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Colonic drug delivery offers numerous pharmaceutical opportunities, including direct access to local therapeutic targets and drug bioavailability benefits arising from the colonic epithelium's reduced abundance of cytochrome P450 enzymes and particular efflux transporters. Current workflows for developing colonic drug delivery systems involve time-consuming, low throughput in vitro and in vivo screening methods, which hinder the identification of suitable enabling materials. Polysaccharides are useful materials for colonic targeting, as they can be utilised as dosage form coatings that are selectively digested by the colonic microbiota. However, polysaccharides are a heterogeneous family of molecules with varying suitability for this purpose. To address the need for high-throughput material selection tools for colonic drug delivery, we leveraged machine learning (ML) and publicly accessible experimental data to predict the release of the drug 5-aminosalicylic acid from polysaccharide-based coatings in simulated human, rat, and dog colonic environments. For the first time, Raman spectra alone were used to characterise polysaccharides for input as ML features. Models were validated on 8 unseen drug release profiles from new polysaccharide coatings, demonstrating the generalisability and reliability of the method. Further, model analysis facilitated an understanding of the chemical features that influence a polysaccharide's suitability for colonic drug delivery. This work represents a major step in employing spectral data for forecasting drug release from pharmaceutical formulations and marks a significant advancement in the field of colonic drug delivery. It offers a powerful tool for the efficient, sustainable, and successful development and pre-ranking of colon-targeted formulation coatings, paving the way for future more effective and targeted drug delivery strategies., Competing Interests: Declaration of competing interest This work was funded by University College London Research Excellence Scholarship and the University College London Centre for Digital Innovation Scholarship (Youssef Abdalla)., (Copyright © 2024. Published by Elsevier B.V.)

Ulcerative colitis (UC) is a challenging inflammatory gastrointestinal disorder, whose therapies encounter limitations in overcoming insufficient colonic retention and rapid systemic clearance. In this study, we report an innovative polymeric prodrug nanoformulation for targeted UC treatment through sustained 5-aminosalicylic acid (5-ASA) delivery. Amphiphilic polymer-based 13.5 nm micelles were engineered to incorporate azo-linked 5-ASA prodrug motifs, enabling cleavage via colonic azoreductases. In vitro, micelles exhibited excellent stability under gastric/intestinal conditions while demonstrating controlled 5-ASA release over 24 h in colonic fluids. Orally administered micelles revealed prolonged 24-h retention and a high accumulation within inflamed murine colonic tissue. At an approximately 60% dose reduction from those most advanced recent studies, the platform halted DSS colitis progression and outperformed standard 5-ASA therapy through a 77-97% suppression of inflammatory markers. Histological analysis confirmed intact colon morphology and restored barrier protein expression. This integrated prodrug nanoformulation addresses limitations in colon-targeted UC therapy through localized bioactivation and tailored pharmacokinetics, suggesting the potential of nanotechnology-guided precision delivery to transform disease management., (© 2024. The Author(s).)

Chemically modified mandua starch was successfully synthesized and applied to coat mesalamine-loaded matrix tablets. The coating material was an aqueous dispersion of mandua starch modified by sodium trimetaphosphate and sodium tripolyphosphate. To investigate the colon-targeting release competence, chemically modified mandua starch film-coated mesalamine tablets were produced using the wet granulation method followed by dip coating. The effect of the coating on the colon-targeted release of the resultant delivery system was inspected in healthy human volunteers and rabbits using roentgenography. The results show that drug release was controlled when the coating level was 10% w / w . The release percentage in the upper gastric phase (pH 1.2, simulated gastric fluid) was less than 6% and reached up to 59.51% w / w after 14 h in simulated colonic fluid. In addition to in vivo roentgenographic studies in healthy rabbits, human volunteer studies proved the colon targeting efficiency of the formulation. These results clearly demonstrated that chemically modified mandua starch has high effectiveness as a novel aqueous coating material for controlled release or colon targeting.

To improve treatment compliance and reach sustained and controlled drug release in the colon, we developed a hollow mesoporous silica nano-suppository that responded to both pH and redox stimuli. Firstly, we prepared hollow mesoporous silica nanoparticles containing disulfide bonds (HMSN-SS) and loaded them with 5-ASA. Secondly, we modified the surface of HMSN-SS with polydopamine (PDA) and chitosan (CS) and molded the suppository, which we named 5-ASA@HMSN-SS-PDA-CS (5-ASA@HSPC). By administering 5-ASA@HSPC rectally, it acted directly on the affected area. CS helped the nanoparticles adhere to the colon's surface, while PDA dissociates from HMSN-SS due to protonation in the acidic environment of the ulcerative colon. The disulfide bonds were destroyed by the reducing environment of the colon, leading to a stable and slow release of encapsulated 5-ASA from the pores of HMSN. Finally, in vitro release experiments and in vivo pharmacokinetic and pharmacodynamic experiments had demonstrated that 5-ASA@HSPC exhibited a slow and steady action at the colonic site, with an excellent safety profile. This novel approach showed great potential in the treatment of ulcerative colitis., (© 2024. Controlled Release Society.)

Background: There is an obvious correlation between ulcerative colitis and colorectal cancer, and the risk of colorectal cancer in patients with ulcerative colitis is increasing. Therefore, the combination therapy of anti-inflammatory and anti-tumor drugs may show promising to inhibit colon cancer. 5-aminosalicylic acid (5-ASA) with anti-inflammatory function is effective for maintaining remission in patients with ulcerative colitis and may also reduce colorectal cancer risk. Histone deacetylase (HDAC) plays an essential role in the progression of colon cancer. Butyric acid (BA) is a kind of HDAC inhibitor and thus shows tumor suppression to colon cancer. However, the volatile and corrosive nature of BA presents challenges in practical application. In addition, its clinical application is limited due to its non-targeting ability and low bioavailability. We aimed to synthesize a novel dual-prodrug of 5-ASA and BA, referred as BBA, to synergistically inhibit colon cancer. Further, based on the fact that folate receptor (FR) is over-expressed in most solid tumors and it has been identified to be a cancer stem cell surface marker in colon cancer, we took folate as the targeting ligand and used carboxymethyl-β-cyclodextrin (CM-β-CD) to carry BBA and thus prepared a novel inclusion complex of BBA/FA-PEG-CM-β-CD., Results: It was found that BBA/FA-PEG-CM-β-CD showed significant inhibition in cell proliferation against colon cancer cells SW620. It showed a pro-longed in vivo circulation and mainly accumulated in tumor tissue. More importantly, BBA/FA-PEG-CM-β-CD gave great tumor suppression effect against nude mice bearing SW620 xenografts., Conclusions: Therefore, BBA/FA-PEG-CM-β-CD may have clinical potential in colon cancer therapy., (© 2021. The Author(s).)

Inflammatory bowel disease incidence has been constantly rising for the past few decades. Current therapies attempt to mitigate its symptoms since no cure is established. The most commonly prescribed drug for these patients is 5-aminosalicylic acid (5-ASA). Due to the low rate and seriousness of side effects compared to other therapies, 5-ASA is still largely prescribed in many stages of inflammatory bowel disease, including scenarios where evidence suggests low effectiveness. Although commercialized formulations have come a long way in improving pharmacokinetics, it is still necessary to design and develop novel delivery systems capable of increasing effectiveness at different stages of the disease. In particular, micro- and nano-sized particles might be the key to its success in Crohn's disease and in more serious disease stages. This review provides an overview on the clinical significance of 5-ASA formulations, its limitations, challenges, and the most recent micro- and nanoparticle delivery systems being designed for its controlled release. Emergent alternatives for 5-ASA are also discussed, as well as the future prospects for its application in inflammatory bowel disease therapies., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Purpose: This study aims to overcome the challenges of the current oral targeted drug delivery system, such as the complex preparation process, poor biocompatibility, and delayed drug release., Methods: Here, a non-covalent polymer hydrogel was prepared using the mechanochemical method, and the solid phase loading of 5-amino salicylic acid (5-ASA) was realized., Results: The results obtained from the thermodynamics study, particle size analysis, and electron microscopy show that chitosan (CS) and sodium alginate (SA) form a pH-sensitive hydrogel under the mechanochemical force and also maintain good stability in aqueous solution. Fluorescent tracers study showed that the pH-sensitive hydrogel could achieve the targeted drug release in the colon and the retention time was over 12 h. Next, in vivo efficacy studies, change in mice body weight, DAI (disease activity index) score, thymus, and spleen index, and the diseased state of the mice colon revealed that the pH-sensitive hydrogel is an improved drug delivery system over 5-ASA API commercial preparations as observed in the efficacy and toxicological studies., Conclusion: This method uses an innovative preparation technology that without the need of cross-linking agent to produce an efficient colon-targeted drug delivery system for the treatment of ulcerative colitis.

Medication adherence is an important factor in inflammatory bowel disease therapy, which includes regular supplementation of malabsorbed vitamins. Absorption of folic acid is limited due to the damaging of the gastrointestinal tract, which can increase the chances to develop megaloblastic anaemia and colorectal cancer. In this work, 5-aminosalicylates (mesalazine, balsalazide, sulfasalazine and olsalazine) and folic acid were characterized regarding their pharmacokinetic related properties (hydrophobicity, phospholipid and plasma protein binding) using the biomimetic chromatographic approach. Despite the high binding percentage of 5-aminosalicylates for human serum albumin (> 61.44%), results have shown that folic acid binding to human serum albumin protein is far greater (69.40%) compared to α1-acid-glycoprotein (3.45%). Frontal analysis and zonal elution studies were conducted to provide an insight into the binding of folic acid to human serum albumin and potential competition with 5-aminosalicylates. The analytical method for the simultaneous determination of assay in proposed fixed-dose combinations was developed and validated according to ICH Q2 (R1) and FDA method validation guidelines. Separation of all compounds was achieved within 16 min with satisfactory resolution (R s  > 3.67) using the XBridge Phenyl column (150 × 4.6 mm, 3.5 µm). High linearity (r > 0.9997) and precision (RSD < 2.29%) was obtained, whilst all recoveries were within the regulatory defined range by British (100.0 ± 5.0%) and United States Pharmacopeia (100.0 ± 10.0%).

5-aminosalicylate is a fundamental treatment for patients with ulcerative colitis with mild-to-moderate disease; however, evidence for 5-aminosalicylate treatment is unclear in some situations. This review discusses the clinical guidelines and previous studies, and highlights the following points: (1) Although rectal 5-aminosalicylate is effective for proctitis, physicians should endeavor to reduce patient's distress when administering suppositories or enema as the first-line therapy. It should be clarified whether oral 5-aminosalicylate alone with a drug delivery system that allows higher 5-aminosalicylate concentrations to reach the distal colon would be as effective as rectal 5-aminosalicylate therapy. (2) There has been no direct evidence demonstrating the clinical efficacy of switching the 5-aminosalicylate treatment to other 5-aminosalicylate formulations. However, switching to a different 5-aminosalicylate formulation may be indicated if clinical symptoms are not progressive. (3) Several studies have shown that colonic mucosal 5-aminosalicylate concentration correlates with clinical and endoscopic severity; however, it is unclear whether a high 5-aminosalicylate concentration has therapeutic efficacy. (4) The maximum dose of 5-aminosalicylate is necessary for patients with risk factors for recurrence or hospitalization. (5) Optimization of 5-aminosalicylate dosage may be indicated even for quiescent patients with ulcerative colitis if mucosal healing is not obtained, and if patients have multiple risk factors for recurrence. (6) Furthermore, the discontinuation of 5-aminosalicylate is acceptable when biologics are used. Because there are many "old studies" providing evidence for 5-aminosalicylate formulations, more clinical studies are needed to establish new evidence.

This study aimed to simultaneously determine mesalazine (5-ASA) and its major metabolite N-Ac-5-ASA in the plasma and to evaluate the impact of different food patterns on the relative bioavailability and pharmacokinetics of a single oral dose of 5-ASA in healthy subjects. In this single-dose, open-label, 3-period, 3-treatment crossover study, the subjects received a single, oral dose of 500-mg enteric-coated mesalazine tablet together with either a low-fat or a high-fat breakfast or under fasting condition (reference). The pharmacokinetic parameters were determined by noncompartmental methods and analyzed with a linear mixed-effect model. The geometric least squares mean ratio for the area under the plasma concentration-time curve from zero to infinity of N-Ac-5-ASA was 1.05 (90% confidence interval [CI], 0.70-1.58) for high-fat/fasted condition and 1.06 (90%CI, 0.82-1.36) for low-fat/fasted condition. The least squares mean ratio of 5-ASA was 0.86 (90%CI, 0.65-1.14) for high-fat/fasted condition and 0.78 (90%CI, 0.60-1.02) for low-fat/fasted condition. All P values were >.05. The mean maximum plasma concentration and the time to reach the maximum plasma concentration of N-Ac-5-ASA were 2084 ng/mL, 8 hours; 2639 ng/mL, 11 hours, and 2409 ng/mL, 9 hours for fasted, high-fat, and low-fat, respectively. The values of 5-ASA were 1950 ng/mL, 7 hours; 2869 ng/mL, 9 hours; and 2837 ng/mL, 8 hours for fasted, high-fat, and low-fat condition. 5-ASA was well tolerated under all 3 conditions. Food delayed the absorption of 5-ASA, especially a high-fat meal. Therefore, enteric-coated mesalazine tablets should be taken before meals to avoid causing patients slow response and any effect of food on its efficacy., (© 2019, The American College of Clinical Pharmacology.)

Background: Oral 5-aminosalicylic acid (5-ASA, mesalazine) is the first choice therapeutic agent for treating mild-to-moderate ulcerative colitis (UC). Unfortunately a significant group of patients fail to respond. Therapeutic drug monitoring might help to maintain or induce remission by providing a tool for optimization of 5-ASA therapy. However, plasma and urine concentrations of 5-ASA reflect systemic uptake and are not useful to evaluate therapeutic effect., Objectives: To explore if mucosal and faecal 5-ASA values correlate with disease activity and/or therapeutic effects in patients with inflammatory bowel disease, especially UC., Method: We identified studies that analysed 5-ASA in faeces or mucosa of humans using an oral 5-ASA formulation, using PubMed and Embase., Results: In total, 39 studies (n = 939) were included, 27 on faecal 5-ASA, 9 on mucosal concentrations, and 3 on both faecal and mucosal values. We included 33 cross-sectional studies, 3 randomised clinical trials, 2 longitudinal cohorts and 1 randomized cross-over study. Mucosal 5-ASA concentrations in healthy subjects and patients on equivalent doses of 5-ASA were not found to differ remarkably. In the sub-analysis of mucosal 5-ASA concentrations in patients with active or quiescent UC, a higher concentration was seen during remission. Faecal concentrations were associated with 5-ASA doses but not with disease activity. Differences in faecal or mucosal 5-ASA values could not be ascribed to different 5-ASA formulations., Conclusions: An increase of the mucosal 5-ASA concentrations was observed during remission in patients with UC. No clear relationship between the faecal 5-ASA excretion and the therapeutic efficacy was identified., (© 2019 The Author(s) Published by S. Karger AG, Basel.)

The Chinese natural product, berberine, has biological properties that support its potential efficacy as a colon cancer prevention agent. Its longstanding use in China to treat gastrointestinal tract and rheumatologic disorders is generally regarded as safe, supporting initial investigations in an at-risk population, such as individuals with ulcerative colitis. However, the safety of berberine in this population is not established. Individuals living in China with biopsy-proven ulcerative colitis, ≤grade 2 dysplasia, and with a ulcerative colitis disease activity index (UCDAI) score ≤1 on mesalamine, were randomized 3:1 in a double-blind phase I trial to berberine 900 mg/day or placebo for 3 months, with the primary objective of assessing safety. Blood samples and biopsies of the colorectum, from prespecified locations, were collected prior to and following therapy. Secondary endpoints included changes in UCDAI score, and in tissue and plasma markers of inflammation. Of toxicities at least possibly related, one episode of grade 3 elevation in transaminases and one episode of grade 1 nausea were observed among 12 individuals on berberine, and none were observed among 4 on placebo. The mean plasma berberine concentration was 3.5 nmol/L after berberine treatment, significantly higher than 0.5 nmol/L with placebo. Berberine significantly decreased the Geboes grade in colonic tissue, but had a nonsignificant effect on other tissue or blood biomarkers related to cell growth and inflammation. The combination of berberine and mesalamine is well tolerated in Chinese with ulcerative colitis and may enhance mesalamine's anti-inflammatory effects in colonic tissue., (©2019 American Association for Cancer Research.)

5-aminosalicylic acid (5-ASA) is the most widely used drug for the treatment of ulcerative colitis. The benefits of targeted delivery of 5-ASA to the large intestine are well known, resulting in reduced systemic absorption and increased local concentrations at the disease site. In the present study, a 5-ASA colon delivery system based on the time-dependent strategy, exploiting the relatively consistent small intestinal transit time (SITT), was manufactured and evaluated in vitro as well as in vivo. The system was obtained by successive spray-coating of an immediate-release tablet core with low-viscosity HPMC and Eudragit® L. The enteric film was effective in preventing release during the acidic stage of the in vitro test, while the HPMC coating brought about reproducible lag phases prior to release in phosphate buffer medium. A γ-scintigraphy investigation pointed out that, following administration to fasted and fed volunteers, disintegration of the units never occurred prior to colon arrival. In all cases, a lag time preceded the appearance of the drug and its N-acetyl metabolite in the bloodstream, which was found to correlate with the time of disintegration in a linear mode. The plasma levels of the drug and metabolite as well as their cumulative urinary recovery were relatively low with respect to those reported when 5-ASA is delivered to the small bowel., (Copyright © 2019 Elsevier B.V. All rights reserved.)

This study is using the targeted approach and anti-inflammatory action of the probiotic biomass to lessen the side effects of therapeutic agents of ulcerative colitis. The aim of the present study is to prepare mesalamine loaded eudragit S-100 with probiotic microparticles by spray drying method. The in-vitro release of the optimized formulation was 90.55 ± 2.42 in 24 hr, which display controlled drug release of mesalamine at a particular region. Mesalamine loaded eudragit S-100 with probiotic microparticles (F12) presented average particle size of 4.91 µm. The statistical analysis was done by one way ANOVA and then comparison test of Bonferroni was done and p values <.05 were considered as significant. The effects of spray dried microparticles over inflamed Caco-2 cell were also evaluated by determining the concentration of IL-8. From in-vivo study it was seen that pretreatment of mesalamine with probiotic prevents DNBS (Dinitrobenzenesulfonic acid) induced colitis in rats and represents protective action against ulcerative colitis because of its antioxidant and anti-inflammatory actions. The results give the foundation for a combination of targeted approach along with the anti-inflammatory potential of the probiotic which might help to decrease the problems which are seen with the traditional cure and management of ulcerative colitis.

Enteric coatings have shown in vivo dissolution rates that are poorly predicted by traditional in vitro tests, with the in vivo dissolution being considerably slower than in vitro. To provide a more mechanistic understanding of this, the dependence of the release properties of various enteric-coated (EC) products on bulk pH and bicarbonate molarity was investigated. It was found that, at presumably in vivo-relevant values, the bicarbonate molarity is a more significant determinant of the dissolution profile than the bulk pH. The findings also indicate that this steep relationship between the dissolution of enteric coatings and bicarbonate molarity limits those coatings' performance in vivo. This is attributed to the relatively low bicarbonate molarities in human intestinal fluids. Further, the hydration and dehydrations kinetics of carbonic acid and carbon dioxide are not sufficiently rapid to reach equilibrium in the diffusion layer surrounding a dissolving ionizable solid. This results in the effective pKa of bicarbonate in the diffusion layer being lower than that determined potentiometrically at equilibrium in the bulk surrounding fluid. These results demonstrate the importance of thoroughly investigating the intestinal bicarbonate concentrations and using bicarbonate buffers or properly designed surrogates (if possible) when evaluating enteric drug products during product development and quality control., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: 5-aminosalicylic acid (5-ASA) is the first-line therapy for ulcerative colitis (UC). 5-ASA acts locally in the colonic mucosa by numerous proposed mechanisms, and is metabolised by N-acetyltransferase (NAT). Large variations in mucosal 5-ASA concentrations have been reported, but the underlying mechanisms are not understood., Aim: To study the relationship between 5-ASA concentration, 5-ASA formulation, NAT genotype and bacterial microbiome in patients with UC., Methods: Patients with quiescent UC, using monotherapy of Mezavant (n = 18), Asacol (n = 14) or Pentasa (n = 10), 4.0-4.8 g/day were included. 5-ASA was measured in colonic mucosal biopsies and serum by ultra-high performance liquid chromatography. NAT genotypes were determined by Sanger sequencing. Bacterial microbiome was sequenced from faeces and mucosa by 16S rRNA sequencing using Illumina Miseq., Results: Mezavant provided the highest mucosal 5-ASA levels (geometric mean 2.39 ng/mg), followed by Asacol (1.60 ng/mg, 33% lower, P = 0.50) and Pentasa (0.57 ng/mg, 76% lower, P = 0.033). Mucosal 5-ASA concentration was not associated with NAT genotype, but serum 5-ASA concentration and NAT1 genotype was associated (P = 0.044). Mucosal 5-ASA concentration was positively associated with mucosal bacterial diversity (P = 0.0005) and bacterial composition. High mucosal 5-ASA concentration was related to reduced abundance of pathogenic bacteria such as Proteobacteria, and increased abundance of several favourable bacteria such as Faecalibacterium., Conclusions: Mucosal 5-ASA concentration is positively associated with bacterial diversity and a mucosal bacterial composition that are perceived favourable in UC. Mezavant yielded higher mucosal 5-ASA concentrations than Pentasa. 5-ASA may have beneficial effects on the mucosal microbiome, and high concentrations possibly amend dysbiosis in UC., (© 2019 The Authors. Alimentary Pharmacology & Therapeutics Published by John Wiley & Sons Ltd.)

Background: Oral mesalamine (5-amino salicylic acid [5-ASA]) is an anti-inflammatory agent commonly used to treat inflammatory bowel disease such as ulcerative colitis and Crohn's disease. The transfer of mesalamine into human milk has to date been poorly described at the current dosages and newer formulations. This study was designed to determine transfer of mesalamine into human milk as a function of maternal dose and time, and dosage form., Study Design: Ten breastfeeding mothers (age 28-41 years) suffering from inflammatory bowel disease were recruited who provided milk samples at 0, 1, 2, 4, 8, 12, and 24 hours after a single daily dose of oral mesalamine in pH-dependent gastroresistant coated tablets (1.2, 2.4, 3.6, and 4.8 g). Milk samples were analyzed using liquid chromatography/tandem mass spectrometry., Results: A total of 10 women were enrolled for the study. The calibration curve for mesalamine was linear over a concentration range of 0.32-200 ng/mL. Irrespective of maternal dose, mesalamine levels in milk were exceedingly low. However, a wide range of mesalamine levels were observed among all the participants. The relative infant doses were all lower than 0.1% (range 0.003-0.085%)., Conclusion: Regardless of dose and high variability, mesalamine levels in human milk were present in exceedingly low levels. The mothers in this study reported no side effects with their infants. These results suggest that the transfer of mesalamine into milk is very low and poses minimal risks to the breastfed infant.

We have successfully conjugated mesalamine (5-aminosalicylic acid, 5-ASA) with xylan, a biopolymer isolated from pineapple stem waste, to form xylan-5-ASA conjugate. The biopolymer was used to provide colon-targeting properties for 5-ASA, a golden standard anti-inflammatory agent commonly used for ulcerative colitis treatment. A series of data from FTIR spectroscopy, UV-Vis spectrophotometry, and HPLC confirmed the xylan-5-ASA conjugate formation. To ensure successful colon targeting properties, in vitro and in vivo drug release studies after oral administration of xylan-5-ASA conjugate to Wistar rats were performed. Xylan-5-ASA conjugate was able to retain 5-ASA release in the upper gastrointestinal tract fluid simulation but rapidly released 5-ASA in the rat colon fluid simulation. In vivo release profile shows a very low peak plasma concentration, reached at 6 h after xylan-5-ASA conjugate administration. The delayed release and the lower bioavailability of 5-ASA from xylan-5-ASA conjugate administration compared to free 5-ASA administration confirmed the successful local colon delivery of 5-ASA using xylan-5-ASA conjugate. The administration of xylan-5-ASA conjugate also exhibited greater efficacy in recovering 2,4,6-trinitrobenzene sulfonic acid-induced colon ulcer compared to free 5-ASA administration. Taken together, xylan isolated from pineapple stem waste is promising to obtain colon targeting property for 5-ASA.

Background/aims: Thiopurines are key drugs in maintenance therapy for treating inflammatory bowel disease (IBD). Time-dependent 5-aminosalicylates (5-ASA) releasing preparations (time-dependent 5-ASA) increase 6-thioguanine nucleotide (6-TGN), an active metabolite of thiopurines. However, the effects of pH-dependent 5-ASA releasing preparations (pH-dependent 5-ASA) on thiopurine metabolism were not reported., Methods: We conducted a retrospective study of 134 IBD patients who received thiopurine treatment. The 6-methylmercaptopurine (6-MMP)/6-TGN values after taking the same dose of thiopurine preparations for at least 28 days were included., Results: There was a significant decrease in the 6-MMP/6-TGN ratio in time-dependent 5-ASA compared with group without 5-ASA preparations and the pH-dependent 5-ASA group (p = 0.008 and < 0.001 respectively). Spearman's rank correlation coefficient indicated a negative relationship between the daily oral dose of time-dependent 5-ASA and the 6-MMP/6-TGN ratio (r = -0.362, p = 0.003). Multivariate logistic regression analysis was performed in the groups with 6-MMP/6-TGN ratios of 1 or more and less than 1. The use of time-dependent 5-ASA and concomitant allopurinol negatively affected the independent 6-MMP/6-TGN ratio (p = 0.006 and 0.007 respectively)., Conclusion: Our study revealed that time-dependent but not pH-dependent 5-ASA decreases the 6-MMP/6-TGN ratio. We also confirmed that concomitant allopurinol results in a low 6-MMP/6TGN ratio., (© 2019 S. Karger AG, Basel.)

Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) of unknown etiology, probably caused by a combination of genetic and environmental factors. The treatment of patients with active UC depends on the severity, localization and history of IBD medication. According to the classic step-up approach, treatment with 5-aminosalicylic acid compounds is the first step in the treatment of mild to moderately active UC. Corticosteroids, such as prednisolone are used in UC patients with moderate to severe disease activity, but only for remission induction therapy because of side effects associated with long-term use. Thiopurines are the next step in the treatment of active UC but monotherapy during induction therapy in UC patients is not preferred because of their slow onset. Therapeutic drug monitoring (TDM) of the pharmacologically active metabolites of thiopurines, 6-thioguanine nucleotide (6-TGN), has proven to be beneficial. Thiopurine S-methyltransferase (TMPT) plays a role in the metabolic conversion pathway of thiopurines and exhibits genetic polymorphism; however, the clinical benefit and relevance of TPMT genotyping is not well established. In patients with severely active UC refractory to corticosteroids, calcineurin inhibitors such as ciclosporin A (CsA) and tacrolimus are potential therapeutic options. These agents usually have a rather rapid onset of action. Monoclonal antibodies (anti-tumor necrosis factor [TNF] agents, vedolizumab) are the last pharmacotherapeutic option for UC patients before surgery becomes inevitable. Body weight, albumin status and antidrug antibodies contribute to the variability in the pharmacokinetics of anti-TNF agents. Additionally, the use of concomitant immunomodulators (thiopurines/methotrexate) lowers the rate of immunogenicity, and therefore the concomitant use of anti-TNF therapy with an immunomodulator may confer some advantage compared with monotherapy in certain patients. TDM of anti-TNF agents could be beneficial in patients with primary nonresponse and secondary loss of response. The potential benefit of applying TDM during vedolizumab treatment has yet to be determined.

A series of temperature responsive hydrogels consisting of (1,3)-(1,6) β-Glucan and poly (N-isopropyl acrylamide) (PNIPAM) was synthesized by redox polymerization at room temperature. Tetramethylethylenediamine (TEMED) and potassium persulfate (KPS) were used as a redox pair. β-glucan was methacrylated (MA-β-Glucan) and used as a biodegradable and bio-compatible cross-linker to prepare β-glucan-PNIPAM based temperature responsive hydrogels. Swelling behavior of the hydrogels at different temperatures was investigated. The 5-ASA release from the hydrogels was monitored using UV-VIS spectrophotometer at 37 °C. It is notable that, the swelling and release behaviors of the hydrogels significantly change depending on the hydrogel compositions and temperature. Their thermal stability was determined using thermogravimetric analysis (TGA), assuming the extent of intermolecular interaction between PNIPAM and β-glucan is proportional to thermal stability, which increased with the amount of PNIPAM. Volume phase transition temperature (VPTT) of the hydrogels was precisely determined by derivative differential scanning calorimeter (DDSC). They possessed variable VPTT with the compositions. The presence of β-glucan in the PNIPAM network brought VPTT closer to the body temperature (from 32.8 °C to 35.5 °C), indicating that the VPTT could be tuned by the hydrogel compositions. Their in-vivo biocompatibility was tested against WS1 human fibroblast cells in phosphate buffer saline (PBS, pH 7.4). It was demonstrated that, using MA-β-glucan as a cross-linker resulted in more bio-compatible thermo-responsive hydrogels indicating the enhancement of hydrophilic β-Glucan on the swollen hydrogel surface., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Drug release and availability at the site of action are the major factors determining the clinical response for locally-acting gastrointestinal (GI) drug products. The present work focused on the prediction of site and extent of in vivo mesalazine release after oral administration to a variety of subjects using individualized in vitro drug release experiments. First, experiments mimicking GI passages in average adult subjects were performed. Then, results from a study screening fasted in vivo pH and transit profiles in individual subjects were translated into a novel in vitro dissolution model enabling to mimic individual GI pH-profiles and transit times with physiologically relevant dissolution media. A selection of monolithic and multiparticulate mesalazine formulations with pH-dependent and pH-independent drug release was screened with the novel dissolution model. Results of the study indicate that dosage form performance can be significantly different in individual subjects and highlight the importance of addressing individual physiological parameters relevant to intraluminal drug release when the aim is to predict the in vivo performance of locally-acting mesalazine formulations in individual patients. The novel in vitro dissolution approach thus represents a valuable tool for both improving individual oral therapy with locally-acting GI drug products and assessing bioequivalence of these formulations., (Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.)

Background and Aims: Mesalamine is commonly used to treat ulcerative colitis (UC). Although mesalamine acts topically, in vitro data suggest that intracellular transport is required for its beneficial effect. Genetic variants in mucosal transport proteins may affect this uptake, but the clinical relevance of these variants has not been studied. The aim of this study was to determine whether variants in genes involved in cellular transport affect the response to mesalamine in UC., Methods: Subjects with UC from a 6-week clinical trial using multiple doses of mesalamine were genotyped using a genome-wide array that included common exome variants. Analysis focused on cellular transport gene variants with a minor allele frequency >5%. Mesalamine response was defined as improvement in Week 6 Physician's Global Assessment (PGA) and non-response as a lack of improvement in Week 6 PGA. Quality control thresholds included an individual genotyping rate of >90%, SNP genotyping rate of >98%, and exclusion for subjects with cryptic relatedness. All included variants met Hardy-Weinberg equilibrium (p>0.001)., Results: 457 adults with UC were included with 280 responders and 177 non-responders. There were no common variants in transporter genes that were associated with response to mesalamine. The genetic risk score of responders was similar to that of non-responders (p = 0.18). Genome-wide variants demonstrating a trend towards mesalamine response included ST8SIA5 (p = 1x10-5)., Conclusions: Common transporter gene variants did not affect response to mesalamine in adult UC. The response to mesalamine may be due to rare genetic events or environmental factors such as the intestinal microbiome.

Mesalamine (5-ASA) consists of the first-line therapy for the treatment of ulcerative colitis; however, it has low bioavailability, can cause several systemic adverse events, and has low treatment adherence due to the inconvenient dosing scheme. In this work, a new drug delivery system consisting of chondroitin sulfate linked to 5-ASA was synthesized using a carbodiimide as conjugating agent. The system was characterized by spectroscopic techniques (UV, ATR-FTIR, XRD, and NMR 1 H) and thermal analysis (TG/DTG and DSC), suggesting the conjugation between the drug and the polymer. The in vitro release and the corresponding kinetics were also evaluated, revealing that approximately 40% of the drug linked was released at pH9 for up to 50h, following Higuchi's model. The conjugate did not show cytotoxicity for the human monocytic cell line at the doses tested, and an in vivo biodistribution study showed that the conjugate remained in the lower GIT for up to 8h with no uptake in the upper GIT. These data corroborate with the radiation found per segment of GIT and in blood. For this last test the conjugate was radiolabeled with Technetium-99m to allow the scintigraphy evaluation and radiation quantification. In conclusion, the polymeric conjugate was successfully synthesized and demonstrated a mucoadhesiveness on the colon as desired, thus supporting its potential use in the treatment of ulcerative colitis., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Introduction: Bioequivalence testing for locally acting gastrointestinal drugs is a challenging issue for both regulatory authorities and pharmaceutical industries. The international regulatory framework has been characterized by the lack of specific bioequivalence tests that has generated a negative impact on the market competition and drug use in clinical practice. Areas covered: This review article provides an overview of the European Union and United States regulatory frameworks on bioequivalence criteria for locally acting gastrointestinal drugs, also discussing the most prominent scientific issues and advances that has been made in this field. A focus on oral modified release mesalamine formulations will be also provided, with practical examples of the regulatory pathways followed by pharmaceutical companies to determine bioequivalence. Expert commentary: The development of a scientific rationale to demonstrate bioequivalence in this field has been complex and often associated with uncertainties related to scientific and regulatory aspects. Only in recent years, thanks to advanced knowledge in this field, the criteria for bioequivalence assessment are undergoing substantial changes. This new scenario will likely result in a significant impact on pharmaceutical companies, promoting more competition through a clearer regulatory approach, conceived for streamlining the demonstration of therapeutic equivalence for locally acting gastrointestinal drugs.

Background: Absorption windows in particular segments of the small intestine can contribute to the development of orally administered drug formulations and can limit the bioavailability of released compounds., Objective: The aim of this study was to evaluate use of wireless capsule enteroscopy regarding the disintegration kinetic process of tablets in the small intestine and its comparison with the levels of the model drug (5- aminosalicylic acid; 5-ASA), and its majority metabolite (N-acetyl-5-aminosalicylic acid; N-acetyl-5-ASA) in blood plasma., Methods: Tablets were endoscopically introduced into the duodenum and their disintegration was monitored using wireless capsule enteroscopy in anaesthetised pigs. In parallel, blood plasma time profiles of the model drug (5-ASA) released from tablets and its metabolite (N-acetyl-5-ASA) were detected., Results: The disintegration of tablets was evident in the proximal jejunum (until the 90-minute mark) and culminated at the 3rd hour. The maximum plasmatic concentration of 5-ASA was reached at the 3rd hour and in the case of its metabolite (N-acetyl-5-ASA) at the 4th hour., Conclusion: The study demonstrated the advantage of combination of wireless capsule enteroscopy and bioanalytical determination of pharmacokinetic parameters in an animal experiment to localise the disintegration site of solid dosage form and following kinetics of intestinal absorption of the released active agent., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

5-[(4-carboxybutanoyl)amino]-2-hydroxybenzoic acid (C2) is a novel synthetic derivative of 5-aminosalicylic acid (5-ASA), which is currently being evaluated ex vivo as an anti-inflammatory agent and has shown satisfactory results. This study aimed to obtain the pharmacokinetic profiles, tissue distribution and plasma protein binding of C2 in Wistar Rats. Additionally, an HPLC method was developed and validated to quantify C2 in rat plasma. The pharmacokinetic profiles of intragastric, intravenous and intraperitoneal administration routes at singles doses of 100, 50, and 100 mg/kg, respectively, were studied in Wistar rats. The elimination half-life of intravenously administered C2 was approximately 33 min. The maximum plasma level of C2 was reached approximately 24 min after intragastric administration, with a Cmax value of 2.5 g/mL and an AUCtot value of 157 μg min-1/mL; the oral bioavailability was approximately 13%. Following a single intragastric or oral dose (100 mg/kg), C2 was distributed and detected in all examined tissues (including the brain and colon). The results showed that C2 accumulates over time. The plasma protein binding results indicated that the unbound fraction of C2 at concentrations of 1 to 20 μg/mL ranged from 89.8% to 92.5%, meaning that this fraction of C2 is available to cross tissues. Finally, the blood-plasma partitioning (BP ratio) of C2 in rat plasma was 0.71 and 0.6 at concentrations of 5 and 10 μg/mL, respectively, which indicates that C2 is free in the plasmatic phase and not inside blood cells. The results of this study suggest that a fraction of the administered C2 dose is absorbed in the stomach, and the fraction that is not absorbed reaches the small intestine and colon. This distribution constitutes the main advantage of C2 compared with 5-ASA for the treatment of ulcerative colitis (UC) and Crohn's disease (CD).

The aim of the present study was to design a new pH-enzyme double-dependent mesalamine colon-specific delivery system. The drug release behaviors in vitro and pharmacokinetics and biodistribution in vivo were further evaluated. The mean particle diameters of mesalamine-coated microparticles were 312.2 µm. In vitro, a small amount of mesalamine was released in HCl at a pH of 1.2 and PBS medium at a pH of 7.4 for 5 hours, and 71% of the entrapped mesalamine was further released during the subsequent 20 hours of incubation. A greater area under the plasma concentration-time curve (AUC)0-t was obtained for the coated microparticles (1.9-fold) compared to the suspensions group, which indicated that the encapsulated mesalamine had mostly been absorbed in rats over the period of 12 hours. The AUC0-t of the coated microparticles in colon was 2.63-fold higher compared to the suspensions (P<0.05). Hence, mesalamine-coated microparticles are considered to maintain the drug concentration within target ranges for a long period of time.

Objective: To establish a developed HPLC-ESI-MS/MS method for simultaneous determination of mesalazine (5-ASA) and its major metabolite N-Ac-5-ASA in human plasma and to investigate bioequivalence of two enteric-coated mesalazine tablets as well as the effect of high-fat food on the pharmacokinetics of 5-ASA and N-Ac-5-ASA., Methods: In this open-label, randomized, crossover, two-states, four-period study, 20 healthy Chinese volunteers were randomized to receive a single oral dose of trial or reference preparation (2 × 250 mg) under fasting and fed state. Plasma samples were obtained at 0, 1, 2, 3, 4, 4.5, 5, 5.5, 6, 6.5, 7, 8, 10, 12, 24, and 36 hours postdose and were measured by a developed HPLC-ESI-MS/MS method. Safety and tolerability were assessed throughout the study., Results: The HPLC-ESI-MS/MS method required only 7.0 minutes run time and was successfully applied in analyzing ~ 2,000 samples. High-fat-food administration prolonged tmax of 5-ASA and N-Ac-5-ASA (p < 0.05), while AUC was not significantly affected by the meal (p > 0.05). The 90% confidence intervals (CIs) of the fed/fasting and trial/reference ratios of log-transformed Cmax and AUC were within 80-125%. The two one-sided t-tests showed that the trial and reference preparation were bioequivalent (p > 0.05)., Conclusions: This developed HPLC-ESI-MS/MS method is suitable for massive biomedical analysis. Trial and reference preparations are bioequivalent under fasting and fed state. High-fat-food administration delays the absorption of mesalazine while total exposure is not affected. Dietary habits should always be taken into consideration when enteric-coated mesalazine tablets were prescribed to patients.

Background: Limited data are available on mesalamine (5-aminosalicylic acid; 5-ASA) use in pediatric ulcerative colitis (UC)., Aim: To evaluate pharmacokinetic and safety profiles of 5-ASA and metabolite acetyl-5-ASA (Ac-5-ASA) after once-daily, oral administration of multimatrix mesalamine to children and adolescents with UC., Methods: Participants (5-17 years of age; 18-82 kg, stratified by weight) with UC received multi-matrix mesalamine 30, 60, or 100 mg/kg/day once daily (to 4,800 mg/day) for 7 days. Blood samples were collected pre-dose on days 5 and 6. On days 7 and 8, blood and urine samples were collected and safety was evaluated. 5-ASA and Ac-5-ASA plasma and urine concentrations were analyzed by non-compartmental methods and used to develop a population pharmacokinetic model., Results: Fifty-two subjects (21 [30 mg/kg]; 22 [60 mg/kg]; 9 [100 mg/kg]) were randomized. On day 7, systemic exposures of 5-ASA and Ac-5-ASA exhibited a dose-proportional increase between 30 and 60 mg/kg/day cohorts. For 30, 60, and 100 mg/kg/day doses, mean percentages of 5-ASA absorbed were 29.4%, 27.0%, and 22.1%, respectively. Simulated steady-state exposures and variabilities for 5-ASA and Ac-5-ASA (coefficient of variation approximately 50% and 40%-45%, respectively) were similar to those observed previously in adults at comparable doses. Treatment-emergent adverse events were reported by ten subjects. Events were similar among different doses and age groups with no new safety signals identified., Conclusion: Children and adolescents with UC receiving multimatrix mesalamine demonstrated 5-ASA and Ac-5-ASA pharmacokinetic profiles similar to historical adult data. Multimatrix mesalamine was well tolerated across all dose and age groups. ClinicalTrials.gov Identifier: NCT01130844.

Mesoporous silica SBA-15 was synthesized and functionalized with bridged polysilsesquioxane monomers obtained by the reaction of 3-aminopropyltriethoxy silane with glycidyl methacrylate in 2:1 ratio. The synthesized mesoporous silica materials were characterized by elemental analysis, infrared spectroscopy, nuclear magnetic resonance spectroscopy, nitrogen adsorption, X-ray diffraction, thermogravimetry and scanning electron microscopy. The nuclear magnetic resonance in the solid state is in agreement with the sequence of carbon distributed in the attached organic chains, as expected for organically functionalized mesoporous silica. After functionalization with organic bridges the BET surface area was reduced from 1311.80 to 494.2m(2)g(-1) and pore volume was reduced from 1.98 to 0.89cm(3)g(-1), when compared to original precursor silica. Modification of the silica surface with organic bridges resulted in high loading capacity and controlled release of ibuprofen and mesalamine in biological fluids. The Korsmeyer-Peppas model better fits the release data indicating Fickian diffusion and zero order kinetics for synthesized mesoporous silica. The drug release rate from the modified silica was slow in simulated gastric fluid, (pH1.2) where less than 10% of mesalamine and ibuprofen were released in initial 8h, while comparatively high release rates were observed in simulated intestinal (pH6.8) and simulated body fluids (pH7.2). The preferential release of mesalamine at intestinal pH suggests that the modified silica could be a simple, efficient, inexpensive and convenient carrier for colon targeted drugs, such a mesalamine and also as a controlled drug release system., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Olsalazine sodium, salicylate derivative (prodrug) is effectively bioconverted to mesalazine (5-aminosalicylic acid; 5-ASA), which has an anti-inflammatory activity in ulcerative colitis. In this article, a novel highly sensitive and selective method was developed and validated to determine mesalazine in human plasma using a derivatization technique to enhance the signal intensity by using ultra- high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) with an electrospray ionization interface. The sample preparation consisted of a derivatization with propionyl anhydride followed by liquid liquid extraction (LLE) to remove the interference and minimize the matrix effect of human plasma. The multiple reaction monitoring (MRM) mode of the negative ion was performed and the transitions of m/z 208.1→107.0 and m/z 211.1→110.1 were used to measure the derivative of mesalazine and mesalazine-d3. The chromatographic separation was achieved using kinetex XB-C18 (100×4.6mm 2.6μ) analytical column with 0.1% formic acid in water and acetonitrile as mobile phase with a gradient elution. Nominal retention times of mesalazine and IS were 3.08 and 3.07min, respectively. Absolute recovery was found to be between 82-95% for analyte and about 78% for IS. The standard curves was linear (r(2)>0.995) in the concentration range 0.10 to 12.0ng/mL with lower limit of quantification (LLOQ) in human plasma was 0.10ng/mL. The average intra-day/inter-day precision values (%CV) were in the range from 0.6-2.9 % and 1.3-3.8 %, respectively, while the average accuracy value was 103.8-107.2%. This method has been successfully applied to the human pharmacokinetics of olsalazine sodium 250mg capsules following single oral administration., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Aims: Postprandial administration of solid oral dosage forms greatly changes the dissolution environment compared to fasted state administration. The aims of this study were to investigate and forecast the effect of co-administration of a meal on drug release for delayed and/or extended release mesalamine formulations as well as design of in vitro tests to distinguish among formulations in a biorelevant way., Methods: Five different mesalamine formulations (Asacol® 400 mg, Mezavant® 1200 mg, Pentasa® 500 mg and Salofalk® in the 250 mg and 500 mg strengths) were investigated with biorelevant dissolution methods using the USP apparatus III and USP apparatus IV (open loop mode) under both fasted and fed state conditions, as well as with the dissolution methods described in pharmacopeia for delayed and extended release mesalamine products., Results: Using the biorelevant experimental conditions proposed in this study, changes in release in the proximal gut due to meal intake are forecast to be minimal for Asacol®, Mezavant®, Pentasa® and Salofalk® 500 mg, while for Salofalk® 250 mg release was predicted to occur much earlier under fed state conditions. The USP apparatus III generally tended to result in faster dissolution rates and forecast more pronounced food effects for Salofalk® 250 mg than the USP apparatus IV. The biorelevant dissolution gradients were also able to reflect the in vivo behavior of the formulations., Conclusions: In vitro biorelevant models can be useful in the comparison of the release behavior from different delayed and extended release mesalamine formulations as well as forecasting effects of concomitant meal intake on drug release., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The purpose was to propose two-stage single-compartment models for evaluating dissolution characteristics in distal ileum and ascending colon, under conditions simulating the bioavailability and bioequivalence studies in fasted and fed state by using the mini-paddle and the compendial flow-through apparatus (closed-loop mode). Immediate release products of two highly dosed active pharmaceutical ingredients (APIs), sulfasalazine and L-870,810, and one mesalamine colon targeting product were used for evaluating their usefulness. Change of medium composition simulating the conditions in distal ileum (SIFileum ) to a medium simulating the conditions in ascending colon in fasted state and in fed state was achieved by adding an appropriate solution in SIFileum . Data with immediate release products suggest that dissolution in lower intestine is substantially different than in upper intestine and is affected by regional pH differences > type/intensity of fluid convection > differences in concentration of other luminal components. Asacol® (400 mg/tab) was more sensitive to type/intensity of fluid convection. In all the cases, data were in line with available human data. Two-stage single-compartment models may be useful for the evaluation of dissolution in lower intestine. The impact of type/intensity of fluid convection and viscosity of media on luminal performance of other APIs and drug products requires further exploration., (© 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.)

Introduction: Oral formulations of 5-aminosalicylic acid (5-ASA) for treatment of ulcerative colitis have been developed to minimize absorption prior to the drug reaching the colon. In this study, we investigate the release of 5-ASA from available oral mesalamine formulations in physiologically relevant pH conditions., Methods: Release of 5-ASA from 6 mesalamine formulations (APRISO®, Salix Pharmaceuticals, Inc., USA; ASACOL® MR, Procter & Gamble Pharmaceuticals UK Ltd.; ASACOL® HD, Procter & Gamble Pharmaceuticals, USA; MEZAVANT XL®, Shire US Inc.; PENTASA®, Ferring Pharmaceuticals, Ltd., UK; SALOFALK®, Dr. Falk Pharma UK Ltd.) was evaluated using United States Pharmacopeia apparatus I and II at pH values of 1.0 (2 h), 6.0 (1 h), and 6.8 (8 h). Dissolution profiles were determined for each formulation, respectively., Results: Of the tested formulations, only the PENTASA formulation demonstrated release of 5-ASA at pH 1.0 (48%), with 56% cumulative release after exposure to pH 6.0 and 92% 5-ASA release after 6-8 h at pH 6.8. No other mesalamine formulation showed >1% drug release at pH 1.0. The APRISO formulation revealed 36% 5-ASA release at pH 6.0, with 100% release after 3 h at pH 6.8. The SALOFALK formulation revealed 11% 5-ASA release at pH 6.0, with 100% release after 1 h at pH 6.8. No 5-ASA was released by the ASACOL MR, ASACOL HD, and MEZAVANT XL formulations at pH 6.0. At pH 6.8, the ASACOL MR and ASACOL HD formulations exhibited complete release of 5-ASA after 4 and 2 h, respectively, and the MEZAVANT XL formulation demonstrated complete 5-ASA release over 6-7 h., Conclusion: 5-Aminosalicylic acid release profiles were variable among various commercially available formulations., Funding: Shire Development LLC.

The aminosalicylate mesalazine (mesalamine) forms the mainstay of treatment in ulcerative colitis (UC), a disease for which many commercial modified-release products have been developed with the aim of providing targeted gastrointestinal release. The release profiles of five of these commercial formulations were evaluated in bicarbonate buffer using a novel dissolution model that mimics the dynamic conditions of the gastrointestinal tract. Monolithic and multi-particulate mesalazine formulations with pH-dependent and/or independent release mechanisms were evaluated (Asacol(®) 800, Octasa(®), Mezavant(®) XL, Salofalk(®), Pentasa(®)), and each of the products displayed a distinctive dissolution profile. The dissolution results for Mezavant(®) XL (Lialda(®)) (lag time 290 min) demonstrated good correlation with previously reported in vivo disintegration times assessed by gamma-scintigraphy in humans. Octasa(®) showed a similar lag time to Mezavant(®) XL. Drug release from Asacol(®) 800 (Asacol(®) HD) showed a wide standard deviation, reflecting the great variability in vivo. Salofalk(®) displayed both delayed release and extended release characteristics. Pentasa(®) released more than 50% of its drug load in the stomach compartment of the model, which is attributed to the absence of a gastro-resistant coating in this product. The new dissolution method provided a realistic and discriminative in vitro assessment of mesalazine release from different formulations. These results demonstrate that this strategy can be used to predict intestinal release behaviour, and potentially aid the rational design of products developed to target different sites of the gut., (Copyright © 2015. Published by Elsevier B.V.)

A simple, specific and sensitive LC-MS/MS method was developed and validated for the determination of mesalazine in beagle dog plasma. The plasma samples were prepared by protein precipitation, then the separation of the analyte was achieved on a Waters Spherisorb C6 column (150 × 4.6 mm, 5 µm) with a mobile phase consisting of 0.2% formic acid in water-methanol (20:80, v/v). The flow rate was set at 1.0 mL/min with a split ratio of 3:2. Mass spectrometric detection was achieved by a triple-quadrupole mass spectrometer equipped with an electrospray source interface in positive ionization mode. Quantitation was performed using selected reaction monitoring of precursor-product ion transitions at m/z 154 → m/z 108 for mesalazine and m/z 285 → m/z 193 for diazepam (internal standard). The linear calibration curve of mesalazine was obtained over the concentration range 50-30,000 ng/mL. The matrix effect of mesalazine was within ±9.8%. The intra- and inter-day precisions were <7.9% and the accuracy (relative error) was within ±3.5%. The validated method was successfully applied to investigate the pharmacokinetics of mesalazine in healthy beagle dogs after rectal administration of mesalazine suppository., (Copyright © 2014 John Wiley & Sons, Ltd.)

The first proof of concept in vivo for a new type of microbiota-sensitive film coatings allowing for colon targeting is presented. The efficacy of these polysaccharide barriers to optimize drug release for the treatment of inflammation is demonstrated in an experimental colitis model with Wister rats. 5-Aminosalicylic acid (5-ASA) pellets were prepared by extrusion-spheronization and coated with Nutriose:ethylcellulose (EC) 1:4 or peas starch:ethylcellulose 1:2 blends. The pellets were mixed with standard chow, and the daily drug dose was 150mg/kg. For reasons of comparison, also commercially available Pentasa pellets and placebo pellets were studied. At day 3 after the beginning of the treatment, colitis was induced by intrarectal administration of trinitrobenzene sulfonic acid (TNBS). Animals were sacrificed on day 6. Macroscopic and histological evaluations of colitis were performed blindly. In addition, inflammatory markers were evaluated using ELISA and real-time PCR. Rats receiving TNBS and placebo pellets developed a severe colitis in the distal half of the colon. 5-ASA administered in the form of Pentasa pellets reduced macroscopic inflammation by only 5%. In contrast, the colon lesions were much less severe upon treatment with Nutriose:EC- and peas starch:EC-coated pellets: The macroscopic score was reduced by 25 and 24%, respectively. Decreases of 37 and 38% of the histological lesions confirmed the efficacy of these new colon targeting systems. Also, inflammatory markers (MPO, IL-1β mRNA, TNF mRNA) were significantly decreased in rats receiving Nutriose:EC- and peas starch:EC-coated pellets compared to Pentasa pellets. Furthermore, real-time PCR analysis indicated increased activation of the target receptor PPAR-γ and the HMGCS2 gene in rats upon administration of 5-ASA loaded Nutriose:EC- and peas starch:EC pellets compared to the commercial product. Also, HPLC-MS/MS analysis of plasma samples demonstrated that the level of the main metabolite of the drug (N-acetyl-5-ASA) was much lower upon administration of Nutriose:EC or peas starch:EC coated pellets compared to Pentasa pellets, indicating that undesired premature drug release in the upper gastrointestinal tract was more effectively hindered. In addition to the rat study, in vivo imaging of transgenic mice expressing the luciferase gene evidenced much more pronounced PPAR-γ activation upon 5-ASA administration in the form of Nutriose:EC-coated pellets versus Pentasa pellets. All these results clearly demonstrate the superiority of these microbiota-sensitive polysaccharide-based film coatings for colon targeting in vivo., (Copyright © 2014 Elsevier B.V. All rights reserved.)

5-Aminosalicylic acid (5-ASA) is an orally administered therapeutic agent for inflammatory bowel diseases, such as ulcerative colitis and Crohn's disease. We hypothesized that the absorption of 5-ASA is mediated by the polyspecific carnitine/organic cation transporter (OCTN1/SLC22A4), based on the similarity of chemical structure between 5-ASA and other OCTN1 substrates. Therefore, we examined the involvement of this transporter in the disposition of 5-ASA in vivo by using octn1 gene knockout (octn1(-/-)) mice. After oral administration of 5-ASA, the plasma concentrations of 5-ASA and its primary metabolite, N-acetyl-5-aminosalicylate (Ac-5-ASA), in octn1(-/-) mice were much lower than those in wild-type mice. The time required to reach maximum plasma concentration was also delayed in octn1(-/-) mice. On the other hand, the plasma concentration profiles of both 5-ASA and Ac-5-ASA after intravenous administration of 5-ASA (bolus or infusion) were similar in the two strains. Uptake of 5-ASA from the apical to the basal side of isolated small-intestinal tissues of octn1(-/-) mice, determined in an Ussing-type chamber, was lower than that in wild-type mice. Further, uptake of 5-ASA in HEK293 cells stably transfected with the OCTN1 gene, assessed as the sum of cell-associated 5-ASA and Ac-5-ASA, was higher than that in HEK293 cells transfected with the vector alone. Overall, these results indicate that OCTN1 is involved, at least in part, in the gastrointestinal absorption of 5-ASA.

The medical management of inflammatory bowel disease (IBD) in the older patient extends beyond luminal disease activity. Factors such as comorbidity, functional status, polypharmacy, and age-related changes in physical reserve and drug metabolism may affect therapeutic decision making. The older patient with IBD is more susceptible to disease-related complications and also to adverse events with therapy, particularly immunosuppression. Appropriate medication selection along with multidisciplinary care, factoring not only disease activity but also these age-related risk factors, may improve therapeutic outcomes and decrease adverse events to therapy., (Copyright © 2014 Elsevier Inc. All rights reserved.)

For drugs expected to act locally in the colon, and for successful treatment, a delivery device is necessary, in order to limit the systemic absorption which decreases effectiveness and causes important side effects. Various delayed release systems are currently commercialized; most of them based on pH-dependent release which is sensitive to gastrointestinal pH variation. This study proposes a novel excipient for colon delivery. This new preparation consists in the complexation between carboxymethyl starch (CMS) and Lecithin (L). As opposed to existing excipients, the new complex is pH-independent, inexpensive, and easy to manufacture and allows a high drug loading. FTIR, X-ray, and SEM structural analysis all support the hypothesis of the formation of a complex. By minor variation of the excipient content within the tablet, it is possible to modulate the release time and delivery at specific sites of the gastrointestinal tract. This study opens the door to a new pH-independent delivery system for mesalamine targeted administration. Our novel formulation fits well with the posology of mesalamine, used in the treatment of Inflammatory Bowel Disease (IBD), which requires repeated administrations (1g orally four times a day) to maintain a good quality of life., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Aim: To compare the mucosal concentrations of 5-aminosalicylic acid (5-ASA) resulting from different pharmaceutical formulations and analyse the influence of inflammation on the mucosal concentrations., Methods: The study included 130 inflammatory bowel disease (IBD) patients receiving 5-ASA as pH-dependent-release formulations (73 patients), time-dependent-release formulations (11 patients), or pro-drugs (18 patients). In addition, 28 patients were receiving topical treatment (2-4 g/d) with pH-dependent-release formulations. Endoscopic biopsies were obtained from the sigmoid region during the colonoscopy. The 5-ASA concentrations (ng/mg) were measured in tissue homogenates using high-pressure liquid chromatography with electrochemical detection. The t test and Mann-Whitney test, when appropriate, were used for statistical analysis., Results: Patients receiving pH-dependent-release formulations showed significantly higher mucosal concentrations of 5-ASA (51.75 ± 5.72 ng/mg) compared with patients receiving pro-drugs (33.35 ± 5.78 ng/mg, P = 0.01) or time-dependent-release formulations (38.24 ± 5.53 ng/mg, P = 0.04). Patients with endoscopic remission had significantly higher mucosal concentrations of 5-ASA than patients with active disease (60.14 ± 7.95 ng/mg vs 35.66 ± 5.68 ng/mg, P = 0.02). Similar results were obtained when we compared patients with the histological appearance of remission and patients with active histological inflammation (67.53 ± 9.22 ng/mg vs 35.53 ± 5.63 ng/mg, P < 0.001). Significantly higher mucosal concentrations of 5-ASA were detected in patients treated with both oral and topical treatments in combination compared with patients who received oral treatment with pH-dependent-release formulations alone (72.33 ± 11.23 ng/mg vs 51.75 ± 5.72 ng/mg, P = 0.03)., Conclusion: IBD patients showed significant variability in mucosal 5-ASA concentrations depending on the type of formulation, and the highest mean concentration was achieved using pH-dependent-release formulations.

The present study was aimed to exploit the antibacterial/antifungal and film coating potential of Chitosan-EDTA (CH-EDTA) conjugate in combination with mesalamine (anti-inflammatory agent) for the early recovery from TNBS induced coilitis. The results suggested CH:EDTA (1:1) spray coated mesalamine tablets has an ability to transport drug in buffer pH 6.8 with rat caecal content condition. The CH-EDTA shows high level of adhesiveness of coat with core tablet. Further, FTIR, DSC and SEM analysis suggested spray coating of CH-EDTA on tablets was beneficial as compared to ladling method as it enhances interaction density and showed resistance from pH (1.2, 6.8 and 7.4). The pharmacokinetic parameters, AUC and AUMC of spray coated tablets were respectively, 4.70 fold and 2.10 fold increased. A synergistic therapeutic effect with CH-EDTA spray coated mesalamine was observed as evaluated by colon/body weight ratio, clinical activity score and damage score. X ray image study supported that CH-EDTA conjugate successfully delivered MSA tablets to large intestine. Histopathology of colon tissues showed rapid recovery from TNBS induced colitis in rats within 4 days. The findings revealed decreased recovery period was due to combined effect of both CH-EDTA and MSA to treat TNBS induced colitis., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Background: 5-Aminosalicylate (5-ASA) formulations are approved for the treatment of ulcerative colitis (UC). Determination of the colonic pharmacokinetics of 5-ASA is challenging. A dynamic model of 5-ASA colonic amounts after oral delayed-release 5-ASA (Asacol), oral extended delayed-release 5-ASA (Lialda), 5-ASA enema (Rowasa), foam and suppositories (Canasa) was developed to determine the colonic kinetics of these agents., Methods: We created a model with Stella software. Colonic 5-ASA in the right, transverse, descending, sigmoid colon, and rectum were estimated for adults after recommended doses of the above formulations. Simulations of active mild/moderate UC and in remission were performed and compared using Student's t-test for differences in means., Results: For UC in remission, the highest amounts of 5-ASA were from Asacol in the right and transverse colon (P < 0.01), Lialda in the descending and sigmoid colon (P < 0.01), and Rowasa in the rectum (P < 0.01). For active UC, sigmoid amounts were highest with foam (P < 0.01), and rectal amounts highest with Rowasa (P < 0.01). Differences in rectosigmoid amounts of 5-ASA from enemas and suppositories for UC in remission occurred based on the relationship between the timing of administration relative to the daily bowel movement (P < 0.01)., Conclusions: Compared to Asacol, Lialda results in higher 5-ASA amounts in the left colon. Asacol with Rowasa provides highest 5-ASA amounts across the entire colon. Higher 5-ASA amounts from topical formulations occur when the insertion occurs soon after the daily bowel movement. This model provides a rationale for further investigation.

A multiparticulate product for colon-specific delivery of a small molecule drug has been developed and characterized. Microcrystalline cellulose core beads containing 5-aminosalicylic acid produced by extrusion-spheronization were coated with chitosan and Aquacoat(®) ECD mixtures according to a factorial design. Coated beads were characterized in terms of drug release, shape, and friability. The optimum formulation was enteric coated and exposed to media simulating conditions in the stomach, small intestine, and colon. Release studies in simulated intestinal fluid revealed that the drug release rate from the coated beads, which were spherical and rugged, depended on the level of chitosan in the coat and the coat thickness. Enlarged pores observed on the surface of the coated beads exposed to the medium containing rat cecal and colonic enzymes are believed to have caused a significant enhancement of the drug release rate compared to the control exposed only to simulated gastric and intestinal fluids. The release mechanisms involved polymer relaxation and dissolved drug diffusion for simulated intestinal fluid and simulated colonic fluid, respectively. From the facilitated drug release in a colonic environment and the inhibition of drug release under gastric and intestinal conditions, it can be concluded that this multiparticulate system demonstrates the potential for colon-specific drug delivery., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Cationic polymers have been widely used as drug delivery systems. Herein, an oxidized sodium alginate/chitosan (OSA/CS) core-shell microgel was prepared via water-in-oil emulsion method. Morphological properties of the resulting microgel were determined by transmission electron microscopy, hydrodynamic diameter of the microgel was characterized by dynamic light scattering. The objective of this work was to achieve the colon-specific delivery of an antiulcerative colitis drug using a fully nontoxic carrier. 5-aminosalicylic acid (5-ASA) was chosen as a model drug, which is rapidly absorbed before entering the colon, thus it is necessary to develop a colon-specific delivery system for it. The in vitro drug release profile was established in buffer solutions with 0.1 M HCl/NaCl (pH 1.2) and 0.1 M phosphate buffered saline (pH 7.4) at 37 °C. The results indicated that this OSA/CS core-shell microgel inhibited the release of 5-ASA in stomach to a certain extent and is degradable in physiological conditions. Due to the excellent biocompatible nature of CS and OSA, this core-shell microgel has good biocompatibility and may have potential applications in oral controlled drug delivery systems.

Objective: To evaluate the efficacy and safety of extended-release mesalamine granules in the maintenance of remission in ulcerative colitis (UC)., Data Sources: Literature was obtained through searches of MEDLINE (1990-June 2012) using the terms mesalamine granules, ulcerative colitis, Apriso, and Salofalk. Bibliographies from retrieved articles were searched for additional citations., Study Selection and Data Extraction: All English-language articles reporting on use of extended-release mesalamine granules in humans identified through the search were evaluated and included., Data Synthesis: The preferred initial treatment for induction and maintenance of remission in mild to moderate UC is agents from the 5-aminosalicylate class (balsalazide, mesalamine, olsalazine, sulfasalazine). Mesalamine granules are available as an encapsulated product in the US and as a nonencapsulated formulation in Europe. Data evaluating encapsulated mesalamine granules for induction of remission are lacking; however, the European mesalamine granule formulation has been evaluated for induction of remission. Patients receiving mesalamine granules for induction achieved clinical and endoscopic remission more frequently than those receiving placebo. Two pivotal, randomized, double-blind, placebo-controlled, multicenter studies have evaluated encapsulated mesalamine granules for maintenance in 562 adults in remission from UC. In both studies, the proportion of patients who remained relapse-free at 6 months was higher for those receiving encapsulated mesalamine granules than placebo. Mesalamine granules are well tolerated, with headache, nausea, and upper respiratory infections being the most frequently reported adverse effects., Conclusions: Current evidence supports the use of extended-release mesalamine granules for maintenance of remission in mild to moderate UC. Further studies are necessary to examine the ideal dose and regimen of encapsulated mesalamine granules for induction of remission in UC.

The purpose of this study was to develop and evaluate a colon-specific, pulsatile drug delivery system, which consists of an impermeable capsule body filled with a 5-aminosalicylic acid rapid-disintegrating tablet and a pectin-based erodible plug placed in the opening of the capsule body. To obtain an appropriate gel-forming ability and suitable lag time for the colon-specific drug delivery, high-methoxy pectin (HM-pectin) was formulated with lactose and lowmethoxy pectin (LM-pectin) with HPMC to prepare the plug tablet. In order to evaluate the lag time, prior to the rapid drug release, both the formulation of the plug tablet and in vitro release medium were studied. The lag time prior to the rapid drug release was mainly determined by the HM-pectin/lactose or LM-pectin/HPMC ratio. The addition of pectinase or rat cecal content into the release medium shortened the lag time significantly, which predicted the probable enzyme sensitivity of pectin plug tablet. In vivo studies showed that the plasma concentration of drug can only be detected 6h after oral administration of the pulsatile capsule, which indirectly proved the colon-specific characteristics. These results show that the pulsatile capsule may have the therapeutic action for colon-specific drug delivery.

Introduction: Ulcerative colitis (UC) is an inflammatory disease of the colon characterized by periods of active disease and remission. The pathogenesis of this disease is likely a complex interaction of genetic predisposition, environmental factors, and immune system dysregulation, and is not completely understood. A Multi-MatriX (MMX®) system formulation of mesalamine, MMX mesalamine (SPD476; Lialda®; Mesavancol®; Mezavant®), allows for high-dose, once-daily dosing for patients with mild-to-moderate UC. Mesalamine is a topically active agent with anti-inflammatory properties., Areas Covered: Available literature regarding MMX mesalamine is extensively reviewed in this article, covering its chemical makeup, mechanism of action, pharmaceutics and pharmacokinetics, clinical efficacy, and safety and tolerability., Expert Opinion: A dose of 2.4 and 4.8 g was used in large Phase III clinical trials and was efficacious for induction of clinical and endoscopic remission in UC. MMX mesalamine was also efficacious in large multicenter maintenance studies for the maintenance of clinical and endoscopic remission. The introduction of the first once-daily mesalamine has given practitioners and patients more flexibility in dosing administration, which will ultimately lead to higher satisfaction and improved clinical outcomes.

Topical delivery of 5-aminosalicylic acid (5-ASA) to the colonic mucosa is important in order to achieve effective drug concentration in the site of inflammation and to minimize its systemic availability. 5-ASA loaded pellets were prepared by an extrusion/spheronization method. Mucoadhesive biopolymer chitosan was incorporated into the pellets, and drug delivery to the colon was controlled by the pH-sensitive polymer Eudragit® FS. Dissolution profiles of coated pellets revealed no drug release at pH 1.2 within 2h and release as intended in the simulated distal ileum and colon. In vivo, chitosan-core drug loaded pellets (AMCh) showed 2.5-fold higher drug metabolite concentration than after chitosan free pellets (AM) administration in the inflamed colonic tissue. Additionally, AMCh demonstrated decreased in AUC in colitis group (1507 ± 400 ng h/ml) compared with AM (1907 ± 122 ng h/ml). In terms of therapeutic efficiency, administration of pellets markedly decreased the colon/body weight ratio (colitis: 0.0355 ± 0.0028; AM 0.0092 ± 0.0033; AMCh 0.0086 ± 0.0022) and myeloperoxidase activity (colitis: 3212 ± 294 U/g tissue; AM 796 ± 211 U/g; AMCh 552 ± 319 U/g). Bioadhesive chitosan pellets showed additional beneficial properties for colonic 5-ASA delivery in the treatment of inflammatory bowel disease by increasing the drug concentration locally., (Copyright © 2012 Elsevier B.V. All rights reserved.)