Novel preparation of PLGA/HP55 nanoparticles for oral insulin delivery

Dual-modified nanoparticles overcome sequential absorption barriers for oral insulin delivery

The efficacy of oral insulin drug delivery is seriously hampered by multiple gastrointestinal barriers, especially transepithelial barriers, including apical endocytosis, lysosomal degradation, cytosolic diffusion and basolateral exocytosis. In this study, a functional nanoparticle (PG-FAPEP) with dual-modification was constructed to sequentially address these important absorption obstacles for improved oral insulin delivery. The dual surface decorations folate and charge-convertible tripeptide endowed PG-FAPEP with the ability to target the apical and basolateral sides of enterocytes, respectively. After fast diffusion across the mucus layer, PG-FAPEP could be efficiently internalized into epithelial cells via a folate receptor-mediated pathway and subsequently became positively charged in acidic lysosomes due to the surface tripeptide, triggering the proton sponge effect to escape lysosomes. When entering the cytosolic medium, PG-FAPEP was converted to neutral charge again, attenuating intracellular adhesion, and gained improved motility toward the basolateral side. Finally, the tripeptide helped PG-FAPEP recognize the proton-coupled oligopeptide transporter (PHT1) in the basolateral membrane, boosting intact exocytosis across intestinal epithelial cells. The in vivo studies further verified that PG-FAPEP could traverse the intestinal epithelium by folate receptor-mediated endocytosis, lysosomal escape, and PHT1-mediated exocytosis, exhibiting a high oral insulin bioavailability of 14.3% and a prolonged hypoglycemic effect. This formulation addresses multiple absorption barriers on demand with a simple dual-modification strategy. Therefore, these features allow PG-FAPEP to unleash the potential of oral macromolecule delivery.

Nanoparticles integrating natural and synthetic polymers for in vivo insulin delivery

The aims of the current study were to develop insulin-loaded nanoparticles comprised of various polymers at different compositions, and to evaluate their ability to lower blood glucose levels in diabetic rats following subcutaneous and oral administrations. Several combinations of natural and synthetic polymers have been utilized for preparation of nanoparticles including, chitosan, alginate, albumin and Pluronic. Nanosized (170 nm-800 nm) spherical particles of high encapsulation efficiency (15-52%) have been prepared. Composition and ratios between the integrated polymers played a pivotal role in determining size, zeta potential, and in vivo hypoglycemic activity of particles. After subcutaneous and oral administration in diabetic rats, some of the insulin-loaded nanoparticles were able to induce much higher hypoglycemic effect as compared to the unloaded free insulin. For instance, subcutaneous injection of nanoparticles comprised of chitosan combined with sodium tripolyphosphate, Pluronic or alginate/calcium chloride, resulted in comparable hypoglycemic effects to free insulin, at two-fold lower dose. Nanoparticles were well-tolerated after oral administration in rats, as evidenced by by measuring levels of alanine aminotransferase, aspartate aminotransferases, albumin, creatinine and urea. This study indicates that characteristics and delivery efficiency of nanomaterials can be controlled via utilizing several natural/synthetic polymers and by fine-tuning of combination ratio between polymers.

Therapeutic Advancements in the Management of Diabetes Mellitus with Special Reference to Nanotechnology

For improvisation of diabetic's quality of life, nanotechnology is facilitating the development of advanced glucose sensors as well as efficient insulin delivery systems. Our prime focus of the review is to highlight the advancement in diabetic research with special reference to nanotechnology at its interface. Recent studies are more focused on enhancing sensitivity, accuracy, and response by employing metal as well as nanoparticles based glucose sensors. Moreover, the review focuses on nanoscale based approaches i.e. closed-loop insulin delivery systems, which detect any fluctuation in blood glucose levels and allow controlled release of a drug, thus are also called self-regulating insulin release system. Additionally, this review summarizes the role of nanotechnology in the diagnosis and treatment of diabetic complications through little advancement in the existing techniques. To improve health, as well as the quality of life in diabetic's new sensing systems for blood glucose level evaluation and controlled administration of drugs through efficient drug delivery systems should be explored.

Novel technique of insulin loading into porous carriers for oral delivery

The increasing demand for oral macromolecule delivery encouraged the development of microencapsulation technologies to protect such drugs against gastric and enzymatic degradation. However, microencapsulation often requires harsh conditions that may jeopardize their biological activity. Accordingly, many trials attempted to load macromolecules into porous drug carriers to bypass any formulation induced instability. In this study, we prepared chitosan coated porous poly (d, l-lactide-co-glycolide) (PLGA) microparticles (MPs) loaded with insulin using a novel loading technique; double freeze-drying. The results showed a significant increase in drug loading using only 5 mg/ml initial insulin concentration and conveyed a sustained drug release over uncoated MPs. Furthermore, SEM and confocal microscopy confirmed pore blocking and insulin accumulation within the MPs respectively. The oral pharmacodynamic data on rats also proved the preservation of insulin bioactivity after formulation. Finally, the new coating technique proved to be efficient in producing robust layer of chitosan with higher insulin loading while maintaining insulin activity.

Multifunctional Composite Microcapsules for Oral Delivery of Insulin

In this study, we designed and developed a new drug delivery system of multifunctional composite microcapsules for oral administration of insulin. Firstly, in order to enhance the encapsulation efficiency, insulin was complexed with functional sodium deoxycholate to form insulin-sodium deoxycholate complex using hydrophobic ion pairing method. Then the complex was encapsulated into poly(lactide-co-glycolide) (PLGA) nanoparticles by emulsion solvent diffusion method. The PLGA nanoparticles have a mean size of 168 nm and a zeta potential of −29.2 mV. The encapsulation efficiency was increased to 94.2% for the complex. In order to deliver insulin to specific gastrointestinal regions and reduce the burst release of insulin from PLGA nanoparticles, hence enhancing the bioavailability of insulin, enteric targeting multifunctional composite microcapsules were further prepared by encapsulating PLGA nanoparticles into pH-sensitive hydroxypropyl methyl cellulose phthalate (HP55) using organic spray-drying method. A pH-dependent insulin release profile was observed for this drug delivery system in vitro. All these strategies help to enhance the encapsulation efficiency, control the drug release, and protect insulin from degradation. In diabetic fasted rats, administration of the composite microcapsules produced a great enhancement in the relative bioavailability, which illustrated that this formulation was an effective candidate for oral insulin delivery.

Oral delivery of diabetes peptides - Comparing standard formulations incorporating functional excipients and nanotechnologies in the translational context

While some orally delivered diabetes peptides are moving to late development with standard formulations incorporating functional excipients, the demonstration of the value of nanotechnology in clinic is still at an early stage. The goal of this review is to compare these two drug delivery approaches from a physico-chemical and a biopharmaceutical standpoint in an attempt to define how nanotechnology-based products can be differentiated from standard oral dosage forms for oral bioavailability of diabetes peptides. Points to consider in a translational approach are outlined to seize the opportunities offered by a better understanding of both the intestinal barrier and of nano-carriers designed for oral delivery.

Formulation and comparative in vitro evaluation of various dexamethasone-loaded pH-sensitive polymeric nanoparticles intended for dermal applications

pH-sensitive nanoparticles have a great potential for dermal and transfollicular drug delivery. In this study, pH-sensitive, dexamethasone-loaded Eudragit^® L 100, Eudragit^® L 100-55, Eudragit^® S 100, HPMCP-50, HPMCP-55 and cellulose acetate phthalate nanoparticles were prepared by nanoprecipitation and characterized. The pH-dependent swelling, erosion, dissolution and drug release kinetics were investigated in vitro using dynamic light scattering and Franz diffusion cells, respectively. Their toxicity potential was assessed by the ROS and MTT assays. 100-700nm nanoparticles with high drug loading and entrapment efficiency were obtained. The nanoparticles bear no toxicity potential. Cellulose phthalates nanoparticles were more sensitive to pH than acrylates nanoparticles. They dissolved in 10mM pH 7.5 buffer and released>80% of the drug within 7h. The acrylate nanoparticles dissolved in 40mM pH 7.5 buffer and released 65-70% of the drug within 7h. The nanoparticles remained intact in 10 and 40mM pH 6.0 buffers (HPMCP nanoparticles dissolved in 40mM pH 6.0 buffer) and released slowly. The nanoparticles properties could be modulated by blending the different polymers. In conclusion, various pH-sensitive nanoparticles that could release differently on the skin surface and dissolve and release in the hair follicles were obtained.

Insulin administration: present strategies and future directions for a noninvasive (possibly more physiological) delivery

Insulin is a life-saving medication for people with type 1 diabetes, but traditional insulin replacement therapy is based on multiple daily subcutaneous injections or continuous subcutaneous pump-regulated infusion. Nonphysiologic delivery of subcutaneous insulin implies a rapid and sustained increase in systemic insulin levels due to the loss of concentration gradient between portal and systemic circulations. In fact, the liver degrades about half of the endogenous insulin secreted by the pancreas into the venous portal system. The reverse insulin distribution has short- and long-term effects on glucose metabolism. Thus, researchers have explored less-invasive administration routes based on innovative pharmaceutical formulations, which preserve hormone stability and ensure the therapeutic effectiveness. This review examines some of the recent proposals from clinical and material chemistry point of view, giving particular attention to patients' (and diabetologists') ideal requirements that organic chemistry could meet.

A review of biodegradable polymeric systems for oral insulin delivery

Currently, repeated routine subcutaneous injections of insulin are the standard treatment for insulin-dependent diabetic patients. However, patients' poor compliance for injections often fails to achieve the stable concentration of blood glucose. As a protein drug, the oral bioavailability of insulin is low due to many physiological reasons. Several carriers, such as macromolecules and liposomes have been used to deliver drugs in vivo. In this review article, the gastrointestinal barriers of oral insulin administration are described. Strategies for increasing the bioavailability of oral insulin, such absorption enhancers, enzyme inhibitors, enteric coatings are also introduced. The potential absorption mechanisms of insulin-loaded nanoparticles across the intestinal epithelium, including intestinal lymphatic route, transcellular route and paracellular route are discussed in this review. Natural polymers, such as chitosan and its derivates, alginate derivatives, γ-PGA-based materials and starch-based nanoparticles have been exploited for oral insulin delivery; synthetic polymers, such as PLGA, PLA, PCL and PEA have also been developed for oral administration of insulin. This review focuses on recent advances in using biodegradable natural and synthetic polymers for oral insulin delivery along with their future prospects.

Polymer-based nanoparticles for oral insulin delivery: Revisited approaches

Diabetes mellitus is a high prevalence and one of the most severe and lethal diseases in the world. Insulin is commonly used to treat diabetes in order to give patients a better life condition. However, due to bioavailability problems, the most common route of insulin administration is the subcutaneous route, which may present patients compliance problems to treatment. The oral administration is thus considered the most convenient alternative to deliver insulin, but it faces important challenges. The low stability of insulin in the gastrointestinal tract and low intestinal permeation, are problems to overcome. Therefore, the encapsulation of insulin into polymer-based nanoparticles is presented as a good strategy to improve insulin oral bioavailability. In the last years, different strategies and polymers have been used to encapsulate insulin and deliver it orally. Polymers with distinct properties from natural or synthetic sources have been used to achieve this aim, and among them may be found chitosan, dextran, alginate, poly(γ-glutamic acid), hyaluronic acid, poly(lactic acid), poly(lactide-co-glycolic acid), polycaprolactone (PCL), acrylic polymers and polyallylamine. Promising studies have been developed and positive results were obtained, but there is not a polymeric-based nanoparticle system to deliver insulin orally available in the market yet. There is also a lack of long term toxicity studies about the safety of the developed carriers. Thus, the aims of this review are first to provide a deep understanding on the oral delivery of insulin and the possible routes for its uptake, and then to overview the evolution of this field in the last years of research of insulin-loaded polymer-based nanoparticles in the academic and industrial fields. Toxicity concerns of the discussed nanocarriers are also addressed.

Chitosan-graft-PAMAM–alginate core–shell nanoparticles: a safe and promising oral insulin carrier in an animal model

Calcium chloride cross-linked PAMAM grafted chitosan–alginate core–shell nanoparticles are demonstrated as potential low-toxicity carriers for oral insulin delivery.

Development and evaluation of a novel topical treatment for acne with azelaic acid-loaded nanoparticles

Azelaic acid (AzA) is used in the treatment of acne. However, side effects and low compliance have been associated with several topical treatments with AzA. Nanotechnology presents a strategy that can overcome these problems. Polymeric nanoparticles can control drug release and targeting and reduce local drug toxicity. The aim of this study was to produce and evaluate an innovative topical treatment for acne with AzA-loaded poly-DL-lactide/glycolide copolymer nanoparticles. A soft white powder of nanoparticles was prepared. The mean size of loaded nanoparticles was < 400 nm and zeta potential was negative. Spherical nanoparticles were observed by scanning electron microscopy. Encapsulation efficiency was around 80% and a strong interaction between the polymer and the drug was confirmed by differential scanning calorimetric analysis. In vitro drug release studies suggested a controlled and pulsatile release profile. System efficacy tests suggested similar results between the loaded nanoparticles and the nonencapsulated drug against the most common bacteria associated with acne. Cytotoxicity of AzA-loaded nanoparticles was concentration dependent, although not pronounced. The occluded patch test seemed to indicate that the formulation excipients were safe and thus AzA-loaded nanoparticles appear to be an efficient and safe treatment for acne.

Paclitaxel-loaded poly(glycolide-co-ε-caprolactone)-b-D-α-tocopheryl polyethylene glycol 2000 succinate nanoparticles for lung cancer therapy

In order to improve the therapeutic efficacy and minimize the side effects of lung cancer chemotherapy, the formulation of paclitaxel-loaded poly(glycolide-co-ε-caprolactone)-b-D-α-tocopheryl polyethylene glycol 2000 succinate nanoparticles (PTX-loaded [PGA-co-PCL]-b-TPGS_2k NPs) was prepared. The novel amphiphilic copolymer (PGA-co-PCL)-b-TPGS_2k was synthesized by ring-opening polymerization and characterized by proton nuclear magnetic resonance spectroscopy and gel permeation chromatography. The PTX-loaded (PGA-co-PCL)-b-TPGS_2k NPs were characterized in terms of size, size distribution, zeta potential, drug encapsulation, surface morphology, and drug release. In vitro cellular uptakes of NPs were investigated with confocal laser scanning microscopy, indicating the coumarin 6-loaded (PGA-co-PCL)-b-TPGS_2k NPs could be internalized by human lung cancer A-549 cells. The antitumor effect of PTX-loaded NPs was evaluated, both in vitro and in vivo, on an A-549 cell tumor-bearing mouse model via intratumoral injection. The commercial PTX formulation Taxol was chosen as the reference. Experimental results showed that the PTX-loaded NPs possessed higher cytotoxicity and could effectively inhibit the growth of tumor. All the results suggested that amphiphilic copolymer (PGA-co-PCL)-b-TPGS_2k could act as a potential biological material for nanoformulation in the treatment of lung cancer.