Oral delivery of insulin has always been a research highlight in the field of pharmaceutics.The key issue is to improve the bioavailability of orally delivered insulin by overcoming the multiple barriers to absorption of insulin simultaneously.Rapid breakthroughs in formulation technique of nanomedicine shed a light on effective oral delivery of insulin.In this publication,the current status of insulin-loaded nanoparticles was reviewed.The efficiency and shortcomings of insulin nanoparticles in overcoming the multiple barriers to absorption are discussed.The review ends with some prospects and challenges for the success of administering insulin-loaded nanoparticle orally in diabetes treatment.
Key words:
Insulin
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Nanoparticles
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Nanodrug delivery systems
基于既往研究结果,针对胰岛素吸收的多重屏障,笔者提出高效的胰岛素口服纳米给药系统需符合“4P原则”(4Ps rules),形象地描述为“活得好”(protection from proteolysis)、“钻得深”(penetration through mucus layer)、“进得去”(permeation through intestinal epithelial layer)和“放得出”(programmed release from delivery system)。“活得好”即保护胰岛素不受胃肠道内酶的降解,克服胰岛素口服吸收的酶屏障。“钻得深”即具有较强的黏液层穿透能力,能够克服胰岛素吸收的黏液层屏障。“进得去”即具有较强的穿透肠上皮细胞层的能力,能够克服胰岛素吸收的肠上皮细胞屏障。“放得出”即能够在合适的部位将胰岛素从纳米粒中释放,从而起效。
CHEN MC,SONAJEK,CHEN KJ,et al.A review of the prospects for polymeric nanoparticle platforms in oral insulin delivery[J].Biomaterials,2011,32(36):9826-9838.
Success in the oral delivery of therapeutic insulin can significantly improve the quality of life of diabetic patients who must routinely receive injections of this drug. However, oral absorption of insulin is limited by various physiological barriers and remains a major scientific challenge. Various technological solutions have been developed to increase the oral bioavailability of insulin. Having received considerable attention, nano-sized polymeric particles are highly promising for oral insulin delivery. This review article describes the gastrointestinal barriers to oral insulin delivery, including chemical, enzymatic and absorption barriers. The potential transport mechanisms of insulin delivered by nanoparticles across the intestinal epithelium are also discussed. Finally, recent advances in using polymeric nanoparticles for oral insulin delivery and their effects on insulin transport are reviewed, along with their future.
MOROZE,MATOORIS,LEROUX JC.Oral delivery of macromolecular drugs:where we are after almost 100 years of attempts[J].Adv Drug Deliv Rev,2016,101:108-121.
Abstract Since the first attempt to administer insulin orally in humans more than 90years ago, the oral delivery of macromolecular drugs (>1000g/mol) has been rather disappointing. Although several clinical pilot studies have demonstrated that the oral absorption of macromolecules is possible, the bioavailability remains generally low and variable. This article reviews the formulations and biopharmaceutical aspects of orally administered biomacromolecules on the market and in clinical development for local and systemic delivery. The most successful approaches for systemic delivery often involve a combination of enteric coating, protease inhibitors and permeation enhancers in relatively high amounts. However, some of these excipients have induced local or systemic adverse reactions in preclinical and clinical studies, and long-term studies are often missing. Therefore, strategies aimed at increasing the oral absorption of macromolecular drugs should carefully take into account the benefit-risk ratio. In the absence of specific uptake pathways, small and potent peptides that are resistant to degradation and that present a large therapeutic window certainly represent the best candidates for systemic absorption. While we acknowledge the need for systemically delivering biomacromolecules, it is our opinion that the oral delivery to local gastrointestinal targets is currently more promising because of their accessibility and the lacking requirement for intestinal permeability enhancement. Copyright 2016 Elsevier B.V. All rights reserved.
LUNDQUISTP,ARTURSSONP.Oral absorption of peptides and nanoparticles across the human intestine:opportunities,limitations and studies in human tissues[J].Adv Drug Deliv Rev,2016,106(Pt B):256-276.
Abstract In this contribution, we review the molecular and physiological barriers to oral delivery of peptides and nanoparticles. We discuss the opportunities and predictivity of various in vitro systems with special emphasis on human intestine in Ussing chambers. First, the molecular constraints to peptide absorption are discussed. Then the physiological barriers to peptide delivery are examined. These include the gastric and intestinal environment, the mucus barrier, tight junction between epithelial cells, the enterocytes of the intestinal epithelium, and the subepithelial tissue. Recent data from human proteome studies are used to provide information about the protein expression profiles of the different physiological barriers to peptide and nanoparticle absorption. Strategies that have been employed to increase peptide absorption across each of the barriers are discussed. Special consideration is given to attempts at utilizing endogenous transcytotic pathways. To reliably translate in vitro data on peptide or nanoparticle permeability to the in vivo situation in a human subject, the in vitro experimental system needs to realistically capture the central aspects of the mentioned barriers. Therefore, characteristics of common in vitro cell culture systems are discussed and compared to those of human intestinal tissues. Attempts to use the cell and tissue models for in vitro-in vivo extrapolation are reviewed. Copyright 2016. Published by Elsevier B.V.
BAKHRU SH,FURTADOS,MORELLO AP,et al.Oral delivery of proteins by biodegradable nanoparticles[J].Adv Drug Deliv Rev,2013,65(6):811-821.
Successful administration of therapeutic proteins via the oral route has long eluded the drug delivery community; a variety of factors, both physical and physiological, have hindered the myriad approaches to increasing the bioavailability of orally administered therapeutic proteins, including: 1) pre-systemic degradation by enzymes and 2) poor penetration of the intestinal mucosa and epithelium. Even when bypassing the harsh, acidic environment of the stomach, the intestines pose significant obstacles to systemic uptake. For example, the lining of the gastrointestinal tract comprises a thick wall of epithelial cells covered by a layer of polysaccharides and mucus. In this review, we will discuss the biology underlying intestinal uptake of protein-containing, biodegradable nanoparticles, review insulin delivery as the most accepted model for oral delivery of proteins, and present a variety of new material systems enabling novel approaches to oral protein delivery which we believe will bring to bear the next therapeutic advances in our field.
TOBIOAM,S NCHEZA A,VILAA A,et al.The role of PEG on the stability in digestive fluids and in vivo fate of PEG-PLA nanoparticles following oral administration[J].Colloids Surf B Biointerfaces,2000,8(3/4):315-323.
The aim of the present work was to evaluate if the presence of a polyethylenglycol (PEG) coating around PLA nanoparticles would affect their interaction with biological surfaces, following oral administration to rats. For this purpose, a model antigen, 125I-radiolabeled tetanus toxoid, was encapsulated in PLA and PLA-PEG nanoparticles by a modified water-in-oil-in-water solvent evaporation technique. Firstly, the stability of the nanoparticles in simulated gastrointestinal fluids was evaluated. Results showed an interaction between the nanoparticles and the enzymes of the digestive fluids, this interaction being considerably reduced by the PEG coating around the particles. On the other hand, the PLA forming the nanoparticles was found to be only slightly degraded (9% converted to lactate for PLA nanoparticles and 3% for PLA-PEG nanoparticles) and that the encapsulated tetanus toxoid remained mostly associated to the nanoparticles upon incubation in the digestive fluids for up to 4 h. Finally, the in vivo experiments showed that, after oral administration to rats, the levels of encapsulated radioactive antigen in the blood stream and lymphatics were higher for PLA-PEG nanoparticles than for PLA nanoparticles. In conclusion, the PLA-PEG nanoparticles have a promising future as protein delivery systems for oral administration.
NETSOMBOONK,BERNKOP-SCHNURCHA.Mucoadhesive vs. mucopenetrating particulate drug delivery[J].Eur J Pharm Biopharm,2016,98:76-89.
Mucus layer is a hydrophilic absorption barrier found in various regions of the body. The use of particulate delivery systems showed potential in drug delivery to mucosal membranes by either prolonging drug residence time at the absorption or target membrane or promoting permeation of particles across mucus gel layer to directly reach underlying epithelium. Mucoadhesive particles (MAP) are advantageous for delivering drug molecules to various mucosal membranes including eyes, oral cavity, bladder and vagina by prolonging drug residence time on those membranes. In contrast, a broader particle distribution and deeper penetration of the mucus gel layer are accomplished by mucopenetrating particles (MPP) especially in the gastrointestinal tract. Based on the available literature in particular dealing within vivoresults none of both systems (MAP and MPP) seems to be advantageous over the other. The choice of system primarily depends on the therapeutic target and peculiar properties of the target mucosa including thickness of the mucus gel layer, mucus turnover rate and water movement within the mucus. Future trends are heading in the direction of combining both systems to one i.e. mucoadhesive and mucopenetrating properties on the same particles.
MALHAIREH,GIMEL JC,ROGERE,et al.How to desi-gn the surface of peptide-loaded nanoparticles for efficient oral bioavailability?[J].Adv Drug Deliv Rev,2016,106(Pt B):320-336.
The oral administration of proteins is a current challenge to be faced in the field of therapeutics. There is currently much interest in nanocarriers since they can enhance oral bioavailability. For lack of a clear definition, the key characteristics of nanoparticles have been highlighted. Specific surface area is one of these characteristics and represents a huge source of energy that can be used to control the biological fate of the carrier. The review discusses nanocarrier stability, mucus interaction and absorption through the intestinal epithelium. The protein corona, which has raised interest over the last decade, is also discussed. The universal ideal surface is a myth and over-coated carriers are not a solution either. Besides, common excipients can be useful on several targets. The suitable design should rather take into account the composition, structure and behavior of unmodified nanomaterials.
SHANW,ZHUX,TAOW,et al.Enhanced oral delivery of protein drugs using zwitterion-functionalized nanoparticles to overcome both the diffusion and absorption barriers[J].ACS Appl Mater Interf,2016,8(38):25444-25453.
Oral delivery of protein drugs based on nanoparticulate delivery system requires permeation of the nanoparticles through mucus layer and subsequent absorption via epithelial cells. However, overcoming these two barriers needs very different or even contradictory surface properties of nanocarriers, which greatly limits the oral bioavailability of macromolecular drugs. Here we reported a simple zwitterions-based nanoparticle (NP) delivery platform, which showed a great potency in simultaneously overcoming both the mucus and epithelium barriers. The dense and hydrophilic coating of zwitterions endows the NPs with excellent mucus penetrating ability. Moreover, the zwitterions-based NPs also possessed excellent affinity with epithelial cells, which significantly improved (4.5-fold) the cellular uptake of DLPC NPs, compared to PEGylated NPs. Our results also indicated that this affinity was due to the interaction between zwitterions and cell surface transporter PEPT1. Moreover, the developed NPs loaded with ins...
ZHUX,WUJ,SHANW,et al.Sub-50 nm nanoparticles with biomimetic surfaces to sequentially overcome the mucosal diffusion barrier and the epithelial absorption barrier[J].Adv Funct Mater,2016,26(16):2728-2738.
Abstract Although nanoparticles (NPs) have been used for many drug delivery applications, oral absorption of NPs has remained a big challenge. NPs for oral delivery of biotherapeutics have to penetrate both the diffusion barrier of the mucus and the absorption barrier of the epithelium. This creates an obstacle for developing an effective NP platform for oral delivery because overcoming these two barriers requires different or even contradictory surface properties. Inspired by the features of some viruses, this study reports the development of a unique sub-50 nm polymeric NP platform that possesses a large amount of targeting ligands anchored on the surface while being moderately concealed under a 鈥渕uco-inert鈥 shield. NP library screening demonstrates a strong correlation between the relative lengths of the surface components and NP behavior on mucosal tissue. When a balance is obtained regarding optimal shielding of ligands, the NPs exhibit both excellent mucus permeation and transepithelial transport, and are efficiently absorbed into systemic circulation. Insulin-loaded NPs as a model oral therapy for diabetes generates a hypoglycemic response on diabetic animals following oral administration. This study demonstrates the great potency of a NP platform that exhibits an affinity balance between mucus and epithelium in facilitating the oral delivery of biotherapeutics.
SHANW,ZHUX,LIUM,et al.Overcoming the diffusion barrier of mucus and absorption barrier of epithelium by self-assembled nanoparticles for oral delivery of insulin[J].ACS Nano,2015,9(3):2345-2356.
Nanoparticles (NPs) have demonstrated great potential for the oral delivery of protein drugs that have very limited oral bioavailability. Orally administered NPs could be absorbed by the epithelial tissue only if they successfully permeate through the mucus that covers the epithelium. However, efficient epithelial absorption and mucus permeation require very different surface properties of a nanocarrier. We herein report self-assembled NPs for efficient oral delivery of insulin by facilitating both of these two processes. The NPs possess a nanocomplex core composed of insulin and cell penetrating peptide (CPP), and a dissociable hydrophilic coating of N-(2-hydroxypropyl) methacrylamide copolymer (pHPMA) derivatives. After systematic screening using mucus-secreting epithelial cells, NPs exhibit excellent permeation in mucus due to the "mucus-inert" pHPMA coating, as well as high epithelial absorption mediated by CPP. The investigation of NP behavior shows that the pHPMA molecules gradually dissociate from the NP surface as it permeates through mucus, and the CPP-rich core is revealed in time for subsequent transepithelial transport through the secretory endoplasmic reticulum/Golgi pathway and endocytic recycling pathway. The NPs exhibit 20-fold higher absorption than free insulin on mucus-secreting epithelium cells, and orally administered NPs generate a prominent hypoglycemic response and an increase of the serum insulin concentration in diabetic rats. Our study provides the evidence of using pHPMA as dissociable "mucus-inert" agent to enhance mucus permeation of NPs, and validates a strategy to overcome the multiple absorption barriers using NP platform with dissociable hydrophilic coating and drug-loaded CPP-rich core.
SHARMAR,GUPTAU,GARG NK,et al.Surface engin-eered and ligand anchored nanobioconjugate:an effective therapeutic approach for oral insulin delivery in experimental diabetic rats[J].Colloids Surf B Biointerfaces,2015,127:172-181.
The present study was designed to enhance intestinal absorption of insulin by nanobioconjugate formulated with PEGylation and Concanavalin A based targeted synergistic approach. The attempts were aimed at maximizing bioavailability and therapeutic efficacy of insulin by incorporating it in Concanavalin A anchored PEGylated nanoconstructs. The Con A anchored PEGylated PLGA diblock copolymer was synthesized by modified surface functionalization method, and was then characterized by FTIR and 1 H NMR spectrum analysis. The nanoparticles from synthesized polymers were prepared and characterized for mean size and distribution by laser diffraction spectroscopy. The physicochemically characterized (by SEM and TEM) formulations were evaluated for optimum particle size, polydispersity index, zeta potential and entrapment efficiency 196.302±024.502nm, 0.1502±020.04, 6125.602±021.68 and 44.602±023.5% respectively. The insulin encapsulation efficiency and in vitro release were assessed by bicinchoninic protein assay (BCA). The in vitro results corroborated in vivo studies carried out in experimentally created diabetic albino rats. The nano-encapsulated insulin was discovered to meet the requirements by achieving better stability, improved absorption and enhanced oral bioavailability elucidated by in vivo and in vitro bioassays.
SHENGJ,HEH,HANL,et al.Enhancing insu-lin oral absorption by using mucoadhesive nanoparticles loaded with LMWP-linked insulin conjugates[J].J Control Release,2016,233:181-190.
Although significant progress has been achieved, effective oral delivery of protein drugs such as insulin by nanoparticle-based carrier systems still faces certain formidable challenges. Considerable amount of protein drug is released from the nanoparticles (NPs) in the gastrointestinal (GI) tract. Because of their low permeability through the intestinal mucosa, the released protein would be soon degraded by the large amount of proteases in the GI tract. Herein, we report an oral insulin delivery system that can overcome the above-mentioned problems by mucoadhesive NPs (MNPs) loaded with cell penetrating peptide-linked insulin conjugates. On one hand, after conjugation with low molecular weight protamine (LMWP), a cell penetrating peptide (CPP), insulin showed greatly improved permeability through intestinal mucus layer and epithelia. On the other hand, the mucoadhesive N -trimethyl chitosan chloride-coated PLGA nanoparticles (MNPs) that were loaded with conjugates enhanced the retention in the intestinal mucus layer. By adopting this delivery strategy, the LMWP-insulin conjugates released from the MNPs could be deprived from enzymatic degradation, due to the short distance in reaching the epithelia and the high permeation of the conjugates through epithelia. The oral delivery system of insulin designed by us showed a long-lasting hypoglycemia effect with a faster onset in diabetic rats. The pharmacological availability of orally delivered conjugates-loaded MNPs was 17.985.61% relative to subcutaneously injected insulin solution, with a 2-fold higher improvement over that by MNPs loaded with native insulin. Our results suggested that conjugation with CPP followed by encapsulation in MNPs provides an effective strategy for oral delivery of macromolecular therapeutics.
SONAJEK,LIN KJ,WEY SP,et al.Biodistri-bution,pharmacodynamics and pharmacokinetics of insulin analogues in a rat model:oral delivery using pH-responsive nanoparticles vs.subcutaneous injection[J].Biomaterials,2010,31(26):6849-6858.
In this study, we report the biodistribution of aspart-insulin, a rapid-acting insulin analogue, following oral or subcutaneous (SC) administration to rats using the single-photon emission computed tomography (SPECT)/computed tomography (CT). Oral delivery of aspart-insulin was achieved using a pH-responsive nanoparticle (NP) system composed of chitosan (CS) and poly(纬-glutamic acid). The results obtained in the SPECT/CT study indicate that the orally administered aspart-insulin was absorbed into the systemic circulation, while the drug carrier (CS) was mainly retained in the gastrointestinal tract.Via the SC route, the peak aspart-insulin concentration in the peripheral tissue/plasma was observed at 20min after injection. Within 3h, half of the initial dose (ID) of aspart-insulin was degraded and excreted into the urinary bladder. In contrast, via oral delivery, there was constantly circulating aspart-insulin in the peripheral tissue/plasma during the course of the study, while 20% of the ID of aspart-insulin was metabolized and excreted into the urinary bladder. In the pharmacodynamic (PD) and pharmacokinetic (PK) evaluation in a diabetic rat model, the orally administered aspart-insulin loaded NPs produced a slower hypoglycemic response for a prolonged period of time, whereas the SC injection of aspart-insulin produced a more pronounced hypoglycemic effect for a relatively shorter duration. Finally, comparison of the PD/PK profiles of the orally administered aspart-insulin with those of the SC injection of NPH-insulin, an intermediate-acting insulin preparation, suggests the suitability of our NP system to be used as a non-invasive alternative for the basal insulin therapy.
YINL,DINGJ,HEC,et al.Drug permeability and mucoa-dhesion properties of thiolated trimethyl chitosan nanoparticles in oral insulin delivery[J].Biomaterials,2009,30(29):5691-5700.
Abstract Trimethyl chitosan-cysteine conjugate (TMC-Cys) was synthesized in an attempt to combine the mucoadhesion and the permeation enhancing effects of TMC and thiolated polymers related to different mechanisms for oral absorption. TMC-Cys with various molecular weights (30, 200, and 500 kDa) and quaternization degrees (15 and 30%) was allowed to form polyelectrolyte nanoparticles with insulin through self-assembly, which demonstrated particle size of 100-200 nm, zeta potential of +12 to +18 mV, and high encapsulation efficiency. TMC-Cys/insulin nanoparticles (TMC-Cys NP) showed a 2.1-4.7-fold increase in mucoadhesion compared to TMC/insulin nanoparticles (TMC NP), which might be partly attributed to disulfide formation between TMC-Cys and mucin as evidenced by DSC measurement. Compared to insulin solution and TMC NP, TMC-Cys NP induced increased insulin transport through rat intestine by 3.3-11.7 and 1.7-2.6 folds, promoted Caco-2 cell internalization by 7.5-12.7 and 1.7-3.0 folds, and augmented uptake in Peyer's patches by 14.7-20.9 and 1.7-5.0 folds, respectively. Such results were further confirmed by in vivo experiment with the optimal TMC-Cys NP. Biocompatibility assessment revealed lack of toxicity of TMC-Cys NP. Therefore, self-assembled nanoparticles between TMC-Cys and protein drugs could be an effective and safe oral delivery system.
LIUM,ZHANGJ,ZHUX,et al.Efficient mucus permea-tion and tight junction opening by dissociable “mucus-inert” agent coated trimethyl chitosan nanoparticles for oral insulin delivery[J].J Control Release,2016,222(Suppl C):67-77.
Abstract Oral administration of protein drugs is greatly impeded by the lack of drug carriers that can efficiently overcome the absorption barriers of mucosa tissue, which consists of not only epithelium but also a blanket of mucus gel. We herein report a novel self-assembled nanoparticle (NP) platform for oral delivery of insulin by facilitating the efficient permeation through both of these two barriers. The NP possesses a core composed of insulin and trimethyl chitosan (TMC), and a dissociable "mucus-inert" hydrophilic coating of N-(2-hydroxypropyl) methacrylamide copolymer (pHPMA) derivative. The NPs exhibited free Brownian motion and excellent permeability in mucus, which enabled the access of the NP core to the epithelial cell surface underneath the mucus. Moreover, investigation of NP behavior showed that the pHPMA molecules started to dissociate as the NP permeates through mucus, and the TMC NP core was then exposed to facilitate transepithelial transport via paracellular pathway. The pHPMA coating significantly improved transepithelial transport of TMC-based NP and their ability to open tight junctions between the mucus-secreting epithelial cells. Moreover, in diabetic rats, pHPMA coated NPs generated a prominent hypoglycemic response following oral administration, and exhibited a relative bioavailability 2.8-fold higher than that of uncoated TMC-based NPs. Our study provided the evidence of using pHPMA as "mucus-inert" agent to enhance mucus permeation of TMC-based NPs, and validated a novel strategy to overcome the multiple absorption barriers using NP platform with dissociable hydrophilic coating and TMC-based core possessing tight junction-opening ability. Copyright 2015 Elsevier B.V. All rights reserved.
JAINS,RATHI VV,JAIN AK,et al.Folate-decorated PL-GA nanoparticles as a rationally designed vehicle for the oral delivery of insulin[J].Nanomedicine(Lond),2012,7(9):1311-1337.
Aims:The present study reports a novel approach for enhancing the oral absorption and hypoglycemic activity of insulin via encapsulation in folate-(FA) coupled polyethylene glycol (PEG)ylated polylactide-co-glycolide (PLGA) nanoparticles (NPs; FA-PEG-PLGA NPs).Materials & methods:Insulin-loaded FA-PEG-PLGA NPs (size 65260 nm; insulin loading 656.5% [w/w]; encapsulation efficiency: 87.0 ± 1.92%) were prepared by double-emulsion solvent evaporation method. The bioavailability and hypoglycemic activity of orally administered FA–insulin NPs were studied in diabetic rats.Results & conclusion:FA-PEG-PLGA NPs (50 U/kg) exhibited a twofold increase in the oral bioavailability (double hypoglycemia) without any hypoglycemic shock as compared to subcutaneously administered standard insulin solution. Insulin NPs maintained a continual blood glucose level for 24 h, which, however, was transient (<8 h) in the case of subcutaneous insulin and associated with severe hypoglycemic shock. Overall, we have developed a patient-compliant, oral nanoformulation of insulin, once-daily administration of which would be sufficient to control diabetes for at least 24 h. Original submitted 16 November 2011; Revised submitted 2 February 2012; Published online 14 May 2012
HURKATP,JAINA,JAINA,et al.Concanavalin A conju-gated biodegradable nanoparticles for oral insulin delivery[J].J Nanopart Res,2012,14(11):1-14.
Major research issues in oral protein delivery include the stabilization of protein in delivery devices which could increase its oral bioavailability. The study deals with development of oral insulin delivery system utilizing biodegradable poly(lactic-co-glycolic acid) (PLGA) nanoparticles and modifying its surface with Concanavalin A to increase lymphatic uptake. Surface-modified PLGA nanoparticles were characterized for conjugation efficiency of ligand, shape and surface morphology, particle size, zeta potential, polydispersity index, entrapment efficiency, and in vitro drug release. Stability of insulin in the developed formulation was confirmed by SDS-PAGE, and integrity of entrapped insulin was assessed using circular dichroism spectrum. Ex vivo study was performed on Wistar rats, which exhibited the higher intestinal uptake of Con A conjugated nanoparticles. In vivo study performed on streptozotocin-induced diabetic rats which indicate that a surface-modified nanoparticle reduces blood glucose level effectively within 4 h of its oral administration. In conclusion, the present work resulted in successful production of Con A NPs bearing insulin with sustained release profile, and better absorption and stability. The Con A NPs showed high insulin uptake, due to its relative high affinity for non-reducing carbohydrate residues i.e., fucose present on M cells and have the potential for oral insulin delivery in effective management of Type 1 diabetes condition.
JAINA,JAIN SK.L-Valine appended PLGA nanoparticles for oral insulin delivery[J].Acta Diabetol,2015,52(4):663-676.
Abstract AIMS: Oral insulin delivery has been the major research issue, since many decades, due to several obvious advantages over other routes. However, this route poses several constraints for the delivery of peptides and proteins which are to be worked upon. The small intestine has been shown to be able to transport the L-forms of amino acids against a concentration gradient and that they compete for the mechanism concerned. So, L-valine was used as a ligand for carrier-mediated transport of insulin-loaded polylactic-co-glycolic acid (PLGA) nanoparticles (NPs). METHODS: L-Valine-conjugated PLGA nanoparticles were prepared using double emulsion solvent evaporation method. The NPs and conjugated NPs were characterized for their size, drug entrapment efficiency, zeta potential, polydispersity index and in vitro insulin release. RESULTS: Ex vivo studies on intestine revealed that conjugated nanoparticles showed greater insulin uptake as compared to non-conjugated nanoparticles. In vivo studies were performed on streptozotocin-induced diabetic rabbits. Oral suspension of insulin-loaded PLGA nanoparticles reduced blood glucose level from 265.402±028.5 to 246.602±022.402mg/dL within 402h which further decreased to 198.702±027.102mg/dL value after 802h. The ligand-conjugated formulation on oral administration produced hypoglycaemic effect (216.902±021.902mg/dL) within 402h of administration, and the hypoglycaemic effect prolonged till 1202h of oral administration. Simultaneously, the insulin concentration in withdrawn samples was also assessed and found that profile of insulin level is in compliance with the blood glucose reduction profile. CONCLUSIONS: Hence, it is concluded that the L-valine-conjugated NPs bearing insulin are the promising carrier for the transportation of insulin across the intestine on oral administration.
ZHUX,WUJ,SHANW,et al.Polymeric nano-particles amenable to simultaneous installation of exterior targeting and interior therapeutic proteins[J].Angew Chem Int Ed Engl,2016,55(10):3309-3312.
Abstract Effective delivery of therapeutic proteins is a formidable challenge. Herein, using a unique polymer family with a wide-ranging set of cationic and hydrophobic features, we developed a novel nanoparticle (NP) platform capable of installing protein ligands on the particle surface and simultaneously carrying therapeutic proteins inside by a self-assembly procedure. The loaded therapeutic proteins (e.g., insulin) within the NPs exhibited sustained and tunable release, while the surface-coated protein ligands (e.g., transferrin) were demonstrated to alter the NP cellular behaviors. In鈥卾ivo results revealed that the transferrin-coated NPs can effectively be transported across the intestinal epithelium for oral insulin delivery, leading to a notable hypoglycemic response.
KAMEIN,MORISHITAM,EHARAJ,et al.Per-meation characteristics of oligoarginine through intestinal epithelium and its usefulness for intestinal peptide drug delivery[J].J Control Release,2008,131(2):94-99.
Cell-penetrating peptides such as HIV-1 Tat and oligoarginine are attractive tools for the intracellular delivery of therapeutic macromolecules. Although we have found that oligoarginine enhances the intestinal absorption of therapeutic peptides, especially insulin, the mechanism underlying the ability of oligoarginine to increase intestinal drug absorption is unclear. In addition, there is no information about the permeation characteristics of these functional peptides through the biological intestinal membrane. Therefore, in this study the permeation characteristics of oligoarginine itself across the intestinal membrane were first determined to obtain the information about absorption enhancement mechanisms. Incubation at low temperature and coincubation with heparin reduced the tissue distribution and permeation of fluorescein-labeled oligoarginine (FL-D-R6) through the rat ileal membrane. These results suggest that the attachment of FL-D-R6 to cell-surface proteoglycans and energy-dependent endocytosis are involved in its permeation through the ileal epithelial membrane. Based on the characteristics of oligoarginine, we attempted to facilitate the intestinal permeation of the peptide drug, leuprolide, using the function of oligoarginine. However, leuprolide permeation was not achieved when leuprolide was applied with oligoarginine to mucosal side of rat ileal sheets or when a leuprolide-oligoarginine conjugate was administered. These findings emphasize that any strategy using oligoarginine to improve intestinal drug permeation requires an intermolecular interaction, such as an electrostatic interaction, and a covalent linkage between the macromolecular drug and oligoarginine may hamper the ability of oligoarginine to enhance intestinal epithelial permeation of therapeutic peptides and proteins. (C) 2008 Elsevier B.V. All rights reserved.
HEH,SHENGJ,DAVID AE,et al.The use of low molecular weight protamine chemical chimera to enhance monomeric insulin intestinal absorption[J].Biomaterials,2013,34(31):7733-7743.
Although oral delivery of insulin offers a number of unmatched advantages, it nevertheless is beset by the poor permeability of insulin molecules through the epithelial cell membranes of the intestinal mucosal layer. We previously reported the development of low molecular weight protamine (LMWP) as a non-toxic yet potent cell-penetrating peptide, of which via covalent linkage was capable of translocating protein cargos through the membranes of almost all cell types. It is therefore hypothesized that LMWP could be practically employed as a safe and effective tool to deliver insulin across the intestinal mucosal membrane, thereby augmenting its absorption through the GI tract. However, formulating 1:1 monomeric insulin/LMWP conjugate presents a tall order of challenge, as the acidic insulin and basic LMWP would automatically form tight aggregates through electrostatic interactions. In this paper, we developed an innovative conjugation strategy to solve this problem, by using succinimidyl-[(N-maleimidopropionamido)-polyethyleneglycol] ester (NHS-PEG-MAL) as an intermediate cross-linker during the coupling process. Both SDSAGE and MALDI鈥揟OF mass spectroscopy confirmed the formation of a homogenous, monomeric (1:1 ratio) insulin/LMWP conjugate without encountering the conventional problem of substrate aggregation. Cell culture studies demonstrated that transport of the Insulin-PEG-LMWP conjugate across the intestinal mucosal monolayer was augmented by almost five-folds compared to native insulin. Furthermore, results from the in situ loop absorption tests in rats showed that systemic pharmacological bioavailability of insulin was significantly enhanced after its conjugation with LMWP. Overall, the presented chemical conjugation with LMWP could offer a reliable and safe means to improve the intestinal permeability of therapeutic peptides/proteins, shedding light of the possibility for their effective oral delivery.
Sufficient mucosal permeability is the bottleneck problem in developing an efficient intestinal delivery system of . -penetrating -based nanocomplexes for the enhanced mucosal permeation of were developed in this study. Penetratin, a -penetrating was site-specifically modified with a bis--group. -loaded nanocomplexes were prepared by self-assembly using penetratin or its bis--modified derivative (P-bis-CD). A stronger intermolecular interaction and higher complex stability were observed for P-bis-CD nanocomplexes than the penetratin nanocomplexes. P-bis-CD nanocomplexes were significantly more efficient for the permeation of as compared to the penetratin nanocomplexes both in vitro and in situ. Interestingly, different cellular internalization mechanisms were observed for the two nanocomplexes. In diabetic , intestinal administration of P-bis-CD nanocomplexes resulted in a prominent hypoglycemic effect which lasted for 6 h with maximum inhibitory rate at 60%. The relative pharmacological availability and bioavailability of P-bis-CD nanocomplexes were 10.6% and 7.1%, which were 3.0-fold and 2.3-fold higher than that of penetratin nanocomplexes, respectively. In addition, no sign of toxicity was observed after 7 consecutive days of administration of P-bis-CD nanocomplexes with endotoxin. These results demonstrated that P-bis-CD was a promising epithelium permeation enhancer for and suggested that the chemical modification of penetration was a feasible strategy to enhance their potential.
CHENS,GUOF,DENGT,et al.Eudragit S100-coated chitosan nanoparticles co-loading tat for enhanced oral colon absorption of insulin[J].AAPS Pharm Sci Tech,2017,18(4):1277-1287.
Abstract In order to improve oral absorption of insulin, especially the absorption at the colon, Eudragit S100庐 (ES)-coated chitosan nanoparticles loading insulin and a trans-activating transcriptional peptide (Tat) were employed as the vehicle. In vitro releases of insulin and Tat from ES-coated chitosan nanoparticles had a pH-dependant characteristic. A small amount of the contents was released from the coated nanoparticles at pH 1.2 simulated gastric fluid, while a fairly fast and complete release was observed in pH 7.4 medium. Caco-2 cell was used as the model of cellular transport and uptake studies. The results showed that the cellular transport and uptake of insulin for ES-coated chitosan nanoparticles co-loading insulin and Tat (ES-Tat-cNPs) were about 3-fold and 4-fold higher than those for the nanoparticles loading only insulin (ES-cNPs), respectively. The evaluations in vivo of ES-Tat-cNPs were conducted on diabetic rats and normal minipigs, respectively. The experimental results on rats revealed that the pharmacodynamical bioavailability of ES-Tat-cNPs had 2.16-fold increase compared with ES-cNPs. After oral administration of nanoparticle suspensions to the minipigs, insulin bioavailability of ES-Tat-cNPs was 1.73-fold higher than that of ES-cNPs, and the main absorption site of insulin was probably located in the colon for the two nanoparticles. In summary, this report provided an exploratory means for the improvement of oral absorption of insulin.
LIUX,LIUC,ZHANGW,et al.Oligoarginine-modified bi-odegradable nanoparticles improve the intestinal absorption of insulin[J].Int J Pharm,2013,448(1):159-167.
The strategy of oral administration of bioactive macromolecules using cell-penetrating peptides (CPPs) is restricted to covalent linkage or electrostatic interaction between the cargo and CPPs. In the present study, we devised an approach utilizing CPP-functionalized poly(lactic-co-glycolic acid) (PLGA) nanoparticles as a carrier for oral delivery of insulin. Pegylated PLGA nanoparticles were modified with poly(arginine)8 enantiomers (l-R8 and d-R8) via a maleimide-mediated covalent conjugating procedure. The physical and chemical features of the nanoparticles were characterized, which confirmed the successful immobilization of R8 to the nanoparticles. Using a Caco-2 cell monolayer model, R8-modified nanoparticles were found to exhibit significantly increased cellular uptake and transportation. Pharmacokinetics and pharmacodynamics of the insulin-loaded nanoparticles were evaluated with rats by intestinal administration. Compared to the unmodified nanoparticles, l-R8 and d-R8 modified-nanoparticles increased the relative bioavailabilities of insulin by 3.2- and 4.4-times, meanwhile, improved the hypoglycemic effects by 2.5- and 3.7-times, respectively. Neither of the R8-modified nanoparticles caused perceptible histological toxicities. The results implied that surface modification of biodegradable nanoparticles with poly(arginine)8, especially with the d-form enantiomer, showed remarkable advancement in promoting the intestinal absorption of insulin. This delivery system is also promising for the delivery of a wide variety of bioactive macromolecules by oral administration.
DAMGEC,SOCHAM,UBRICHN,et al.Poly(epsilon-caprolactone)/eudragit nanoparticles for oral delivery of aspart-insulin in the treatment of diabetes[J].J Pharm Sci,2010,99(2):879-889.
Nanoparticles prepared with a blend of a biodegradable polyester (poly(0208-caprolactone)) and a polycationic nonbiodegradable acrylic polymer (Eudragit0003 RS) have been used as a drug carrier for oral administration of a short-acting insulin analogue, aspart-insulin. Insulin-loaded nanoparticles, about 700090009nm in diameter, encapsulated 97.5% of insulin and were able to release about 70% of their content in vitro in a neutral medium over 24090009h. When administered orally to diabetic rats, insulin-loaded nanoparticles (50090009IU/kg) decreased fasted glycemia for a prolonged period of time and improved the glycemic response to glucose in a time-dependent manner, with a maximal effect between 12 and 24090009h after their administration. In parallel, plasma insulin levels increased. However, higher (100090009IU/kg) and lower (25090009IU/kg) doses of insulin did not exert any biological effect. It is concluded that polymeric nanoparticles composed of poly(0208-caprolactone)/Eudragit0003 RS are able to preserve the biological activity of the insulin analogue aspart-insulin; however, the postprandial peak suppression was prolonged more than 24090009h by comparison with regular insulin working only 60900098090009h. This effect may be explained by the monomeric configuration of aspart-insulin, which is probably better taken up by the intestinal mucosa than regular insulin. 0008 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:879090009889, 2010
CHO HJ,OHJ,CHOO MK,et al.Chondroitin sulfate-capped gold nanoparticles for the oral delivery of insulin[J].Int J Biolog Macromol,2014,63:15-20.
Chondroitin sulfate (CS)-capped gold nanoparticles (AuNPs) were synthesized and its feasibility for oral insulin (INS) delivery was investigated in vivo . CS was used as both reducing and stabilizing agent in the synthesis of AuNPs with around 48nm mean diameter, narrow size distribution, and negative zeta potential. After loading INS into CS-capped AuNPs structure, NPs with about 123nm mean diameter, narrow size distribution, and negative zeta potential were successfully fabricated. By surface plasmon resonance (SPR) measurement, 0.5% (w/v) CS was chosen for the synthesis of AuNPs. Stability of AuNPs and AuNPs/INS was maintained for 7 weeks according to SPR study. Cytotoxicity of AuNPs/INS in Caco-2 cells was measured and no significant cytotoxicity was observed in tested AuNPs concentration range. In the streptozotocin-induced diabetic rat model, the oral administration of AuNPs/INS exhibited an efficient regulation of glucose level, compared to INS solution-treated group. The mean INS concentration in plasma at 120min after oral administration of AuNPs/INS was 6.61-fold higher than that of INS solution-administered group. All of these findings indicate the successful application of CS-capped AuNPs for oral delivery of INS to the therapy of diabetes.
ZHAO XH,SHANC,ZU YG,et al.Preparation,charac-terization,and evaluation in vivo of Ins-SiO2-HP55(insulin-loaded silica coating HP55) for oral delivery of insulin[J].Int J Pharm,2013,454(1):278-284.
Insulin is the most effective and durable drug in the treatment of advanced stage diabetes. However, oral delivering insulin was a tough task for rapid enzymatic degradation. In this work, we designed and developed a delivery system composed of enteric nanosphere for oral delivery of insulin. The silica was selected for loading insulin, which surface has a lot of pores with a powerful adsorption capacity, advantages for permeability and slow-release. The insulin-loaded silica (Ins-SiO2) was prepared by adsorption in HCl solution. The Ins-SiO2 obtained was coated with the hydroxypropyl methylcellulose phthalate (HP55) by desolvation method, which is a good enteric coating material. The Ins-SiO2-HP55, an enteric nanosphere of insulin obtained were characterized by transmission electron microscope (TEM), surface area, Fourier-transform infrared (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results showed that insulin was loaded most in the pores of silica, while the HP55 coated on the extent of Ins-SiO2. In vitro drug release results revealed that the release of insulin from Ins-SiO2-HP55 was markedly reduced in simulated gastric fluid (SGF). By contrast, the release amount of insulin from Ins-SiO2-HP55 was increased significantly in simulated intestinal fluid (SIF). In vivo evaluation on diabetic animals showed the blood glucose level of diabetic rats could be effectively reduced after oral administration Ins-SiO2-HP55. There is marked hypoglycemic effect after 1h of taking the Ins-SiO2-HP55. After 3h, the GLU of rats of the Ins-SiO2-HP55 stably kept from 4.85 to 2.67 mmol/L that was significantly less than the normal level (6.7 mmol/L). However, that of rats taking raw insulin kept from 8.03 to 6.56 mmol/L that is higher than the normal level. These results suggested that Ins-SiO2-HP55 could have potential value in oral administration systems of diabetes chemotherapy.
Biodistri-bution,pharmacodynamics and pharmacokinetics of insulin analogues in a rat model:oral delivery using pH-responsive nanoparticles vs.subcutaneous injection
, 杨晓宇
