Colon-specific delivery of prednisolone-appended alpha-cyclodextrin conjugate: alleviation of systemic side effect after oral administration

Glucocorticoids-based prodrug design: Current strategies and research progress

Attributing to their broad pharmacological effects encompassing anti-inflammation, antitoxin, and immunosuppression, glucocorticoids (GCs) are extensively utilized in the clinic for the treatment of diverse diseases such as lupus erythematosus, nephritis, arthritis, ulcerative colitis, asthma, keratitis, macular edema, and leukemia. However, long-term use often causes undesirable side effects, including metabolic disorders-induced Cushing's syndrome (buffalo back, full moon face, hyperglycemia, etc.), osteoporosis, aggravated infection, psychosis, glaucoma, and cataract. These notorious side effects seriously compromise patients' quality of life, especially in patients with chronic diseases. Therefore, glucocorticoid-based advanced drug delivery systems for reducing adverse effects have received extensive attention. Among them, prodrugs have the advantages of low investment, low risk, and high success rate, making them a promising strategy. In this review, we propose the strategies for the design and summarize current research progress of glucocorticoid-based prodrugs in recent decades, including polymer-based prodrugs, dendrimer-based prodrugs, antibody-drug conjugates, peptide-drug conjugates, carbohydrate-based prodrugs, aliphatic acid-based prodrugs and so on. Besides, we also raise issues that need to be focused on during the development of glucocorticoid-based prodrugs. This review is expected to be helpful for the research and development of novel GCs and prodrugs.

Multifunctionality of cyclodextrin-based polymeric nanoparticulate delivery systems for chemotherapeutics, combination therapy, and theranostics

As cancer being the most difficult disease to treat, different kinds of medications and therapeutic approaches have been prominently developed by scientists. For certain families of drugs, such as immuno-therapeutics or antibody-drug conjugates, efficient delivery systems are required during administration to protect the drugs from chemical degradation or biological inactivation. Delivery systems with the ability to carry different therapeutics or diagnostic agents or both, hold promising potential to tackle the abnormalities behind cancer. In this context, this review provides updated insights on how cyclodextrin-based polymeric nanosystems have become an effective treatment approach against cancer. Cyclodextrins (CDs) are natural oligosaccharides that are famously exploited in pharmaceutical research due to their exceptional quality of entrapping water-insoluble molecules inside their hydrophobic core and providing enhanced solubility with the help of their hydrophilic exterior. Combining the properties of CDs with polymeric nanoparticles (PNPs) brings out excellent versatile and tunable profiles, thanks to the submicron-sized PNPs. By introducing the significance of CD as a delivery system, a collective discussion on different binding approaches and release mechanisms of CD-drug complexation, followed by their characterization studies has been done in this review. Further, in light of recent studies, the article majorly focuses on conveying how promoting CD to a polymeric and nanoscale elevates the multifunctional advantages against cancer that can be successfully applied in combination therapy and theranostics. Moreover, CD-based delivery systems including CALAA-01, CRLX101, and CRLX301, have demonstrated improved tumor targeting, reduced side effects, and prolonged drug release in preclinical studies and clinical trials.

Colon-Targeted Trans-Cinnamic Acid Ameliorates Rat Colitis by Activating GPR109A

We designed colon-targeted trans-cinnamic acid (tCA) and synthesized its conjugates with glutamic acid (tCA-GA) and aspartic acid (tCA-AA). We evaluated the anti-colitic activity of colon-targeted tCA using a dinitrobenzenesulfonic acid-induced rat colitis model. The conjugates lowered the distribution coefficient and Caco-2 cell permeability of tCA and converted to tCA in the cecum, with higher rates and percentages with tCA-GA than with tCA-AA. Following oral gavage, tCA-GA delivered a higher amount of tCA to the cecum and exhibited better anti-colitic effects than tCA and sulfasalazine (SSZ), which is the current treatment for inflammatory bowel disease. In the cellular assay, tCA acted as a full agonist of GPR109A (EC50: 530 µM). The anti-colitic effects of tCA-GA were significantly compromised by the co-administration of the GPR109A antagonist, mepenzolate. Collectively, colon-targeted tCA potentiated the anti-colitic activity of tCA by effectively activating GPR109A in the inflamed colon, enabling tCA to elicit therapeutic superiority over SSZ.

Orally Fast Disintegrating Cyclodextrin/Prednisolone Inclusion-Complex Nanofibrous Webs for Potential Steroid Medications

Prednisolone is a widely used immunosuppressive and anti-inflammatory drug type that suffers from low aqueous solubility and bioavailability. Due to the inclusion complexation with cyclodextrins (CDs), prednisolone's drawbacks that hinder its potential during the administration can be eliminated effectively. Here, we have early shown the electrospinning of free-standing nanofibrous webs of CD/prednisolone inclusion complexes (ICs) in the absence of a polymer matrix. In this study, hydroxypropyl-beta-CD (HPβCD) has been used to form ICs with prednisolone and generate nanofibrous webs with a drug loading capacity of ∼10% (w/w). Pullulan/prednisolone nanofibrous webs have been also fabricated as a control sample having the same drug loading (∼10%, w/w). It has been demonstrated that prednisolone has been found in an amorphous state in the HPβCD/prednisolone nanofibrous web due to inclusion complexation, while it has retained its crystal structure in the pullulan/prednisolone nanofibrous web. Therefore, the HPβCD/prednisolone IC nanofibrous web has shown a faster and enhanced release profile and superior disintegration feature in artificial saliva than the pullulan/prednisolone nanofibrous web. The complexation energy calculated using ab initio modeling displayed a more favorable interaction between HPβCD and prednisolone in the case of a molar ratio of 2:1 than 1:1 (CD: drug). Here, the HPβCD/prednisolone IC nanofibrous web has been developed without using a toxic component or solvent to dissolve drug molecules and boost drug loading in amorphous nature. The investigation of IC nanofibrous webs has been conducted to formulate a promising alternative to the orally disintegrating tablet formulation of prednisolone in the market. The nanofibrous structure and the improved physicochemical properties of prednisolone arising with the complexation might ensure a faster disintegration and onset of action against commercially available and orally disintegrating delivery systems during the desired treatment.

Cyclodextrins as Anti-inflammatory Agents: Basis, Drugs and Perspectives

Inflammation is a biological response of the immune system to harmful stimuli. Importantly, inflammation is also a hallmark of several human diseases such as cancer or diabetes. Novel drugs to treat this response are constantly researched, but the formulation is usually forgotten. Cyclodextrins (CDs) are a well-known excipient for complexing and drug delivery. Anti-inflammatory drugs and bioactive compounds with similar activities have been favored from these CD processes. CDs also illustrate anti-inflammatory activity per se. This review tried to describe the capacities of CDs in this field, and is divided into two parts: Firstly, a short description of the inflammation disease (causes, symptoms, treatment) is explained; secondly, the effects of different CDs alone or forming inclusion complexes with drugs or bioactive compounds are discussed.

Preparation and evaluation of conjugate nanogels of glycyl-prednisolone with natural anionic polysaccharides as anti-arthritic delivery systems

Although prednisolone (PD) is used as an anti-arthritis drug due to its rapid and strong anti-inflammatory potential, its frequent and large dosing often brings about adverse effects. Therefore, targeting therapy has attracted increasing attention to overcome such adverse effects. In the present study, nanogels (NGs) composed of macromolecule-PD conjugates were developed as a novel targeting delivery system, and their anti-inflammatory potential was examined. Conjugates were prepared by carbodiimide coupling between glycyl-prednisolone (GP) and the natural anionic polysaccharides, alginic acid (AL) and hyaluronic acid (HA). NGs were produced by the evaporation of organic solvent from the conjugate solution. The obtained NGs, named AL-GP-NG and HA-GP-NG, respectively, were examined for particle characteristics, in vitro release, pharmacokinetics, and in vivo efficacy. Both NGs were several hundred nanometers in size, had negative zeta potentials, and several % (w/w) drug contents. They released PD gradually at pH 7.4 and 6. They exhibited fairly good retention in the systemic circulation. In the efficacy examination using rats with adjuvant-induced arthritis, both NGs showed the stronger and more prolonged suppression of paw inflammation than PD alone. These suggested that the present NGs should be possibly useful as anti-arthritis targeting therapeutic systems.

Cyclodextrins-Peptides/Proteins Conjugates: Synthesis, Properties and Applications

Cyclodextrins (CDs) are a family of macrocyclic oligosaccharides mostly composed of six, seven, or eight α-D-glucopyranose units with α-1,4-glycosidic bonds to form toroidal structures. The CDs possess a hydrophilic exterior and hydrophobic interior with the ability to form an inclusion complex, especially with hydrophobic molecules. However, most existing studies are about conjugation CDs with peptide/protein focusing on the formation of new systems. The CD-peptide/protein can possess new abilities; particularly, the cavity can be applied in modulation properties of more complexed proteins. Most studies are focused on drug delivery, such as targeted delivery in cell-penetrating peptides or co-delivery. The co-delivery is based mostly on polylysine systems; on the other hand, the CD-peptide allows us to understand biomolecular mechanisms such as fibryllation or stem cell behaviour. Moreover, the CD-proteins are more complexed systems with a focus on targeted therapy; these conjugates might be controllable with various properties due to changes in their stability. Finally, the studies of CD-peptide/protein are promising in biomedical application and provide new possibilities for the conjugation of simple molecules to biomolecules.

Advances of Regulatory B Cells in Autoimmune Diseases

With the ability to induce T cell activation and elicit humoral responses, B cells are generally considered as effectors of the immune system. However, the emergence of regulatory B cells (Bregs) has given new insight into the role of B cells in immune responses. Bregs exhibit immunosuppressive functions via diverse mechanisms, including the secretion of anti-inflammatory cytokines and direct cell contact. The balance between Bregs and effector B cells is important for the immune tolerance. In this review, we focus on recent advances in the characteristics of Bregs and their functional roles in autoimmunity.

Influence of gamma radiation on Amphotericin B incorporated in PVP hydrogel as an alternative treatment for cutaneous leishmaniosis

Amphotericin B (Amph-B) is an antifungal drug used intravenously for the treatment of leishmaniasis. Side-effects from Amph-B treatment can arise such as cardiac arrhythmia and renal dysfunctions, which will lead to discontinuation of treatment. Unfortunately, patients in endemic countries do not have access to alternative therapies. The objective of this study was to analyze the effects of Cobalt-60 gamma irradiation on crosslinking polymeric hydrogels (Hydg) and the incorporation of Amph-B into the gel as a controlled-release drug delivery alternative. Polyvinylpyrrolidone (PVP)/Amph-B solutions were irradiated with 15 kGy at 0 °C and 25 °C. The drug's stability was ascertained by UV-visible spectrometry, liquid chromatography/mass spectrometry and proton nuclear magnetic resonance. Irradiated Hydg/Amph-B achieved similar stability to the standard Amph-B solution and was enough to promote hydrogel crosslinking. In vitro trials were carried out to ensure Amph-B was still biologically active after irradiation. The results from flow cytometry and MTT assay show that Amph-B had an IC₅₀ = 16.7 nM. A combination of Hydg at 1.324 gmL^-1 and Amph-B at 25.1 nM for 24 h lead to the greatest inhibition of L. amazonensis promastigotes, and could be used as an alternative treatment method for cutaneous leishmaniosis.

Combination of inulin and β-cyclodextrin properties for colon delivery of hydrophobic drugs

Colon drug delivery is aimed at the administration of selected drugs to act locally or even systematically. Corticosteroid drugs are often used exerting even pronounced side effects due to systemic absorption. Here a new drug delivery system (DDS) based on the chemical conjugation of β-cyclodextrin to inulin to form the INUCD bioconjugate is described. It was designed with the aim to provide this DDS with colon degradable portions (inulin) which degradation products have direct beneficial effects on the well-being of the colon and with a carrier that can solubilize hydrophobic drugs (β-cyclodextrin). This system was specifically designed to promote a local/topical activity with a significant reduction of the drug systemic absorption. The INUCD bioconjugate was obtained by a simple chemistry binding β-cyclodextrin to an inulin succinate previously synthesized. The bioconjugate was then characterized in terms of physicochemical properties by ATR-FTIR, ¹H NMR, DSC and TGA, DLS and SEM. Furthermore phase-solubility test by using curcumin as a model drug were performed as well as biologic evaluations for cytocompatibility and drug transport across in vitro simulated physiological barriers. Moreover enzymatic degradation studies by inulinase were performed. From the gained results a predictable local drug release of the payload could be attained so allowing a local delivery of e.g. corticosteroids thus avoiding a systemic absorption especially in prolonged therapies.

A Colon-Targeted Prodrug, 4-Phenylbutyric Acid-Glutamic Acid Conjugate, Ameliorates 2,4-Dinitrobenzenesulfonic Acid-Induced Colitis in Rats

An elevated level of endoplasmic reticulum (ER) stress is considered an aggravating factor for inflammatory bowel disease (IBD). To develop an ER-stress attenuator that is effective against colitis, 4-phenylbutyric acid (4-PBA), a chemical chaperone that alleviates ER stress, was conjugated with acidic amino acids to yield 4-PBA-glutamic acid (PBA-GA) and 4-PBA-aspartic acid (PBA-AA) conjugates. The PBA derivatives were converted to 4-PBA in the cecal contents, and the conversion was greater with PBA-GA than that with PBA-AA. After oral administration of PBA-GA (oral PBA-GA), up to 2.7 mM PBA was detected in the cecum, whereas 4-PBA was not detected in the blood, indicating that PBA-GA predominantly targeted the large intestine. In 2,4-dinitrobenzenesulfonic acid-induced colitis in rats, oral PBA-GA alleviated the damage and inflammation in the colon and substantially reduced the elevated levels of ER stress marker proteins in the inflamed colon. Moreover, PBA-GA was found to be as effective as the currently used anti-IBD drug, sulfasalazine. In conclusion, PBA-GA is a colon-targeted prodrug of 4-PBA and is effective against rat colitis probably via the attenuation of ER stress in the inflamed colon.

The Anti-Inflammatory Effect of Pistacia Lentiscus in a Rat Model of Colitis

Introduction

The mastic tree (Pistacia lentiscus), belonging to the Anacardiaceae family, has anti-inflammatory and antioxidant properties. This study aims to assay the anti-inflammatory effects of mastic in rats with colitis.

Methods

Forty-eight male Sprague-Dawley rats were randomly divided into six groups of control, colitis without treatment, colitis with mastic (400 mg/kg/daily) administered orally or intra-rectally, colitis with prednisolone (5 mg/kg of body weight), and colitis with sesame oil for seven successive days. Treatment effects were evaluated by determining cytokines (TNFα, IL6) and myeloperoxidase (MPO) activity, macroscopic scores, and histopathological parameters. The results of each group are compared with colitis without treatment group.

Results

After administering sesame oil, the MPO level was reduced significantly compared to colitis without the treatment group (P=0.025). The mastic oil (400 mg/kg orally) administration was effective in reducing colitis severity through the reduction in the total colitis index (p=0.046) after 7 days. The Intra-rectal administration of mastic decreased TNF-α significantly, similar to prednisolone and control groups compared to the colitis without treatment group (p=0.024). The IL-6 did not change in the mastic and sesame oil groups.

Conclusion

According to our results, mastic and sesame oil have anti-inflammatory properties, suggesting that they could be used as natural sources to lessen the ulcerative colitis inflammation.

Cyclodextrin as a magic switch in covalent and non-covalent anticancer drug release systems

Cancer has been a threat to human health, so its treatment is a huge challenge to the present medical field. One of commonly used methods is the controlled release of anticancer drug to reduce the dose for patients, increase the stability of drug treatment and minimize side effects. Cyclodextrin is a kind of cyclic oligosaccharide produced by amylase hydrolysis. Because cyclodextrin contains a cavity structure and active hydroxyl groups, it has a positive effect on the study of the controlled release of anticancer drugs. This article reviews the controlled release of current anticancer drugs based on cyclodextrins as a "flexible switch", and discusses the classification of different types of release systems, highlighting their role in cancer treatment. Moreover, the opportunities and challenges of cyclodextrin as a magic switch in the controlled release of anticancer drugs are discussed.

Nanogels of a Succinylated Glycol Chitosan-Succinyl Prednisolone Conjugate: Release Behavior, Gastrointestinal Distribution, and Systemic Absorption

Recently, the potential of nanoparticles (NPs) in ulcerative colitis (UC) therapy has been increasingly demonstrated. Namely, anionic NPs have been found to be accumulated efficiently to the UC damaged area due to epithelial enhanced permeability and retention (eEPR) effect. Previously, a novel anionic nanogel system (NG(S)) was prepared, and evaluated for the efficacy and toxicity. In the present study, release behaviors and biodistribution were investigated in detail to elucidate the functional mechanisms. Rats with 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced ulcerative colitis (UC) were used as biomodels. In vitro release was examined with or without the contents of the cecum or distal colon. Gastrointestinal distribution and plasma concentrations were investigated after the intragastric administration of 10 mg prednisolone (PD) eq./kg. At pH 1.2 and 6.8, release behaviors were slow, but controlled. Overall release was not markedly different irrespective of coexistence of intestinal contents. In in vivo studies, a large amount of PD was distributed in the lower parts of the gastrointestinal tract 6 and 12 h after administration with NG(S). PD accumulated well in the colonic parts, and prolonged release was noted. The systemic absorption of PD with NG(S) was hardly found. NG(S) concentrated the drug in the colon and showed controlled release. These behaviors were considered to lead to the previously reported good results, promotion of effectiveness and suppression of toxic side effects.

Conjugation of Amisulpride, an Anti-Psychotic Agent, with 5-Aminosalicylic Acid via an Azo Bond Yields an Orally Active Mutual Prodrug against Rat Colitis

Amisulpride (ASP), an anti-psychotic agent, is a pharmacologically equivalent to sulpiride (SP). Because SP demonstrates anti-ulcer and anti-colitic activities, ASP with an aniline moiety was azo-coupled to salicylic acid to generate 5-(aminoethanoylsulfamoyl)-N-[(1-ethylpyrrolidin-2-yl)methyl]-2-methoxybenzamide (ASP-azo-ASA), with the expectation that it would act as a colon-specific mutual prodrug against colitis. Following a 24 h incubation, approximately 80% of ASP-azo-ASA was cleaved to form ASP and 5-aminosalicylic acid (5-ASA) in the cecal contents, whereas it remained stable in the small intestinal contents. Oral gavage of ASP-azo-ASA (oral ASP-azo-ASA) delivered 5-ASA to the cecum to levels comparable with those observed for sulfasalazine (SSZ; clinical colon-specific prodrug of 5-ASA) and without detectable concentrations of ASP in the blood, indicating efficient colonic delivery. Oral ASP-azo-ASA ameliorated 2, 4-dinitrobenzenesulfonic acid hydrate (DNBS)-induced colitis in rats more effectively than oral SSZ. Additionally, oral ASP-azo-ASA lowered the levels of inflammatory mediators in the inflamed distal colon more effectively than oral SSZ. Combined treatment with 5-ASA and ASP via the rectal route more effectively reversed colonic damage and inflammation than treatment with 5-ASA or ASP alone, confirming the mutual anti-colitic actions of 5-ASA and ASP. In conclusion, ASP-azo-ASA is an orally active mutual prodrug against rat colitis with limited systemic absorption of ASP.

Nanogels of Succinylated Glycol Chitosan-Succinyl Prednisolone Conjugate: Preparation, In Vitro Characteristics and Therapeutic Potential

A novel anionic nanogel system was prepared using succinylated glycol chitosan-succinyl prednisolone conjugate (S-GCh-SP). The nanogel, named NG(S), was evaluated in vitro and in vivo. S-GCh-SP formed a nanogel via the aggregation of hydrophobic prednisolone (PD) moieties and the introduced succinyl groups contributed to the negative surface charge of the nanogel. The resultant NG(S) had a PD content of 13.7% (w/w), was ca. 400 nm in size and had a ζ-potential of −28 mV. NG(S) released PD very slowly at gastric pH and faster but gradually at small intestinal pH. Although NG(S) was easily taken up by the macrophage-like cell line Raw 264.7, it did not decrease cell viability, suggesting that the toxicity of the nanogel was very low. The in vivo evaluation was performed using rats with trinitrobenzene sulfonic acid (TNBS)-induced colitis. NG(S) and PD alone were not very effective at 5 mg PD eq./kg. However, NG(S) at 10 mg PD eq./kg markedly suppressed colonic damage, whereas PD alone did not. Furthermore, thymus atrophy was less with NG(S) than with PD alone. These results demonstrated that NG(S) is very safe, promotes drug effectiveness and has low toxicity. NG(S) has potential as a drug delivery system for the treatment of ulcerative colitis.

A colon-specific prodrug of metoclopramide ameliorates colitis in an experimental rat model

Background

We examined whether metoclopramide (MCP), a modulator of dopamine and serotonin receptors, alleviated colitis and had synergistic effects when coadministered with 5-aminosalicylic acid (5-ASA) in an experimental model of colitis.

Methods

MCP azo-linked to 5-ASA (5-[4-chloro-2-{2-(diethylamino)ethylcarbamoyl}– 1-methoxyphenyl]azosalicylic acid, MCP-azo-ASA) was synthesized, where 5-ASA was used as a colon-targeting carrier and an anti-colitic agent, and the ability of MCP-azo-ASA to target the colon in vitro and in vivo was evaluated.

Results

Our results indicate that MCP-azo-ASA was cleaved to MCP and 5-ASA in the cecal contents, but not in the contents of the small intestine. Oral gavage with equimolar concentrations of MCP-azo-ASA and sulfasalazine (SSZ, a colon-specific prodrug of 5-ASA widely used clinically) demonstrated that the two prodrugs delivered comparable amounts of 5-ASA to the cecum. MCP was barely detected in the blood after oral gavage with MCP-azo-ASA. In a rat model of 2,4-dinitrobenzene sulfonic acid hydrate (DNBS)-induced colitis, MCP-azo-ASA alleviated colonic damage in a dose-dependent manner. Moreover, MCP-azo-ASA reduced the concentrations of inflammatory mediators in the inflamed colon. At low equimolar doses, MCP-azo-ASA, but not SSZ, resulted in significant anti-colitic effects, which indicates that MCP has anti-colitic activity. MCP-azo-ASA had anti-colitic effects equal to those of SSZ at high equimolar doses.

Conclusion

Thus, our results indicate that MCP-azo-ASA is a colon-specific prodrug of MCP. Targeted delivery of MCP to the colon ameliorated DNBS-induced colitis in rats, and we did not observe any synergistic effects of MCP after co-delivery with 5-ASA.

Prodrugs for colon-restricted delivery: Design, synthesis, and in vivo evaluation of colony stimulating factor 1 receptor (CSF1R) inhibitors

The ability to restrict low molecular weight compounds to the gastrointestinal (GI) tract may enable an enhanced therapeutic index for molecular targets known to be associated with systemic toxicity. Using a triazolopyrazine CSF1R inhibitor scaffold, a broad range of prodrugs were synthesized and evaluated for enhanced delivery to the colon in mice. Subsequently, the preferred cyclodextrin prodrug moiety was appended to a number of CSF1R inhibitory active parent molecules, enabling GI-restricted delivery. Evaluation of a cyclodextrin prodrug in a dextran sodium sulfate (DSS)-induced mouse colitis model resulted in enhanced GI tissue levels of active parent. At a dose where no significant depletion of systemic monocytes were detected, the degree of pharmacodynamic effect-measured as reduction in macrophages in the colon-was inferior to that observed with a systemically available positive control. This suggests that a suitable therapeutic index cannot be achieved with CSF1R inhibition by using GI-restricted delivery in mice. However, these efforts provide a comprehensive frame-work in which to pursue additional gut-restricted delivery strategies for future GI targets.

Colon-targeting mutual prodrugs of 5-aminosalicylic acid and butyrate for the treatment of ulcerative colitis

The aim of this study was to design and synthesize four colon-targeting mutual prodrugs of 5-aminosalicylic acid (5-ASA) and butyrate, and evaluate their therapeutic effects on ulcerative colitis.

A Comparison of Aerosolization and Homogenization Techniques for Production of Alginate Microparticles for Delivery of Corticosteroids to the Colon

Alginate microparticles incorporating hydrocortisone hemisuccinate were produced by aerosolization and homogenization methods to investigate their potential for colonic drug delivery. Microparticle stabilization was achieved by CaCl₂ crosslinking solution (0.5 M and 1 M), and drug loading was accomplished by diffusion into blank microparticles or by direct encapsulation. Homogenization method produced smaller microparticles (45-50 μm), compared to aerosolization (65-90 μm). High drug loadings (40% wt/wt) were obtained for diffusion-loaded aerosolized microparticles. Aerosolized microparticles suppressed drug release in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) prior to drug release in simulated colonic fluid (SCF) to a higher extent than homogenized microparticles. Microparticles prepared using aerosolization or homogenization (1 M CaCl₂, diffusion loaded) released 5% and 17% of drug content after 2 h in SGF and 4 h in SIF, respectively, and 75% after 12 h in SCF. Thus, aerosolization and homogenization techniques show potential for producing alginate microparticles for colonic drug delivery in the treatment of inflammatory bowel disease.

Mucoadhesive microparticulates based on polysaccharide for target dual drug delivery of 5-aminosalicylic acid and curcumin to inflamed colon

In this work, thiolated chitosan/alginate composite microparticulates (CMPs) coated by Eudragit S-100 were developed for colon-specific delivery of 5-aminosalicylic acid (5-ASA) and curcumin (CUR), and the use of it as a multi drug delivery system for the treatment of colitis. The physicochemical properties of the CMPs were evaluated. In vitro release was performed in gradually pH-changing medium simulating the conditions of different parts of GIT, and the results showed that the Eudragit S-100 coating has a pH-sensitive release property, which can avoid drug being released at a pH lower than 7. An everted sac method was used to evaluate the mucoadhesion of CMPs. Ex vivo mucoadhesive tests showed CMPs have excellent mucosa adhesion for the colonic mucosa of rats. In vivo treatment effect of enteric microparticulates systems was evaluated in colitis rats. The results showed superior therapeutic efficiency of this drug delivery system for the colitis rats induced by TNBS. Therefore, the enteric microparticulates systems combined the properties of pH dependent delivery, mucoadhesive, and control release, and could be an available tool for the treatment of human inflammatory bowel disease.

5-Aminosalicylic Acid Azo-Linked to Procainamide Acts as an Anticolitic Mutual Prodrug via Additive Inhibition of Nuclear Factor kappaB

To improve the anticolitic efficacy of 5-aminosalicylic acid (5-ASA), a colon-specific mutual prodrug of 5-ASA was designed. 5-ASA was coupled to procainamide (PA), a local anesthetic, via an azo bond to prepare 5-(4-{[2-(diethylamino)ethyl]carbamoyl}phenylazo)salicylic acid (5-ASA-azo-PA). 5-ASA-azo-PA was cleaved to 5-ASA and PA up to about 76% at 10 h in the cecal contents while remaining stable in the small intestinal contents. Oral gavage of 5-ASA-azo-PA and sulfasalazine, a colon-specific prodrug currently used in clinic, to rats showed similar efficiency in delivery of 5-ASA to the large intestine, and PA was not detectable in the blood after 5-ASA-azo-PA administration. Oral gavage of 5-ASA-azo-PA alleviated 2,4,6-trinitrobenzenesulfonic acid-induced rat colitis. Moreover, combined intracolonic treatment with 5-ASA and PA elicited an additive ameliorative effect. Furthermore, combined treatment with 5-ASA and PA additively inhibited nuclear factor-kappaB (NFκB) activity in human colon carcinoma cells and inflamed colonic tissues. Finally, 5-ASA-azo-PA administered orally was able to reduce inflammatory mediators, NFκB target gene products, in the inflamed colon. 5-ASA-azo-PA may be a colon-specific mutual prodrug acting against colitis, and the mutual anticolitic effects occurred at least partly through the cooperative inhibition of NFκB activity.

Calcium pectinate gel beads obtained from callus cultures pectins as promising systems for colon-targeted drug delivery

Low methyl-esterified pectins obtained from the cell walls of the campion (SV, SV>300), tansy (TV, TV>300) and duckweed (LM, LM>300) callus cultures and apple pectin (AP, Classic AU 701) were used as the carriers for colon delivery of prednisolone. The pectins with molecular weight more than 300kDa (SV>300, TV>300, LM>300) formed gels which exhibited the higher gel strength. The higher gel strength of these gels appeared to be related to the higher Mw and the lower degree of methylesterification (DE) of these pectins. Release aspects of prednisolone in the simulated gastric (pH 1.25), intestinal (pH 7.0) and colonic (pH 7.0+pectinase) media were investigated. The LM-5%, AP-3% and AP-5% beads destroyed in simulated intestinal medium probably due to the higher DE of the LM and AP pectins. The SV>300-3% and TV>300-3% prednisolone loaded bead systems showed a high stability at pH 1.25 and pH 7.0. Prednisolone release occurred in a larger extent in colonic medium due to the enzymatic erosion of the beads. The SV>300-3% and TV>300-3% particles showed a more controlled release that appeared to be related to the lower DE, rhamnogalacturonan content, rhamnogalacturonan I branching and the higher linearity and Mw of the TV>300 and SV>300 pectins, as well as to the higher gel strength. This in vitro study suggests that calcium pectinate gel beads obtained from callus cultures pectins can be proposed as potential systems for colon-targeted drug delivery.

Comparison of Simple Eudragit Microparticles Loaded with Prednisolone and Eudragit-Coated Chitosan-Succinyl-Prednisolone Conjugate Microparticles: Part II. In Vivo Evaluation of Efficacy, Toxicity, and Biodisposition Characteristics

We previously prepared and evaluated simple Eudragit S100 microparticles loaded with prednisolone (ES-MP) and Eudragit S100-coated chitosan-succinyl-prednisolone conjugate microparticles (Ch-MP/ES) in vitro. In this work, the effectiveness, toxic side effects (5 mg prednisolone (PD) eq/kg × 3 d, 10 mg PD eq/kg × 3 d), and pharmacokinetic characteristics (5 mg PD eq/kg) were examined using rats with colitis induced through 2,4,6-trinitrobenzenesulfonic acid. ES-MP did not change the efficacy or toxic side effects of PD, and this was attributed to incomplete delivery to the target site and prolonged systemic drug absorption by ES-MP. On the other hand, Ch-MP/ES promoted the efficacy of PD and ameliorated its toxic side effects due to better delivery to the target site, very slow drug release and the strong suppression of drug absorption. Only Ch-MP/ES, which markedly changed drug release characteristics, improved the in vivo features of PD.

Colon-targeted delivery of piceatannol enhances anti-colitic effects of the natural product: potential molecular mechanisms for therapeutic enhancement

Piceatannol (PCT), an anti-colitic natural product, undergoes extensive Phase II hepatic metabolism, resulting in very low bioavailability. We investigated whether colon-targeted delivery of PCT could enhance anti-colitic effects and how therapeutic enhancement occurred at the molecular level. Molecular effects of PCT were examined in human colon carcinoma cells and inflamed colons. The anti-colitic effects of PCT in a colon-targeted capsule (colon-targeted PCT) were compared with PCT in a gelatin capsule (conventional PCT) in a trinitrobenzene sulfonic acid-induced rat colitis model. Colon-targeted PCT elicited greatly enhanced recovery of the colonic inflammation. In HCT116 cells, PCT inhibited nuclear factor kappaB while activating anti-colitic transcription factors, nuclear factor-erythroid 2 (NF-E2) p45-related factor 2, and hypoxia-inducible factor-1. Colon-targeted PCT, but not conventional PCT, modulated production of the target gene products of the transcription factors in the inflamed colonic tissues. Rectal administration of PCT, which simulates the therapeutic action of colon-targeted PCT, also ameliorated rat colitis and reproduced the molecular effects in the inflamed colonic tissues. Colon-targeted delivery increased therapeutic efficacy of PCT against colitis, likely resulting from multitargeted effects exerted by colon-targeted PCT. The drug delivery technique may be useful for therapeutic optimization of anti-colitic lead compounds including natural products.

Lipophilic modification enhances anti-colitic properties of rosmarinic acid by potentiating its HIF-prolyl hydroxylases inhibitory activity

Inhibition of hypoxia inducible factor-prolyl hydroxylase-2 (HPH), leading to activation of hypoxia inducible factor (HIF)-1 is a potential therapeutic strategy for the treatment of colitis. Rosmarinic acid (RA), an ester of caffeic acid and 3,4-dihydroxyphenyllactic acid is a naturally occurring polyphenolic compound with two catechols, a or inhibition of HPH. To improve accessibility of highly hydrophilic RA to HPH, an intracellular target, RA was chemically modified to decrease hydrophilicity. Of the less-hydrophilic derivatives, rosmarinic acid methyl ester (RAME) most potently inhibited HPH. Accordingly, RAME prevented hydroxylation of HIF-1α and consequently stabilized HIF-1α protein in cells. RAME inhibition of HPH and induction of HIF-1α were diminished by elevated doses of the required factors of HPH, 2-ketoglutarate and ascorbate. RAME induction of HIF-1α led to activation of an ulcer healing pathway, HIF-1-vascular endothelial growth factor (VEGF), in human colon carcinoma cells. RAME administered rectally ameliorated TNBS-induced rat colitis and substantially decreased the levels of pro-inflammatory mediators in the inflamed colonic tissue. In parallel with the cellular effects of RAME, RAME up-regulated HIF-1α and VEGF in the inflamed colonic tissue. Thus, lipophilic modification of RA improves its ability to inhibit HPH, leading to activation of the HIF-1-VEGF pathway. RAME, a lipophilic RA derivative, may exert anti-colitic effects via activation of the ulcer healing pathway.

Drug delivery strategies in the therapy of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a frequently occurring disease in young people, which is characterized by a chronic inflammation of the gastrointestinal tract. The therapy of IBD is dominated by the administration of anti-inflammatory and immunosuppressive drugs, which suppress the intestinal inflammatory burden and improve the disease-related symptoms. Established treatment strategies are characterized by a limited therapeutical efficacy and the occurrence of adverse drug reactions. Thus, the development of novel disease-targeted drug delivery strategies is intended for a more effective therapy and demonstrates the potential to address unmet medical needs. This review gives an overview about the established as well as future-oriented drug targeting strategies, including intestine targeting by conventional drug delivery systems (DDS), disease targeted drug delivery by synthetic DDS and disease targeted drug delivery by biological DDS. Furthermore, this review analyses the targeting mechanisms of the respective DDS and discusses the possible field of utilization in IBD.

Caffeic acid phenethyl ester activation of Nrf2 pathway is enhanced under oxidative state: structural analysis and potential as a pathologically targeted therapeutic agent in treatment of colonic inflammation

Caffeic acid phenethyl ester (CAPE) is a polyphenolic natural product that possesses numerous biological activities including anti-inflammatory effects. CAPE-mediated nuclear factor-erythroid 2 p45 (NF-E2)-related factor 2 (Nrf2) activation is likely responsible for some of its biological effects. CAPE was chemically modified to yield CAPE analogues that were subjected to experiments examining cellular Nrf2 activity. CAPE and the CAPE analogue with a catechol moiety, but not the other analogues, activated the Nrf2 pathway. In addition, only biotin-labeled CAPE analogues with the catechol moiety precipitated Kelch-like ECH associated protein 1 (Keap1) when incubated with cell lysates and streptavidin agarose beads. Sodium hypochlorite (NaOCl) oxidation of the catechol moiety in CAPE produced an oxidized, electrophilic form of CAPE (Oxi-CAPE) and greatly enhanced the ability of CAPE to activate Nrf2 and to bind to Keap1. Rectal administration of CAPE ameliorated 2,4,6-trinitrobenzene sulfonic acid-induced rat colitis and activated the Nrf2 pathway in the inflamed colon, and incubation of CAPE in the lumen of the inflamed distal colon generated Oxi-CAPE. However, these biological effects and chemical change of CAPE were not observed in the normal colon. Our data suggest that CAPE requires the catechol moiety for the oxidation-enhanced activation of the Nrf2 pathway and has potential as a pathologically targeted Nrf2-activating agent that is exclusively activated in pathological states with oxidative stress such as colonic inflammation.

Use of propolis hydroalcoholic extract to treat colitis experimentally induced in rats by 2,4,6-trinitrobenzenesulfonic Acid

This study focused on the therapeutic effect of a propolis SLNC 106 (PI) extract on experimental colitis. Wistar adult rats received 0.8 mL rectal dose of one of the following solutions: saline (group S), 20 mg TNBS in 50% ethanol (group TNBS), 20 mg TNBS in 50% ethanol and propolis extract in saline (group TNBS-P), propolis extract in saline (group SP), and 20 mg TNBS in 50% ethanol and 50 mg/kg mesalazine (group TNBS-M). The animals were euthanized 7 or 14 days after the colitis induction. Samples of the distal colon were harvested for the analysis of myeloperoxidase (MPO) enzyme activity and for morphometric analysis in paraffin-embedded histological sections with hematoxylin-eosin or histochemical staining. The animals treated with TNBS exhibited the typical clinical signs of colitis. Increased MPO activity confirmed the presence of inflammation. TNBS induced the development of megacolon, ulceration, transmural inflammatory infiltrate, and thickened bowel walls. Treatment with propolis moderately reduced the inflammatory response, decreased the number of cysts and abscesses, inhibited epithelial proliferation, and increased the number of goblet cells. The anti-inflammatory activity of the propolis SLNC 106 extract was confirmed by the reductions in both the inflammatory infiltrate and the number of cysts and abscesses in the colon mucosa.

Glycyrrhizin enhances therapeutic activity of a colon-specific methylprednisolone prodrug against experimental colitis

BACKGROUND

Co-administration of a reduction inhibitor and a colon-specific prodrug of a glucocorticoid susceptible to colonic reductive metabolism is suggested as a strategy to circumvent the therapeutic loss of the glucocorticoid delivered to and acting locally at the large intestine.

AIMS

We examined whether the strategy was feasible as a pharmacotherapy for treatment of inflammatory bowel disease.

METHODS

Glycyrrhizin (GCZ), a reduction inhibitor, was tested for its inhibition of the colonic metabolism of methylprednisolone (MP). Therapeutic activity against TNBS-induced rat colitis and adrenal suppression were compared after oral administration of methylprednisolone 21-sulfate sodium (MPS), a colon-specific prodrug of MP, or MPS/GCZ to colitic rats.

RESULTS

Upon incubation of MP with the cecal contents, MP disappeared, and this was delayed by addition of GCZ. In addition, more MP produced from MPS in the cecal contents accumulated in the presence of GCZ. Consistent with these results, upon oral administration of MPS/GCZ, MPS or MP, MP was detected at a greater level in the large intestine for MPS/GCZ. MPS/GCZ ameliorated TNBS-induced colitis of rats, and this therapeutic effect was superior to that of MPS and MP. Moreover, MPS/GCZ decreased the plasma levels of corticosterone and ACTH to a greater extent than MPS, but less than MP.

CONCLUSIONS

Co-administration of GCZ, a reduction inhibitor, may be a plausible strategy to reduce the therapeutic loss of MP produced from MPS in the large intestine, thus improving the therapeutic property of the prodrug against inflammatory bowel disease.

The effect of plasticizers on the erosion and mechanical properties of polymeric films

Cellulose acetate phthalate and Pluronic F-127 combined together (70:30 wt:wt) create a rigid, surface-eroding association polymer. To impart flexibility into the polymer system and allow for a drug delivery film that can contour to varying wound shapes, plasticizers were added. Triethyl citrate or tributyl citrate was combined with cellulose acetate phthalate and Pluronic F-127 at 0, 10, or 20 wt%. Mechanical analysis was performed on the films as they were prepared and following a 2-h incubation in phosphate-buffered saline. Tensile tests showed that higher plasticizer content increased the % elongation but decreased the elastic modulus and ultimate tensile strength. The effect triethyl citrate had on the % elongation was twice as much than that of tributyl citrate. After incubation, % elongation, elastic modulus, and ultimate tensile strength all increased because plasticizer leached out of the films. Microcomputed tomography and scanning electron microscopy were performed on the samples both before and after incubation to determine how erosion and leaching of plasticizer affected the interior and exterior structure of the films. Porosity increased as plasticizer content increased; however, plasticizer content did not have a significant effect on the rate of erosion. The mechanical properties of cellulose acetate phthalate-Pluronic films can be adjusted by the type and amount of plasticizer added to the system and therefore can be tailored for different drug delivery applications.

Targeted drug delivery to renal proximal tubule epithelial cells mediated by 2-glucosamine

In order to develop a novel kidney-targeted drug delivery system, we synthesized prednisolone carbamate-glucosamine conjugate (PCG) using 2-glucosamine as a ligand, and investigated its potential targeting efficacy. In vitro studies demonstrated that PCG could remarkably improve the uptake of drug by kidney cells. And the specific uptake of PCG could be largely reduced by the inhibitors of megalin receptor. More importantly, PCG showed an excellent kidney targeting property in vivo, and the concentration of the conjugate in the kidney was 8.1-fold higher than that of prednisolone group at 60 min after intravenous injection. Besides, PCG could significantly reverse the disease progression in renal ischemia-reperfusion (I/R) injury animal models. Furthermore, PCG presented no adverse effect on bone density while prednisolone resulted in severe osteoporosis. Thus, it indicated that 2-glucosamine could be a potential ligand for kidney-targeted delivery of prednisolone.

Biological activity of some derivatives of β-cyclodextrin

New compounds of β-cyclodextrin containing covalently bound (conjugated) residues of acetylsalicylic and 1-(4-isobutylphenyl)-propionic acids were synthesized in the reaction of chlorides of the corresponding acids with β-cyclodextrin. We studied antiplatelet and antiphlogistic properties of these substances. It was shown that new compounds are comparable and in some cases are superior to the reference drugs acetylsalicylic acid and ibuprofen by anti-inflammatory and antiaggregant activities.

Development of a gastroretentive pulsatile drug delivery platform

Objectives

To develop a novel gastroretentive pulsatile drug delivery platform by combining the advantages of floating dosage forms for the stomach and pulsatile drug delivery systems.

Methods

A gastric fluid impermeable capsule body was used as a vessel to contain one or more drug layer(s) as well as one or more lag-time controlling layer(s). A controlled amount of air was sealed in the innermost portion of the capsule body to reduce the overall density of the drug delivery platform, enabling gastric floatation. An optimal mass fill inside the gastric fluid impermeable capsule body enabled buoyancy in a vertical orientation to provide a constant surface area for controlled erosion of the lag-time controlling layer. The lag-time controlling layer consisted of a swellable polymer, which rapidly formed a gel to seal the mouth of capsule body and act as a barrier to gastric fluid ingress.

Key findings

By varying the composition of the lag-time controlling layer, it was possible to selectively program the onset of the pulsatile delivery of a drug.

Conclusions

This new delivery platform offers a new method of delivery for a variety of suitable drugs targeted in chronopharmaceutical therapy. This strategy could ultimately improve drug efficacy and patient compliance, and reduce harmful side effects by scaling back doses of drug administered.