5-Aminosalicylic acid in the treatment of inflammatory bowel disease

Xylan from Pineapple Stem Waste: a Potential Biopolymer for Colonic Targeting of Anti-inflammatory Agent Mesalamine

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.

Management of Radiation Proctitis

Radiation proctitis is radiation-induced rectal mucositis, occurring as a result of radiation therapy for various pelvic malignancies. The management of radiation proctitis is challenging as guidelines are not currently available, and studies of the various treatment modalities are limited. There are various medical, endoscopic, and surgical measures for treating chronic radiation proctitis. Medical options such as anti-inflammatory agents, antioxidants, formalin application, and hyperbaric oxygen may improve bleeding related to chronic radiation proctitis. Endoscopic measures such as argon plasma coagulation are effective and safe. Surgery is considered for refractory or severe cases. A review and discussion of the different treatment modalities is presented.

Exploring the Management of Radiation Proctitis in Current Clinical Practice

INTRODUCTION

Radiation proctitis is radiation induced rectal mucositis, occurring as a consequence to radiation therapy of the pelvic organs for various pelvic region malignancies. The management of radiation proctitis is extremely challenging as no recommended guidelines are available and limited number of studies are there in the literature involving the various treatment options.

AIM

The aim of the study is the in-depth review of published literature to see the role of various treatment modalities in the management of radiation proctitis.

MATERIALS AND METHODS

An integrative review was undertaken within PubMed, MEDLINE, PMC, GOOGLE SEARCH databases and articles published upto February 2015 were reviewed and analysed. A total of 54 studies were included.

RESULTS

Literature suggests that non surgical therapies are the first line of treatment and surgery is reserved for advanced or refractory cases. Endoscopic therapies form the mainstay of treatment in managing the patients of radiation proctitis. Argon plasma coagulation and laser therapies are preferred. Radiofrequency ablation, cryoablation and mesenchymal stem cell therapy are the upcoming modalities. Medical therapy can be tried alone or in conjunction to endoscopic therapies. In the resistant or refractory cases, surgery can be looked for in the form of diversion or resection with or without anastamosis.

CONCLUSION

Though, a number of options are available, still a lot can be explored in this field to improve the morbidity in the patients and to confirm the superiority of one treatment over other.

Design and synthesis of heterobimetallic topoisomerase I and II inhibitor complexes: in vitro DNA binding, interaction with 5'-GMP and 5'-TMP and cleavage studies

New potential cancer chemotherapeutic complexes Cu-Sn(2)/Zn-Sn(2) 3 and 4 were designed and prepared as topoisomerases inhibitors; their in vitro DNA binding studies were carried out which reveal strong electrostatic binding via phosphate backbone of DNA helix, in addition to other binding modes viz. coordinate covalent and partial intercalation. To throw insight to molecular binding event at the target site, UV-vis titrations of 3 and 4 with mononucleotides of interest, viz, 5'-GMP and 5'-TMP were carried out, (in case of 4) by (1)H and (31)P NMR. Cleavage studies employing gel electrophoresis demonstrate both the complexes 3 and 4 are efficient cleavage agents and are specific groove binders (complex 3 binds to both major and minor groove while complex 4 is specifically minor groove binder only). In addition, the complexes show high inhibition activity against topoisomerase I and II. However, complex 4 exhibits significant inhibitory effects on the Topo I activity at a very low concentration approximately 2.5 microM.

Late rectal complications after prostate brachytherapy for localized prostate cancer: incidence and management

This review of the literature on late rectal complications after prostate brachytherapy indicated that it is a highly effective treatment modality for patients with clinically localized prostate cancer but can cause chronic radiation proctitis. The most common manifestation of chronic radiation proctitis was anterior rectal wall bleeding, which often occurred within the first 2 years after brachytherapy. It is interesting to note that the rates of late rectal morbidity appear to have declined over time, which may reflect improvements in implantation techniques and imaging. Rectal biopsy as part of the workup to evaluate rectal bleeding can lead to rectal fistula and the need for colostomy, a rare but major complication. The authors recommend 1) screening colonoscopy before brachytherapy for patients who have not had a screening colonoscopy within the preceding 3 years to rule out colorectal malignancies and, thus, facilitate conservative management should rectal bleeding occur; 2) lifestyle modifications during treatment to limit exposure of the rectum to radiation; and 3) conservative management for rectal bleeding that occurs within 2 years after brachytherapy. Cancer 2009. (c) 2009 American Cancer Society.

Identification of 5-aminosalicylic acid, ciprofloxacin and azithromycin by abrasive stripping voltammetry

Solid microparticles of 5-aminosalicylic acid, ciprofloxacin, and azithromycin were mechanically immobilized on the surface of the paraffin impregnated graphite electrode and investigated by square-wave and cyclic voltammetry in order to develop a method for their qualitative determination. 5-Aminosalicylic acid is oxidized at 0.540 V in the quasireversible electrode reaction, which is followed by the chemical transformation of the product, while ciprofloxacin and azithromycin are oxidized at 1.2 V and 0.94 V, respectively, in totally irreversible electrode reactions. The detection of these drugs in commercial dosage formulations is reported.

Composite film-coated tablets intended for colon-specific delivery of 5-aminosalicylic acid: using deesterified pectin

Combinations of Eudragit RS and deesterified pectin, polygalacturonic acid (PGA), or its potassium and sodium salts, when applied as a film coat, has a potential value as a colon-specific delivery system. Dispersions of PGA in Eudragit RS were used as the film former for coating of 5-aminosalicylic acid (5-ASA) tablet cores. Drug release behavior was assessed, in vitro, under simulating conditions in term of pH and time to in vivo during their transit to the colon. Negligible drug release occurred during first 5 hr where the coated tablets were in the stomach and small intestine. After that, the pectinolytic enzymes were added into the pH 6.8 medium to simulate the in vivo condition where there is the digestion of bacteria in the colon. The release of 5-ASA from the coated tablets occurred linearly as a function of time. Drug release depended on the composition of the mixed film, as well as the ratio of Eudragit RS to PGA or its salts. The highest drug release from the coated tablets of about 40% was obtained when the ratio of Eudragit RS to potassium salt of PGA was 2.5 to 1. Drug release profiles seemed to conform to the mechanism involving the osmotically driven release and formation of channels in the film caused by dissolution of PGA salts. Channel formation was, in most cases, activated by the presence of pectinolytic enzymes, showing that the PGA in the mixed film was subjected to enzymic breakdown. In conclusion, PGA could be used as an additive in Eudragit RS films to control the release of colonic delivery system.

Determination of 5-aminosalicylic acid in pharmaceutical formulation by differential pulse voltammetry

The oxidative behaviour of 5-aminosalicylic acid (5-ASA) has been investigated by differential pulse voltammetry using a glassy carbon electrode in different buffer systems. Linear sweep voltammetry was used to study the influence of pH on the peak current and peak potential. The solution conditions and instrumental parameters were optimized to obtain a good sensitivity. The Britton-Robinson buffer of pH 1.81 was selected as a suitable analytical medium in which 5-ASA exhibited a sensitive diffusion controlled oxidative peak at 0.564 V (vs. Ag/AgCl). The peak current varied linearly with drug concentration in the range between 1 x 10(-4) and 2 x 10(-6) M. The proposed voltammetric method has been applied to the determination of the drug in commercial delayed-release tablet forms. A mean recovery of 101.23% with a relative standard deviation of 1.35% was obtained.

Review article: current therapeutic options for radiation proctopathy

Radiation proctopathy is a common unfortunate complication following radiation therapy of pelvic malignancies. Symptoms of chronic radiation proctopathy include haematochezia, urgency, constipation, tenesmus, diarrhoea and rectal pain. Currently, a wide variety of pharmacological options, endoscopic cautery techniques and surgical procedures have been proposed for the treatment of chronic radiation proctopathy. Although these have been proposed primarily as treatment for rectal bleeding, the control of other symptoms has been noted with some of these agents. Pharmacological options include 5-aminosalicylic acid preparations, coticosteroid enemas, sucralfate (oral, enemas), formalin, short chain fatty acid enemas, oestrogen/progesterone, hyperbaric oxygen, antioxidants, sodium pentosan polysulphate and misoprostol rectal suppositories. Of these, sucralfate and formalin therapy appear to be effective for bleeding control. Misoprostol rectal suppositories and oral sucralfate may be useful in the prevention of acute and chronic symptoms of radiation proctopathy. Endoscopic cautery techniques have included the use of Nd:YAG laser and argon laser for coagulation of bleeding neovascular telangiectasias. Argon plasma coagulation offers a safe non-contact method of delivering haemostasis which has proven to be particularly useful in targeting difficult to reach lesions tangentially. Surgery is generally reserved for severe refractory cases involving ongoing haemorrhage, obstruction, stricture formation, fistulas and perforation. Given that formal randomized placebo-controlled studies are lacking for most treatments, the management of these patients is often challenging and unclear. Hence, there is a need for more research and education on radiation proctopathy.

Bioavailability of single and multiple doses of a new oral formulation of 5-ASA in patients with inflammatory bowel disease and healthy volunteers

AIMS

An oral multiparticulate coated formulation of 5-aminosalicylic acid (5-ASA: mesalazine) has been developed to provide a controlled release of the drug, in a pH-dependent fashion, in the distal ileum and colon. The purpose of the present study was to assess the systemic availability of the drug and its metabolite, acetyl-5-ASA, following single (800 mg) and multiple (2400 mg for 56 days) oral dose administration.

METHODS

Three groups were investigated: six healthy volunteers, six patients with ulcerative colitis, and nine patients with Crohn's disease in remission. In the single oral dose study (800 mg) all three groups participated, whereas in the multiple oral dose study (2400 mg/day for 56 days) only the patients with inflammatory bowel disease took part. Plasma and urine 5-ASA and Ac-5-ASA were measured for 48 h.

RESULTS

In the single oral dose regimen, systemic absorption of 5-ASA and Ac-5-ASA were low and did not differ between the three groups. Only about 20% of the 5-ASA given was absorbed, with more than 80% of the drug being available in the terminal ileum and colon for therapeutic activity. The multiple oral dose regimen in patients with inflammatory bowel disease produced a significantly higher plasma concentration and urine excretion of both 5-ASA and Ac-5-ASA by the end of the treatment, in comparison to the first dose. There was a statistically higher systemic absorption of 5-ASA in patients with ulcerative colitis than in patients with Crohn's disease. After 56 days of dosing, no adverse event was reported and laboratory screening tests remained within normal ranges.

CONCLUSIONS

The new oral 5-ASA formulation is gradually released throughout the small and large intestine, reflected by a low plasma concentration of the drug and its metabolite, with about 80% of the drug being available for ileum-colon therapeutic activity.

High-performance liquid chromatographic assay of 5-aminosalicylic acid (5-ASA) and its metabolites N-beta-D-glucopyranosyl-5-ASA, N-acetyl-5-ASA, N-formyl-5-ASA and N-butyryl-5-ASA in biological fluids

A fast, highly sensitive high-performance liquid chromatographic method for the simultaneous determination of 5-aminosalicylic acid (5-ASA) and its metabolites N-beta-D-glucopyranosyl-5-ASA, N-formyl-5-ASA, N-acetyl-5-ASA and N-butyryl-5-ASA has been developed using a dynamically modified silica approach on a 40 mm x 4.6 mm I.D. column packed with 3-microns Hypersil. Plasma proteins are precipitated with acetonitrile. After extraction of the acetonitrile into 1,1,1-trichloroethane an undiluted aqueous phase containing the analytes is obtained. The detection limits are in the range 0.002-0.05 microgram/ml in plasma at a signal-to-noise ratio of 3 using fluorescence detection.

New metabolites of the drug 5-aminosalicylic acid. II. N-formyl-5-aminosalicylic acid

1. A new metabolite of the drug 5-aminosalicylic acid (5-ASA) has been found in urine from pigs and in plasma of humans. The metabolite has been isolated from pig urine using an XAD-2 column and purified using preparative h.p.l.c. 2. The metabolite has been identified as N-formyl-5-ASA (5-formamidosalicylic acid) using 1H- and 13C-n.m.r. spectrometry and mass spectroscopy and the structure was confirmed by chemical synthesis. 3. N-Formyl-5-ASA is stable in human plasma and in potassium phosphate buffers between pH 3.0 and 9.0. It is hydrolysed below pH 3.0. 4. N-Formyl-5-ASA was readily formed in rat liver homogenate when 5-ASA and N-formyl-L-kynurenine were added. Thus N-formyl-5-ASA might be formed by the actions of formamidase in vivo. 5. N-Formyl-5-ASA has been found in human plasma from healthy volunteers dosed i.v. with 5-ASA (250 mg). N-beta-D-glucopyranosyl-5-ASA, N-acetyl-5-ASA and N-formyl-5-ASA were quantified in human plasma using a h.p.l.c. assay.

Mesalamine in ulcerative colitis

Sulfasalazine has been used for many years in the management of ulcerative colitis. As many as 20 percent of patients treated with it experience intolerable adverse effects usually attributed to its sulfapyridine component. The other active component is 5-aminosalicylic acid (5-ASA); the only 5-ASA enema preparation currently available in the U.S. is mesalamine (Rowasa, Reid-Rowell) containing 5-ASA 4 g in 60 mL. In clinical trials, mesalamine has proved efficacious in treating refractory cases of distal ulcerative colitis, proctitis, and proctosigmoiditis. Because of its high cost compared with more conventional treatment modalities, it should be reserved for cases that are either refractory or intolerant to conventional treatment.

Absorption of oral mesalazine-containing preparations and the influence of famotidine on the absorption

The mesalazine-containing preparations Asacol, Pentasa, and Salofalk (=Claversal) are frequently used in the treatment of inflammatory bowel disease. The release patterns of these formulations are time- and/or pH-dependent. The aim of this study was to investigate the patterns of absorption of these preparations and the influence of raised intragastric pH on absorption. Gastric pH was raised by simultaneous administration of famotidine. Absorption was determined by assaying with a high-performance liquid chromatography method the urinary excretion of acetylmesalazine, the major metabolite of mesalazine. A large intra- and inter-individual variability in absorption was found for all three formulations, both with and without concomitant famotidine administration. Asacol and Pentasa were significantly less absorbed than Salofalk. A significant lower absorption of mesalazine was seen when Asacol was combined with famotidine. Variations in gastric pH have negligible effect on the bioavailability of mesalazine in vivo.

Clinical evidence supporting the radical scavenger mechanism of 5-aminosalicylic acid

5-Aminosalicylic acid, the therapeutically active metabolite of sulfasalazine, was exposed to oxygen-derived free radicals produced by the Fenton reaction in vitro, and several metabolites were detected and characterized by high performance liquid chromatography and ultraviolet spectrophotometry. The majority of these metabolites were present in methanolic extracts of feces samples from sulfasalazine-treated patients with inflammatory bowel disease but not in rheumatoid arthritis patients with normal bowel function. The presence of these metabolites, which have not been demonstrated in vivo before, provides evidence of an interaction between 5-aminosalicylic acid and oxygen-derived free radicals in sulfasalazine-treated patients with inflammatory bowel disease. Since the concentration of lipid peroxides, which is dependent on the release of oxygen-derived free radicals, was significantly increased in pretreatment rectal biopsies of the patients, and further was normalized concomitantly with a significant improvement in disease activity over the 5-wk treatment period, an important role of the radical scavenger mechanism of 5-aminosalicylic acid in sulfasalazine therapy of chronic inflammatory bowel disease is strongly suggested.

New metabolites of the drug 5-aminosalicylic acid. I: N-beta-D-glucopyranosyl-5-aminosalicylic acid

1. A new unstable metabolite of 5-aminosalicylic acid (5-ASA) was found in plasma from healthy volunteers dosed with 5-ASA i.v. 2. The metabolite was prepared by incubation of 5-ASA with rat liver homogenate, and isolated using preparative h.p.l.c. 3. The metabolite was identified as N-beta-D-glucopyranosyl-5-aminosalicylic acid by n.m.r. spectroscopy and by FAB mass spectrometry. 4. N-beta-D-Glucopyranosyl-5-ASA was formed non-enzymically from 5-ASA and glucose in phosphate buffer pH 7.4, and was unstable under weakly acidic conditions, decomposition increasing with temperature, i.e. decomposition was complete after 30 min at pH 5.0 and 23 degrees C.

Failure of 5-aminosalicylic acid enemas to improve chronic radiation proctitis

Radiation proctitis is a well-known complication of abdominal and pelvic radiation. Conventional medical and surgical treatment often is disappointing. 5-Aminosalicylic acid (5-ASA) is the active component in sulfasalazine and is effective in the treatment of distal ulcerative colitis. Four patients with radiation proctitis were treated with 4 g 5-ASA by enema nightly for two to six months. Patients were seen monthly, interviewed, and a sigmoidoscopic exam performed. No change was seen in the degree of mucosal inflammation on follow-up sigmoidoscopic exams. Three patients noted no change in their symptoms of bleeding, pain, or tenesmus. One patient noted initial improvement, but this was not sustained. 5-ASA enemas do not appear to be effective in the treatment of radiation proctitis.

Inhibition of intestinal macrophage chemotaxis to leukotriene B4 by sulphasalazine, olsalazine, and 5-aminosalicylic acid

Purified intestinal macrophages obtained at resections for colonic neoplasms were investigated for chemotaxis to leukotriene B4 (LTB4) by the Millipore filter assay and leading front technique. Possible inhibition by drugs effective in the treatment of chronic inflammatory bowel disease (sulphasalazine, olsalazine, its active moiety 5-aminosalicylic acid (5-ASA), and the 5-ASA metabolite N-acetylated-5-ASA (ac-5-ASA)) was tested at therapeutic colonic concentrations of 0.01-10 mM. Leukotriene B4 at a dose of 10 nM was equipotent with casein (5 g litre-1) as regards chemoattraction of macrophages. Sulphasalazine, olsalazine and 5-ASA were potent inhibitors of macrophages chemotaxis to LTB4 with IC50 values of 0.43, 0.39 and 0.24 mM, respectively. These concentrations are below the lowest concentration of 5-ASA (2 mM) in the colonic lumen during conventional sulphasalazine treatment of patients with chronic inflammatory bowel disease. The inhibition of macrophage chemotaxis by these drugs may be important for this limitation of the local inflammatory process in chronic inflammatory bowel disease, and may in part explain the beneficial effect of systemic and local treatment with sulphasalazine. Leukotriene B4 appears to be an important inflammatory mediator for the activation of macrophages in colonic inflammation.

4-Aminosalicylic acid, in contrast to 5-aminosalicylic acid, has no effect on arachidonic acid metabolism in human neutrophils, or on the free radical 1,1-diphenyl-2-picrylhydrazyl

5-Aminosalicylic acid seems to be the active moiety of sulfasalazine in the treatment of chronic inflammatory bowel disease. Even if the precise mode of action is obscure, it is assumed that two of the main mechanisms are inhibitory effects on the lipoxygenation of arachidonic acid and interaction with free radicals. As 4-aminosalicylic acid has been claimed to be beneficial in the topical treatment of ulcerative colitis, it was tested whether this drug possesses any influence on the 5-lipoxygenase activity in human neutrophils in vitro or whether it acts as a radical scavenger. The change of the amino residue from carbon-5 to carbon-4 abolished the effect in the two systems tested. The reported clinical observations on 4-aminosalicylic acid in the treatment of chronic inflammatory bowel disease remain to be confirmed and cannot be explained by interference with arachidonic acid metabolism or free oxygen radicals.

Lack of effect of 5-aminosalicylic acid on platelet aggregation and fibrinolytic activity in vivo and in vitro

We have studied platelet aggregation and fibrinolytic activity in six patients with chronic inflammatory bowel disease treated with 5-aminosalicylic acid (mesalazine). There were no changes in these measurements during normal treatment, i.e. 1.5 g per day with a slow-release formulation, nor after an intravenous dose of 250 mg. Also in vitro tests were negative, in contrast to the inhibition seen with aspirin (acetylsalicylic acid). We conclude that treatment with mesalazine does not constitute a hazard to these patients in regard to prolonged bleeding time caused by an influence on platelet aggregation or fibrinolytic activity.