A pH-sensitive microsphere system for the colon delivery of tacrolimus containing nanoparticles

Assessing acute colitis induced by dextran sulfate sodium in rats and its impact on gastrointestinal fluids

Dextran sulfate sodium (DSS) is commonly used to induce colitis in rats. While the DSS-induced colitis rat model can be used to test new oral drug formulations for the treatment of inflammatory bowel disease, the effect of the DSS treatment on the gastrointestinal tract has not been thoroughly characterized. Additionally, the use of different markers to assess and confirm successful induction of colitis is somewhat inconsistent. This study aimed to investigate the DSS model to improve the preclinical evaluation of new oral drug formulations. The induction of colitis was evaluated based on the disease activity index (DAI) score, colon length, histological tissue evaluation, spleen weight, plasma C-reactive protein, and plasma lipocalin-2. Furthermore, the study investigated how the DSS-induced colitis affected the luminal pH, lipase activity, and concentrations of bile salts, polar lipids, and neutral lipids. For all evaluated parameters, healthy rats were used as a reference. The DAI score, colon length, and histological evaluation of the colon were effective disease indicators in DSS-induced colitis rats, while spleen weight, plasma C-reactive protein, and plasma lipocalin-2 were not. The luminal pH of the colon and bile salt- and neutral lipid concentrations in regions of the small intestine were lower in DSS-induced rats compared to healthy rats. Overall, the colitis model was deemed relevant for investigating ulcerative colitis-specific formulations.

Preparation and Characterization of a Novel Multiparticulate Dosage Form Carrying Budesonide-Loaded Chitosan Nanoparticles to Enhance the Efficiency of Pellets in the Colon

An attempt was made to conquer the limitation of orally administered nanoparticles for the delivery of budesonide to the colon. The ionic gelation technique was used to load budesonide on chitosan nanoparticles. The nanoparticles were investigated in terms of size, zeta potential, encapsulation efficiency, shape and drug release. Then, nanoparticles were pelletized using the extrusion-spheronization method and were investigated for their size, mechanical properties, and drug release. Pellets were subsequently coated with a polymeric solution composed of two enteric (eudragit L and S) and time-dependent polymers (eudragit RS) for colon-specific delivery. All formulations were examined for their anti-inflammatory effect in rats with induced colitis and the relapse of the colitis after discontinuation of treatment was also followed. The size of nanoparticles ranged between 288 ± 7.5 and 566 ± 7.7 nm and zeta potential verified their positive charged surface. The drug release from nanoparticles showed an initial burst release followed by a continuous release. Pelletized nanoparticles showed proper mechanical properties and faster drug release in acidic pH compared with alkaline pH. It was interesting to note that pelletized budesonide nanoparticles released the drug throughout the GIT in a sustained fashion, and had long-lasting anti-inflammatory effects while rapid relapse was observed for those treated with conventional budesonide pellets. It seems that there is a synergistic effect of nanoformulation of budesonide and the encapsulation of pelletized nanoparticles in a proper coating system for colon delivery that could result in a significant and long-lasting anti-inflammatory effect.

Microfluidized Dextran Microgels Loaded with Cisplatin/SPION Lipid Nanotherapeutics for Local Colon Cancer Treatment via Oral Administration

Multifunctional sequential targeted delivery system is developed as an efficient therapeutic strategy against malignant tumors with selective accumulation and minimal systemic drug absorption. The therapeutic system is comprised of microfluidized dextran microgels encapsulating cisplatin/superparamagnetic iron oxide nanoparticles (SPIONs)-loaded trilaurin-based lipid nanoparticles (LNPs). The microgel system is imparted hierarchically dual targeting via dextran and folic acid (FA) residues, leading to increases both in retention of the microgels in colon and in cellular uptake of the therapeutic LNPs by colon cancer cells while being used for oral therapeutic delivery. Encapsulation of the therapeutic LNPs into dextran microgels attained by microfluidized crosslinking reaction reduces gastrointestinal adhesion and prevents the FA-modified LNPs from cellular transport by proton-coupled FA transporters in small intestine during their oral delivery to colon. Upon enzymatic degradation of the dextran microgels by dextranase present exclusively in colon, LNPs thus released become more recognizable and readily internalized by FA receptor-overexpressing colon cancer cells. The combined chemo/magnetothermal therapeutic effect of dual targeted lipid nanoparticle-loaded microgels from entrapped lipidized cisplatin and alternating magnetic field-treated SPIONs significantly inhibits tumor growth and suppresses metastatic peritoneal carcinomatosis in orthotopic colon cancer-bearing mice.

Preparing simvastatin nanoparticles by a combination of pH-sensitive and timed-release approaches for the potential treatment of ulcerative colitis

In this study, an emulsion solvent evaporation method was used to produce Eudragit RL (ERL) nanoparticles (NPs) loaded with simvastatin (SIM) for the treatment of ulcerative colitis (UC). Accordingly, the effects of different formulation variables on the properties of NPs were evaluated using the Box-Behnken design. The optimized NPs were then coated by Eudragit FS30D (EFS30D). Drug release was studied in different physiological environments. Colitis was induced by 3% of acetic acid in rats, which received NPs of SIM (10 mg/kg/day), mesalazine (150 mg/kg/day), blank NPs and normal saline orally for 5 days. Macroscopic histopathological evaluation and biochemical analysis, including myeloperoxidase (MPO) activity and malondialdehyde (MDA) level in the colon tissues, were carried out in this study. The optimized SIM-ERL NPs showed the particle size of 182.48 ± 4.57 nm, the polydispersity index of 0.29 ± 0.12, the zeta potential of 26.45 ± 4.57 mV, drug loading % of 34.64 ± 0.48, the encapsulation efficiency % of 98.68 ± 0.69, and the release efficiency % of 35.78 ± 1.37. Coating the optimized NPs with EFS30D caused an increase in particle size and a decrease in the zeta potential of NPs. The optimized SIM-EFS30D/RL NPs improved the macroscopic and histopathological scores. Also, MPO activity and MDA level were reduced significantly by NPs, as compared to the control group. Therefore, this drug delivery system can be an alternative to the previous treatments of UC.

Development, Characterization, and Investigation of In Vivo Targeted Delivery Efficacy of Luteolin-Loaded, Eudragit S100-Coated mPEG-PLGA Nanoparticles

Luteolin (Lu) is a kind of flavonoid that has been proved to treat non-alcoholic fatty liver disease by alleviating intestinal microbiota disorder. In this study, luteolin was coated with methoxy poly(ethylene glycol)-poly(dl-lactide-co-glycolic acid) (mPEG-PLGA) using an emulsion solvent evaporation method, and the optimum preparation process was determined by a single-factor experiment combined with response surface methodology (RSM). Methacrylic acid-methyl methacrylate (1:2) copolymer (Eudragit S100) was then used to coat the surface of Lu/mPEG-PLGA nanoparticles. The physical parameters of Eudragit S100-coated Lu/mPEG-PLGA nanoparticles (Lu-NPs), such as appearance, particle size, potential, particle size distribution and drug release, and stability in vitro, were evaluated. In addition, its cytotoxicity in vitro, pharmacokinetics, tissue distribution, and toxicity in vivo were also studied. The results showed that the prepared Lu-NPs had uniform particle size distribution, high encapsulation efficiency, and good stability. Normal colonic epithelial cells showed good tolerance to Lu-NPs. After oral administration, the blood concentration of luteolin peaked at 8 h, and the main tissue distribution was within the colon, confirming its colon-targeted profile. Safety assessments also indicated that no significant changes were observed in main organs after administration of Lu-NPs. The use of Eudragit S100-coated Lu/mPEG-PLGA nanoparticles is a new strategy for colon-targeted delivery of luteolin that encourages luteolin to fulfill its role in the colon.

Impact of oral gavage technique of drug-containing microcontainers on the gastrointestinal transit and absorption in rats

Oral gavage is the most common way to administer drug formulations orally to rats. Yet, the technique applied and its influence on gastrointestinal (GI) transit receive little attention. This study aims to investigate the impact of three oral gavage techniques on GI transit and drug absorption utilizing microcontainers (MCs). The MCs were filled with paracetamol and BaSO₄ (1:1 w/w ratio), coated with Eudragit S100, and filled into size-9 gelatin capsules. An in vitro study confirmed the intactness of the coating, and the capsules were administered to rats with air, water, or a piston. X-ray imaging determined the locations of the MCs, and the corresponding plasma concentration of paracetamol established a correlation with the location. The fastest GI transit occurred with air-dosing, while water-dosing caused delayed gastric emptying for 3h with non-quantifiable paracetamol absorption. Piston-dosed MCs were retained in the stomach for up to 1h, though for 3h in one rat. Air-dosing caused discomfort and stress in rats, thus limiting its ethical and physiological relevance. Water-dosing confined its use due to delayed gastric emptying. In conclusion, the oral gavage technique affected the GI transit of MCs and, consequently, drug absorption. Piston-dosing appeared to be the superior dosing technique.

Adalimumab Decorated Nanoparticles Enhance Antibody Stability and Therapeutic Outcome in Epithelial Colitis Targeting

Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the gastrointestinal tract with increasing incidence worldwide. Although a deeper understanding of the underlying mechanisms of IBD has led to new therapeutic approaches, treatment options are still limited. Severe adverse events in conventional drug therapy and poor drug targeting are the main cause of early therapy failure. Nanoparticle-based targeting approaches can selectively deliver drugs to the site of inflammation and reduce the risk of side effects by decreasing systemic availability. Here, we developed a nanoparticulate platform for the delivery of the anti-TNF-α antibody adalimumab (ADA) by covalent crosslinking to the particle surface. ADA binding to nanoparticles improved the stability of ADA against proteolytic degradation in vitro and led to a significantly better therapeutic outcome in a murine colitis model. Moreover, immobilization of ADA reduced systemic exposure, which can lead to enhanced therapeutic safety. Thus, nanoparticle protein decoration constitutes a platform through which epithelial delivery of any biological of interest to the inflamed gut and hence a local treatment can be achieved.

Optimization study of combined enteric and time-dependent polymethacrylates as a coating for colon targeted delivery of 5-ASA pellets in rats with ulcerative colitis

Formulation design for colon-specific delivery of 5-aminosalicylic acid (5-ASA) could bring some therapeutic benefits in the treatment of ulcerative colitis (UC). In the current study, a 3² full factorial design was used to predict optimum coating composed of two enteric (poly methacrylic acid, methyl methacrylates 1:2 and 1:1) and time-dependent (poly ethyl acrylate, methyl methacrylate, trimethylammonio ethyl methacrylate chloride 1:2:0.1) polymethacrylates for colon-specific delivery of 5-ASA pellets. A unique coating composition and coating level predicted by the model was applied onto either inulin-free 5-ASA pellets or inulin-bearing 5-ASA pellets and the coated pellets were examined by dissolution test in-vitro. The coated pellets were also tested in a rat model of UC and compared with the a commercially available colonic delivery system of 5-ASA. The ratio of the two enteric polymethacrylates and time-dependet polymethacrylate of 16:64:20 w/w at a coating level of 15% was discovered as the optimum coating for delivery of 5-ASA pellets to the colon. In general, the coated pellets offered a better therapeutic outcome compared to commercially available colonic delivery system of 5-ASA and uncoated pellets in terms of colitis activity index and the colon's tissue enzymes of MDA and GSH. It seems that the coating composed of enteric and pH-dependent polymethacrylates could tune up the rate of drug release from 5-ASA-coated pellets and trigger drug release based on pH and time.

Prevention of vascular-allograft rejection by protecting the endothelial glycocalyx with immunosuppressive polymers

Systemic immunosuppression for the mitigation of immune rejection after organ transplantation causes adverse side effects and constrains the long-term benefits of the transplanted graft. Here we show that protecting the endothelial glycocalyx in vascular allografts via the enzymatic ligation of immunosuppressive glycopolymers under cold-storage conditions attenuates the acute and chronic rejection of the grafts after transplantation in the absence of systemic immunosuppression. In syngeneic and allogeneic mice that received kidney transplants, the steric and immunosuppressive properties of the ligated polymers largely protected the transplanted grafts from ischaemic reperfusion injury, and from immune-cell adhesion and thereby immunocytotoxicity. Polymer-mediated shielding of the endothelial glycocalyx following organ procurement should be compatible with clinical procedures for transplant preservation and perfusion, and may reduce the damage and rejection of transplanted organs after surgery.

Colon-targeted delivery of tacrolimus using pH-responsive polymeric nanoparticles for murine colitis therapy

The present study aimed at constructing an oral nanoparticle delivery system loaded with tacrolimus (FK506) for effective treatment of inflammatory bowel disease. A FK506/HP-β-CD inclusion compound was prepared by grinding to increase drug solubility. To address the side- effects in non-target organs and systemic toxicity of FK506, pH-responsive Eudragit S100 (ES100) and hyaluronic acid (HA) with high affinity to CD44 receptor were adsorbed onto the surface of chitosan (CS) nanoparticles loaded with FK506/HP-β-CD through electrostatic interactions to obtain FK506@ES100/HA/CS/HP-β-CD nanoparticles (FK506@EHCh NPs). Caco-2 cells and Raw 264.7 macrophages were used to confirm the lack of cytotoxicity and good uptake ability of the newly generated nanoparticles. FK506@EHCh NPs significantly suppressed secretion of TNF-α, IL-1β and IL-6 by LPS-activated Raw 264.7 macrophages. A dextran sodium sulfate (DSS)-induced inflammatory bowel disease (IBD) murine model was established to further confirm the colon targeting and in vivo efficacy of oral IR-775@EHCh NPs. Based on the collective results, we conclude that packaging FK506 into active targeting nanocarriers sensitive to pH facilitates concentration of the drug within the sites of intestinal inflammation and improves the drug levels in target tissues, thus avoiding systemic side-effects and improving efficacy. In view of the promising results obtained in this study, the potential of EHCh nanoparticles for drug delivery and targeted treatment of inflammatory bowel disease warrants further investigation.

Pectin based multi-particulate carriers for colon-specific delivery of therapeutic agents

In case of colon-specific delivery of therapeutic agents through oral route, microbial/enzyme-triggered release approach has several advantages over other approaches due to unique microbial ecosystem in the colon. Multiple-unit carriers have an edge over single-unit carriers for this purpose. Among different materials/polymers explored, pectin appears as a promising biopolymer to construct microbial-triggered colon-specific carriers. Pectin is specifically degraded by colonic enzymes but insusceptible to upper gastro-intestinal enzymes. In this article, utilization of pectin solely or in combination with other polymers and/or colonic-delivery approaches is critically discussed in detail in the context of multi-particulate systems. Several studies showed that pectin-based carriers can prevent the release of payload in the stomach but start to release in the intestine. Hence, pectin alone may construct delayed release formulation but may not be sufficient for effective colon-targeting. On the other hand, combination of pectin with other materials/polymers (e.g., chitosan and Eudragit® S-100) has demonstrated huge promise for colon-specific release of payload. Hence, smartly designed pectin-based multi-particulate carriers, especially in combination with other polymers and/or colon-targeting approaches (e.g., microbial-triggered + pH-triggered or microbial-triggered + pH-triggered + time-release or microbial-triggered + pH-triggered + pressure-based), can be successful colon-specific delivery systems. However, more clinical trials are necessary to bring this idea from bench to bedside.

Application of inulin/Eudragit RS in 5-ASA pellet coating with tuned, sustained-release feature in an animal model of ulcerative colitis

A tunable release of 5-aminosalicylic acid (5-ASA) could bring therapeutic benefits in the treatment of inflammatory bowel disease (IBD). A 3² factorial design was used to achieve a tuned delivery of 5-ASA pellets in the small and large intestine using a coating composed of inulin/Eudragit RS (RS). The ratio of inulin/RS and coating level were independent variables while the dependent variables were the percent of drug release at pH 1.2 in 2 h and total release of drug in 10 h at pH 6.8. 5-ASA release from pellets was examined at different pH levels and the therapeutic efficacy of the optimum pellets was compared to 5-ASA pellets of Pentasa in rats with ulcerative colitis. The inulin/RS of 18/82 at a coating level of 16% was found to be the optimum for delivery of the drug to the small and large intestine. The coated pellets offered a superior therapeutic outcome compared to uncoated pellets and Pentasa in terms of colitis activity index (CAI), and the colon's tissue enzymes of GSH and MDA. The optimum coating composed of inulin and RS could offer a tuned sustained release of 5-ASA throughout the small and large intestine with the sensitivity of drug release to microbial degradation.

Development and Characterization of a Tacrolimus/Hydroxypropyl-β-Cyclodextrin Eye Drop

Uveitis is a vision inflammatory disorder with a high prevalence in developing countries. Currently, marketed treatments remain limited and reformulation is usually performed to obtain a tacrolimus eye drop as a therapeutic alternative in corticosteroid-refractory eye disease. The aim of this work was to develop a mucoadhesive, non-toxic and stable topical ophthalmic formulation that can be safely prepared in hospital pharmacy departments. Four different ophthalmic formulations were prepared based on the tacrolimus/hydroxypropyl-β-cyclodextrin (HPβCD) inclusion complexes’ formation. Phase solubility diagrams, Nuclear Magnetic Resonance (NMR) and molecular modeling studies showed the formation of 1:1 and 1:2 tacrolimus/HPβCD inclusion complexes, being possible to obtain a 0.02% (w/v) tacrolimus concentration by using 40% (w/v) HPβCD aqueous solutions. Formulations also showed good ophthalmic properties in terms of pH, osmolality and safety. Stability studies proved these formulations to be stable for at least 3 months in refrigeration. Ex vivo bioadhesion and in vivo ocular permanence showed good mucoadhesive properties with higher ocular permanence compared to the reference pharmacy compounding used in clinical settings (t_1/2 of 86.2 min for the eyedrop elaborated with 40% (w/v) HPβCD and Liquifilm^® versus 46.3 min for the reference formulation). Thus, these novel eye drops present high potential as a safe alternative for uveitis treatment, as well as a versatile composition to include new drugs intended for topical ophthalmic administration.

Application of Polymeric Nano-Materials in Management of Inflammatory Bowel Disease

Inflammatory Bowel Disease (IBD) is an umbrella term used to describe disorders that involve Crohn's disease (CD), ulcerative colitis (UC) and pouchitis. The disease occurrence is more prevalent in the working group population which not only hampers the well being of an individual but also has negative economical impact on society. The current drug regime used therapy is very costly owing to the chronic nature of the disease leading to several side effects. The condition gets more aggravated due to the lower concentration of drug at the desired site. Therefore, in the present scenario, a therapy is needed which can maximize efficacy, adhere to quality of life, minimize toxicity and doses, be helpful in maintaining and stimulating physical growth of mucosa with minimum disease complications. In this aspect, nanotechnology intervention is one promising field as it can act as a carrier to reduce toxicity, doses and frequency which in turn help in faster recovery. Moreover, nanomedicine and nanodiagnostic techniques will further open a new window for treatment in understanding pathogenesis along with better diagnosis which is poorly understood till now. Therefore the present review is more focused on recent advancements in IBD in the application of nanotechnology.

Orally administered mesoporous silica capped with the cucurbit[8]uril complex to combat colitis and improve intestinal homeostasis by targeting the gut microbiota

RATIONALE

Inflammatory bowel diseases (IBDs) are still awaiting innovative treatments that can maximize the efficiency of site-specific drug release in the colon while enhancing intestinal homeostasis.

METHODS

Herein, we present multilayer-coated mesoporous silica (MSs) which release payload drugs specifically in the colon tract in the presence of azoreductase produced by the gut microbiota, and simultaneously rejuvenate the tryptophan metabolism of the microbiome to induce activation of the aryl hydrocarbon receptor (AHR) for increased anti-inflammatory effects. The MSs were prepared by using cucurbit[8]uril (CB[8]) as a supramolecular "handcuff" to assemble chitosan/hyaluronic acid multilayers on the periphery of a mesoporous silica core.

RESULTS

Strikingly, although MSs remained fairly stable in both acidic and neutral pH, they exhibited excellent responsiveness towards dithionite, an azo-reducing agent employed as a substitute to mimic the specific azoreductase environment in vitro. In comparison with the drug in its free form, hydrocortisone-loaded MSs showed optimized accumulation of therapeutics in the colonic mucosa with minimized premature release in the upper gastrointestinal tract in in vivo imaging and biodistribution studies. The enhanced therapeutic effects of MSs were confirmed in dextran sodium sulfate-induced colitis in mice with promoted colonic epithelial barrier integrity, elevated level of AHR agonists and modulated production of inflammatory cytokines. Furthermore, 16S rRNA analysis showed that the disrupted gut homeostasis of colitic mice was partly corrected by MSs.

CONCLUSION

This novel drug delivery system using self-assembly of tryptophan-functionalized chitosan, which was precomplexed with CB[8], and azobenzene-functionalized hyaluronic acid on the surface of mesoporous silica nanoparticles provides a synergistic gut microbiota-targeting approach for IBD therapy.

pH-dependent ileocolonic drug delivery, part II: preclinical evaluation of novel drugs and novel excipients

Novel drugs and novel excipients in pH-dependent ileocolonic drug delivery systems have to be tested in animals. Which animal species are suitable and what in vivo methods are used to verify ileocolonic drug delivery?

Advances in Oral Drug Delivery for Regional Targeting in the Gastrointestinal Tract - Influence of Physiological, Pathophysiological and Pharmaceutical Factors

The oral route is by far the most common route of drug administration in the gastrointestinal tract and can be used for both systemic drug delivery and for treating local gastrointestinal diseases. It is the most preferred route by patients, due to its advantages, such as ease of use, non-invasiveness, and convenience for self-administration. Formulations can also be designed to enhance drug delivery to specific regions in the upper or lower gastrointestinal tract. Despite the clear advantages offered by the oral route, drug delivery can be challenging as the human gastrointestinal tract is complex and displays a number of physiological barriers that affect drug delivery. Among these challenges are poor drug stability, poor drug solubility, and low drug permeability across the mucosal barriers. Attempts to overcome these issues have focused on improved understanding of the physiology of the gastrointestinal tract in both healthy and diseased states. Innovative pharmaceutical approaches have also been explored to improve regional drug targeting in the gastrointestinal tract, including nanoparticulate formulations. This review will discuss the physiological, pathophysiological, and pharmaceutical considerations influencing drug delivery for the oral route of administration, as well as the conventional and novel drug delivery approaches. The translational challenges and development aspects of novel formulations will also be addressed.

Application of PLGA nano/microparticle delivery systems for immunomodulation and prevention of allotransplant rejection

INTRODUCTION

Allograft transplantation is an effective end-point therapy to replace the function of an impaired organ. The main problem associated with allotransplantation is the induction of immune responses that results in acute and chronic graft rejection. To modulate the response of the immune system, transplant recipients generally take high dose immunosuppressant drugs for life. These drugs are associated with serious side effects such as infection with opportunistic pathogens and the development of neoplasia.

AREAS COVERED

We reviewed the obstacles to successful transplantation and PLGA-based strategies to reduce immune-mediated allograft rejection.

EXPERT OPINION

Biomaterial-based approaches using micro- and nanoparticles such as poly (lactic-co-glycolic acid) (PLGA) can be used to achieve controlled release of drugs. This approach decreases the required effective dose of drugs and enables local delivery of these agents to specific tissues and cells, whilst decreasing systemic effects.

The hurdles of nanotoxicity in transplant nanomedicine

Nanomedicine has matured significantly in the past 20 years and a number of nanoformulated therapies are cleared by regulatory agencies for use across the globe. Transplant medicine is one area that has significantly benefited from the advancement of nanomedicine in recent times. However, while nanoparticle-based therapies have improved toxicological profiles of some drugs, there are still a number of aspects regarding the biocompatibility and toxicity of nanotherapies that require further research. The goal of this article is to review toxicological profiles of immunosuppressant therapies and their conversion into nanomedicine formulations as well as introduce future challenges associated with current in vitro and in vivo toxicological models.

Novel polyurethane-based nanoparticles of infliximab to reduce inflammation in an in-vitro intestinal epithelial barrier model

In this study we examined the potential of novel biodegradable polymers of polyesterurethane (PU), and its PEGylated (PU-PEG) form as nanocarriers of Infliximab (INF), to treat inflammation in an in-vitro epithelial model. Nanoparticles (NPs) formulated were of average size of 200-287 nm. INF loading of NPs (INF-NPs) resulted in an increase in size and zeta potential. No cytotoxicity was observed for any of the NPs. Cellular interaction and uptake of PU NPs were similar compared with polycaprolactone (PCL) NPs and significantly higher to Poly(lactic-co-glycolic) acid (PLGA) NPs. Cellular interaction was higher for corresponding PEG-NPs. INF-PU and INF-PU-PEG NPs showed a rapid rate and extent of recovery of the epithelial barrier function in inflamed Caco-2 cell monolayers and decreased cytokine levels in inflamed monocytes. Results obtained in this study are promising and the potential of PU and PU-PEG NPs for drug delivery and targeting to treat gastrointestinal inflammation warrants further investigation.

Synthesis of poly(lactide-co-glycerol) as a biodegradable and biocompatible polymer with high loading capacity for dermal drug delivery

Due to the low cutaneous bioavailability of tacrolimus (TAC), penetration enhancers are used to improve its penetration into the skin. However, poor loading capacity, non-biodegradability, toxicity, and in some cases inefficient skin penetration are challenging issues that hamper their applications for the dermal TAC delivery. Here we present poly(lactide-co-glycerol) (PLG) as a water soluble, biodegradable, and biocompatible TAC-carrier with high loading capacity (14.5% w/w for TAC) and high drug delivery efficiencies into the skin. PLG was synthesized by cationic ring-opening copolymerization of a mixture of glycidol and lactide and showed 35 nm and 300 nm average sizes in aqueous solutions before and after loading of TAC, respectively. Delivery experiments on human skin, quantified by fluorescence microscopy and LC-MS/MS, showed a high ability for PLG to deposit Nile red and TAC into the stratum corneum and viable epidermis of skin in comparison with Protopic® (0.03% w/w, TAC ointment). The cutaneous distribution profile of delivered TAC proved that 80%, 16%, and 4% of the cutaneous drug level was deposited in the stratum corneum, viable epidermis, and upper dermis, respectively. TAC delivered by PLG was able to efficiently decrease the IL-2 and TSLP expressions in human skin models. Taking advantage of the excellent physicochemical and biological properties of PLG, it can be used for efficient dermal TAC delivery and potential treatment of inflammatory skin diseases.

Drug nanocarriers to treat autoimmunity and chronic inflammatory diseases

Nanoparticles represent a new generation of drug delivery systems that can be engineered to harness optimal target selectivity for specific cells and tissues and high drug loading capacity, allowing for improved pharmacokinetics and enhanced bioavailability of therapeutics. The spontaneous propensity of both organic and colloidal nanoparticles to be captured by the cells of the reticuloendothelial system encouraged their utilization as passive targeting systems that can be preferentially directed to innate immune cells, such as macrophages, dendritic cells and neutrophils. The natural affinity for phagocytic cells suggests the possible implementation of nanoparticles as an immunotherapeutic platform for inflammatory diseases and autoimmune disorders. Here we discuss the recent advances in the application of nanotechnology to induce antigen-specific tolerance in autoimmunity and the use of nanoparticles for anti-inflammatory therapies, including treatment of inflammatory bowel diseases, psoriasis and rheumatoid arthritis.

Vildagliptin loaded triangular DNA nanospheres coated with eudragit for oral delivery and better glycemic control in type 2 diabetes mellitus

Diabetes mellitus type 2 is a multidimensional disease associated with poor glycemic control through compromised sensitivity of pancreatic islet α and β cells against glucose and dwindled secretion of insulin which is linked with the quantity of incretin hormones that are abridged by dipeptidyl peptidase-4 (DPP-4) in diseased condition. Vildagliptin (VG) inhibits DPP-4 therefore regulates the incretins that conversely maintains glycemic control. The safe reach and absorption of VG from intestine was dubious. Therefore we used Electrostatic Attraction Method to develop drug loaded DNA nanotechnology triangles coated by Eudragit (Eud) to make stable nanospheres of Vildagliptin (VG). We further analyzed the formulated nanospheres by AFM, XRD, DSC, SEM, TGA, ATR-FTIR and native PAGE. Additionally the efficacy of formulated nanospheres for drug release and glycemic control was assessed in Db/Db mouse. Our results showed that formulated nanospheres are smooth, spherical, stable and uniform in size ranging from 500 to 2000 nm with drug entrapment efficiency up to 95 ± 2% and extended drug release up to 15 ± 2 h. FTIR and DSC results confirmed the absence of VG-DNA-Eud interaction and XRD studies revealed a change in the crystalline status of the VG in nanospheres. Ex-vivo studies indicate that Eud-DNA-VG nanospheres effectively bypasses the acidic pH of the stomach and enhances glycemic control in Db/Db mouse without any risk of pancreatitis or pancreatic cancer. To the best of our knowledge, this is the first study conclusively reporting that VG loaded DNA Nano-architects coated with Eudragit are stable, safe and may improve therapeutic outcomes after oral delivery.

Nanoparticulate Drug Delivery Systems Targeting Inflammation for Treatment of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic, idiopathic inflammatory set of conditions that can affect the entire gastrointestinal (GI) tract and is associated with an increased risk of colorectal cancer. To date there is no curative therapy for IBD; therefore life-long medication can be necessary for IBD management if surgery is to be avoided. Drug delivery systems specific to the colon have improved IBD treatment and several such systems are available to patients. However, current delivery systems for IBD do not target drugs to the site of inflammation, which leads to frequent dosing and potentially severe side effects that can adversely impact patients' adherence to medication. There is a need for novel drug delivery systems that can target drugs to the site of inflammation, prolong local drug availability, improve therapeutic efficacy, and reduce drug side effects. Nanoparticulate (NP) systems are attractive in designing targeted drug delivery systems for the treatment of IBD because of their unique physicochemical properties and capability of targeting the site of disease. This review analyzes the microenvironment at the site of inflammation in IBD, highlighting the pathophysiological features as possible cues for targeted delivery; discusses different strategies and mechanisms of NP targeting IBD, including size-, charge-, ligand-receptor, degradation- and microbiome-mediated approaches; and summarizes recent progress on using NPs towards improved therapies for IBD. Finally, challenges and future directions in this field are presented to advance the development of targeted drug delivery for IBD treatment.

Effects of nanoparticle-encapsulated curcumin on HIV-gp120-associated neuropathic pain induced by the P2X3 receptor in dorsal root ganglia

HIV-1 envelope glycoprotein (Glycoprotein 120, gp120) can directly stimulate primary sensory afferent neurons and cause chronic neuropathic pain. The P2X₃ receptor in the dorsal root ganglia (DRG) is associated with the transmission of neuropathic pain. Curcumin isolated from the herb Curcuma rhizome has anti-inflammatory and anti-tumor effects. The water solubility, targeting and bioavailability of curcumin can be improved by nanoparticle encapsulation. In this study, we sought to explore the effects of nanoparticle-encapsulated curcumin (nano curcumin) on HIV-gp120-induced neuropathic pain mediated by the P2X₃ receptor in DRG neurons. The results showed that mechanical and thermal hyperalgesia in rats treated with gp120 were increased compared to those in the control group. The expression levels of P2X₃ mRNA and protein in rats treated with gp120 were higher than those in the control group. Nano curcumin treatment decreased mechanical hyperalgesia and thermal hyperalgesia and upregulated the expression levels of P2X₃ mRNA and protein in rats treated with gp120. Nano curcumin treatment also reduced the ERK1/2 phosphorylation levels in gp120-treated rat DRG. In addition, P2X₃ agonist α,β-methylene ATP (α,β-meATP)-induced currents in DRG neurons cultured with gp120 significantly decreased after co-treatment with nano curcumin. Therefore, nano curcumin treatment may inhibit P2X₃ activation, decrease the sensitizing DRG primary afferents and relieve mechanical hyperalgesia and thermal hyperalgesia in gp120-treated rats.

Design, Characterization, and In Vivo Pharmacokinetics of Tacrolimus Proliposomes

The objective of this study was to develop proliposomal formulation for a poorly bioavailable drug, tacrolimus. Proliposomes were prepared by thin film hydration method using different lipids such as hydrogenated soy phosphatidylcholine (HEPC), soy phosphatidylcholine (SPC), distearyl phosphatidylcholine (DSPC), dimyristoylphosphatidylcholine (DMPC), and dimyristoylphosphatidylglycerol sodium (DMPG) and cholesterol in various ratios. Proliposomes were evaluated for particle size, zeta potential, in vitro drug release, in vitro permeability, and in vivo pharmacokinetics. In vitro drug release was carried out in purified water using USP type II dissolution apparatus. In vitro drug permeation was studied using parallel artificial membrane permeation assay (PAMPA) and everted rat intestinal perfusion techniques. In vivo pharmacokinetic studies were conducted in male Sprague-Dawley (SD) rats. Among the different formulations, proliposomes with drug/DSPC/cholesterol in the ratio of 1:2:0.5 demonstrated the desired particle size and zeta potential. Enhanced drug release was observed with proliposomes compared to pure tacrolimus in purified water after 1 h. Tacrolimus permeability across PAMPA and everted rat intestinal perfusion models was significantly higher with proliposomes. The optimized formulation of proliposomes indicated a significant improvement in the rate and absorption of tacrolimus. Following a single oral administration, a relative bioavailability of 193.33% was achieved compared to pure tacrolimus suspension.

Microparticles as controlled drug delivery carrier for the treatment of ulcerative colitis: A brief review

Ulcerative colitis is the chronic relapsing multifactorial gastrointestinal inflammatory bowel disease, which is characterized by bloody or mucus diarrhea, tenesmus, bowel dystension, anemia. The annual incidence of ulcerative colitis in Asia, North America and Europe was found to be 6.3, 19.2 and 24.3 per 100,000 person-years. The major challenge in the treatment of ulcerative colitis is appropriate local targeting and drug related side-effects. To overcome these challenges, microparticulate systems seem to be a promising approach for controlled and sustained drug release after oral administration. The main goal of this article is to explore the role of microparticles in ulcerative colitis for the appropriate targeting of drugs to colon. There are different approaches which have been studied over the last decade, including prodrugs, polymeric approach, time released system, pH sensitive system, which show the site specific drug delivery to colon. Among these approaches, microparticulate drug delivery system has been gaining an immense importance for local targeting of drug to colon at a controlled and sustained rate. Combined approaches such as pH dependent and time dependent system provide the maximum release of drug into colon via oral route. This article embraces briefly about pathophysiology, challenges and polymeric approaches mainly multiparticulate systems for site specific drug delivery to colon in sustained and controlled manner so that drug related side-effects by reducing dosage frequency can be minimized.

Size-dependent nanoparticulate drug delivery in inflammatory bowel diseases

INTRODUCTION

Inflammatory bowel disease (IBD) is a chronic autoimmune disease, whose main forms are Crohn's disease and ulcerative colitis. The main treatment of IBD includes oral administration of anti-inflammatory or immunosuppressive agents enclosed in traditional dosage forms, intended to release the active ingredient in the large intestine. However, most of them have been designed based on the physiology of healthy colon, which differs distinctly from conditions met in IBD patients risking adverse effects and patient intolerance. The use of nanoparticles as a drug carrier for treatment of IBD is a promising approach that is capable of solving this problem. Previous studies have shown a size-dependent behavior, where reducing the particle size, increases the targeting efficacy and the residence time compared to healthy controls.

AREAS COVERED

This review covers the utilization of nanoparticles as drug delivery carriers for treating IBD. They can reach the inflamed colonic sites either by endothelial or epithelial delivery employing passive and active targeting strategies. The effect of particle size is analyzed in detail while elucidating other essential parameters such as the particle surface properties.

EXPERT OPINION

One of the most important advantages of nanoparticles is their passive targeting to the inflamed colonic tissues due to their size. Recent findings underline that this size-dependent bioadhesion behavior can be further enhanced by selecting smart surface properties to help in penetrating the mucus and reach the inflamed sites.

Enhanced therapeutic efficacy of budesonide in experimental colitis with enzyme/pH dual-sensitive polymeric nanoparticles

Current colon-targeted drug-delivery approaches for colitis therapy often utilize single pH-triggered systems, which are less reliable due to the variation of gut pH in individuals and in disease conditions. Herein, we prepared budesonide-loaded dual-sensitive nanoparticles using enzyme-sensitive azo-polyurethane and pH-sensitive methacrylate copolymer for the treatment of colitis. The therapeutic potential of the enzyme/pH dual-sensitive nanoparticles was evaluated using a rat colitis model and compared to single pH-triggered nanoparticles. Clinical activity scores, colon/body weight ratios, myeloperoxidase activity, and proinflammatory cytokine levels were markedly decreased by dual-sensitive nanoparticles compared to single pH-triggered nanoparticles and budesonide solution. Moreover, dual-sensitive nanoparticles accumulated selectively in inflamed segments of the colon. In addition, dual-sensitive nanoparticle plasma concentrations were lower than single pH-triggered nanoparticles, and no noticeable in vitro or in vivo toxicity was observed. Our results demonstrate that enzyme/pH dual-sensitive nanoparticles are an effective and safe colon-targeted delivery system for colitis therapy.

The in vivo fate of nanoparticles and nanoparticle-loaded microcapsules after oral administration in mice: Evaluation of their potential for colon-specific delivery

Anti-cancer drug loaded-nanoparticles (NPs) or encapsulation of NPs in colon-targeted delivery systems shows potential for increasing the local drug concentration in the colon leading to improved treatment of colorectal cancer. To investigate the potential of the NP-based strategies for colon-specific delivery, two formulations, free Eudragit® NPs and enteric-coated NP-loaded chitosan-hypromellose microcapsules (MCs) were fluorescently-labelled and their tissue distribution in mice after oral administration was monitored by multispectral small animal imaging. The free NPs showed a shorter transit time throughout the mouse digestive tract than the MCs, with extensive excretion of NPs in faeces at 5h. Conversely, the MCs showed complete NP release in the lower region of the mouse small intestine at 8h post-administration. Overall, the encapsulation of NPs in MCs resulted in a higher colonic NP intensity from 8h to 24h post-administration compared to the free NPs, due to a NP 'guarding' effect of MCs during their transit along mouse gastrointestinal tract which decreased NP excretion in faeces. These imaging data revealed that this widely-utilised colon-targeting MC formulation lacked site-precision for releasing its NP load in the colon, but the increased residence time of the NPs in the lower gastrointestinal tract suggests that it is still useful for localised release of chemotherapeutics, compared to NP administration alone. In addition, both formulations resided in the stomach of mice at considerable concentrations over 24h. Thus, adhesion of NP- or MC-based oral delivery systems to gastric mucosa may be problematic for colon-specific delivery of the cargo to the colon and should be carefully investigated for a full evaluation of particulate delivery systems.

Micro and nanoparticle drug delivery systems for preventing allotransplant rejection

Despite decades of advances in transplant immunology, tissue damage caused by acute allograft rejection remains the primary cause of morbidity and mortality in the transplant recipient. Moreover, the long-term sequelae of lifelong immunosuppression leaves patients at risk for developing a host of other deleterious conditions. Controlled drug delivery using micro- and nanoparticles (MNPs) is an effective way to deliver higher local doses of a given drug to specific tissues and cells while mitigating systemic effects. Herein, we review several descriptions of MNP immunotherapies aimed at prolonging allograft survival. We also discuss developments in the field of biomimetic drug delivery that use MNP constructs to induce and recruit our bodies' own suppressive immune cells. Finally, we comment on the regulatory pathway associated with these drug delivery systems. Collectively, it is our hope the studies described in this review will help to usher in a new era of immunotherapy in organ transplantation.

Evaluation of In Vivo Transfection Efficiency of Eudragit Coated Nanoparticles of Chitosan-DNA: A pH-sensitive System Prepared for Oral DNA Delivery

Background:

Success of any gene therapy protocol relies mostly on using an efficient carrier to direct nucleic acid to the place of action. The system should also have transfection ability at release site. Different routes are available for delivering genetic materials to the target organs, amongst them; oral delivery is particularly attractive for certain reasons. However, serious obstacles, like acidic environment of stomach and presence of protease and nuclease enzymes in gastrointestinal (GI) tract, make oral route a highly challenging option.

Objectives:

The present study suggests preparation of gene nanoparticles (NPs) of chitosan within a layer of Eudragit L100 for oral delivery of nucleic acid. The nanoparticles have some features both in size and polymer properties that can be penetrating enough to transfect epithelial layer cells of intestine and protect the entrapped materials against stomach harsh condition.

Materials and Methods:

In this experimental study, conducted in Iran, particles were prepared by coacervation technique followed by encapsulation of nanoparticle within a coat of Eudragit L100 using solvent evaporation technique. Formulation behavior was monitored both in vitro and in vivo. Stability of particle construction and release profile of DNA were examined at pH of ± 0.8 environ pKa of Eudragit. Size and zeta potential of particles were measured. To demonstrate transfection efficiency of the constructed carrier, reverse transcription polymerase chain reaction (RT-PCR) was carried out using human insulin specific primers on total RNA extracted from upper part of small intestine of 48-hour post-transfected rats (sampled by simple random selection, n = 3).

Results:

The mean size and zeta potential of particles were 300 ± 4 nm and 14 ± 0.5 mV, respectively. Encapsulation of this system was 89.6 ± 1.2%. DNA release from batches was less than 12% at pH = 5.2 and more than 60% at pH = 6.8 with significant difference of P < 0.05. RT-PCR product confirmed the presence of insulin transcript of 437 bp in upper intestinal extracts of the transfected rats. No band of DNA was seen after RT-PCR of placebo form of nanoparticles received group.

Conclusions:

Eudragit coated nanoparticle of chitosan is an efficient choice for oral delivery of DNA to upper part of GI tract.

Nanomedicines in gastroenterology and hepatology

Nanoscale systems are currently under investigation for multiple different diagnostic and therapeutic applications. These systems can be used to identify pathologically changed tissues or to selectively deliver drugs to these sites; both applications have an extremely high potential to ameliorate therapeutic outcomes for patients. Tissues as well as single cells can be targeted because of the small size of these systems, which enables enhanced diagnosis and increased specificity of therapy. Drug loads can be delivered directly to the site of action, which can result in a reduction in incidence and severity of adverse systemic effects. Several nano-based platform technologies are currently under investigation for use in therapeutic approaches, mainly for anti-inflammatory and anti-cancer therapies. Although many nanoscale systems show promising therapeutic outcomes in preclinical studies, only a limited number are ready for clinical use. This Review will discuss the diverse nanomaterials currently available and the first specific uses for select gastroenterological and hepatological pathologies. The discussion of diagnostic and therapeutic applications will consider realities of market introduction of these sometimes very complex systems in light of remaining regulatory challenges and hurdles for industrial production.

Advances in oral nano-delivery systems for colon targeted drug delivery in inflammatory bowel disease: selective targeting to diseased versus healthy tissue

Colon targeted drug delivery is an active area of research for local diseases affecting the colon, as it improves the efficacy of therapeutics and enables localized treatment, which reduces systemic toxicity. Targeted delivery of therapeutics to the colon is particularly advantageous for the treatment of inflammatory bowel disease (IBD), which includes ulcerative colitis and Crohn's disease. Advances in oral drug delivery design have significantly improved the bioavailability of drugs to the colon; however in order for a drug to have therapeutic efficacy during disease, considerations must be made for the altered physiology of the gastrointestinal (GI) tract that is associated with GI inflammation. Nanotechnology has been used in oral dosage formulation design as strategies to further enhance uptake into diseased tissue within the colon. This review will describe some of the physiological challenges faced by orally administered delivery systems in IBD, the important developments in orally administered nano-delivery systems for colon targeting, and the future advances of this research.

FROM THE CLINICAL EDITOR

Inflammatory Bowel Disease (IBD) poses a significant problem for a large number of patients worldwide. Current medical therapy mostly aims at suppressing the active inflammatory episodes. In this review article, the authors described and discussed the various approaches current nano-delivery systems can offer in overcoming the limitations of conventional drug formulations.