Effective incorporation of insulin in mucus permeating self-nanoemulsifying drug delivery systems

Evaluation of a mucoadhesive auto-nanoemulsifying drug delivery system (SNEDDS) for oral insulin administration

This study investigated the potential of self-nanoemulsifying drug delivery systems (SNEDDS) to optimize the oral bioavailability of insulin. Insulin complexes with phospholipids and enzymatically-modified phospholipids were developed and incorporated into the SNEDDS using Lauroglycol FCC as the oily phase and Cremophor EL and Labrafil M1944CS as the surfactant and co-surfactant, respectively. Additionally, mucoadhesive polysaccharides (sodium alginate and guar gum) were added further to enhance the bioavailability of insulin in these systems. The objective was to increase the bioavailability and bioactivity of an insulin-modified phosphatidylcholine complex by incorporating mucoadhesives into the SNEDDS. After polymer inclusion, the resulting nanoemulsions exhibited droplet diameters ranging from 57 to 83 nm. Cytotoxicity and apparent permeability tests were conducted on Caco-2 and NIH 3 T3 cell lines, revealing that toxicity was related to the concentrations of insulin and surfactant in the nanosystems-formulations containing guar gum as a mucoadhesive showed better tolerance to cell death in the Caco-2 line. In a murine diabetes model, the SNEDDS were observed to reduce glucose levels by up to 61.63 %, with a relative bioavailability of 2.25 % compared to subcutaneously administered insulin. These results suggest that SNEDDS incorporating mucoadhesives could represent a promising strategy for improving oral insulin delivery.

Recent Progress in the Oral Delivery of Therapeutic Peptides and Proteins: Overview of Pharmaceutical Strategies to Overcome Absorption Hurdles

Purpose

Proteins and peptides have secured a place as excellent therapeutic moieties on account of their high selectivity and efficacy. However due to oral absorption limitations, current formulations are mostly delivered parenterally. Oral delivery of peptides and proteins (PPs) can be considered the need of the hour due to the immense benefits of this route. This review aims to critically examine and summarize the innovations and mechanisms involved in oral delivery of peptide and protein drugs.

Methods

Comprehensive literature search was undertaken, spanning the early development to the current state of the art, using online search tools (PubMed, Google Scholar, ScienceDirect and Scopus).

Results

Research in oral delivery of proteins and peptides has a rich history and the development of biologics has encouraged additional research effort in recent decades. Enzyme hydrolysis and inadequate permeation into intestinal mucosa are the major causes that result in limited oral absorption of biologics. Pharmaceutical and technological strategies including use of absorption enhancers, enzyme inhibition, chemical modification (PEGylation, pro-drug approach, peptidomimetics, glycosylation), particulate delivery (polymeric nanoparticles, liposomes, micelles, microspheres), site-specific delivery in the gastrointestinal tract (GIT), membrane transporters, novel approaches (self-nanoemulsifying drug delivery systems, Eligen technology, Peptelligence, self-assembling bubble carrier approach, luminal unfolding microneedle injector, microneedles) and lymphatic targeting, are discussed. Limitations of these strategies and possible innovations for improving oral bioavailability of protein and peptide drugs are discussed.

Conclusion

This review underlines the application of oral route for peptide and protein delivery, which can direct the formulation scientist for better exploitation of this route.

Development of a novel squalene/α-tocopherol-based self-emulsified nanoemulsion incorporating Leishmania peptides for induction of antigen-specific immune responses

Vaccination has emerged as the most effective strategy to confront infectious diseases, among which is leishmaniasis, that threat public health. Despite laborious efforts there is still no vaccine for humans to confront leishmaniasis. Multi-epitope protein/peptide vaccines present a number of advantages, however their use along with appropriate adjuvants that may also act as antigen carriers is considered essential to overcome subunit vaccines' low immunogenicity. In the present study, a stable self-emulsified nanoemulsion was developed and double-adjuvanted with squalene and α-tocopherol. The prepared nanoemulsion droplets exhibited low cytotoxicity in a certain range of concentrations, while they were efficiently taken up by macrophages and dendritic cells in vitro as well as in vivo in secondary lymphoid organs. To further characterize nanoformulation's potent antigen delivery capability, three multi-epitope Leishmania peptides were incorporated into the nanoemulsion. Peptide encapsulation resulted in dendritic cells' functional differentiation characterized by elevated levels of maturation markers and intracellular cytokine production. Intramuscular administration of the nanoemulsion incorporating Leishmania peptides induced antigen-specific spleen cell proliferation as well as elicitation of CD4+ central memory cells, supporting the potential of the developed nanoformulation to successfully act also as an antigen delivery vehicle and thus encouraging further preclinical studies on its vaccine candidate potency.

Future Nanotechnology-Based Strategies for Improved Management of Helicobacter pylori Infection

Helicobacter pylori (H. pylori) is a recalcitrant pathogen, which can cause gastric disorders. During the past decades, polypharmacy-based regimens, such as triple and quadruple therapies have been widely used against H. pylori. However, polyantibiotic therapies can disturb the host gastric/gut microbiota and lead to antibiotic resistance. Thus, simpler but more effective approaches should be developed. Here, some recent advances in nanostructured drug delivery systems to treat H. pylori infection are summarized. Also, for the first time, a drug release paradigm is proposed to prevent H. pylori antibiotic resistance along with an IVIVC model in order to connect the drug release profile with a reduction in bacterial colony counts. Then, local delivery systems including mucoadhesive, mucopenetrating, and cytoadhesive nanobiomaterials are discussed in the battle against H. pylori infection. Afterward, engineered delivery platforms including polymer-coated nanoemulsions and polymer-coated nanoliposomes are poposed. These bioinspired platforms can contain an antimicrobial agent enclosed within smart multifunctional nanoformulations. These bioplatforms can prevent the development of antibiotic resistance, as well as specifically killing H. pylori with no or only slight negative effects on the host gastrointestinal microbiota. Finally, the essential checkpoints that should be passed to confirm the potential effectiveness of anti-H. pylori nanosystems are discussed.

Counterion optimization for hydrophobic ion pairing (HIP): Unraveling the key factors

In the present study, various surfactants were combined with insulin (INS), bovine serum albumin (BSA) and horseradish peroxidase (HRP) via hydrophobic ion pairing to increase lipophilicity and facilitate incorporation into self-emulsifying drug delivery systems (SEDDS). Lipophilicity of model proteins was successfully increased, achieving log Dn-butanol/water values up to 3.5 (INS), 3.2 (BSA) and 1.2 (HRP). Hereby, key factors responsible for complex formation were identified. In particular, surfactants with branched alkyl chains or chain lengths greater than C12 showed favorable properties for hydrophobic ion pairs (HIP). Furthermore, flexibility of the carbon chain resulted in higher lipophilicity and suitability of polar head groups of surfactants for HIP decreased in the rank order sulfonate > sulfosuccinate > phosphate = sulfate > carbonate > phosphonic acids = sulfobetaines. Stability studies of formed HIP complexes were performed in various gastrointestinal fluids and their solubility was determined in commonly used SEDDS excipients. Formed complexes were stable in simulated gastrointestinal fluids and could be incorporated into SEDDS formulations (C1: 10% caprylocaproyl polyoxyl-8 glycerides, 20% PEG-40 hydrogenated castor oil, 20% medium-chain triglycerides, 50% n-butanol; C2: 10% caprylocaproyl polyoxyl-8 glycerides, 20% PEG-40 hydrogenated castor oil, 20% medium-chain triglycerides, 40% n-butanol, 10% 1,2-butanediol), resulting in suitable payloads of up to 11.9 mg/ml for INS, 1.0 mg/ml for BSA and 1.6 mg/ml for HRP.

Nanoparticle-Mediated Strategies for Enhanced Drug Penetration and Retention in the Airway Mucosa

Airway mucus is a complex viscoelastic gel composed mainly of water, glycoproteins, lipids, enzymes, minerals, etc. Among them, glycoproteins are the main factors determining mucus's gel-like rheology. Airway mucus forms a protective barrier by secreting mucin, which represents a barrier for absorption, especially for more lipophilic drugs. It rapidly removes drugs from the airway through the physiological mucus clearance mechanism so drugs cannot remain in the lungs or reach the airway epithelial tissue for a long time. Significant progress has been made in enhancing drug lung deposition recently, but strategies are still needed to help drugs break through the lung mucosal barrier. Based on the physiopathological mechanisms of airway mucus, this paper reviews and summarizes strategies to enhance drug penetration and retention in the airway mucosa mediated by nano-delivery systems, including mucosal permeation systems, mucosal adhesion systems, and enzyme-modified delivery systems. On this basis, the potential and challenges of nano-delivery systems for improving airway mucus clearance are revealed. New ideas and approaches are provided for designing novel nano-delivery systems that effectively improve drug retention and penetration in the airway mucus layer.

Bioinspired fine-tuning of the mechanical rigidity of SNEDDS for the efficient crossing of multiple gastrointestinal barriers

Nanoproperties, such as size, charge, and rigidity, have been demonstrated to be crucial for nanovehicles to overcome numerous gastrointestinal obstacles. However, the facile approach of modifying the rigidity of nanovehicles remains scarce, limiting understanding of how rigidity impacts their oral delivery. Inspired by the fact that cellular phospholipid content regulates plasma membrane rigidity, the rigidity of self-nanoemulsifiying drug delivery system (SNEDDS) could be fine-tuned via phosphocholine content while their size and zeta potential remain unchanged, using insulin as a model drug. Notably, soft SNEDDS exerted longer gastrointestinal transit time, higher drug release rate, stronger gastrointestinal stability and relatively lower mucus permeation but superior epithelial transcytosis than their hard counterparts in a macropinocytosis-dependent manner. The rigidity-related enhanced transcytosis was attributed to improved endocytosis, lysosome escape capability and exocytosis. Rats with type 1 diabetes exhibited greater oral insulin absorption and blood glucose lowering effect with soft SNEDDS. This study demonstrated the regulatory role of phospholipids in nanovehicle rigidity, which could help develop mechanically optimized nanomedicines in the future.

Comparison of virus-capsid mimicking biologic-shell based versus polymeric-shell nanoparticles for enhanced oral insulin delivery

Virus-capsid mimicking mucus-permeable nanoparticles are promising oral insulin carriers which surmount intestinal mucus barrier. However, the impact of different virus-capsid mimicking structure remains unexplored. In this study, utilizing biotin grafted chitosan as the main skeleton, virus-mimicking nanoparticles endowed with biologic-shell (streptavidin coverage) and polymeric-shell (hyaluronic acid/alginate coating) were designed with insulin as a model drug by self-assembly processes. It was demonstrated that biologic-shell mimicking nanoparticles exhibited a higher intestinal trans-mucus (>80%, 10 min) and transmucosal penetration efficiency (1.6-2.2-fold improvement) than polymeric-shell counterparts. Uptake mechanism studies revealed caveolae-mediated endocytosis was responsible for the absorption of biologic-shell mimicking nanoparticles whereas polymeric-shell mimicking nanoparticles were characterized by clathrin-mediated pathway with anticipated lysosomal insulin digestion. Further, in vivo hypoglycemic study indicated that the improved effect of regulating blood sugar levels was virus-capsid structure dependent out of which biologic-shell mimicking nanoparticles presented the best performance (5.1%). Although the findings of this study are encouraging, much more work is required to meet the standards of clinical translation. Taken together, we highlight the external structural dependence of virus-capsid mimicking nanoparticles on the muco-penetrating and uptake mechanism of enterocytes that in turn affecting their in vivo absorption, which should be pondered when engineering virus-mimicking nanoparticles for oral insulin delivery.

Self-emulsifying drug delivery systems (SEDDS): In vivo-proof of concept for oral delivery of insulin glargine

In spite of recent progress made in the field of peptide and protein delivery, oral administration of insulin and similar drugs remains a challenge. In this study, lipophilicity of insulin glargine (IG) was successfully increased via hydrophobic ion pairing (HIP) with sodium octadecyl sulfate to enable incorporation into self-emulsifying drug delivery systems (SEDDS). Two SEDDS formulations (F1: 20% Labrasol®ALF, 30% polysorbate 80, 10% Croduret 50, 20% oleyl alcohol, 20% Maisine® CC; F2: 30% Labrasol®ALF, 20% polysorbate 80, 30% Kolliphor® HS 15, 20% Plurol® oleique CC 497) were developed and loaded with the IG-HIP complex. Further experiments confirmed increased lipophilicity of the complex, achieving Log D_{SEDDS/release medium} values of 2.5 (F1) and 2.4 (F2) and ensuring sufficient amounts of IG within the droplets after dilution. Toxicological assays indicated minor toxicity and no toxicity inherent to the incorporated IG-HIP complex. SEDDS formulations F1 and F2 were administered to rats via oral gavage and resulted in a bioavailability of 0.55% and 0.44%, corresponding to a 7.7-fold and 6.2-fold increased bioavailability, respectively. Thus, incorporation of complexed insulin glargine into SEDDS formulations provides a promising approach to facilitate its oral absorption.

Hydrophobic Ion Pairing of Small Molecules: How to Minimize Premature Drug Release from SEDDS and Reach the Absorption Membrane in Intact Form

The present work aimed to form hydrophobic ion pairs (HIPs) of a small molecule remaining inside the oily droplets of SEDDS to a high extent. HIPs of ethacridine and various surfactants classified by functional groups of phosphates, sulfates, and sulfonates were formed and precipitation efficiency, log D_{n-octanol/water}, and solubility in different excipients were investigated. Most lipophilic HIPs were incorporated into SEDDS and evaluated regarding drug release. Docusate HIPs showed the highest increase in lipophilicity with a precipitation efficiency of 100%, a log D_{n-octanol/water} of 2.66 and a solubility of 132 mg/mL in n-octanol, 123 mg/mL in oleyl alcohol, and 40 mg/mL in medium chain triglycerides. Docusate HIPs were incorporated into three SEDDS of increasing lipophilicity (F1 < F2 < F3) based on medium chain triglycerides, oleyl alcohol, Kolliphor EL, and Tween 80 (F1: 1 + 5 + 2 + 2; F2: 3 + 3 + 2 + 2; F3: 5 + 1 + 4 + 0). Highest achievable payloads ranged from 74.49 mg/mL (F3) to 97.13 mg/mL (F1) and log D_SEDDS/RM increased by at least 7.5 units (4.99, F1). Drug release studies via the diffusion membrane method confirmed minor release of docusate HIPs from all SEDDS (<2.7% within 4 h). In conclusion, highly lipophilic HIPs remain inside the oily phase of SEDDS and likely reach the absorption membrane in intact form.

Lactoferrin as a Component of Pharmaceutical Preparations: An Experimental Focus

Lactoferrin is an 80 kDa monomeric glycoprotein that exhibits multitask activities. Lactoferrin properties are of interest in the pharmaceutical field for the design of products with therapeutic potential, including nanoparticles and liposomes, among many others. In antimicrobial preparations, lactoferrin has been included either as a main bioactive component or as an enhancer of the activity and potency of first-line antibiotics. In some proposals based on nanoparticles, lactoferrin has been included in delivery systems to transport and protect drugs from enzymatic degradation in the intestine, favoring the bioavailability for the treatment of inflammatory bowel disease and colon cancer. Moreover, nanoparticles loaded with lactoferrin have been formulated as delivery systems to transport drugs for neurodegenerative diseases, which cannot cross the blood-brain barrier to enter the central nervous system. This manuscript is focused on pharmaceutical products either containing lactoferrin as the bioactive component or formulated with lactoferrin as the carrier considering its interaction with receptors expressed in tissues as targets of drugs delivered via parenteral or mucosal administration. We hope that this manuscript provides insights about the therapeutic possibilities of pharmaceutical Lf preparations with a sustainable approach that contributes to decreasing the resistance of antimicrobials and enhancing the bioavailability of first-line drugs for intestinal chronic inflammation and neurodegenerative diseases.

Preparation and characterisation of self-emulsifying drug delivery system (SEDDS) for enhancing oral bioavailability of metformin hydrochloride using hydrophobic ion pairing complexation

AIM

The aim of this study was preparation of a self-emulsifying drug delivery system (SEEDS) containing metformin hydrochloride.

METHODS

Hydrophobic ion paired complexes were prepared by electrostatic interaction between metformin and sodium lauryl sulphate (SLS). The nanodroplets were optimised using two-level full factorial methodology and their morphology were examined. In vitro release of metformin from SEDDS was evaluated in simulated gastric and intestinal fluids. Finally, the ex-vivo efficacy of the optimised formulation in enhancing the intestinal permeability of metformin was evaluated using non-everted intestinal sac.

RESULTS

The data revealed that in weight ratio 1:4(metformin: SLS), the highest recovery was achieved. The physico-chemical properties of the optimised nano-droplets including size, polydispersity index (PdI), zeta potential, and loading efficiency (%) were 192.33 ± 9.9 nm, 0.275 ± 0.051; -1.52 mV, and 93.75 ± 0.77% (w/w), respectively.

CONCLUSIONS

The data obtained from the intestinal transport study demonstrated that SEDDS can significantly enhance the oral permeability of the compound.

Hydrophobic ion pairing-based self-emulsifying drug delivery systems: a new strategy for improving the therapeutic efficacy of water-soluble drugs

INTRODUCTION

Self-emulsifying drug delivery systems (SEDDS) are formulations consisting of oil phase, emulsifiers, and co-emulsifiers, which can be spontaneously emulsified in the body to form O/W microemulsion. Traditionally, SEDDS are used commercially for the improvement of oral absorption and in vivo performances for poorly water-soluble drugs. However, SEDDS formulations were rarely reported for the delivery of water-soluble drugs. Recent studies have found that SEDDS have the potential for water-soluble macromolecular drugs by the application of the hydrophobic ion pairing (HIP) technology.

AREAS COVERED

This review summarized the characteristics of HIP complexes in SEDDS and introduced their advantages and discussed the future prospects of HIP-based SEDDS in drug delivery.

EXPERT OPINION

Hydrophobic ion pairing (HIP) is a technology that combines lipophilic structures on polar counterions to increase the lipophilicity through electrostatic interaction. Recent studies showed that HIP-based SEDDS offer an effective way to increase the mucosal permeability and improve the chemical stability for antibiotics, proteases, DNA-based drugs, and other water-soluble macromolecular drugs. It is believed that HIP-based SEDDS offer a potential and attractive method capable of delivering hydrophilic macromolecules with ionizable groups for oral administration.

Enhanced oral absorption of insulin: hydrophobic ion pairing and a self-microemulsifying drug delivery system using a D-optimal mixture design

The lipophilicity of a peptide drug can be considerably increased by hydrophobic ion pairing with amphiphilic counterions for successful incorporation into lipid-based formulations. Herein, to enhance the oral absorption of insulin (INS), a self-microemulsifying drug delivery system (SMEDDS) formulation was developed. Prior to optimization, INS was complexed with sodium n-octadecyl sulfate (SOS) to increase the loading into the SMEDDS. The INS–SOS complex was characterized via scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and its dissociation behavior. The SMEDDS was optimized using a D-optimal mixture design with three independent variables including Capmul MCM (X₁, 9.31%), Labrasol (X₂, 49.77%), and Tetraglycol (X₃, 40.92%) and three response variables including droplet size (Y₁, 115.2 nm), INS stability (Y₂, 46.75%), and INS leakage (Y₃, 17.67%). The desirability function was 0.766, indicating excellent agreement between the predicted and experimental values. The stability of INS-SOS against gastrointestinal enzymes was noticeably improved in the SMEDDS, and the majority of INS remained in oil droplets during release. Following oral administration in diabetic rats, the optimized SMEDDS resulted in pharmacological availabilities of 3.23% (50 IU/kg) and 2.13% (100 IU/kg). Thus, the optimized SMEDDS is a good candidate for the practical development of oral delivery of peptide drugs such as INS.

Functional Excipients and Novel Drug Delivery Scenario in Self-nanoemulsifying Drug Delivery System: A Critical Note

Lipid-based formulations have emerged as prospective dosage forms for extracting the therapeutic effects of existing lipophilic compounds and novel chemical entities more efficiently. Compared to other excipients, lipids have the added benefit of enhancing the bioavailability of lipophilic and highly metabolizable drugs due to their unique physicochemical features and similarities to in vivo components. Furthermore, lipids can minimize the needed dose and even the toxicity of drugs with poor aqueous solubility when employed as the primary excipient. Hence, the aim of the present review is to highlight the functional behavior of lipid excipients used in SNEDD formulation along with the stability aspects of the formulation in vivo. Moreover, this review also covered the importance of SNEDDS in drug delivery, the therapeutic and manufacturing benefits of lipids as excipients, and the technological advances made so far to convert liquid to solid SNEDDS like melt granulation, adsorption on solid support, spray cooling, melt extrusion/ spheronization has also highlighted. The mechanistic understanding of SNEDD absorption in vivo is highly complex, which was discussed very critically in this review. An emphasis on their application and success on an industrial scale was presented, as supported by case studies and patent surveys.

Recent Advances in Oral Peptide or Protein-Based Drug Liposomes

The high physiology and low toxicity of therapeutic peptides and proteins have made them a hot spot for drug development in recent years. However, their poor oral bioavailability and unstable metabolism make their clinical application difficult. The bilayer membrane of liposomes provides protection for the drug within the compartment, and their high biocompatibility makes the drug more easily absorbed by the body. However, phospholipids—which form the membranes—are subjected to various digestive enzymes and mucosal adhesion in the digestive tract and disintegrate before absorption. Improvements in the composition of liposomes or modifying their surface can enhance the stability of the liposomes in the gastrointestinal tract. This article reviews the basic strategies for liposome preparation and surface modification that promote the oral administration of therapeutic polypeptides.

Development of Self-Emulsifying Drug Delivery Systems (SEDDSs) Displaying Enhanced Permeation of the Intestinal Mucus Following Sustained Release of Prototype Thiol-Based Mucolytic Agent Load

In this study, mucoactive self-emulsifying drug delivery systems (SEDDSs) based on sustained release of N-acetylcysteine (NAC) were developed for providing effective intestinal mucopermeation. Polymeric ionic complexes of NAC were formed with polyethyleneimine (PEI), Eudragit E 100, and Eudragit RS 100 and loaded into a novel SEDDS. The SEDDSs exhibited a stable average size of 75 ± 12 nm (polydispersity index (PDI) < 0.3) and showed a rise in the zeta potential from −17.31 mV to −7.72 mV. On Caco-2 cells, SEDDSs at 1−3% were non-cytotoxic. An average of 91.8 ± 5.4% NAC was released from SEDDSs containing Eudragit E 100 (p ≤ 0.05) and Eudragit RS 100 (p ≤ 0.001) complexes at a significantly slower rate within 80 min, whereas the SEDDS containing PEI released NAC in a matter of seconds. Similarly, the SEDDS complexes revealed a time-dependent reduction in mucus dynamic viscosity of 52.6 ± 19.9%. Consequently, as compared with a blank SEDDS, mucodiffusion revealed about 2- and 1.8-fold significantly greater mucopermeation of SEDDSs anchoring Eudragit E 100−NAC and RS 100−NAC complexes (p ≤ 0.05), respectively. The mucoactive SEDDSs, which steadily released NAC while permeating the mucus, were linked to a significantly increased mucopermeation in vitro as a result of optimal mucolytic targeting.

Multi-strategic approaches for enhancing active transportation using self-emulsifying drug delivery system

Oral delivery is the most desired route of drug administration and it can be more beneficial for patients suffering from chronic diseases wherein frequent parenteral administration of proteins such as insulin and calcitonin is required. The BCS class II drugs show low aqueous solubility and high permeability whereas BCS class IV drugs suffer from low aqueous solubility and low permeability. Additionally, biologic drugs are highly sensitive to presence of bioenzymes and bile salts when administered orally. Self-emulsifying drug delivery system (SEDDS) is a thermodynamically stable lipid formulation that enhances oral absorption of active ingredients via the opening of tight junctions, increasing the membrane fluidity, and thus overcomes the physiological barriers like viscous mucus layer, strong acid conditions and enzymatic degradation. An understanding of different theories that govern SEDDS formation and drug release can help in formulating a highly stable and effective drug delivery system. Poorly permeable drugs such as chlorpromazine require modification using methods like hydrophobic ion pairing, complexation with phospholipids, etc. to enable high entrapment efficiency which is discussed in the article. Additionally, the article gives an overview of the influence of polymers, length of fatty acids chain and zeta potential in enhancing permeation across the intestinal membrane.

Development of Fluorescently Labeled Self-Emulsifying Drug Delivery Systems (SEDDS) for Prolonged Stability, In Vitro Sustained Release and Cellular Uptake

AIM

In this study, four fluorescein hydrophobic ionic complexes were formed with the cationic polymers Eudragit RS, Eudragit RL, Eudragit E, and polyethyleneimine (PEI) to provide fluorescein sustained release, sustained cellular uptake, and stability.

METHODS

Complexes were loaded in a self-emulsifying drug delivery system (SEDDS) composed of 40% Tween 80, 20% Kolliphor EL, 15% 2-n-Octyl-1-dodecanol, and 25% dipropylene glycol. SEDDS were investigated regarding their size, polydispersity index (PDI), zeta potential, and cytotoxicity. Fluorescein release from SEDDS was performed in phosphate buffer (pH 6.8 and pH 8) and the released fluorescein was evaluated for cellular uptake. Moreover, fluorescein from all of the SEDDS pre-concentrates was released at different time points to check its long-term stability over six months.

RESULTS

The average fluorescein load in SEDDS was 0.045%. SEDDS showed an average droplet size of 24.9 ± 1.6 nm with PDI ≤ 0.3. SEDDS complexes diluted 1:100 increased the zeta potential from -7.3 mV to +3.7 mV and provided > 85% cell viability. An 92.27 ± 3.18% fluorescein exhibited a few seconds of immediate release when used as control or PEI complex in SEDDS. On the contrary, Eudragit-fluorescein complexes in SEDDS showed sustained release of 87.01 ± 5.22% fluorescein in ≤ 70 min with 22.19 ± 14.56% and 59.27 ± 16.57% released at 10 min in pH 6.8 and pH 8 release media, respectively. Comparatively, the medium at pH 6.8 maintained a significantly improved sustained fluorescein release (p ≤ 0.001). Furthermore, Eudragit RS/RL compared to Eudragit E significantly exhibited a slower fluorescein release rate from SEDDS (p ≤ 0.01). The cellular uptake of the released fluorescein was 72.4 ± 8.2% for all SEDDS complexes after 3 h. Eudragit complexes compared to PEI complex in SEDDS significantly showed more sustained fluorescein cellular uptake at 1 h and 2 h (p ≤ 0.001). However, SEDDS complexes showed the longest fluorescein stability with PEI after six months, whereas fluorescein stability for SEDDS containing fluorescein as Eudragit complex and control showed 39.1% and 82.5% fluorescence decrease, respectively after three months.

CONCLUSION

In the developed SEDDS, the presence of hydrophobic ionic complexes can significantly promote longer stability and sustained cellular uptake of fluorescein while releasing in a sustained manner.

Oral delivery of therapeutic peptides and proteins: Technology landscape of lipid-based nanocarriers

The oral administration of therapeutic peptides and proteins is favoured from a patient and commercial point of view. In order to reach the systemic circulation after oral administration, these drugs have to overcome numerous barriers including the enzymatic, sulfhydryl, mucus and epithelial barrier. The development of oral formulations for therapeutic peptides and proteins is therefore necessary. Among the most promising formulation approaches are lipid-based nanocarriers such as oil-in-water nanoemulsions, self-emulsifying drug delivery systems (SEDDS), solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC), liposomes and micelles. As the lipophilic character of therapeutic peptides and proteins can be tremendously increased such as by the formation of hydrophobic ion pairs (HIP) with hydrophobic counter ions, they can be incorporated in the lipophilic phase of these carriers. Since gastrointestinal (GI) peptidases as well as sulfhydryl compounds such as glutathione and dietary proteins are too hydrophilic to enter the lipophilic phase of these carriers, the incorporated therapeutic peptide or protein is protected towards enzymatic degradation as well as unintended thiol/disulfide exchange reactions. Stability of lipid-based nanocarriers towards lipases can be provided by the use to excipients that are not or just poorly degraded by these enzymes. Nanocarriers with a size <200 nm and a mucoinert surface such as PEG or zwitterionic surfaces exhibit high mucus permeating properties. Having reached the underlying absorption membrane, lipid-based nanocarriers enable paracellular and lymphatic drug uptake, induce endocytosis and transcytosis or simply fuse with the cell membrane releasing their payload into the systemic circulation. Numerous in vivo studies provide evidence for the potential of these delivery systems. Within this review we provide an overview about the different barriers for oral peptide and protein delivery, highlight the progress made on lipid-based nanocarriers in order to overcome them and discuss strengths and weaknesses of these delivery systems in comparison to other technologies.

Exploring the potential of redispersible nanocomplex-in-microparticles for enhanced oral insulin delivery

Polyelectrolyte nanocomplex (PEC) is a promising carrier for insulin encapsulation. However, tenacious enzymatic degradation and insufficient penetration in mucus and enterocyte are the dominating obstacles for their oral insulin delivery. Besides, the rate of insulin release should be tuned to achieve desired therapeutic effect and meanwhile with scale-up potential. Thus, PEC embedded microparticles were fabricated in this study to solve the above dilemma. First of all, insulin loaded PEC with sodium dodecyl sulfate (SDS) coating was prepared by self-assembly method and then spray-dried using different ratio chitosan (CS)/ polyvinyl alcohol (PVA) as the matrix to obtain the microparticles. Influence of the CS/PVA ratio on the in vitro and in vivo properties of the redispersed PEC was investigated systemically. It was demonstrated that when CS 50 kDa was used in the matrix, all the PEC could be well redispersed with particle size less than 250 nm, and good stability in the gastrointestinal tract, further improved enzymatic stability was achieved by nanoparticles-in-microparticles design, with CS/PVA 1:1 and 4:1 groups showing better and comparable protection. Insulin release from the microparticles decreased with the increase of CS ratio in the CS/PVA matrix. Spray-dried microparticles had less influence on the mucus penetration of the in situ redispersed PEC, with enhanced insulin permeation observed in different intestinal segments in a CS/PVA ratio dependent manner. And the CS/PVA 1:1 group, which presented good enzymatic stability, enhanced mucus penetration and moderate insulin release rate, exhibited the highest relative pharmacological availability of 6.80%. In conclusion, PEC in microparticles design using CS/PVA as the composite matrix is a potential platform for enhanced oral insulin delivery.

Challenges of peptide and protein drug delivery by oral route: Current strategies to improve the bioavailability

Advancement in biotechnology provided a notable expansion of peptide and protein therapeutics, used as antigens, vaccines, hormones. It has a prodigious potential to treat a broad spectrum of diseases such as cancer, metabolic disorders, bone disorders, and so forth. Protein and peptide therapeutics are administered parenterally due to their poor bioavailability and stability, restricting their use. Hence, research focuses on the oral delivery of peptides and proteins for the ease of self-administration. In the present review, we first address the main obstacles in the oral delivery system in addition to approaches used to enhance the stability and bioavailability of peptide/protein. We describe the physiochemical parameters of the peptides and proteins influencing bioavailability in the systemic circulation. It encounters, many barriers affecting its stability, such as poor cellular membrane permeability at the GIT site, enzymatic degradation (various proteases), and first-pass hepatic metabolism. Then describe the current approaches to overcome the challenges mentioned above by the use of absorption enhancers or carriers, structural modification, formulation and advance technology.

Potential therapeutic applications of AKAP disrupting peptides

The 3'-5'-cyclic adenosine monophosphate (cAMP)/PKA pathway represents a major target for pharmacological intervention in multiple disease conditions. Although the last decade saw the concept of highly compartmentalized cAMP/PKA signaling consolidating, current means for the manipulation of this pathway still do not allow to specifically intervene on discrete cAMP/PKA microdomains. Since compartmentalization is crucial for action specificity, identifying new tools that allow local modulation of cAMP/PKA responses is an urgent need. Among key players of cAMP/PKA signaling compartmentalization, a major role is played by A-kinase anchoring proteins (AKAPs) that, by definition, anchor PKA, its substrates and its regulators within multiprotein complexes in well-confined subcellular compartments. Different tools have been conceived to interfere with AKAP-based protein-protein interactions (PPIs), and these primarily include peptides and peptidomimetics that disrupt AKAP-directed multiprotein complexes. While these molecules have been extensively used to understand the molecular mechanisms behind AKAP function in pathophysiological processes, less attention has been devoted to their potential application for therapy. In this review, we will discuss how AKAP-based PPIs can be pharmacologically targeted by synthetic peptides and peptidomimetics.

Computational avenues in oral protein and peptide therapeutics

Proteins and peptides are amongst the most sought-after biomolecules because of their exceptional potential to cater to a vast range of diseases. Although widely studied and researched, the oral delivery of these biomolecules remains a challenge. Alongside formulation strategies, approaches to overcome the inherent barriers for peptide absorption are being designed at the molecular level to establish a sound rationale and to achieve higher bioavailability. Computer-aided drug design (CADD) is a modern in silico approach for developing successful bio-formulations. CADD enables intricate study of the biomolecules in conjunction with their target sites or receptors at the molecular level. Knowledge of the molecular interactions of proteins and peptides makes way for the pre-screening of suitable formulation components and facilitates their delivery.

Models to evaluate the barrier properties of mucus during drug diffusion

Mucus is widely disseminated in the nasal cavity, oral cavity, respiratory tract, eyes, gastrointestinal tract, and reproductive tract to prevent the invasion of pathogenic bacteria and toxins. The mucus layer through its continuous secretion can prevent the passage of macromolecular substances such as pathogenic bacteria and toxins, thereby reducing the occurrence of inflammation. Without a doubt, mucus also hinders oral absorption. The physiological and biochemical properties of intestinal mucus and the different types of mucus barrier models need to be predominated. To find ways to increase the bioavailability of drugs in the future, this article summarizes mucus composition, barrier properties, mucus models, and mucoadhesive/mucopenetrating particles to highlight the information they can afford. Collectively, the review seeks to provide a state-of-the-art roadmap for researchers who must contend with this critical barrier to drug delivery.

Oral Drug Delivery: Conventional to Long Acting New-Age Designs

The Oral route of administration forms the heartwood of the ever-growing tree of drug delivery technology. It is one of the most preferred dosage forms among patients and controlled release community. Despite the high patient compliance, the deliveries of anti-cancerous drugs, vaccines, proteins, etc. via the oral route are limited and have recorded a very low bioavailability. The oral administration must overcome the physiological barriers (low solubility, permeation and early degradation) to achieve efficient and sustained delivery. This review aims at highlighting the conventional and modern-age strategies that address some of these physiological barriers. The modern age designs include the 3D printed devices and formulations. The superiority of 3D dosage forms over conventional cargos is summarized with a focus on long-acting designs. The innovations in Pharmaceutical organizations (Lyndra, Assertio and Intec) that have taken giant steps towards commercialization of long-acting vehicles are discussed. The recent advancements made in the arena of oral peptide delivery are also highlighted. The review represents a comprehensive journey from Nano-formulations to micro-fabricated oral implants aiming at specific patient-centric designs.

Highly-loaded protein nanocarriers prepared by Flash NanoPrecipitation with hydrophobic ion pairing

The efficient encapsulation of therapeutic proteins into delivery vehicles, particularly without loss of function, remains a significant research hurdle. Typical liposomal formulations achieve drug loadings on the order of 3-5% and encapsulation efficiencies around 50%. We demonstrate the encapsulation of model proteins with isoelectric points above and below pH 7 into nanocarriers (NCs) with protein loadings as high as 46% and encapsulation efficiencies above 95%. This is done by combining the continuous nanofabrication process Flash NanoPrecipitation (FNP) with the technique of hydrophobic ion pairing by forming and encapsulating an ionic complex within a nanocarrier stabilized by a block copolymer surface layer. We complex and encapsulate lysozyme with two anionic hydrophobic counterions, sodium oleate and sodium dodecyl sulfate, using either a pre-formed complex or in situ pairing. The strategy successfully forms NCs ~150 nm in diameter and achieves encapsulation efficiencies over 95%. Protein release rate from the NCs in physiological conditions and the bioactivity of released lysozyme are measured, and both are found to vary with the complexing counterion and the protein/counterion ratio used during formulation. Protein release on the time scale of weeks is observed, and up to 100% bioactivity is measured from released lysozyme. 16 quaternary ammonium cationic counterions are tested to encapsulate ovalbumin in 32 formulations. Of these, 19 successfully form ~150 nm NCs with loadings up to 29% and encapsulation efficiencies up to 88%. We divide the formulations into four regimes and identify chemical factors responsible for the success or failure of a given counterion to formulate NCs with the desirable size, loading, and encapsulation efficiency. A successful ovalbumin NC formulation was then tested in vivo in a mouse nasal vaccine model and found to induce a higher titer of OVA-specific IgG than unencapsulated ovalbumin. Taken together, these findings suggest that Flash NanoPrecipitation with hydrophobic ion pairing is an attractive platform for encapsulating high molecular weight proteins into NCs. In particular, the ability to tune protein release rate by varying the counterion or protein/counterion ratio used during formulation is a useful feature.

New perspectives in oral peptide delivery

Owing to their structural diversity, peptides are a unique source of innovative active ingredients. However, their development has been challenging because of their disadvantageous pharmacokinetic (PK) properties. Over the past decade, many attempts have been made to improve the oral bioavailability of peptide drugs. In this review, we highlight the most recent and promising techniques aimed at the improvement of the oral bioavailability of peptides. The most recent findings will influence future approaches of pharmaceutical companies in the development of new, more efficient, and safer orally delivered peptides.

Self-Nano-Emulsifying Drug-Delivery Systems: From the Development to the Current Applications and Challenges in Oral Drug Delivery

Approximately one third of newly discovered drug molecules show insufficient water solubility and therefore low oral bio-availability. Self-nano-emulsifying drug-delivery systems (SNEDDSs) are one of the emerging strategies developed to tackle the issues associated with their oral delivery. SNEDDSs are composed of an oil phase, surfactant, and cosurfactant or cosolvent. SNEDDSs characteristics, their ability to dissolve a drug, and in vivo considerations are determinant factors in the choice of SNEDDSs excipients. A SNEDDS formulation can be optimized through phase diagram approach or statistical design of experiments. The characterization of SNEDDSs includes multiple orthogonal methods required to fully control SNEDDS manufacture, stability, and biological fate. Encapsulating a drug in SNEDDSs can lead to increased solubilization, stability in the gastro-intestinal tract, and absorption, resulting in enhanced bio-availability. The transformation of liquid SNEDDSs into solid dosage forms has been shown to increase the stability and patient compliance. Supersaturated, mucus-permeating, and targeted SNEDDSs can be developed to increase efficacy and patient compliance. Self-emulsification approach has been successful in oral drug delivery. The present review gives an insight of SNEDDSs for the oral administration of both lipophilic and hydrophilic compounds from the experimental bench to marketed products.

The Role of Counter-Ions in Peptides-An Overview

Peptides and proteins constitute a large group of molecules that play multiple functions in living organisms. In conjunction with their important role in biological processes and advances in chemical approaches of synthesis, the interest in peptide-based drugs is still growing. As the side chains of amino acids can be basic, acidic, or neutral, the peptide drugs often occur in the form of salts with different counter-ions. This review focuses on the role of counter-ions in peptides. To date, over 60 peptide-based drugs have been approved by the FDA. Based on their area of application, biological activity, and results of preliminary tests they are characterized by different counter-ions. Moreover, the impact of counter-ions on structure, physicochemical properties, and drug formulation is analyzed. Additionally, the application of salts as mobile phase additives in chromatographic analyses and analytical techniques is highlighted.

New and novel approaches for enhancing the oral absorption and bioavailability of protein and peptides therapeutics

The advancement of the oral route for macromolecules has gained a lot of attention due to its noninvasive nature, safe and challenging in active research but with limited success. Oral administration poses challenges due to poor solubility, short half-life, quick elimination and the physical, chemical and biological barriers of the gastrointestinal tract. Approaches of past for improving oral absorption, such as enhancers, mucoadhesive delivery and enzyme inhibitors have been taken over by novel approaches like advanced liposomes, self-nanoemulsifying drug delivery system, nanoparticles and targeted delivery. Eudratech™ Pep, Peptelligence, Rani Pill and Pharm Film are the emerging technologies for delivering oral proteins and peptide. Calcitonin, semaglutide and octreotide are the peptides available in the market for oral delivery as outcomes of these technologies.

Self-Emulsifying Drug Delivery Systems: Hydrophobic Drug Polymer Complexes Provide a Sustained Release in Vitro

The aim of this study was to develop hydrophobic ionic drug polymer complexes in order to provide sustained drug release from self-emulsifying drug delivery systems (SEDDS). Captopril (CTL) was used as an anionic model drug to form ionic complexes with the cationic polymers Eudragit RS, RL, and E. Complexes of polymer to CTL charge ratio 1:1, 2:1, and 4:1 were incorporated in two SEDDS, namely FA which was 40% Kolliphor RH 40, 20% Kolliphor EL, and 40% castor oil and FB, which was 40% Kolliphor RH 40, 30% glycerol, 15% Kolliphor EL, and 15% castor oil. Blank and complex loaded SEDDS were characterized regarding their droplet size, polydispersity index (PDI), and zeta potential. Resazurin assay was performed on Caco-2 cells to evaluate the biocompatibility of SEDDS. Release of CTL from SEDDS was determined in release medium containing 0.2 mg/mL of 5,5'-dithiobis(2-nitrobenzoic acid) (DNTB) allowing quantification of free drug released into solution via a thiol/disulfide exchange reaction between CTL and DNTB forming a yellow dye. The droplet size of SEDDS FA and SEDDS FB were in the range of 100 ± 20 nm and 40 ± 10 nm, respectively, with a PDI < 0.5. The zeta potential of SEDDS FA and SEDDS FB increased after the incorporation of complexes. Cell viability remained above 80% after incubation with SEDDS FA and SEDDS FB in a concentration of 1% and 3% for 4 h. Without any polymer, CTL was entirely released from both SEDDS within seconds. In contrast, the higher the cationic lipophilic polymer to CTL ratio in SEDDS, the more sustained was the release of CTL. Among the polymers which were evaluated, Eudragit RL provided the most sustained release. SEDDS FA containing Eudragit RL and CTL in a ratio of 1:1 released 64.78 ± 8.28% of CTL, whereas SEDDS FB containing the same complex showed a release of 91.85 ± 1.17% within 1 h. Due to the formation of lipophilic ionic polymer complexes a sustained drug release from oily droplets formed by SEDDS can be achieved. Taking into account that drugs are otherwise instantly released from SEDDS, results of this study might open the door for numerous additional applications of SEDDS for which a sustained drug release is essential.

Using Self-Nanoemulsifying System to Improve Oral Bioavailability of a Pediatric Antiepileptic Agent Stiripentol: Formulation and Pharmacokinetics Studies

This study aimed to develop a self-nanoemulsifying drug delivery system (SNEDDS) for poorly water-soluble drug stiripentol (STP) with enhanced oral bioavailability. Optimal excipients were selected by constructing pseudo-ternary phase diagrams using determined solubilities of STP, and then the proper composition of SNEDDS was investigated by employing a central composite design method. The optimized SNEDDS was composed of oil (ethyl oleate 39.61%), surfactant (Cremophor® RH 40 43.18%), co-surfactant (1,2-propanediol 17.21%), and STP of 50 mg/mL. The hydrodynamic size, zeta potential, and polydispersity index (PDI) were found to be 45.52 ± 1.99 nm, - 21.67 ± 0.24 mV, and 0.076 ± 0.011, respectively. The optimized STP-SNEDDS showed good stability in accelerated and dilution stability studies. It was also helpful to suppress STP degradation in acidic solution. Compared with STP suspension, STP-SNEDDS presented much faster dissolution rate. STP-SNEDDS successfully resulted in superior levels of C_max and AUC_{0 → 6 h} (4048.38 ± 704.54 μg/L and 7754.58 ± 1489.37 h μg/L, respectively) to STP suspension (1894.09 ± 1077.64 μg/L and 3556.93 ± 2470.01 h μg/L, respectively). The relative oral bioavailability of STP was 218.01%. The brain biodistribution studies showed that STP-SNEDDS presented significantly higher STP concentrations in the brain at 0.5 h and 1 h than that of STP suspension after administration. These findings indicated that a SNEDDS-based oral formulation of STP would be helpful for increasing its therapeutic potential.

Hydrophobic ion pairing (HIP) of (poly)peptide drugs: Benefits and drawbacks of different preparation methods

In order to incorporate hydrophilic macromolecular drugs into lipid-based formulations (LBF), HIP has shown great potential. In this study, different HIP methods were compared with each other. Hydrophobic complexes were formed between bovine serum albumin (BSA) and either dodecyl sulfate, cetyl trimethylammonium or 1,2-dipalmitoyl-sn-glycero-3-phosphate applying the organic solvent-free method, Bligh-Dyer method and biphasic metathesis reaction either with ethyl acetate or chloroform as organic phase. Complex formation efficiency was determined. Hydrophobicity of the obtained complexes was characterized by their apparent partition coefficient between 1-butanol and water. The highest complex formation efficiency was achieved with the Bligh-Dyer method, followed by the organic solvent-free method and the biphasic metathesis reaction. When applying the organic solvent-free method, complex formation efficiency was hampered at higher surfactant concentrations due to the formation of micelles. Furthermore, this method could only be applied for water-soluble compounds. On the contrary, the Bligh-Dyer method was robust towards high surfactant concentrations. Moreover, it enables the use of water-insoluble compounds. The rank order Bligh-Dyer method > organic solvent-free method > biphasic metathesis reaction was confirmed by the log D. According to these results, the Bligh-Dyer method appears advantageous for HIP. However, the organic-solvent free method is an adequate alternative for water-soluble compounds.

Advanced trends in protein and peptide drug delivery: a special emphasis on aquasomes and microneedles techniques

Proteins and peptides have a great potential as therapeutic agents; they have higher efficiency and lower toxicity, compared to chemical drugs. However, their oral bioavailability is very low; also, the transdermal peptide delivery faces absorption limitations. Accordingly, most of proteins and peptides are administered by parenteral route, but there are many problems associated with this route such as patient discomfort, especially for pediatric use. Thus, it is a great challenge to develop drug delivery systems for administration of proteins and peptides by routes other than parenteral one. This review provides an overview on recent advances adopted for protein and peptide drug delivery, focusing on oral and transdermal routes. This is followed by an emphasis on two recent approaches adopted as delivery systems for protein and peptide drugs, namely aquasomes and microneedles. Aquasomes are nanoparticles fabricated from ceramics developed to enhance proteins and peptides stability, providing an adequate residence time in circulation. It consists of ceramic core coated with poly hydroxyl oligomer, on which protein and peptide drug can be adsorbed. Aquasomes preparation, characterization, and application in protein and peptide drug delivery are discussed. Microneedles are promising transdermal approach; it involves creation of micron-sized pores in the skin for enhancing the drug delivery across the skin, as their length ranged between 150 and 1500 μm. Types of microneedles with different drug delivery mechanisms, characterization, and application in protein and peptide drug delivery are discussed. Graphical abstract.

Development and In Vitro Evaluation of Stearic Acid Phosphotyrosine Amide as New Excipient for Zeta Potential Changing Self-Emulsifying Drug Delivery Systems

PURPOSE

Development of zeta potential changing SEDDS containing newly synthesized derivative stearic acid phosphotyrosine amide.

METHODS

Stearoyl chloride was conjugated with phosphotyrosine, which is substrate for the brush border enzyme intestinal alkaline phosphate. The synthesized derivative was implemented in different SEDDS formulations and the zeta potential changing properties and the concluding mucus diffusion abilities were evaluated.

RESULTS

Stearic acid phosphotyrosine amide was successfully synthesized and incorporated into SEDDS. A SEDDS formulation containing the new derivative showed a zeta potential of -14 mV before, and + 2 mV after enzymatic cleavage by intestinal alkaline phosphatase. Experiments on a Caco-2 monolayer demonstrated that the phosphate cannot only be cleaved by isolated enzyme, but also by enzyme, which was expressed by cells. The mucus diffusion abilities of the untreated, negatively charged SEDDS were significantly higher compared to the enzymatically cleaved, positively charged SEDDS.

CONCLUSION

The developed stearic acid phosphotyrosine represents a promising excipient for zeta potential changing SEDDS. Graphical Abstract.

In vitro evaluation of a self-emulsifying drug delivery system (SEDDS) for nasal administration of dimenhydrinate

The objective of the study was the development and in vitro characterization of a self-emulsifying drug delivery system (SEDDS) for the nasal application of dimenhydrinate. Final composition of SEDDS was established based on drug solubility and stability studies. Dimenhydrinate was loaded into the SEDDS pre-concentrates to 7.5% (m/v). The droplet size of the final SEDDS formulations was in a range between 60 and 220 nm. Permeability, as well as tissue toxicity, of the formulations was investigated using bovine nasal mucosa. Enhancement in permeation up to 2.8-fold compared to pure dimenhydrinate was confirmed. Furthermore, toxicity studies did not reveal any serious tissue damages related to the SEDDS. Additionally, irritation potential of SEDDS was evaluated in ciliary beat frequency measurements. Incorporation of dimenhydrinate into SEDDS might therefore be considered as a promising approach within the field of nasal delivery of antiemetics by utilizing permeation enhancement strategy.

Nanoformulation strategies for improving intestinal permeability of drugs: A more precise look at permeability assessment methods and pharmacokinetic properties changes

The therapeutic efficacy of orally administered drugs is often restricted by their inherent limited oral bioavailability. Low water solubility, limited permeability through the intestinal barrier, instability in harsh environment of the gastrointestinal (GI) tract and being substrate of the efflux pumps and the cytochrome P450 (CYP) can impair oral drug bioavailability resulting in erratic and variable plasma drug profile. As more drugs with low membrane permeability are developed, new interest is growing to enhance their intestinal permeability and bioavailability. A wide variety of nanosystems have been developed to improve drug transport and absorption. Sufficient evidence exists to suggest that nanoparticles are able to increase the transepithelial transport of drug molecules. However, key questions remained unanswered. What types of nanoparticles are more efficient? What are preclinical (or clinical) achievements of each type of nanoformulation in terms of pharmacokinetic (PK) parameters? Addressing this issue in this paper, we have reviewed the current literature regarding permeability enhancement, permeability assessment methods and changes in PK parameters following administration of various nanoformulations. Although permeability enhancement by various nanoformulations holds great promise for oral drug delivery, many challenges still need to be addressed before development of more clinically successful nanoproducts.

Chitosan-Coated Alginate Nanoparticles Enhanced Absorption Profile of Insulin Via Oral Administration

BACKGROUND

In this study, four nanoparticle formulations (F1 to F4) comprising varying ratios of alginate, Pluronic F-68 and calcium chloride with a constant amount of insulin and chitosan as a coating material were prepared using polyelectrolyte complexation and ionotropic gelation methods to protect insulin against enzymatic degradation.

METHODS

This study describes the formulation design, optimisation, characterisation and evaluation of insulin concentration via oral delivery in rats. A reversed-phase high-performance liquid chromatography (HPLC) method was developed and validated to quantify insulin concentration in rat plasma. The proposed method produced a linear response over the concentration range of 0.39 to 50 µg/ml.

RESULTS

In vitro release study showed that dissolution of insulin in simulated gastric juice of pH 1.2 was prevented by alginate core and chitosan coating but rapidly released in simulated intestinal fluid (pH 6.8). Additionally, Formulation 3 (F3) has a particle size of 340.40 ± 2.39 nm with narrow uniformity exhibiting encapsulation efficiency (EE) of 72.78 ± 1.25 % produced highest absorption profile of insulin with a bioavailability of 40.23 ±1.29% and reduced blood glucose after its oral administration in rats.

CONCLUSION

In conclusion, insulin oral delivery system containing alginate and chitosan as a coating material has the ability to protect the insulin from enzymatic degradation thus enhance its absorption in the intestine. However, more work should be done for instance to involve human study to materialise this delivery system for human use.