Review article: balsalazide therapy in ulcerative colitis

The aminosalicylate - folate connection

Two aminosalicylate isomers have been found to possess useful pharmacological behavior: p-aminosalicylate (PAS, 4AS) is an anti-tubercular agent that targets M. tuberculosis, and 5-aminosalicylate (5AS, mesalamine, mesalazine) is used in the treatment of ulcerative colitis (UC) and other inflammatory bowel diseases (IBD). PAS, a structural analog of pABA, is biosynthetically incorporated by bacterial dihydropteroate synthase (DHPS), ultimately yielding a dihydrofolate (DHF) analog containing an additional hydroxyl group in the pABA ring: 2'-hydroxy-7,8-dihydrofolate. It has been reported to perturb folate metabolism in M. tuberculosis, and to selectively target M. tuberculosis dihydrofolate reductase (mtDHFR). Studies of PAS metabolism are reviewed, and possible mechanisms for its mtDHFR inhibition are considered. Although 5AS is a more distant structural relative of pABA, multiple lines of evidence suggest a related role as a pABA antagonist that inhibits bacterial folate biosynthesis. Structural data support the likelihood that 5AS is recognized by the DHPS pABA binding site, and its effects probably range from blocking pABA binding to formation of a dead-end dihydropterin-5AS adduct. These studies suggest that mesalamine acts as a gut bacteria-directed antifolate, that selectively targets faster growing, more folate-dependent species.

Inflammatory bowel disease biomarkers

Inflammatory bowel disease (IBD) is characterized as chronic inflammation in the gastrointestinal tract, which includes two main subtypes, Crohn's disease and ulcerative colitis. Endoscopy combined with biopsy is the most effective way to establish IBD diagnosis and disease management. Imaging techniques have also been developed to monitor IBD. Although effective, the methods are expensive and invasive, which leads to pain and discomfort. Alternative noninvasive biomarkers are being explored as tools for IBD prognosis and disease management. This review focuses on novel biomarkers that have emerged in recent years. These serological biomarkers and microRNAs could potentially be used for disease management in IBD, thereby decreasing patient discomfort and morbidity.

Drug delivery strategies in the therapy of inflammatory bowel disease

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

Simulated comparison of topical and oral formulations of 5-aminosalicylate for the treatment of ulcerative colitis

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.

Balsalazide in treating colonic diseases

Balsalazide is the newer 5-aminosalicylic acid (5-ASA) prodrug which releases active 5-ASA only into the colon with minimal systemic absorption. The onset of action of this drug is variable, and it may take at least some days to reach clinical effectiveness. Clinical studies found balsalazide faster than mesalazine in the induction of remission, but balsalazide has no benefit compared with mesalazine in preventing relapse in the population selected. However, the high number of pills to take may affect the adherence to the treatment. This 5-ASA prodrug may be effectively used also in patients unable to tolerate other mesalamine compounds for non-hypersensitivity reasons. The costs of balsalazide capsules seem to be lower for the health system, both considering total direct healthcare costs and better outcomes, compared with patients treated with oral mesalazine. Finally, there is also some recent evidence that balsalazide may be effectively used, in combination with probiotics, in treating acute uncomplicated diverticulitis is the colon.

Comparison of mesalazine and balsalazide in induction and maintenance of remission in patients with ulcerative colitis: a meta-analysis

BACKGROUND

5-Aminosalicylates are the standard treatment for induction and maintenance of remission in mild-to-moderate ulcerative colitis. In recent years, the 5-aminosalicylic acid-containing pro-drug balsalazide has been the focus of attention.

AIM

To compare the efficacy and tolerance of balsalazide and mesalazine by meta-analysis.

METHODS

Pubmed, Embase, Scopus, Web of Science, and the Cochrane Central Register of Controlled Trials were searched for studies comparing the efficacy and/or tolerance of balsalazide with mesalazine in the management of UC. The search terms were: "mesalazine" or "5-aminosalicylic acid" and "balsalazide" and "ulcerative colitis." Data were collected from 1966 to 2007 (up to February). There was no language restriction. "Symptomatic remission," "complete remission," "relapse rate," "total adverse events," and "withdrawals because of adverse events" were the key outcomes of interest.

RESULTS

Six randomized placebo-controlled clinical trials met our criteria and were included in the meta-analysis. In these "symptomatic remission," "complete remission," "relapse rate," "total adverse events," and "withdrawals because of adverse events" were evaluated in three, three, two, five, and six of the trials, respectively. They included 653 patients consisting of 55.4% men and 44.6% women randomized to receive either balsalazide or mesalazine. Pooling of three trials for symptomatic remission yielded a significant relative risk (RR) of 1.23 (95% confidence interval of 1.03-1.47, P = 0.02). The summary RR for complete remission in three trials was 1.3 (95% CI of 1.002-1.68, P = 0.048). Pooling of two trials for the outcome of relapse yielded a non-significant RR of 0.77 (95% CI of 0.56-1.07, P = 0.12). Pooling five studies from which data for any adverse events were extracted, yielded a non-significant RR of 0.87 (95% CI of 0.75-1.001, P = 0.53). The summary RR for withdrawals because of adverse events in six trials was 0.69, a non-significant RR (95% CI of 0.37-1.29, P = 0.24).

CONCLUSION

Balsalazide is more effective than mesalazine in induction of remission, but balsalazide has no benefit compared with mesalazine in preventing relapse in the population selected. The number of patients with any adverse events and withdrawals because of severe adverse events is similar for mesalazine and balsalazide.

Balsalazide plus high-potency probiotic preparation (VSL[sharp]3) in the treatment of acute mild-to-moderate ulcerative colitis and uncomplicated diverticulitis of the colon

Balsalazide is a 5-amino salicylic acid prodrug well-tolerated and effective in treating acute ulcerative colitis. VSL[sharp]3, a high-potency probiotic mixture, has proved to be effective in preventing flare-ups of chronic pouchitis and in obtaining remission of mild-to-moderate ulcerative colitis. Recent studies found the association of low-dose balsalazide/VLS no. 3 effective in treating mild-to-moderate ulcerative colitis and in preventing the recurrence of uncomplicated diverticulitis of the colon. In this paper, the framework for using this association to treat ulcerative colitis or to prevent the recurrence of colonic diverticulitis is reviewed, and 2 studies on this therapeutic approach are briefly summarized.

Balsalazide and/or high-potency probiotic mixture (VSL#3) in maintaining remission after attack of acute, uncomplicated diverticulitis of the colon

BACKGROUND AND AIMS

The role of probiotics in the treatment of diverticulitis is still not known. The aim of our study was to investigate whether balsalazide and/or VSL#3 is effective in preventing diverticulitis recurrence.

MATERIALS AND METHODS

In this pilot study, 30 consecutive patients (19 males, 11 females, mean age 60.1 years, range 47-75 years) affected by uncomplicated diverticulitis of the colon were monitored. After obtaining remission, the patients were randomly assigned to one of the following groups as follows: group A, balsalazide 2.25 g daily for 10 days every month plus VSL#3 450 billions/day for 15 days every month and group B, VSL#3 alone 450 billions/day for 15 days every month. Primary end-point was considered the maintaining of remission throughout a 12-month follow-up. Secondary end-points considered were (1) the assessment of the overall scores at the end of the follow-up and (2) the effects of the two different treatments with regards to every symptom assessed.

RESULTS/FINDINGS

One group A patient was withdrawn from the study at the 6th month and one group B patient was lost at the 6th month of follow-up. One group A patient (6.66%) showed relapse of symptoms at the 10th month of follow-up. At the end of follow-up, 11 patients were completely symptom-free (73.33%), whilst 2 patients complained of only mild, recurrent symptoms (13%). Two group B patients (13.33%) showed relapse of the disease at the 5th and 8th month of follow-up, respectively. At the end of follow-up, 8 patients were completely symptom-free (60%), 2 patients complained of mild, recurrent symptoms (13.33%), 1 patient (6.66%) complained of mild but continuous symptoms. No side effects were recorded throughout the follow-up in both groups.

INTERPRETATION/CONCLUSIONS

Combination probiotic/anti-inflammatory drug was found better than probiotic treatment in preventing relapse of uncomplicated diverticulitis of the colon, even if without statistical significance.

Medical therapy for ulcerative colitis 2004

There continue to be evolutionary changes in the management of ulcerative colitis despite the fact that, aside from a variety of aminosalicylate formulations, no new therapies have been approved over the past few decades. Nevertheless, debates continue regarding the optimization of treatment with aminosalicylates and the short- and long-term benefits of immunomodulation in ulcerative colitis. This article focuses on the most recent clinical studies pertaining to the management of ulcerative colitis and explores both the advances and controversies pertaining to aminosalicylate therapy, corticosteroids, cyclosporine, and the purine antimetabolites. Novel therapeutic approaches--including preliminary experience with biological therapies directed at tumor necrosis factor and other cytokines, adhesion molecules, growth factors, and probiotics--will be reviewed. Recent data regarding potential chemoprevention in long-standing ulcerative colitis and management of postoperative complications and pouchitis will also be discussed.

Systematic review: the pharmacokinetic profiles of oral mesalazine formulations and mesalazine pro-drugs used in the management of ulcerative colitis

AIM

: To quantify through systematic review the pharmacokinetic profiles of the oral delayed release and sustained release mesalazine (5-aminosalicylate, 5ASA) formulations (Asacol, Salofalk, Mesasal, Claversal, Pentasa) and pro-drugs (sulfasalazine, olsalazine, balsalazide) used in the management of ulcerative colitis.

METHODS

: Selected articles had: (1) adult healthy volunteers or patients with ulcerative colitis and (2) quantification of pharmacokinetic data to include, at a minimum, urinary excretion of total 5ASA [5ASA plus N-Acetyl-5ASA (N-Ac-5ASA)].

DATA COLLECTION AND ANALYSIS

: Pharmacokinetic data (Tmax, Cmax, AUC, urinary excretion, faecal excretion) of 5ASA, its major metabolite N-Acetyl-5ASA, total 5ASA, and the parent pro-drug compounds was extracted.

MAIN RESULTS

: The summary results for urinary excretion of total 5ASA over 24-96 h in all subjects (either mean or median) were: sulfasalazine mean 11-33% or median 22%; olsalazine mean 14-31% or median 16-27%; balsalazide mean 12-35% or median 20%; Asacol mean 10-35% or median 18-40%; Pentasa mean 15-53% or median 23-34%; Salofalk, Mesasal and Claversal mean 27-56% or median 31-44%. The summary results for faecal excretion of total 5ASA over 24-96 h in all subjects (either mean or median) were: sulfasalazine mean 23-75% or median 38%; olsalazine mean 47-50% or median 17-36%; balsalazide mean 46% or median 22%; Asacol mean 40-64% or median 20-56%; Pentasa mean 12-51% or median 39-59%; Salofalk, Mesasal and Claversal mean 37-44% or median 23-35%.

CONCLUSIONS

: The systemic exposure to 5ASA, as measured by urinary excretion of total 5ASA, and the faecal excretion of total 5ASA is comparable for all oral mesalazine formulations and pro-drugs. Thus, selection of a mesalazine therapy for the treatment of ulcerative colitis should be based on other factors such as efficacy, dose-response, toxicity of the parent compound and its metabolites, compliance issues related to dose forms and dosing schedules, and costs.

Balsalazide: a review of its therapeutic use in mild-to-moderate ulcerative colitis

The aminosalicylate balsalazide is a prodrug which is metabolised by bacterial azo reductases in the colon to release its therapeutically active moiety mesalazine [mesalamine (US) or 5-aminosalicylic acid] and an inert carrier molecule. The systemic absorption of balsalazide and its metabolites is not required for the therapeutic efficacy of the drug, and has been demonstrated to be limited. Data from well designed trials with a duration of 8 to 12 weeks show that oral balsalazide 6.75 g/day is as effective as (two trials) or more effective than (one trial) oral delayed-release (pH-dependent) mesalazine 2.4 g/day and appears to be as effective as oral sulfasalazine 3 g/day in the treatment of active mild-to-moderate ulcerative colitis. In addition, balsalazide appears to have a faster onset of action than mesalazine. Furthermore, balsalazide was as effective as delayed-release mesalazine (dosages used were 1.2 and 1.5 g/day, where 1.6 g/day is recommended) and oral sulfasalazine 2 g/day (recommended dosage) in the prevention of relapse in ulcerative colitis in remission after 6 to 12 months of treatment; the balsalazide dosage was 3 g/day versus mesalazine and 2 g/day versus sulfasalazine. Although not well established, additional benefits may be achieved with balsalazide dosages up to 6 g/day. Data from well designed, 2- to 12-month trials show that balsalazide is well tolerated by patients with ulcerative colitis in both acute and maintenance indications, and is better tolerated than standard formulations of sulfasalazine at therapeutically relevant dosages.

CONCLUSION

Balsalazide is a well tolerated and effective first-line therapeutic option for patients with ulcerative colitis, both for the treatment of active mild-to-moderate disease and as maintenance therapy to prevent disease relapse.