Several formulation types have been explored for the oral delivery of Insulin like hydrogels, capsules, tablets, and patches which have been described briefly by the article. A lot of attempts have been made for developing oral insulin delivery however none of them have been commercialized due to numerous shortcomings. Currently, there are several formulations from the companies that are still in the clinical phase, the success or failure of some is yet to be seen in the future.

Self-assembled chitosan-insulin oral nanoparticles - A critical perspective review

Chitosan is an abundant natural cationic polysaccharide with excellent biodegradability, bioadhesion, and biocompatibility. Chitosan is extensively researched for various particulate oral insulin drug delivery systems. Oral insulin is economically efficient and more convenient than injections, with greater patient compliance. Electrostatic ionic interaction between cationic chitosan and anionic polymer or insulin leads to the formation of spontaneously self-assembled nanoparticles. This simple technique attracted many researchers as it can be carried out quickly in mild conditions without harmful solvents, such as surfactants or chemical cross-linkers that might degrade the insulin structure. The formulated chitosan nanoparticles help to protect the core insulin from enzymatic degradation in the digestive system and improve paracellular intestinal uptake from the enterocytes due to mucoadhesion and reversible tight junction opening. Moreover, functionalized chitosan nanoparticles create newer avenues for targeted and prolonged delivery. This review focuses on modified chitosan-insulin nanoparticles and their implications on oral insulin delivery. Dependent variables and their optimal concentration ranges used in self-assembly techniques for chitosan-insulin nanoparticular synthesis are summarized. This review provides a comprehensive guide to fine-tune the essential factors to formulate stable insulin-chitosan nanoparticles using mild ionic interactions.

Strategic Approaches to Improvise Peptide Drugs as Next Generation Therapeutics

In recent years, the occurrence of a wide variety of drug-resistant diseases has led to an increase in interest in alternate therapies. Peptide-based drugs as an alternate therapy hold researchers' attention in various therapeutic fields such as neurology, dermatology, oncology, metabolic diseases, etc. Previously, they had been overlooked by pharmaceutical companies due to certain limitations such as proteolytic degradation, poor membrane permeability, low oral bioavailability, shorter half-life, and poor target specificity. Over the last two decades, these limitations have been countered by introducing various modification strategies such as backbone and side-chain modifications, amino acid substitution, etc. which improve their functionality. This has led to a substantial interest of researchers and pharmaceutical companies, moving the next generation of these therapeutics from fundamental research to the market. Various chemical and computational approaches are aiding the production of more stable and long-lasting peptides guiding the formulation of novel and advanced therapeutic agents. However, there is not a single article that talks about various peptide design approaches i.e., in-silico and in-vitro along with their applications and strategies to improve their efficacy. In this review, we try to bring different aspects of peptide-based therapeutics under one article with a clear focus to cover the missing links in the literature. This review draws emphasis on various in-silico approaches and modification-based peptide design strategies. It also highlights the recent progress made in peptide delivery methods important for their enhanced clinical efficacy. The article would provide a bird's-eye view to researchers aiming to develop peptides with therapeutic applications.

Graphical Abstract

Multi-responsive starch-based nanocapsules for colon-targeting delivery of peptides: In vitro and in vivo evaluation

Colon-targeting delivery of insulin is surging great interests in revolutionizing diabetes. Herein, insulin-loaded starch-based nanocapsules developed by layer-by-layer self-assembly technology were rationally structured. Interactions between starches and the structural changes of the nanocapsules were unraveled to understand in vitro and in vivo insulin release properties. By increasing the deposition layers of starches, the structural compactness of nanocapsules increased and in turn retarded insulin release in the upper gastrointestinal tract. Spherical nanocapsules deposited at least five layers of starches could deliver insulin to the colon in a high efficiency according to the in vitro and in vivo insulin release performance. The underlying mechanism of the insulin colon-targeting release should ascribe to the suitable changes in compactness of the nanocapsules and the interactions between deposited starches after multi-response to the changes in pH, time and enzymes in gastrointestinal tract. Starch molecules interacted with each other much stronger at the intestine than that at the colon, which guaranteed a compact structure in the intestine but a loose structure in the colon for the colon-targeting nanocapsules. It suggested that rather than controlling the deposition layer of the nanocapsules, controlling the interaction between starches could also regulate the structures of the nanocapsules for colon-targeting delivery system.

Carboxymethyl cellulose@multi wall carbon nanotubes functionalized with Ugi reaction as a new curcumin carrier

In recent years, the fabrication of new drug delivery systems (DDSs) based on functionalization by multi-component reactions (MCRs) has received special attention. In this regard, to obtain a new oral administration system for colon-specific cancer treatment, the CMC@MWCNTs@FCA carrier was designed and prepared from the functionalization of the CMC@MWCNTs as a biocompatible raw material with carboxamide group by the Ugi reaction. FT-IR analysis confirmed the successful synthesis of the product through the change in the functional groups of reagents. Additionally, the crystalline structure and porosity of the samples were studied by XRD and BET techniques. After a detailed characterization, the curcumin (CUR) was loaded on CMC@MWCNTs and CMC@MWCNTs@FCA, respectively, about 29 % and 38 %. In vitro drug release behavior studies for CUR-loaded CMC@MWCNTs@FCA showed the controlled release for it, so 11.6 % and 76.5 % of CUR, respectively were released at pH 1.2 and pH 7.4. Toxicological analysis displayed the IC₅₀ of CMC@MWCNTs@FCA@CUR is 752 μg/mL. In conclusion, the obtained findings display that the fabricated system can be proposed as a biocompatible carrier for specific colon cancer treatment.

Engineered Nano-carrier Systems for the oral targeted delivery of Follicle Stimulating Hormone: Development, characterization, and, assessment of in vitro and in vivo performance and targetability

Follicle stimulating hormone (FSH) is widely used for the treatment of female infertility, where the level of FSH is suboptimal due to which arrest in follicular development and anovulation takes place. Currently, only parenteral formulations are available for FSH in the market. Due to the drawbacks of parenteral administration and the high market shares of FSH, there is a need for easily accessible oral formulation. Therefore, enteric coated capsules filled with FSH loaded nanostructured lipid carriers (NLCs) or liposomes were prepared. Preliminary studies such as circular dichroism, SDS-PAGE, FTIR and ELISA were conducted to analyze FSH. Prepared formulations were optimized with respect to the size, polydispersity index, zeta potential, and entrapment efficiency using the design of experiments. Optimized formulations were subjected to particle counts and distribution analysis, TEM analysis, in vitro drug release, dissolution of enteric coated capsules, cell line studies, everted sac rat's intestinal uptake study, pharmacokinetics, pharmacodynamics, and stability studies. In the case of liposomes, RGD conjugation was done by carbodiimide chemistry and conjugation was confirmed by FTIR, ¹HNMR and Raman spectroscopy. The prepared formulations were discrete and spherical. The release of FSH from enteric coated capsules was slow and sustained. The increased permeability of nano-formulations was observed in Caco-2 monoculture as well as in Caco-2 and Raji-B co-culture models. NLCs and liposomes showed an improvement in oral bioavailability and efficacy of FSH in rats. This may be due to mainly chylomicron-assisted lymphatic uptake of NLCs; whereas, in the case of liposomes, RGD-based targeting of β1 integrins of M cells on Peyer's patches may be the main reason for the better effect by FSH. FSH was found to be stable chemically and conformationally. Overall, the study reveals the successful development and evaluation of FSH loaded NLCs and liposomes.

Fundamental advances in hydrogels for the development of the next generation of smart delivery systems as biopharmaceuticals

Recent advances in developing and applying therapeutic peptides for anticancer, antimicrobial and immunomodulatory remedies have opened a new era in therapeutics. This development has resulted in the engineering of new biologics as part of a concerted effort by the pharmaceutical industry. Many alternative routes of administration and delivery vehicles, targeting better patient compliance and optimal therapeutic bioavailability, have emerged. However, the design of drug delivery systems to protect a range of unstable macromolecules, including peptides and proteins, from high temperatures, acidic environments, and enzymatic degradation remains a priority. Herein, we give chronological insights in the development of controlled-release drug delivery systems that occurred in the last 70 years or so. Subsequently, we summarise the key physicochemical characteristics of hydrogels contributing to the development of protective delivery systems concerning drug-targeted delivery in the chronospatial domain for biopharmaceuticals. Furthermore, we shed some light on promising hydrogels that can be utilised for systemic bioactive administration.

Ocular Delivery of Therapeutic Proteins: A Review

Therapeutic proteins, including monoclonal antibodies, single chain variable fragment (ScFv), crystallizable fragment (Fc), and fragment antigen binding (Fab), have accounted for one-third of all drugs on the world market. In particular, these medicines have been widely used in ocular therapies in the treatment of various diseases, such as age-related macular degeneration, corneal neovascularization, diabetic retinopathy, and retinal vein occlusion. However, the formulation of these biomacromolecules is challenging due to their high molecular weight, complex structure, instability, short half-life, enzymatic degradation, and immunogenicity, which leads to the failure of therapies. Various efforts have been made to overcome the ocular barriers, providing effective delivery of therapeutic proteins, such as altering the protein structure or including it in new delivery systems. These strategies are not only cost-effective and beneficial to patients but have also been shown to allow for fewer drug side effects. In this review, we discuss several factors that affect the design of formulations and the delivery of therapeutic proteins to ocular tissues, such as the use of injectable micro/nanocarriers, hydrogels, implants, iontophoresis, cell-based therapy, and combination techniques. In addition, other approaches are briefly discussed, related to the structural modification of these proteins, improving their bioavailability in the posterior segments of the eye without affecting their stability. Future research should be conducted toward the development of more effective, stable, noninvasive, and cost-effective formulations for the ocular delivery of therapeutic proteins. In addition, more insights into preclinical to clinical translation are needed.

Oral administration of VDAC1-derived small molecule peptides increases circulating testosterone levels in male rats

Cholesterol is the precursor of all steroid hormones, and the entry of cholesterol into the mitochondria is the rate-limiting step of steroidogenesis. Voltage-dependent anion channel (VDAC1) is an outer mitochondrial protein part of a multiprotein complex that imports cholesterol. We previously reported that intratesticular administration of a 25 amino acid peptide blocking the interaction between 14-3-3ϵ with VDAC1 increased circulating levels of testosterone. This fusion peptide was composed of a HIV-1 transactivator of transcription (TAT) protein transduction domain cell-penetrating peptide, a glycine linker, and amino acids 159-172 of VDAC1 (TV159-172). Here, we describe the development of a family of small molecules that increase circulating testosterone levels after an oral administration. We first characterized an animal model where TV159-172 was delivered subcutaneously. This subcutaneous model allowed us to study the interactions between TV159-172 and the hypothalamus-pituitary-gonadal axis (HPG) and identify the biologically active core of TV159-172. The core consisted of the tetrapeptide RVTQ, which we used as a platform to design synthetic peptide derivatives that can be administered orally. We developed a second animal model to test various derivatives of RVTQ and found 11 active compounds. Dose-response experiments identified 4 synthetic peptides that robustly increased androgen levels in a specific manner. We selected RdVTQ as the leading VDAC1-core derivative and profiled the response across the lifespan of Brown-Norway rats. In summary, we present the development of a new class of therapeutics that act within the HPG axis to increase testosterone levels specifically. This new class of small molecules self-regulates, preventing abuse.

Potential of Nuclear Imaging Techniques to Study the Oral Delivery of Peptides

Peptides are small biomolecules known to stimulate or inhibit important functions in the human body. The clinical use of peptides by oral delivery, however, is very limited due to their sensitive structure and physiological barriers present in the gastrointestinal tract. These barriers can be overcome with chemical and mechanical approaches protease inhibitors, permeation enhancers, and polymeric encapsulation. Studying the success of these approaches pre-clinically with imaging techniques such as fluorescence imaging (IVIS) and optical microscopy is difficult due to the lack of in-depth penetration. In comparison, nuclear imaging provides a better platform to observe the gastrointestinal transit and quantitative distribution of radiolabeled peptides. This review provides a brief background on the oral delivery of peptides and states examples from the literature on how nuclear imaging can help to observe and analyze the gastrointestinal transit of oral peptides. The review connects the fields of peptide delivery and nuclear medicine in an interdisciplinary way to potentially overcome the challenges faced during the study of oral peptide formulations.

Application of Nanoparticles: Diagnosis, Therapeutics, and Delivery of Insulin/Anti-Diabetic Drugs to Enhance the Therapeutic Efficacy of Diabetes Mellitus

Diabetes mellitus (DM) is a chronic metabolic disorder of carbohydrates, lipids, and proteins due to a deficiency of insulin secretion or failure to respond to insulin secreted from pancreatic cells, which leads to high blood glucose levels. DM is one of the top four noncommunicable diseases and causes of death worldwide. Even though great achievements were made in the management and treatment of DM, there are still certain limitations, mainly related to the early diagnosis, and lack of appropriate delivery of insulin and other anti-diabetic agents. Nanotechnology is an emerging field in the area of nanomedicine and NP based anti-diabetic agent delivery is reported to enhance efficacy by increasing bioavailability and target site accumulation. Moreover, theranostic NPs can be used as diagnostic tools for the early detection and prevention of diseases owing to their unique biological, physiochemical, and magnetic properties. NPs have been synthesized from a variety of organic and inorganic materials including polysaccharides, dendrimers, proteins, lipids, DNA, carbon nanotubes, quantum dots, and mesoporous materials within the nanoscale size. This review focuses on the role of NPs, derived from organic and inorganic materials, in the diagnosis and treatment of DM.

Intestinal absorption pathways of lisinopril: Mechanistic investigations

Lisinopril is an antihypertensive drug with poor intestinal permeability. Enhancement of intestinal absorption depends on a clear understanding of the permeation pathways and absorption mechanisms. Unfortunately, these are not fully elucidated for lisinopril. Accordingly, the aim was to determine lisinopril permeation pathways and obstacles limiting membrane transport with subsequent nomination of appropriate permeation enhancers. This employed an in situ rabbit intestinal perfusion technique, which revealed site-dependent absorptive clearance (PeA/L) from a lisinopril simple solution (5 μg/ml), with paracellular absorption playing a role. Regional drug permeability ranked as colon> duodenum> jejunum> ileum opposing intestinal expression rank of P-glycoprotein (P-gp) efflux transporters. Duodenal and jejunal perfusion of a higher lisinopril concentration (50 μg/ml) reflected saturable absorption, suggesting carrier-mediated transport. The effect of piperine and verapamil as P-gp inhibitors on intestinal absorption of lisinopril was investigated. Coperfusion with either piperine or verapamil significantly enhanced lisinopril absorption, with enhancement being dominant in the ileum segment. This supported the contribution of P-gp transporters to poor lisinopril permeability. On the other hand, coperfusion of lisinopril with zinc acetate dihydrate significantly multiplied lisinopril PeA/L by 2.3- and 6.6-fold in duodenum and ileum segments, respectively, through magnifying intestinal water flux. The study explored the barriers limiting lisinopril intestinal absorption. Moreover, the study exposed clinically relevant lisinopril interactions with common coadministered cargos that should be considered for an appropriate lisinopril regimen. However, this requires further in vivo verification.

Oromucosal delivery of macromolecules: Challenges and recent developments to improve bioavailability

Owing to their biological diversity, high potency, good tolerability, low immunogenicity, site-specific activity, and great efficacy, macromolecular drugs (i.e., proteins and peptides, antibodies, hormones, nucleic acids, vaccines, etc.) are extensively used as diagnostics, prophylactics, and therapeutics in various diseases. To overcome drawbacks associated with parenteral (invasive) delivery of macromolecules as well as to preserve their therapeutic integrity, oromucosal route (sublingual and buccal) has been proven efficient alternate port of delivery. This review aims to summarize challenges associated with oromucosal route and overtime developments in conventional delivery systems with special emphasis on most recent delivery strategies. Over the past few decades, significant efforts have been made for improving the oromucosal absorption of macromolecules by employing chemical penetration enhancers (CPE), enzyme inhibitors, chemical modification of drug structure (i.e., lipidation, PEGylation, etc.), and mucoadhesive materials in the form of buccal tablets, films (or patches), sprays, fast disintegrating tablets, and microneedles. Adaptation of adjunct strategies (e.g., iontophoresis in conjunction with CPE) has shown significant improvement in oromucosal absorption of macromolecules; however, these approaches were also associated with many drawbacks. To overcome these shortcomings and to further improve therapeutic outcomes, specialized delivery devices called "hybrid nanosystems" have been designed in recent times. This newer intervention showed promising potential for promoting oromucosal absorption and absolute bioavailability of macromolecules along with improved thermostability (cold chain free storage), enabling self-administration, site-specific activity, improving therapeutic efficacy and patient compliance. We anticipate that tailoring of hybrid nanosystems to clinical trials as well as establishing their short- and long-term safety profile would substantiate their therapeutic value as pharmaceutical devices for oromucosal delivery of macromolecules.

A Review of Multifunction Smart Nanoparticle based Drug Delivery Systems

Cancer nano-therapeutics are rapidly evolving and are often used to overcome a number of concerns with traditional drug delivery methods, including non-specific drug targeting and distribution, low oral bioavailability, and poor hydrophilicity. Modern nano-based targeting techniques have been developed as a result of advances in nano vehicle engineering and materials science, which may bring people with cancer a new hope. Clinical trials have been authorized for a number of medicinal nanocarriers. Nanocarriers with the best feasible size and surface attributes have been developed to optimize biodistribution and increase blood circulation duration. Nanotherapeutics can carry preloaded active medicine towards cancerous cells by preferentially leveraging the specific physiopathology of malignancies. In contrast to passive targeting, active targeting strategies involving antigens or ligands, developed against specific tumor sites, boost the selectivity of these curative nanovehicles. Another barrier that nanoparticles may resolve or lessen is drug resistance. Multifunctional and complex nanoparticles are currently being explored and are predicted to usher in a new era of nanoparticles that will allow for more individualized and customized cancer therapy. The potential prospects and opportunities of stimuli-triggered nanosystems in therapeutic trials are also explored in this review.

An update on biomaterials as microneedle matrixes for biomedical applications

Microneedles (MNs) have been developed for various applications such as drug delivery, cosmetics, diagnosis, and biosensing. To meet the requirements of MNs used in these areas, numerous materials have been used for the fabrication of MNs. However, MNs will be exposed to skin tissues after piercing the stratum corneum barrier. Thus, it is necessary to ensure that the matrix materials of MNs have the characteristics of low toxicity, good biocompatibility, biodegradability, and sufficient mechanical properties for clinical application. In this review, the matrix materials currently used for preparing MNs are summarized and reviewed in terms of these factors. In addition, MN products used on the market and their applications are summarized in the end. This work may provide some basic information to researchers in the selection of MN matrix materials and in developing new materials.

Overcoming the shortcomings of peptide-based therapeutics

Peptides have traditionally been perceived as poor drug candidates due to unfavorable characteristics mainly regarding their pharmacokinetic behavior, including plasma stability, membrane permeability and circulation half-life. Nonetheless, in recent years, general strategies to tackle those shortcomings have been established, and peptides are subsequently gaining increasing interest as drugs due to their unique ability to combine the advantages of antibodies and small molecules. Macrocyclic peptides are a special focus of drug development efforts due to their ability to address so called ‘undruggable’ targets characterized by large and flat protein surfaces lacking binding pockets. Here, the main strategies developed to date for adapting peptides for clinical use are summarized, which may soon help usher in an age highly shaped by peptide-based therapeutics. Nonetheless, limited membrane permeability is still to overcome before peptide therapeutics will be broadly accepted.

Do gluten peptides stimulate weight gain in humans?

Observations from animal and in vitro laboratory research, and anecdotal evidence, have led to the suggestion that gluten consumption stimulates weight gain by the presence of peptides expressing opioid activity. Another proposed mechanism is that gluten peptides decrease resting energy expenditure resulting in a positive energy balance. In order to induce such effects in vivo, intact food peptides must be absorbed in sufficient quantities, remain intact in the blood for sufficient time to have long-lasting biological activity and bind to receptors involved in appetite, satiety and energy regulation. However, although peptides from food may pass from the intestine into the blood in extremely low quantities, they are generally rapidly degraded by plasma and vasculum-bound aminopeptidases, resulting in very short half-lives and loss of bioactivity. At present, gluten peptide sequences that influence regulators of energy metabolism have not been identified. Furthermore, data on the quantitative absorption of gluten peptides in the blood stream, their stability and lasting bioactivity are also lacking. Therefore, there is no evidence for proposed effects on driving appetite by the brain, nor on energy expenditure and weight gain. Furthermore, the level of overweight observed in various countries appears to be independent of the level of wheat consumption, and abundant observational evidence in humans shows that the levels of gluten consumption are neither related to daily calorie intake nor to BMI. This narrative review therefore discusses the proposed effects of gluten on bodyweight (BW) and putative biological mechanisms in the light of the current evidence.

Gastrointestinal Microbiota and Their Manipulation for Improved Growth and Performance in Chickens

The gut of warm-blooded animals is colonized by microbes possibly constituting at least 100 times more genetic material of microbial cells than that of the somatic cells of the host. These microbes have a profound effect on several physiological functions ranging from energy metabolism to the immune response of the host, particularly those associated with the gut immune system. The gut of a newly hatched chick is typically sterile but is rapidly colonized by microbes in the environment, undergoing cycles of development. Several factors such as diet, region of the gastrointestinal tract, housing, environment, and genetics can influence the microbial composition of an individual bird and can confer a distinctive microbiome signature to the individual bird. The microbial composition can be modified by the supplementation of probiotics, prebiotics, or synbiotics. Supplementing these additives can prevent dysbiosis caused by stress factors such as infection, heat stress, and toxins that cause dysbiosis. The mechanism of action and beneficial effects of probiotics vary depending on the strains used. However, it is difficult to establish a relationship between the gut microbiome and host health and productivity due to high variability between flocks due to environmental, nutritional, and host factors. This review compiles information on the gut microbiota, dysbiosis, and additives such as probiotics, postbiotics, prebiotics, and synbiotics, which are capable of modifying gut microbiota and elaborates on the interaction of these additives with chicken gut commensals, immune system, and their consequent effects on health and productivity. Factors to be considered and the unexplored potential of genetic engineering of poultry probiotics in addressing public health concerns and zoonosis associated with the poultry industry are discussed.

Challenges in delivering therapeutic peptides and proteins: A silk-based solution

Peptide- and protein-based therapeutics have drawn significant attention over the past few decades for the treatment of infectious diseases, genetic disorders, oncology, and many other clinical needs. Yet, protecting peptide- and protein-based drugs from degradation and denaturation during processing, storage and delivery remain significant challenges. In this review, we introduce the properties of peptide- and protein-based drugs and the challenges associated with their stability and delivery. Then, we discuss delivery strategies using synthetic polymers and their advantages and limitations. This is followed by a focus on silk protein-based materials for peptide/protein drug processing, storage, and delivery, as a path to overcome stability and delivery challenges with current systems.

Poloxamer 188 as surfactant in biological formulations - An alternative for polysorbate 20/80?

Surfactants are used to stabilize biologics. Particularly, polysorbates (Tween® 20 and Tween® 80) dominate the group of surfactants in protein and especially antibody drug products. Since decades drug developers rely on the ethoxylated sorbitan fatty acid ester mixtures to stabilize sensitive molecules such as proteins. Reasons are (i) excellent stabilizing properties, and (ii) well recognized safety and tolerability profile of these polysorbates in humans, especially for parenteral applications. However, over the past decade concerns regarding the stability of these two polysorbates were raised. The search of alternatives with preferably less reservations concerning degradation and product quality reducing issues leads, among others, to poloxamer 188 (e.g. Kolliphor® P188), a nonionic triblock-copolymer surfactant. This review sums up our current knowledge related to the characterization and physico-chemical properties of poloxamer 188, its analytics and stability properties for biological formulations. Furthermore, the advantages and disadvantages as a suitable polysorbate-alternative for the stabilization of biologics are discussed.

Non-invasive ways of administering insulin

BACKGROUND AND AIMS

Insulin is crucial in the management of diabetes. However, requires injection which itself comes with some challenges. Alternative delivery routes have been investigated that are needle-free, with enhanced absorption and bioavailability. This review presents novel non-invasive insulin administration approaches that overcome some hurdles, as well as delineating their advantages and disadvantages.

METHODS

Information was primarily gathered by employing various PubMed scholarly articles for real-world examples in addition to data extraction from supplementary manuscripts. Articles were evaluated between 1958 and 2022. An introductive approach was used to identify matters related to the concept of different ways of administering insulin.

RESULTS

Approaches aim to administer insulin in a safe, stable, and easy to use form, whether via oral, buccal, intranasal, oral inhalation, transdermal, ocular, rectal, or vaginal routes. Some have been shown to clinically improve blood glucose levels, while others are still in the investigational stage.

CONCLUSION

Many approaches have been taken in an attempt to overcome physical barriers of insulin delivery. Some of these systems discussed may reach the market in the future and assist the millions of people who currently take subcutaneous injections of insulin.