The efficacy of oral 5-ASAs in the treatment of active ulcerative colitis: a systematic review

The authors set out to critically review the current data on the efficacy of oral 5-aminosalicylic acid (5-ASA) agents for active ulcerative colitis (UC). Thirty-one studies were identified; 19 met entry criteria. Three trials with mesalamine showed statistical significance versus placebo; those with olsalazine or balsalazide did not. No agent was statistically different from sulfasalazine. In 2 of 3 trials of balsalazide versus mesalamine, results for defined primary and secondary endpoints failed to demonstrate statistically significant differences. Studies suggest that mesalamine is superior to placebo for treating active UC. Five-ASA products appear to be as effective as sulfasalazine, but available data do not suggest a difference in efficacy between any of the 5-ASA preparations.     

The effect of 5-aminosalicylic acid-containing drugs on sulfide production by sulfate-reducing and amino acid-fermenting bacteria

The toxic, bacterial metabolite sulfide is implicated in ulcerative colitis. Ulcerative colitis patients taking 5-aminosalicylic acid-containing drugs have lower fecal sulfide levels than those not taking these drugs. The effects of sulfasalazine, balsalazide, olsalazine, and 5-aminosalicylic acid on sulfide production were studied in a three-stage chemostat pulsed on days 1 to 3 with 5 g sulfasalazine (40 mM) and in pure cultures of amino acid-fermenting and sulfate-reducing bacteria. By the third day of sulfasalazine addition to the chemostat, sulfide concentrations in vessels 1 through 3 had dropped from 1.73, 1.78, and 1.43 mM to 0.01, 0.15, and 0.9 mM, respectively. In pure cultures, 50% inhibition of sulfide production from amino acids occurred at 2.5 +/- 0.05 mM for sulfasalazine, 5 +/- 0.2 mM for olsalazine, 6 +/- 1 mM for balsalazide, and more than 20 mM for 5-aminosalicylic acid. Fifty percent inhibition of sulfide production from sulfate occurred at 0.25 +/- 0.05 mM for sulfasalazine, 0.7 +/- 0.2 mM for balsalazide, and 9.0 +/- 1.0 mM for 5-aminosalicylic acid. The order of effectiveness of equimolar concentrations of drugs (most effective first) in this assay was sulfasalazine, then olsalazine (though given clinically at half the dose of other 5-aminosalicylic acid prodrugs) and balsalazide, and lastly 5-aminosalicylic acid. Inhibition of sulfide production by 5-aminosalicylic acid-containing drugs may contribute to their therapeutic effect in ulcerative colitis.     

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.     

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.     

Colonic targeting of aminosalicylates for the treatment of ulcerative colitis.

Aminosalicylates (5-aminosalicylic acid) represent drugs of first choice in the treatment of ulcerative colitis. Two different therapeutic approaches have been employed to target the active 5-aminosalicylic acid to its site of action. Either inactive azo-prodrugs (e.g. sulfasalazine, olsalazine, balsalazide) or special galenic formulations have been developed for topical delivery of 5-aminosalicylic acid to the colon. However, as intestinal physiology, the extent of ulcerative colitis as well as drug disposition demonstrate large interindividual differences, acute healing rates (40-80%) and the maintenance of remission are quite variable. Apparently, therapeutic effects depend on local concentrations of 5-aminosalicylic acid in the colonic mucosa whereas systemic drug exposure might be one determinant of side effects. In general, 5-aminosalicylic acid is well tolerated and withdrawal from therapy is rare. Following administration of azo-prodrugs (e.g. olsalazine), lower plasma concentrations and higher delivery into the colon of 5-aminosalicylic acid can be observed in comparison to special galenic formulations of 5-aminosalicylic acid. Whether such changes in drug disposition will affect therapeutic efficacy remains to be proved by clinical data. Consequently, selection of a particular agent should be based primarily on clinical efficacy, profile of adverse effects, patients' acceptance and economic considerations.     

Mesalamine induced symptom exacerbation of ulcerative colitis: Case report and brief discussion

This paper describes a rare case in which the oral administration of mesalamine resulted in the exacerbation of ulcerative colitis (UC) in a patient who was previously responsive to mesalamine and whose colitis had been in remission for eight years. Mesalamine and other 5-aminosalicylic acid compounds are the mainstay of treatment for UC; however up to 8% of patients are unable to take the medications due to intolerance or hypersensitivity reactions. Common drug reactions are fever, nausea, diarrhea and abdominal pain; however, exacerbation of UC has rarely been reported. This study highlights the importance of ruling out mesalamine as the causative agent in cases of UC exacerbations.     

Olsalazine in maintenance of clinical remission in patients with ulcerative colitis

Frequent minor side effects are associated with sulfasalazine. The realization that it is the 5-aminosalicylic acid moiety that is the active component of sulfasalazine and that the side effects are probably due to the sulfapyridine has prompted the search for a similar but safer compound. Olsalazine, consisting of two molecules of 5-ASA without sulfasalazine may avoid the problems due to sulfasalazine. One hundred one patients were entered into a double-blind placebo-controlled study of the use of olsalazine 92 g daily) in preventing relapse in patients who had recently recovered from an acute attack of ulcerative colitis. Patients were treated for 12 months. Forty-nine were randomized to olsalazine (39 with limited and 10 with extensive disease) and 52 to placebo (42 with limited and 10 with extensive disease). Life-table analysis showed that the median time to relapse in patients on olsalazine was 342 days, which was significantly longer than the 100 days in the placebo group (P=0.024). The most important side effect experienced with olsalazine that necessitated withdrawal from the study was drug-induced diarrhea in 16% (8/49). There was a similar incidence of minor side effects reported in the two groups, and in no patients were major or dangerous side effects reported. In patients who did not develop diarrhea, olsalazine was well tolerated and successfully prevented rapid relapse in the recently ill patients entered into this study.     

Adverse effects with oral 5-aminosalicyclic acid

Two patients with ulcerative colitis and a past history of allergic reactions to sulfasalazine had similar reactions when treated with 5-aminosalicylic acid. This suggests that, at least in some patients, the adverse effects of sulfasalazine are due to 5-aminosalicylic acid rather than sulfapyridine. Desensitization to sulfasalazine was successfully carried out in one patient but was not attempted in a second.     

Safety of balsalazide therapy in the treatment of inflammatory bowel disease

Balsalazide is a mesalamine prodrug that is generally well tolerated and useful in the treatment of inflammatory bowel disease (IBD). This review will focus on newer safety information regarding the use of balsalazide in the treatment of patients with IBD. In general, mesalamine compounds such as balsalazide are better tolerated than sulfasalazine. Balsalazide therapy should be avoided in patients with known hypersensitivity reaction to salicylates, mesalamine, other balsalazide metabolites, or the components of the Colazal (Salix Pharmaceuticals; Morrisville, NC) capsule (silicon dioxide, magnesium stearate) but may be tolerated in patients who were unable to tolerate other mesalamine compounds for non-hypersensitivity reasons. Overall, balsalazide is well tolerated and effective in the treatment of IBD.     

Olsalazine as an alternative therapy in a patient with sulfasalazine-induced eosinophilic pneumonia

A man with Crohn's colitis developed eosinophilic pneumonia after treatment with sulfasalazine. Challenge with sulfapyridine revealed that this component of sulfasalazine was the likely causative agent. Treatment with olsalazine, a 5-aminosalicylic acid compound (disodium-azodisalicylate), was well tolerated without recurrence of pulmonary symptoms.     

Treatment of ulcerative colitis with oral mesalamine: advances in drug formulation, efficacy expectations and dose response, compliance, and chemoprevention

Sulfasalazine, olsalazine, balsalazide, delayed-release mesalamine, controlled-release mesalamine, mesalamine pellets, and Multi-Matrix System mesalamine are effective first-line therapies for the treatment of mildly to moderately active ulcerative colitis and for subsequent maintenance of remission. For induction therapy it is unclear if there is a dose response above 1.5 g, and for maintenance therapy existing data do not support a dose response above 1.5 g. Sulfasalazine has more frequent side effects than olsalazine, balsalazide, and mesalamine formulations. Once-daily dosing with multi-matrix system mesalamine 1.2 g tablets may lead to optimal compliance. Mesalamine >/= 1.2 g and sulfasalazine >/= 2 g reduce the risk of colorectal cancer in patients with ulcerative colitis. Drug formulations, efficacy expectations and dose response, toxicity expectations, compliance considerations, and chemoprevention considerations are reviewed.     

Sulfasalazine Desensitization in Children and Adolescents with Chronic Inflammatory Bowel Disease

Sulfasalazine is an important therapeutic agent in the management of chronic inflammatory bowel disease (CIBD). Unfortunately, adverse reactions to this drug have been reported in 5-55% of treated patients. These include dose-related side effects like nausea, malaise, and headache or hypersensitivity reactions such as rash, fever, hives, arthralgia, hepatitis, etc. Studies in adults with successful reintroduction of sulfasalazine after a desensitization program have been reported; however, with regard to children, no such data are available. Fourteen children and adolescents (5-16 yr old) diagnosed to have CIBD manifested hypersensitivity to sulfasalazine within 2 months of onset of treatment. All had pancolitis--secondary to Crohn's disease (CD) in four and to ulcerative colitis (UC) in 10. All of them were on steroids. Sulfasalazine was discontinued in all after symptoms of hypersensitivity developed. Three patients with severe reaction were diagnosed prior to desensitization experience. Desensitization, beginning with 5-50 mg of sulfasalazine/day, was attempted in the other 11 children. The dose was gradually increased by 5-50 mg increments every 3 days. Desensitization was successful in only five children, who were ultimately able to tolerate 1.5-3.0 g of sulfasalazine daily again. In the rest (six of 11 patients), oral 5-ASA (Asacol) was administered, and three could not tolerate it. One of these three with intolerance to Asacol required colectomy. One did not tolerate Asacol or Dipentum. Our findings suggest that sulfasalazine desensitization should be attempted in all patients developing hypersensitivity reactions before trying alternative therapy.     

Longterm olsalazine treatment: pharmacokinetics, tolerance and effects on local eicosanoid formation in ulcerative colitis and Crohn's colitis.

To examine pharmacokinetics and tolerance of long term administration of olsalazine (azodisalicylate), increasing doses of the drug were given for one year to 31 patients with ulcerative colitis (UC) and nine patients with Crohn's colitis (CC), refractory to, or intolerant of sulphasalazine, until sustained remission was obtained or a maximum of 4 g/day was reached. Colonic drug metabolism was studied by equilibrium in vivo dialysis of faeces. Complete azoreduction occurred in most cases. Concentrations of 5-aminosalicylic acid, but not N-acetyl-5-aminosalicylic acid, in faecal dialysates increased dose dependently. Serum concentrations disclosed no cumulation in the long term and olsalazine was well tolerated, although loose stools occurred transiently in some patients with extensive disease: this was associated with a larger proportion of unsplit olsalazine in the faecal dialysates. Patients with ulcerative colitis having a high prostaglandin E2 concentration (greater than ng/ml) determined by equilibrium dialysis of rectum, were less likely to benefit from treatment. Olsalazine is a very effective means of delivery of 5-aminosalicylic acid to the colonic mucosa in active disease. Use of the drug in controlled trials may be considered safe even in prolonged high dosage.     

Clinical experience of the tolerance of mesalazine and olsalazine in patients intolerant of sulphasalazine

We assessed the tolerance and safety of two new preparations designed to release 5-aminosalicylic acid in the colon in patients with ulcerative colitis who were intolerant of sulphasalazine. Twenty-eight of 37 patients (76%) given mesalazine and 18 of 21 patients (86%) given olsalazine tolerated the new preparations with no adverse effects. No haematologic or biochemical abnormalities were detected. Adverse reactions to the new preparations were usually but not always similar to those they had previously encountered with sulphasalazine, but a few patients experienced rash and diarrhoea. In some patients intolerant of one of the new preparations, their tolerance of the other was assessed. Three patients intolerant of mesalazine tolerated olsalazine. Similarly, three other patients intolerant of olsalazine tolerated mesalazine. We conclude that not all adverse effects of sulphasalazine are due to the sulphapyridine part of the molecule. Some are due to the released 5-aminosalicylic acid and some to the parent compound. Both drugs are likely to prove useful in the management of patients intolerant of sulphasalazine.     

Measurement of colonic mucosal concentrations of 5-aminosalicylic acid is useful for estimating its therapeutic efficacy in distal ulcerative colitis: comparison of orally administered mesalamine and sulfasalazine

OBJECTIVES: Oral 5-aminosalicylic acid (5-ASA) preparations have been used frequently in the treatment of ulcerative colitis. However, there have been few reports investigating the relationship between colonic mucosal concentrations of 5-ASA and its clinical efficacy when oral sulfasalazine or 5-ASA compounds were administered. The aim of this study is to compare the mucosal concentrations of 5-ASA ensured by sulfasalazine or mesalamine, and to define the clinical significance of the measurement of 5-ASA concentrations in the treatment of distal ulcerative colitis. MATERIALS AND METHODS: Biopsies were taken from the rectum and sigmoid colon of the oral sulfasalazine group (n = 13) and the slow-release 5-ASA (mesalamine) group with (n = 5) or without (n = 11) rectal administration of 5-ASA. High-pressure liquid chromatography was used to measure the tissue concentrations of 5-ASA and its metabolites. We compared the 5-ASA concentrations of the sulfasalazine group with the mesalamine group. Furthermore, we analyzed the relationship between tissue 5-ASA concentrations and the Disease Activity Index (DAI). RESULTS: The concentrations of 5-ASA and acetyl-5-ASA in the sulfasalazine group were higher than those in the group taking oral mesalamine alone (p < 0.01). The concentration of 5-ASA was much higher in the patients who received oral and rectal mesalamine in an enema than in the patients who had oral mesalamine alone. There was a significant inverse correlation between the DAI and concentrations of 5-ASA in the rectum (r = 0.712, p < 0.001). CONCLUSIONS: We demonstrated that the colonic mucosal concentration of 5-ASA was significantly higher in the sulfasalazine group than in the mesalamine group. Furthermore, the concentrations of mucosal 5-ASA may be a good marker for the estimation of its efficacy in the treatment of ulcerative colitis.     

Maintenance Oral Sulfasalazine Prolongs Remission in Ulcerative Proctitis and Proctosigmoiditis

We have retrospectively compared the effectiveness of five different regimens for inducing and maintaining clinical remission in 206 patients with idiopathic proctitis (n = 115) and proctosigmoiditis (n = 91). The five therapeutic regimens were: corticosteroid enemas, 5-aminosalicylic acid (5-ASA) enemas, oral 5-ASA (sulfasalazine or mesalamine), corticosteroid enemas plus oral 5-ASA, or 5-ASA enemas plus oral 5-ASA. Clinical remission was achieved within 28 days of therapy in 47%, and eventually in 94% of these patients. No significant differences in efficacy were found among the five regimens. Most patients ultimately experienced a recurrence of symptoms, but the duration of remission was significantly longer with maintenance oral sulfasalazine or mesalamine (17.2 months) than with no therapy (11.8 months), P less than 0.01. We conclude that several regimens are equally effective in inducing remission of proctitis and proctosigmoiditis, although prolonged therapy may be needed to accomplish this goal. Maintenance oral 5-ASA significantly prolongs symptomatic remission in proctitis and proctosigmoiditis.     

5-Aminosalicylic Acid and Olsalazine Inhibit Tumor Growth in a Rodent Model of Colorectal Cancer

The ability of 5-aminosalicylic acid and olsalazine to inhibit colonic aberrant crypts and tumors was investigated in 1,2-dimethylhydrazine-treated rats. The effect of these drugs on the rates of tumor apoptosis and proliferation was studied as potential mechanisms for their action. 5-Aminosalicylic acid reduced the number of aberrant crypt foci by over one third, while olsalazine had no effect on this parameter. However, both agents effectively reduced tumor number and load, increased the rate of tumor apoptosis, and reduced the rate of tumor cell proliferation. In conclusion, 5-aminosalicylic acid and olsalazine are both ultimately effective chemopreventive agents in this model; however, only 5-aminosalicylic acid inhibited the formation of aberrant crypt foci. The inhibitory effect of these agents in tumors is related to the inhibition of proliferation and the induction of apoptosis.     

Colon-specific prodrugs of 4-aminosalicylic acid for inflammatory bowel disease

Despite the advent of biological products,such as antitumor necrosis factor-αmonoclonal antibodies(infliximab and adalimumab),for treatment of moderate to severe cases of inflammatory bowel disease(IBD),most patients depend upon aminosalicylates as the conventional treatment option.In recent years,the increased knowledge of complex pathophysiological processes underlying IBD has resulted in development of a number of newer pharmaceutical agents like low-molecular-weight heparin,omega-3 fatty acids,probiotics and innovative formulations such as high-dose,oncedaily multi-matrix mesalamine,which are designed to minimize the inflammatory process through inhibition of different targets.Optimization of delivery of existing drugs to the colon using the prodrug approach is another attractive alternative that has been utilized and commercialized for 5-aminosalicylic acid(ASA)in the form of sulfasalazine,balsalazide,olsalazine and ipsalazine,but rarely for its positional isomer 4-ASA-a wellestablished antitubercular drug that is twice as potent as 5-ASA against IBD,and more specifically,ulcerativecolitis.The present review focuses on the complete profile of 4-ASA and its advantages over 5-ASA and colon-targeting prodrugs reported so far for the management of IBD.The review also emphasizes the need for reappraisal of this promising but unexplored entity as a potential treatment option for IBD.     

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.     

Relapse-Preventing Effect and Safety of Sulfasalazine and Olsalazine in Patients with Ulcerative Colitis in Remission: A Prospective, Double-blind, Randomized Multicenter Study

Forty-nine patients with ulcerative colitis in remission were entered into a prospective, double-blind, multicenter trial comparing the relapse-preventing effect and safety of 4 g sulfasalazine and 2 g olsalazine daily during 48 wk. Of the 46 evaluable patients, 23 were assigned to sulfasalazine and 23 to olsalazine. Seven of 23 patients (30.4%) relapsed on sulfasalazine and six of 23 patients (26.1%) on olsalazine (95% confidence interval of the difference -22.0% to 30.3%). The relapse-free survival curves did not differ significantly at any time during the trial period. In both treatment groups, three patients dropped out because of adverse effects. Four patients on sulfasalazine and six patients on olsalazine experienced minor adverse effects. One patient on sulfasalazine had mild leukopenia, and four patients on sulfasalazine and one patient on olsalazine had decreased levels of haptoglobin. Thus, sulfasalazine and olsalazine are equally effective in maintaining remission of ulcerative colitis and are accompanied by a similar incidence of adverse effects.