Influence of olsalazine on gastrointestinal transit in ulcerative colitis

Constipation in ulcerative colitis: pathophysiology and practical management

Clinical experience suggests that there is a cohort of patients with refractory colitis who do have faecal stasis that contributes to symptoms. The underlying physiology is poorly understood, partly because until recently the technology to examine segmental colonic motility has not existed. Patients are given little information on how proximal faecal stasis can complicate colitis. Treatment guidelines are scanty and many patients are offered little apart from laxatives and advice on increasing fibre intake, which often makes symptoms worse. This article aims to review the history, pathology and management, and create impetus for future research on this underappreciated condition.

Current perspectives on the diagnosis and management of functional anorectal disorders in patients with inflammatory bowel disease

Despite advances in inflammatory bowel disease (IBD) therapies, a significant proportion of patients with quiescent disease experience persistent, debilitating symptoms of faecal incontinence (FI), urgency and defaecatory disorders due to anorectal dysfunction. Such symptoms are often underreported or misdiagnosed and can lead to potentially premature treatment 'escalation' and under-utilisation of pelvic floor investigations. In this review article, we consider putative pathophysiological post-inflammatory changes resulting in altered anorectal sensitivity, motility and neuromuscular coordination and how this may drive symptoms in quiescent IBD. Finally, we discuss a pragmatic approach to investigating and managing anorectal dysfunction and highlight areas for future research for this often-neglected group of patients.

Effects of medicines used to treat gastrointestinal diseases on the pharmacokinetics of coadministered drugs: a PEARRL Review

Objectives

Drugs used to treat gastrointestinal diseases (GI drugs) are widely used either as prescription or over-the-counter (OTC) medications and belong to both the 10 most prescribed and 10 most sold OTC medications worldwide. The objective of this review article is to discuss the most frequent interactions between GI and other drugs, including identification of the mechanisms behind these interactions, where possible.

Key findings

Current clinical practice shows that in many cases, these drugs are administered concomitantly with other drug products. Due to their metabolic properties and mechanisms of action, the drugs used to treat gastrointestinal diseases can change the pharmacokinetics of some coadministered drugs. In certain cases, these interactions can lead to failure of treatment or to the occurrence of serious adverse events. The mechanism of interaction depends highly on drug properties and differs among therapeutic categories. Understanding these interactions is essential to providing recommendations for optimal drug therapy.

Summary

Interactions with GI drugs are numerous and can be highly significant clinically in some cases. While alterations in bioavailability due to changes in solubility, dissolution rate, GI transit and metabolic interactions can be (for the most part) easily identified, interactions that are mediated through other mechanisms, such as permeability or microbiota, are less well-understood. Future work should focus on characterising these aspects.

Aminosalicylates for induction of remission or response in Crohn's disease

BACKGROUND

Randomized trials investigating the efficacy of aminosalicylates for the treatment of mildly to moderately active Crohn's disease have yielded conflicting results. A systematic review was conducted to critically examine current available data on the efficacy of sulfasalazine and mesalamine for inducing remission or clinical response in these patients.

OBJECTIVES

To evaluate the efficacy of aminosalicylates compared to placebo, corticosteroids, and other aminosalicylates (alone or in combination with corticosteroids) for the treatment of mildly to moderately active Crohn's disease.

SEARCH METHODS

We searched PubMed, EMBASE, MEDLINE and the Cochrane Central Library from inception to June 2015 to identify relevant studies. There were no language restrictions. We also searched reference lists from potentially relevant papers and review articles, as well as proceedings from annual meetings (1991-2015) of the American Gastroenterological Association and American College of Gastroenterology.

SELECTION CRITERIA

Randomized controlled trials that evaluated the efficacy of sulfasalazine or mesalamine in the treatment of mildly to moderately active Crohn's disease compared to placebo, corticosteroids, and other aminosalicylates (alone or in combination with corticosteroids) were included.

DATA COLLECTION AND ANALYSIS

Data extraction and assessment of methodological quality was independently performed by the investigators and any disagreement was resolved by discussion and consensus. We assessed methodological quality using the Cochrane risk of bias tool. The overall quality of the evidence supporting the outcomes was evaluated using the GRADE criteria. The primary outcome measure was a well defined clinical endpoint of induction of remission or response to treatment. Secondary outcomes included mean Crohn's disease activity index (CDAI) scores, adverse events, serious adverse events and withdrawal due to adverse events. For dichotomous outcomes we calculated the pooled risk ratio (RR) and corresponding 95% confidence interval (CI) using a random-effects model. For continuous outcomes we calculated the mean difference (MD) and 95% CI using a random-effects model. Sensitivity analyses based on a fixed-effect model and duration of therapy were conducted where appropriate.

MAIN RESULTS

Twenty studies (2367 patients) were included. Two studies were judged to be at high risk of bias due to lack of blinding. Eight studies were judged to be at high risk of bias due to incomplete outcomes data (high drop-out rates) and potential selective reporting. The other 10 studies were judged to be at low risk of bias. A non-significant trend in favour of sulfasalazine over placebo for inducing remission was observed, with benefit confined mainly to patients with Crohn's colitis. Forty-five per cent (63/141) of sulfasalazine patients entered remission at 17-18 weeks compared to 29% (43/148) of placebo patients (RR 1.38, 95% CI 1.00 to 1.89, 2 studies). A GRADE analysis rated the overall quality of the evidence supporting this outcome as moderate due to sparse data (106 events). There was no difference between sulfasalazine and placebo in adverse event outcomes. Sulfasalazine was significantly less effective than corticosteroids and inferior to combination therapy with corticosteroids (RR 0.64, 95% CI 0.47 to 0.86, 1 study, 110 patients). Forty-three per cent (55/128) of sulfasalazine patients entered remission at 17 to 18 weeks compared to 60% (79/132) of corticosteroid patients (RR 0.68, 95% CI 0.51 to 0.91; 2 studies, 260 patients). A GRADE analysis rated the overall quality of the evidence supporting this outcome as moderate due to sparse data (134 events). Sulfasalazine patients experienced significantly fewer adverse events than corticosteroid patients (RR 0.43, 95% CI 0.22 to 0.82; 1 study, 159 patients). There was no difference between sulfasalazine and corticosteroids in serious adverse events or withdrawal due to adverse events. Olsalazine was less effective than placebo in a single trial (RR 0.36, 95% CI 0.18 to 0.71; 91 patients). Low dose mesalamine (1 to 2 g/day) was not superior to placebo for induction of remission. Twenty-three per cent (43/185) of low dose mesalamine patients entered remission at week 6 compared to 15% (18/117) of placebo patients (RR = 1.46, 95% CI 0.89 to 2.40; n = 302). A GRADE analysis indicated that the overall quality of the evidence supporting this outcome was low due to risk of bias (incomplete outcome data) and sparse data (61 events). There was no difference between low dose mesalamine and placebo in the proportion of patients who had adverse events (RR 1.33, 95% CI 0.91 to 1.96; 3 studies, 342 patients) or withdrew due to adverse events (RR 1.21, 95% CI 0.75 to 1.95; 3 studies, 342 patients). High dose controlled-release mesalamine (4 g/day) was not superior to placebo, inducing a clinically non significant reduction in CDAI (MD -19.8 points, 95% CI -46.2 to 6.7; 3 studies, 615 patients), and was also inferior to budesonide (RR 0.56, 95% CI 0.40 to 0.78; 1 study, 182 patients, GRADE = low). While high dose delayed-release mesalamine (3 to 4.5 g/day) was not superior to placebo for induction of remission (RR 2.02, 95% CI 0.75 to 5.45; 1 study, 38 patients, GRADE = very low), no significant difference in efficacy was found when compared to conventional corticosteroids (RR 1.04, 95% CI 0.79 to 1.36; 3 studies, 178 patients, GRADE = moderate) or budesonide (RR 0.89, 95% CI 0.76 to 1.05; 1 study, 307 patients, GRADE = moderate). However, these trials were limited by risk of bias (incomplete outcome data) and sparse data (small numbers of events). There was a lack of good quality clinical trials comparing sulfasalazine with other mesalamine formulations. Adverse events that were commonly reported included headache, nausea, vomiting, abdominal pain and diarrhea.

AUTHORS' CONCLUSIONS

Sulfasalazine is only modestly effective with a trend towards benefit over placebo and is inferior to corticosteroids for the treatment of mildly to moderately active Crohn's disease. Olsalazine and low dose mesalamine (1 to 2 g/day) are not superior to placebo. High dose mesalamine (3.2 to 4 g/day) is not more effective than placebo for inducing response or remission. However, trials assessing the efficacy of high dose mesalamine (4 to 4.5 g/day) compared to budesonide yielded conflicting results and firm conclusions cannot be made. Future large randomized controlled trials are needed to provide definitive evidence on the efficacy of aminosalicylates in active Crohn's disease.

Synthesis, colon-targeted studies and pharmacological evaluation of an anti-ulcerative colitis drug 4-Aminosalicylic acid-β-O-glucoside

A glycoside prodrug of 4-aminosalicylic acid (4-ASA) with d-glucose was synthesized for targeted drug delivery to inflammatory bowel. The in vitro assessment of 4-aminosalicylic acid-β-O-glucoside (4-ASA-Glu) as a colon-specific prodrug was studied using colitis rat with the healthy one as control. The stability studies in aqueous buffers (pH 1.2, 6.8 and 7.4) indicated that 4-ASA-Glu was stable over a period of 12 h. The incubation of 4-ASA-Glu with cecal or colonic contents of healthy rats at 37 °C released 4-ASA in 77 or 80% of the dose in 12 h, respectively. The amount of 4-ASA liberated from the incubation of 4-ASA-Glu in cecal or colonic contents of colitis rats at 37 °C was 69 or 79% in 12 h respectively, while less than 9% 4-ASA was detected from the incubation of 4-ASA-Glu with the homogenates of stomach or small intestine. The curative effect of 4-ASA-Glu was evaluated in 2, 4, 6-trinitrobenzenesulfonic acid (TNBS) induced experimental colitis model in male Sprague-Dawley (SD) rats. It was found that 4-ASA-Glu possess significantly ameliorate effect than sulfasalazine, oral 4- and 5-aminosalicylic acid.

Drug-induced gastrointestinal disorders

Drug-induced gastrointestinal disorders can mimic conditions, such as inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) and, hence, recognition can prevent unnecessary investigations and treatment. While the knowledge and awareness relating to the adverse gastrointestinal effects of some medications, such as non-steroidal anti-inflammatory drugs are well established, other commonly prescribed drugs, such as antipsychotics, antidepressants and metformin are less well understood and warrant further study. This review attempts to integrate recent information regarding adverse drug reactions and place this in a useful clinical context.

Drug-induced gastrointestinal disorders

Drug-induced gastrointestinal disorders can mimic conditions, such as inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) and, hence, recognition can prevent unnecessary investigations and treatment. While the knowledge and awareness relating to the adverse gastrointestinal effects of some medications, such as non-steroidal anti-inflammatory drugs are well established, other commonly prescribed drugs, such as antipsychotics, antidepressants and metformin are less well understood and warrant further study. This review attempts to integrate recent information regarding adverse drug reactions and place this in a useful clinical context.

Dextran Carrier Macromolecules for Colon-specific Delivery of 5-Aminosalicylic Acid

Present manuscript describes the sustained and targeted delivery of 5-aminosalicylic acid to the distal ileum and proximal colon, using dextran (40 kDa) as a carrier for targeting 5-aminosalicylic acid at the colonic site by attaching p-aminobenzoic acid and benzoic acid as linkers. Prepared conjugate were characterized by UV, HPLC, FT-IR, and ¹H NMR. The degree of substitution was estimated by complete hydrolysis of conjugates in borate buffer and in vitro hydrolysis study of conjugates was performed in different biological media. It was observed that 5-aminosalicylic acid alone have produced high incidence of gastric ulcer with high ulcer index whereas lower ulcer index was found for the dextran conjugates of 5-aminosalicylic acid. The release pattern of conjugates in 3% w/v rat caecal content was confirmed the colon specificity of 5-aminosalicylic acid conjugates.

Synthesis and evaluation of mutual azo prodrug of 5-aminosalicylic acid linked to 2-phenylbenzoxazole-2-yl-5-acetic acid in ulcerative colitis

In this study, the syntheses of 4-aminophenylbenzoxazol-2-yl-5-acetic acid, (an analogue of a known nonsteroidal anti-inflammatory drug [NSAID]) and 5-[4-(benzoxazol-2-yl-5-acetic acid)phenylazo]-2-hydroxybenzoic acid (a novel mutual azo prodrug of 5-aminosalicylic acid [5-ASA]) are reported. The structures of the synthesized compounds were confirmed using infrared (IR), hydrogen-1 nuclear magnetic resonance (1H NMR), and mass spectrometry (MS) spectroscopy. Incubation of the azo compound with rat cecal contents demonstrated the susceptibility of the prepared azo prodrug to bacterial azoreductase enzyme. The azo compound and the 4-aminophenylbenzoxazol-2-yl-5-acetic acid were evaluated for inflammatory bowel diseases, in trinitrobenzenesulfonic acid (TNB)-induced colitis in rats. The synthesized diazo compound and the 4-aminophenylbenzoxazol-2-yl-5-acetic acid were found to be as effective as 5-aminosalicylic acid for ulcerative colitis. The results of this work suggest that the 4-aminophenylbenzoxazol-2-yl-5-acetic acid may represent a new lead for treatment of ulcerative colitis.

Aminosalicylates for induction of remission or response in Crohn's disease

BACKGROUND

Controlled clinical trials investigating the efficacy of aminosalicylates for the treatment of mildly to moderately active Crohn's disease have yielded conflicting results. A systematic review was conducted to critically examine current available data on the efficacy of sulfasalazine and mesalamine for inducing remission or clinical response in patients with mildly to moderately active Crohn's disease.

OBJECTIVES

To evaluate the efficacy of aminosalicylates compared to placebo, corticosteroids, and other aminosalicylates (alone or in combination with corticosteroids) for the treatment of mildly to moderately active Crohn's disease.

SEARCH STRATEGY

Separate MEDLINE (1966-July 2010), Cochrane Central Register of Controlled Trials (CENTRAL; Issue 3, 2010) and EMBASE database searches (1985-July 2010) of all relevant English and non-English language articles were performed, followed by manual searches of the reference list from potentially relevant papers and review articles, as well as proceedings from annual meetings (1991-2010) of the American Gastroenterological Association (AGA) and American College of Gastroenterology (ACG).

SELECTION CRITERIA

Randomized controlled trials that evaluated the efficacy of sulfasalazine or mesalamine in the treatment of mildly to moderately active Crohn's disease compared to placebo, corticosteroids, and other aminosalicylates (alone or in combination with corticosteroids) were included.

DATA COLLECTION AND ANALYSIS

Data extraction and assessment of methodological quality of each selected study was independently performed by the investigators and any disagreement was resolved by discussion and consensus. The primary outcome measure was a well defined clinical endpoint of induction of remission or response to treatment. Nineteen studies met the inclusion criteria and were analyzed. Pooled relative risks (RR) for inducing remission or clinical response and their 95% confidence intervals were calculated (random effects model) where appropriate.

MAIN RESULTS

Sulfasalazine was more likely to induce remission (RR 1.38; 95% CI 1.02 to 1.87; n = 263) compared to placebo with benefit confined mainly to patients with colitis. Sulfasalazine was less effective than corticosteroids (RR 0.66; 95% CI 0.53 to 0.81; n = 260). Olsalazine was less effective than placebo in a single trial. Low dose mesalamine (1 to 2 g/day) was not superior to placebo (RR = 1.46, 95% CI 0.89-2.40; n = 302) and was less effective than corticosteroids. High dose mesalamine (3 to 4.5 g/day) was not superior to placebo for induction of remission (RR 2.02; 95% CI 0.75 to 5.45) or response (Weighted Mean Difference -19.8 points; 95% CI -46.2 to 6.7; n = 615). In a single randomized controlled trial, 5-ASA was inferior to budesonide (RR 0.56; 95% CI 0.40 to 0.78). No statistically significant difference was found between high dose mesalamine and conventional corticosteroids (RR 1.04; 95% CI 0.79 to 1.36; n = 178). However, relatively few patients were available for analysis. There was a lack of good quality clinical trials comparing sulfasalazine with other mesalamine formulations.

AUTHORS' CONCLUSIONS

Sulfasalazine has modest efficacy compared to placebo and is inferior to corticosteroids for the treatment of mild to moderately active Crohn's disease. Olsalazine and low dose mesalamine (1 to 2 g/day) are not superior to placebo. High dose mesalamine (3 to 4.5 g/day) is not more effective than placebo for inducing response or remission. High dose mesalamine was inferior to budesonide for inducing remission in a single trial. In conclusion, sulfasalazine shows modest efficacy for the treatment of active Crohn's disease. However, the existing data show little benefit for 5-aminosalicylates.

Comparative analysis of the in vitro prosecretory effects of balsalazide, sulfasalazine, olsalazine, and mesalamine in rabbit distal ileum

BACKGROUND

The aminosalicylates remain foundation therapy for mild-to-moderate ulcerative colitis. Pro-drug 5-aminosalicylic acid (5-ASA; mesalamine) formulations have been developed to prevent 5-ASA from the proximal absorption and release of mesalamine, to decrease inflammation, and to improve colonic absorption. Clinically, pro-drugs such as olsalazine have been associated with dose-dependent diarrhea, which was likely secondary to ileal secretion induced by the azo linkages, in 17% of patients. The present study tested the hypothesis that the use of all compounds with azo linkages leads to increased secretion.

METHODS

Intestinal tissue was randomly assigned to serve as controls or to receive brush border addition of equimolar concentrations of the compounds, and the change in short-circuit current was measured.

RESULTS

Mesalamine did not induce secretion at any dose. Mean equivalent doses (0.1 to 10 mM) of balsalazide (range, 6.3 +/- 1.5 to 16.7 +/- 1.3 microA/cm2), olsalazine (range, 2.0 +/- 1.0 to 7.0 +/- 2.1 microA/cm2), and sulfasalazine (3.2 +/- 1.1 to 6.2 +/- 1.5 microA/cm2) significantly stimulated (P < 0.001) secretion. The values for the effective dose that is half the maximal dose for secretion induced by sulfasalazine, olsalazine, and balsalazide were 0.4, 0.7, and 0.9 mM, respectively.

CONCLUSIONS

This study is the first to demonstrate that the use of pro-drugs with azo bonds leads to increased ileal secretion at equimolar concentrations of 5-ASA. Physicians should use caution when providing higher doses of the pro-drug forms of 5-ASA to their patients, as this could lead to increased diarrhea.

Mesalamine derivatives in the treatment of Crohn's disease

The role of the aminosalicylates for induction therapy of mild moderate ulcerative colitis and as maintenance treatment has been substantiated by a large series of controlled clinical trials and confirmatory meta-analyses. Both sulfasalazine and newer derivatives are effective in preventing relapses. It remains to be determined whether certain high-risk groups of patients may benefit from higher doses of mesalamine induction or maintenance therapy. Mesalamine derivatives are also of benefit in the treatment of Crohn's disease. Sulfasalazine is likely not effective in the maintenance of Crohn's disease, although other mesalamine formulations continue to show some prophylactic activity after mesalamine induced remissions and for patients with disease of the ileum who have undergone surgical resection.

Role of mesalazine in acute and long-term treatment of ulcerative colitis and its complications

BACKGROUND

Sulfasalazine, consisting of 5-aminosalicylic acid bound to sulfapyridine by a diazo bond, was first used for treatment of ulcerative colitis in the early 1940s and later found effective in placebo-controlled trials for acute disease and for long-term maintenance of remission. Later studies found that the active moiety is 5-ASA (mesalazine, mesalamine) and the sulfapyridine moiety acts as a carrier molecule but causes many of the symptomatic adverse reactions.

METHODS

Review of the literature.

RESULTS

The finding that 5-ASA in the active motility led to the development of mesalazine prodrugs, olsalazine (Dipentum) and balsalazide (Colazide, Colazal), and targeted release mesalazine preparations, such as Asacol, Pentasa, and Salofalk, as well as enemas and suppository preparations for distal disease. Most patients with adverse effects from sulfasalazine will tolerate mesalazine. Mesalazine has been shown equivalent or superior to sulfasalazine, and superior to placebo, with a dose-response benefit, in inducing remission of acute disease. and comparable to sulfasalazine and superior to placebo for long-term maintenance of remission. Better tolerance of mesalazine and the ability to use higher doses favor its use in patients intolerant of sulfasalazine and in patients failing to respond to usual doses of sulfasalazine. Adverse effects from mesalazine are uncommon, but include idiosyncratic worsening of the colitis symptoms and renal toxicity. Mesalazine is safe to use during pregnancy and for nursing mothers. As maintenance therapy, mesalazine may reduce the risk of developing colorectal carcinoma.

CONCLUSION

Mesalazine represents effective and well-tolerated first-line therapy for mildly to moderately acute disease as well as for the long-term maintenance treatment in the patient with ulcerative colitis.

Pharmacokinetic considerations in gastrointestinal motor disorders

Although it has been recognised that alterations in gastrointestinal motility, whether induced by physiological or pathological processes, have significant effects on the pharmacokinetics of orally administered drugs, this subject has received inappropriately little attention. Studies relating to this topic have focused on healthy volunteers and animals and have largely been confined to the effects of single drug doses. There is limited information about the effects of disease on pharmacokinetics under steady-state conditions. Changes in gastrointestinal motility may affect the pharmacokinetics of orally administered drugs by altering the rate of delivery, bioavailability or mucosal absorption of the drug. In general the rate of absorption and time taken to achieve maximal plasma concentrations for well absorbed drugs may be modified by changes in gastrointestinal motility, but overall bioavailability is not usually affected. In these cases the therapeutic and clinical effects of the alteration in pharmacokinetics will, therefore, depend on which parameters are important for the action of the drug. For poorly absorbed drugs both the rate of absorption and bioavailability are likely to be altered by changes in gastrointestinal motility. However, the complex effects of food and disease, as well as the properties and formulation of any drug (solubility, ease of dispersion, delayed release formulation) often make the prediction of the magnitude, or even the direction, of any effect difficult to predict. Drugs with direct effects on gastrointestinal motility may influence their own patterns of absorption. In patients with gastrointestinal motility disorders, drugs administered in a controlled release formulation, or those with poor bioavailability, are most likely to have a poorly predictable therapeutic effect. Care should be taken to ensure that the formulation of the drug, its timing of administration in relation to meals and the use of coadministered drugs optimise, or at least ensure consistent absorption.

A randomized, double-blind, placebo-controlled trial of olsalazine for active Crohn's disease

: Olsalazine, consisting of two salicylate radicals linked by an azo-bond, is effective in the treatment of active ulcerative colitis. To test its effect in patients with mild to moderate attacks of Crohn's disease, the International Organization for the Study of Inflammatory Bowel Disease (IOIBD) designed a multicentre, randomised, double-blind, placebo-controlled study. Ninety-one patients from four centres were randomised to receive either olsalazine, 1 g b.i.d., or matching placebo tablets. Twenty-six patients had ileal disease; 43, ileocolonic; and 22, colonic. Thirty-five of 46 patients taking olsalazine and 24 of 45 patients taking placebo were withdrawn before the end of the 4-month study. Diarrhoea was the most common reason for withdrawal from the olsalazine group, accounting for 22% of the patients, as compared with 4% in the placebo group. No other side effects were reported. There was no difference in the remission rate or withdrawal rate for active disease in the two groups. However, when an intent-to-treat analysis was performed, only eight of the 46 (17%) olsalazine-treated patients were considered to have entered remission or improved their symptoms compared with 22 of the 45 (49%) placebo-treated patients (p < 0.03). This study was unable to show that patients with mild to moderate attacks of Crohn's disease were significantly improved by treatment with olsalazine at a dose of 1 g daily. However, the potential benefit of a higher dose cannot be excluded.

Targeting of drugs and vaccines to the gut

Targeted delivery to the gastrointestinal tract requires a multi-disciplinary approach to research involving contributions from polymer and material scientists, gastroenterologists, pharmaceutical scientists and technologists. Intestinal delivery is important not only for drugs that act locally, but also for those with systemic activity. In particular, there is considerable interest in the oral delivery of peptides and it is felt that the colon may provide an advantageous absorption site for such molecules. The different targeting mechanisms available to the pharmaceutical scientist to provide site-specific delivery in the gastrointestinal tract will be critically assessed. Delivery systems and targeting agents, which are being developed for the delivery of drugs, may also be exploited for the delivery of vaccines, since many of the delivery problems are common to both areas. Recent developments in the design of oral antigen formulations will be discussed in this review.

Clinical tolerance to three 5-aminosalicylic acid releasing preparations in patients with inflammatory bowel disease intolerant or allergic to sulphasalazine

The clinical tolerance to three 5-aminosalicylic acid (5-ASA) releasing preparations (mesalazine, olsalazine and balsalazide) was assessed in a consecutive series of 43 patients with inflammatory bowel disease who were intolerant to sulphasalazine. The relative contributions to the side-effects of sulphasalazine made by its two components, 5-ASA and sulphapyridine, were also assessed in these patients. Thirty-nine (91%) patients were able to tolerate at least one of the three 5-ASA preparations. Only four (9%) patients were intolerant to all preparations, having adverse reactions previously experienced with sulphasalazine and presumably related to 5-ASA rather than sulphapyridine. The clinical tolerance to mesalazine (63%), olsalazine (70%) and balsalazide (70%) was similar, and tolerance to one drug only was found in nine (18%) patients. The commonest adverse reactions associated with 5-ASA preparations were gastrointestinal. Diarrhoea was a problem in five patients during treatment with olsalazine and three each while on mesalazine and balsalazide. Allergic reactions from 5-ASA preparations were uncommon; of ten patients with rash following sulphasalazine only one developed a rash with mesalazine. The results of this study indicate that the vast majority of patients with inflammatory bowel disease can be managed with at least one of these four 5-ASA containing preparations and that the side-effects of sulphasalazine are multifactorial in aetiology, some being due to the parent molecule, and some to one of its two metabolites, 5-ASA and sulphapyridine.

Prophylactic effects of olsalazine v sulphasalazine during 12 months maintenance treatment of ulcerative colitis. The Danish Olsalazine Study Group

In a Danish multicentre trial we compared the relapse preventing effects of olsalazine and sulphasalazine in patients with ulcerative colitis over a 12 month treatment period. Two hundred and twenty seven patients (118 men) with at least two previous attacks of ulcerative colitis were randomly allocated according to a prearranged treatment schedule to olsalazine 500 mg bd or sulphasalazine 1 g bd in a double blind, double dummy fashion. One hundred and ninety seven patients completed the trial. The relapse rate after 12 month in the olsalazine group was 46.9% v 42.4% in the sulphasalazine group with a 95% confidence interval for the difference in proportions of -9% to 18%. Seven per cent of the patients were withdrawn from the trial because of adverse drug reactions and these were equally distributed between the two groups.

Review article: new developments in the use of 5-aminosalicylic acid in patients with inflammatory bowel disease

Sulphasalazine is composed of sulphapyridine and mesalazine (5-aminosalicylic acid, 5-ASA or mesalazine) joined by an azo bond. Sulphasalazine has been used clinically for 40 years but less than 10 years ago it was recognized that the active moiety is 5-ASA. Sulphapyridine appears to act only as a carrier molecule to deliver mesalazine to the bowel, yet it is the sulphapyridine which appears to be responsible for many of the adverse effects observed with sulphasalazine. Normally, mesalazine is rapidly absorbed from the upper gastrointestinal tract. Since the action of mesalazine is thought to be locally at the site of disease in the intestine, the 5-ASA must be 'protected' to ensure its release in the terminal ileum and colon, the site of bowel inflammation in patients with Crohn's disease or ulcerative colitis. Recent clinical studies have confirmed the efficacy of topical (suppositories and enemas) therapy for ulcerative proctitis and left-sided colitis; oral mesalazine has been proven to be useful for the treatment of acute ulcerative colitis and for the maintenance of remission. There is preliminary evidence for the clinical usefulness of mesalazine in acute Crohn's disease as well as for the maintenance of remission.

Effects of olsalazine and sulphasalazine on jejunal and ileal water and electrolyte absorption in normal human subjects

The effect of sulphasalazine and olsalazine on jejunal and ileal water and electrolyte absorption was investigated in normal subjects by a steady state intestinal perfusion of a physiological glucose bicarbonate electrolyte solution in the absence and presence of increasing concentrations of each drug. (Olsalazine 0.25 g/l, 1.0 g/l, jejunum; 0.5 g/l, 1.0 g/l, ileum; sulphasalazine 0.25 g/l, 0.5 g/l, 2.0 g/l jejunum; 1.0 g/l, 2.0 g/l, ileum.) In the jejunum olsalazine at 1.0 g/l significantly inhibited water, sodium, chloride, and potassium absorption (p less than 0.05). In the ileum olsalazine at 0.5 and 1 g/l significantly inhibited glucose uptake (p less than 0.04) and water absorption (p less than 0.03). In the jejunum sulphasalazine had a dose related and significant inhibitory effect on water, bicarbonate, and sodium absorption and at 2.0 g/l an inhibitory effect on chloride, potassium (p less than 0.005), and glucose (p less than 0.05) absorption. In the ileum sulphasalazine had no significant effect on water and electrolyte absorption. All inhibitory effects were rapidly reversible. These data show that unexplained diarrhoea in patients with ulcerative colitis treated with olsalazine may occur as a consequence of inhibition of water and electrolyte absorption in the small intestine and that the mechanisms of inhibition of sulphasalazine and olsalazine are different.

Olsalazine or sulphasalazine in first attacks of ulcerative colitis? A double blind study

Olsalazine (2 g/day) and sulphasalazine (3 g/day) were compared in a double blind three centre trial in 37 patients presenting with first attack of distal colitis. Sigmoidoscopic appearances, rectal biopsies, and symptom and stool diary records were used to assess benefit and adverse effects. Both groups showed a similar decrease in stool frequency (p less than 0.001). The proportion of unformed stools was also decreased, but to a lesser extent (p less than 0.05) in those taking olsalazine (78% v 55%; p less than 0.001) compared with those taking sulphasalazine (72% v 28%; p less than 0.001). There was a diminution in the proportion of stools containing blood in both groups (olsalazine: 61% v 22%; p less than 0.001/sulphasalazine: 67% v 37%; p less than 0.001). Sigmoidoscopic and histological appearances and clinical activity improved significantly and to a similar extent in both groups. Intolerance was encountered in two patients on olsalazine and four on sulphasalazine; intolerance to sulphasalazine being even higher (five of seven patients) in a preliminary study using a dose of sulphasalazine releasing the same amount of 5-aminosalicylic acid as 2 g olsalazine. Olsalazine was at least as effective as sulphasalazine in the treatment of new patients with distal colitis, and in a dose releasing an equivalent amount of 5-aminosalicylic acid was better tolerated.

Newer 5-aminosalicylic acid based drugs in chronic inflammatory bowel disease

Since the discovery that 5-aminosalicylic acid (5-ASA) is the active moiety of sulphasalazine in the treatment of chronic inflammatory bowel disease, several new 5-ASA based drugs have been developed. These consist either of slow- or delayed-release formulations of plain 5-ASA or sulpha-free azo compounds of 5-ASA. The different formulations and compounds have varying bioavailabilities, which makes it possible to use them alternatively in different clinical situations. A review of the literature is given, together with suggestions as to how the new drugs might be used in different clinical situations.