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

Aminosalicylates

Aminosalicylates are the most common drugs for the primary treatment of inflammatory bowel disease. Various pro-drugs and formulations were developed in order to improve pharmacological profiles, optimize bioavailability and to gain highest efficacy in the treatment of ulcerative colitis (UC) and Crohn's disease. In vitro studies have greatly contributed to the understanding of the molecular actions in vivo and clinical studies have proven aminosalicylates to be effective and safe. This review summarizes the current knowledge on the molecular, pharmacological and clinical properties of aminosalicylates with respect to chemoprevention for UC-associated colorectal cancer.

Review article: delivery and efficacy of topical 5-aminosalicylic acid (mesalazine) therapy in the treatment of ulcerative colitis

BACKGROUND

The use of topical therapy in the treatment of ulcerative colitis has declined in recent years despite evidence of good efficacy.

AIMS

To review US prescription trends for 5-aminosalicylic acid (5-ASA) since the US approval of Asacol extended-release oral mesalazine (mesalamine) in 1992; to estimate the optimal level of 5-ASA exposure in the distal colon; to determine factors influencing distal colonic exposures; and to compare the effectiveness of different 5-ASA formulations (oral, topical suspension, foam, suppositories) in clinical trials.

METHODS

Review of clinical trials, physiologic studies and prescription trends of various mesalazine formulations for treatment of distal ulcerative colitis.

RESULTS

Between 1992 and 2009, prescriptions for oral mesalazine increased sixfold, whereas topical suspensions declined by 10%. In clinical trials, topical therapy resulted in higher remission and clinical response rates than oral therapy, with trends to earlier improvement. The mucosal concentrations of 5-ASA achieved by topical agents in the distal colon were up to 200-fold higher than those achieved by oral administration alone. Despite active colitis, over 40% of a topically administered 4 g 5-ASA suspension (equal to 1.6 g) reached the sigmoid colon. This likely represents a therapeutic exposure of 5-ASA. Although topical therapies are less convenient than oral medications, treatment algorithms have failed to take into account quality of life improvements resulting from more rapid and complete treatment response.

CONCLUSIONS

Topical mesalazine therapy is superior to oral therapy in distal ulcerative colitis for both therapeutic response and drug delivery. Practice patterns should be re-evaluated in light of this information.

New light on the anti-colitic actions of therapeutic aminosalicylates: the role of heme oxygenase

Although a variety of pharmaceutical preparations of aminosalicylate are commonly used in the clinic for the control of inflammatory bowel disease, the mechanisms underlying their therapeutic actions remain unclear. Recent in vivo and in vitro studies have demonstrated that 5-aminosalicylic acid (5-ASA), regarded as the active moiety in aminosalicylate preparations such as sulfasalazine, can induce the heat shock protein, heme oxygenase-1 (HO-1) and up-regulate HO enzyme activity in the colon. As HO-1 can produce endogenous anti-oxidant and anti-inflammatory moieties such as bilirubin and carbon monoxide (CO), these findings suggest a novel mechanism of action for aminosalicylates, acting as anti-colitic agents through the up-regulation of HO-1 enzyme expression and activity.

Influence of 5-aminosalicylic acid on 6-thioguanosine phosphate metabolite levels: a prospective study in patients under steady thiopurine therapy

BACKGROUND AND PURPOSE

5-aminosalicylate (5-ASA) raises levels of 6-thioguanine nucleotides (6-TGN), the active metabolites of thiopurines such as azathioprine (AZA). Changes in levels of each individual TGN - 6-thioguanosine mono-, di- and triphosphate (6-TGMP, 6-TGDP, 6-TGTP) - and of 6-methylmercaptopurine ribonucleotides (6-MMPR) after 5-ASA are not known.

EXPERIMENTAL APPROACH

Effects of increasing 5-ASA doses on AZA metabolites were investigated prospectively in 22 patients with inflammatory bowel disease in 4-week study periods. Patients started with 2 g 5-ASA daily, and then were increased to 4 g daily and followed by a washout period. Thiopurine doses remained unchanged throughout the entire study. Levels of 6-TGMP, 6-TGDP, 6-TGTP and 6-MMPR as well as of 5-ASA and N-acetyl-5-aminosalicylic acid (N-Ac-5-ASA) were determined each study period.

KEY RESULTS

Median baseline levels in 17 patients of 6-TGDP, 6-TGTP and 6-MMPR were 52, 319 and 1676 pmol per 8 x 10(8) red blood cells respectively. After co-administration of 2 g 5-ASA daily, median 6-TGDP and 6-TGTP levels increased but median 6-MMPR levels were unchanged. Increasing 5-ASA to 4 g daily did not affect median 6-TGDP and 6-TGTP levels, but median 6-MMPR levels decreased. After discontinuation of 5-ASA, both 6-TGDP and 6-TGTP levels decreased and median 6-MMPR levels increased. The 6-TGTP/(6-TGDP+6-TGTP)-ratio did not change during the study, but 6-MMPR/6-TGN ratios decreased.

CONCLUSIONS AND IMPLICATIONS

Individual 6-TGN metabolites increased after addition of 5-ASA, but 6-MMPR-levels and the 6-MMPR/6-TGN ratios decreased. Further studies are needed to decide whether this pharmacokinetic interaction would result in improvement of efficacy and/or increased risk of toxicity of AZA.

Prediction of 6-thioguanine nucleotides levels in Japanese patients with inflammatory bowel diseases during long-term thiopurine administration

BACKGROUND

The monitoring of 6-thioguanine nucleotides (6-TGN) levels is warranted during thiopurine therapy for patients with inflammatory bowel diseases.

AIMS

The aim of this study was to elucidate the parameters that can predict the 6-TGN levels among Japanese patients with inflammatory bowel diseases undergoing thiopurine therapy.

MATERIAL AND METHODS

The 6-TGN levels were measured in 54 patients with inflammatory bowel diseases (32 with ulcerative colitis and 22 with Crohn's disease), who had been administered azathioprine or 6-mercaptopurine for more than 90 days. Possible correlations between the hematologic parameters and 6-TGN levels were investigated. The clinical and hematologic variables were evaluated to determine the 6-TGN levels of less than or over 235 pmol/8 x 10(8) RBCs.

RESULTS

The 6-TGN levels correlated significantly with changes in the mean corpuscular volume (R = 0.423, p = 0.001) and the lymphocyte counts (R = -0.280, p = 0.04). A multivariate analysis revealed changes in the mean corpuscular volume (OR: 1.22, 95% CI: 1.07-1.40) and hemoglobin levels (OR: 0.59, 95% CI: 0.35-0.99) to be factors predictive of the 6-TGN levels. An increase in the mean corpuscular volume of 3.5 fl was determined to be the most preferable cut-off value to distinguish patients with 6-TGN >or= 235 pmol/8 x 10(8) RBCs from those with a lower concentration.

CONCLUSIONS

Changes in the mean corpuscular volume are considered to be predictive of the 6-TGN levels in patients with inflammatory bowel diseases receiving thiopurine therapy.

Once-daily dosing of delayed-release oral mesalamine (400-mg tablet) is as effective as twice-daily dosing for maintenance of remission of ulcerative colitis

BACKGROUND & AIMS

The practice of dosing mesalamines in divided doses for the treatment of ulcerative colitis (UC) began with sulfasalazine and was driven by sulfapyridine toxicity. This convention and the assumption that dosing multiple times a day is necessary to treat UC had not been challenged until recently. This study was conducted to determine the efficacy and safety of once-daily dosing of delayed-release mesalamine (Asacol 400-mg tablets) compared with twice-daily dosing for maintaining remission in UC patients.

METHODS

A multicenter, randomized, investigator-blinded, 12-month, active-control trial was conducted to assess the noninferiority of delayed-release mesalamine 1.6-2.4 g/day administered once daily compared with twice daily in patients with mild-to-moderate UC currently in clinical remission. The primary end point was maintenance of clinical remission at month 6.

RESULTS

A total of 1023 patients were randomized and dosed. The primary objective of noninferiority was met. At month 6, 90.5% of patients receiving once-daily dosing had maintained clinical remission, compared with 91.8% of patients receiving twice-daily dosing (95% confidence interval for twice daily - once daily, -2.3 to 4.9). At month 12, 85.4% of patients receiving once-daily dosing had maintained clinical remission, compared with 85.4% of patients receiving twice-daily dosing (95% confidence interval for twice daily - once daily, -4.6 to 4.7). Both regimens had low rates of withdrawals as a result of adverse events and serious adverse events.

CONCLUSIONS

Once-daily dosing of delayed-release mesalamine at doses of 1.6-2.4 g/day was shown to be as effective as twice-daily dosing for maintenance of clinical remission in patients with UC.

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.

Mesalazine vanishing time from rectal mucosa following its topical administration

To investigate how long and how much Mesalazine (M) is available inside the rectal mucosa following its topical instillation, in patients (pts) with Ulcerative Colitis (UC). Two rectal biopsies for M concentration were obtained from 45 UC pts in clinical remission and on oral M treatment (OT), before a 4g enema randomly given to consentient pts every day (Group A, 15 pts), every 2 days (Group B, 15 pts) and every 3 days (Group C, 15 pts). Two additional biopsies were taken 1, 2 and 3 days after the last enema in group A, B and C respectively, at least 10 days later. All biopsies were immediately frozen at -80°C for later assay by means of high-performance light chromatography (HPLC). Data were analyzed using Student's t-test. Mean values±standard deviation of M mucosal concentration (ng/mg of tissue) were 1.32±1.41, 56.1±39.2, 9.65±6.60, and 6.39±5.03 in pts receiving OT alone, groups A, B and C, respectively. Values in Group A were statistically higher (p<0.001) than those in Groups B and C while no differences were found between Groups B and C. Values of OT were lower than groups A, B and C. M mucosal concentration rapidly decreases 2 days after a 4g enema, but after three days is still higher than OT alone. These results may provide data which would be useful to plan topical therapy and improve adherence to treatment.

An investigation of medication adherence to 5-aminosalicylic acid therapy in patients with ulcerative colitis, using self-report and urinary drug excretion measurements

BACKGROUND

Non-adherence to 5-aminosalicylic acid (5-ASA) medication can limit the established benefits of this therapy in ulcerative colitis (UC).

AIM

To determine rates and predictors of non-adherence to 5-ASA therapy in UC patients.

METHODS

Medication adherence was assessed using self-report data and urinary drug excretion measurements. Participants completed a study-specific questionnaire and two validated questionnaires: Beliefs about Medicine Questionnaire (BMQ)-Specific and Satisfaction with Information about Medicines Scale.

RESULTS

A total of 169 participants provided self-report adherence data; 151 also provided urine samples. Adherence rates were 111/151 (68%) according to self-report and 90/151 (60%) according to urine analysis, but the two measures were not correlated (chi(2) = 0.12, P = 0.725). Logistic regression identified a significant association between self-reported non-adherence and younger age [odds ratio (OR) for increased age 0.954, 95% confidence interval (CI) 0.932-0.976] and also doubts about personal need for medication (OR for BMQ - Specific Necessity scores 0.578, 95% CI 0.366-0.913). For non-adherence based on urine analysis, only South Asian ethnicity was independently associated with non-adherence (OR 2.940, 95% CI 1.303-6.638).

CONCLUSIONS

Our observations confirm the difficulty of accurately assessing medication adherence. Nonmodifiable (younger age, South Asian ethnicity) and potentially modifiable (medication beliefs) predictors of non-adherence were identified.

Patient considerations in the management of ulcerative colitis: role of once-daily MMX mesalamine

Mesalamine and its derivatives are effective and well-tolerated therapies for ulcerative colitis. However, patient adherence to traditional mesalamine-based therapy is poor, and is often limited by heavy pill burdens and frequent dosing intervals. This can lead to ineffective disease control, impaired quality of life, and preventable morbidity and mortality. Previous studies have suggested that a once-daily mesalamine regimen would be strongly adhered to in the outpatient setting, but at that time no such formulation of mesalamine existed. In 2007, clinical trial data showed a novel, once-daily, multi-matrix (MMX) formulation of mesalamine to be effective in both remission induction and remission maintenance. This breakthrough in drug delivery allowed the unification of an effective therapeutic with a formulation that enables outpatients to be increasingly adherent to their medication. In theory, this might result in improved outpatient disease control and a decreased number of flares. As the use of MMX mesalamine increases, studies examining the outpatient community adherence rate need to be performed.

Small intestinal efflux mediated by MRP2 and BCRP shifts sulfasalazine intestinal permeability from high to low, enabling its colonic targeting

Sulfasalazine is characterized by low intestinal absorption, which essentially enables its colonic targeting and therapeutic action. The mechanisms behind this low absorption have not yet been elucidated. The purpose of this study was to investigate the role of efflux transporters in the intestinal absorption of sulfasalazine as a potential mechanism for its low small-intestinal absorption and colonic targeting following oral administration. The effects of P-glycoprotein (P-gp), multidrug resistance-associated protein 2 (MRP2), and breast cancer resistance protein (BCRP) inhibitors on sulfasalazine bidirectional permeability were studied across Caco-2 cell monolayers, including dose-response analysis. Sulfasalazine in vivo permeability was then investigated in the rat jejunum by single-pass perfusion, in the presence vs. absence of inhibitors. Sulfasalazine exhibited 19-fold higher basolateral-to-apical (BL-AP) than apical-to-basolateral (AP-BL) Caco-2 permeability, indicative of net mucosal secretion. MRP2 inhibitors (MK-571 and indomethacin) and BCRP inhibitors [fumitremorgin C (FTC) and pantoprazole] significantly increased AP-BL and decreased BL-AP sulfasalazine Caco-2 transport in a concentration-dependent manner. No effect was observed with the P-gp inhibitors verapamil and quinidine. The IC50 values of the specific MRP2 and BCRP inhibitors MK-571 and FTC on sulfasalazine secretion were 21.5 and 2.0 microM, respectively. Simultaneous inhibition of MRP2 and BCRP completely abolished sulfasalazine Caco-2 efflux. Without inhibitors, sulfasalazine displayed low (vs. metoprolol) in vivo intestinal permeability in the rat model. MK-571 or FTC significantly increased sulfasalazine permeability, bringing it to the low-high permeability boundary. With both MK-571 and FTC present, sulfasalazine displayed high permeability. In conclusion, efflux transport mediated by MRP2 and BCRP, but not P-gp, shifts sulfasalazine permeability from high to low, thereby enabling its colonic targeting and therapeutic action. To our knowledge, this is the first demonstration of intestinal efflux acting in favor of oral drug delivery.

A dynamic model of colonic concentrations of delayed-release 5-aminosalicylic acid (Asacol)

BACKGROUND

5-ASA in a pH sensitive tablet (Asacol) is administered as three doses/day to treat ulcerative colitis. Once daily dosing may improve patient adherence. Simulation of colonic levels of 5-ASA can be used to compare dosing regimens.

AIM

To create a dynamic model of colonic concentrations of delayed-release 5-aminosalicylic acid (Asacol).

METHODS

Using published data, we created a computer model with STELLA software to simulate amounts of colonic 5-ASA in the total colon, right, transverse, descending and sigmoid/rectum after daily and three time/day Asacol.

RESULTS

The model predicted similar total and regional amounts of 5-ASA with both regimens. Distribution of 5-ASA was 38% in the right colon, 33% in the transverse colon and 14% each in the descending and sigmoid/rectal colon. Simulated increases in colonic motility and defecation rate exaggerated this 5-ASA distribution, resulting in negligible amounts of 5-ASA in the sigmoid/rectal region.

CONCLUSIONS

This computer model suggests that Asacol can be administered as a single daily dose. The model supports experimental and clinical observations that alternate dose or route of administration may be necessary to achieve adequate 5-ASA amounts in the distal colon during acute exacerbations of ulcerative colitis. This simulation cannot account for all sources of variability in the clinical setting, but provides a rationale for further investigation.

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.

[Effectiveness of new, once-daily 5-aminosalicylic acid in the treatment of ulcerative colitis]

5-aminosalicylate (5-ASA) agents remain the mainstay treatment in ulcerative colitis (UC). A number of oral 5-ASA agents is commercially available, including azo-bond pro-drugs such as sulfasalazine, olsalazine and balsalazide, and delayed- and controlled-release forms of mesalazine. In addition, the effectiveness of oral therapy relies on good compliance, which may be adversely affected by frequent daily dosing and a large number of tablets. Furthermore, poor adherence has been shown to be an important barrier to successful management of patients with UC. Recently, new, once-daily formulations of mesalazine including the unique multi-matrix delivery system and mesalazine granules were proven to be efficacious in inducing and maintaining remission in mild-to-moderate UC, with a good safety profile comparable to that of other oral mesalazine formulations. In addition, they offer the advantage of low pill burden and may contribute to increased long-term compliance and treatment success in clinical practice and might potentially further contribute to a decline in the risk for UC-associated colon cancers. In this systematic review, the authors summarize the available literature on the short- and medium-term efficacy and safety of the new once-daily mesalazine formulations.

Renal effects of long-term treatment with 5-aminosalicylic acid

BACKGROUND

A number of case reports link the use of 5-aminosalicylic acid (5-ASA) to interstitial nephritis in patients with inflammatory bowel disease (IBD).

OBJECTIVE

To investigate whether the long-term use of 5-ASA has harmful effects on renal function in patients with IBD.

METHODS

A retrospective analysis of 171 consecutive outpatients with Crohn's disease or ulcerative colitis was conducted. Serum creatinine levels and body weight were measured before and after treatment to calculate the creatinine clearance (CrCl) rate.

RESULTS

In 171 patients (93 women, 78 men), the mean (+/- SD) dose of 5-ASA was 3.65+/-0.85 g/day with a cumulative dose of 11+/-7.7 kg over an interval of 8.4+/-5.9 years. Serum creatinine concentrations increased from 76.8 micromol/L to 88.7 micromol/L (n=171; P<0.0001) and the CrCl rate fell significantly from 104.6 mL/min to 93.1 mL/min (n=81; P<0.0001). There was one case of interstitial nephritis reported. Treatment groups included mesalamine (74.3%), sulfasalazine (15.2%) and combination (sulfalsalazine/mesalamine [10.5%]) with treatment durations of 7.2+/-4.5, 12.3+/-8.7 and 11.2+/-6.7 years, respectively. The duration of treatment was the most important covariate for change in CrCl and when analyzed by treatment group, those treated with sulfasazine had a strong correlation (r=-0.54, P=0.0145), while nonsignificant in the mesalamine group (r=0.06, P=0.7017). The decline in CrCl was negatively correlated with the pretreatment CrCl rate (r=-0.34; P=0.0024) and positively correlated with the mean daily dose of 5-ASA (r=0.32; P=0.0034).

CONCLUSION

The present study is the first to demonstrate a significant dose- and treatment duration-dependant decline in CrCl. The risks need to be further evaluated because 5-ASA is widely used for long-term maintenance therapy in patients with IBD.

Ulcerative colitis: current medical therapy and strategies for improving medication adherence

Ulcerative colitis (UC) is chronic inflammation of large intestine and often requires lifelong medication. Medical therapy aims to induce and maintain a clinical remission, reduce the risk of colorectal cancer and improve quality of life. Aminosalicylates are currently the first choice therapy both for the induction and the maintenance of remission in the patients with mild-to-moderate UC. For moderate-to-severe cases or those who do not respond to aminosalicylate therapy, additional treatment options including corticosteroids, immunomodulators, biological agents, cyclosporin, tacrolimus and surgery are available. Poor adherence to medication has been an important barrier to successful management of UC. Nonadherence has been associated with increased relapse rates, higher risk of colorectal cancer, poor quality of life and significantly increased healthcare costs. Therefore, improving adherence to medication is an important approach for a better care of the patients with UC. Definitive strategies are required to help the patients effectively self manage their disease and improve adherence. This review examines current medical therapy for UC, research progresses on medication adherence and the possible strategies for improving adherence in these patients.

SIMDOT-AbMe: microphysiologically based simulation tool for quantitative prediction of systemic and local bioavailability of targeted oral delivery formulations

The purpose of this study was to develop a physiologically based simulation tool that is able to predict local as well as systemic bioavailability of 5-aminosalicylic acid (5-ASA)-targeted delivery formulations using the existing understanding of the transport and metabolism mechanisms of 5-ASA. The model accounts for active and passive transcellular transport (absorptive and efflux), passive paracellular transport, intestinal biotransformation, and systemic metabolism and clearance. The intestinal physiology was represented by transverse segments for ileum and proximal colon and longitudinal compartments for the microphysiology of the intestinal tissue. The tool, equipped with an optimization routine that enables tuning model parameters, was developed in Matlab and uses a user-friendly graphical interface for data input and output. Physiologic and kinetic model parameters were estimated either from literature monolayer transport studies using nonlinear curve fitting or obtained directly from the literature. 5-ASA clinical pharmacokinetic profiles of a once-daily (one 4-g/day dose) and twice-daily (two 2-g/day doses) dosing regimen were used to partially calibrate and validate the model, respectively. Simulation results showed that drug C(max) in the gut mucosal layers reached a higher level and was achieved sooner than in the systemic blood level. The computed relative local bioavailability with respect to the systemic bioavailability was 0.063. With use of the model, the relative local bioavailability of different formulations can be established for fast performance verification of new preparations based on measured systemic bioavailability. These types of models play a critical role in designing such preparations and rapidly assessing their effectiveness and will foster efficient experimental designs, saving time and resources.

Review article: 5-aminosalicylate formulations for the treatment of ulcerative colitis--methods of comparing release rates and delivery of 5-aminosalicylate to the colonic mucosa

BACKGROUND

Many oral 5-aminosalicylic acid (5-ASA) formulations are designed to maximize 5-ASA release in the colon where it acts topically on the colonic mucosa. Delayed-release formulations and azo-prodrugs minimize 5-ASA absorption in the upper gastrointestinal (GI) tract.

AIMS

To review methods for assessing 5-ASA release and colonic distribution from oral formulations, and the potential use of this information for guiding clinical decisions.

METHODS

PubMed and recent conference abstracts were searched for articles describing techniques used to assess 5-ASA release from ulcerative colitis (UC) therapies.

RESULTS

In-vitro GI models, although unable to simulate more complex aspects of GI physiology, can provide useful data on 5-ASA release kinetics and bioaccessibility. Gamma-scintigraphy is useful for investigating GI disintegration of different formulations, but may not accurately reflect 5-ASA distribution. Plasma pharmacokinetic studies provide data on systemic exposure, but not on colonic distribution or mucosal uptake. Mucosal biopsies provide direct evidence of colonic distribution and may predict clinical efficacy, but must be interpreted cautiously because of considerable inter-subject variability and other confounding factors.

CONCLUSION

While assessment of 5-ASA release is important, limitations of individual measurement techniques mean that randomized clinical studies in UC patients remain the best guide for dosing and treatment regimen decisions.

Mesalamine with MMX technology for the treatment of ulcerative colitis

Mesalamine with MMX Multi Matrix System technology (hereafter referred to as MMX mesalamine) is an oral, high-strength (1.2 g/tablet), once-daily formulation of 5-aminosalicylic acid used for the treatment of ulcerative colitis. This new formulation has been designed to provide delayed and prolonged 5-aminosalicylic acid release throughout the colon. In recent clinical studies, MMX mesalamine (taken as a once-daily dose of 2.4 or 4.8 g) effectively induced clinical remission and mucosal healing versus placebo in patients with active, mild-to-moderate ulcerative colitis. Once remission was achieved, MMX mesalamine effectively maintained disease remission in the majority of patients for at least 12 months. In this paper, we comprehensively review the results of studies exploring the clinical pharmacology, efficacy and safety of MMX mesalamine in patients with ulcerative colitis, and examine the implications of these findings on clinical practice.

Traditional corticosteroids for induction of remission in Crohn's disease

BACKGROUND

Historically, corticosteroids have been the most commonly used class of medication for induction of remission in Crohn's disease (CD). Corticosteroids down regulate production of inflammatory cytokines and interfere with NF-kappaB production, thereby blunting inflammatory response.

OBJECTIVES

The primary objective was to systematically review the efficacy and safety of traditional corticosteroids (given orally or intravenously) for induction of remission in CD.

SEARCH STRATEGY

The following electronic databases were searched: MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, the Cochrane Inflammatory Bowel Disease and Functional Bowel Disorders (IBD/FBD) Group Specialized Trial Register, and ClinicalTrials.gov. No language restrictions were applied. Reference lists of trials and review articles, as well as recent proceedings from major gastroenterology meetings were manually searched.

SELECTION CRITERIA

Randomized, controlled clinical trials of traditional, systemic corticosteroids for the induction of remission of active CD were included in this review. Control groups included patients receiving either placebo or 5-aminosalicylates (5-ASA). The study population included patients of any age with active CD (as defined by the study authors or validated clinical activity indices), receiving any formulation of systemically available corticosteroid by any oral or parenteral methods of delivery. The primary outcome was induction of remission of CD. Secondary outcomes included clinical response, change in mean CDAI, adverse events and the proportion of patients withdrawing due to adverse events.

DATA COLLECTION AND ANALYSIS

Two independent investigators reviewed studies for eligibility, extracted the data and assessed study quality using Jadad's criteria. A random or fixed effects model was chosen based on an assessment of heterogeneity, and studies were weighted using the DerSimonian & Laird or the Mantel-Haenszel method accordingly. Meta-analysis was performed using RevMan 4.2.10 software.

MAIN RESULTS

Two studies compared corticosteroids to placebo and six studies compared corticosteroids to 5-ASA. Corticosteroids were found to be significantly more effective than placebo at inducing remission in CD (RR 1.99; 95% CI 1.51 to 2.64; P < 0.00001). Corticosteroids were found to be more effective than 5-ASA at inducing remission in studies with long follow-up duration (i.e. > 15 weeks; RR 1.65; 95% CI 1.33 to 2.03; P < 0.00001). Corticosteroids induced adverse events in a higher proportion of patients than placebo (RR 4.89; 95% CI 1.98 to 12.07; P = 0.0006), or low-dose 5-ASA (RR 2.38; 95% CI 1.34 to 4.25; P = 0.003). No difference existed in the proportion of patients experiencing adverse events when steroids were compared to high-dose 5-ASA. Steroids did not induce more study withdrawals due to adverse events than either placebo or 5-ASA.

AUTHORS' CONCLUSIONS

Corticosteroids are effective for induction of remission in patients with CD, particularly when used for more than 15 weeks. Although corticosteroids cause more adverse events than either placebo or low-dose 5-ASA, these adverse events did not lead to increased study withdrawal in the included studies. Further information is required to determine the optimal duration of treatment and tapering protocol to maximize the efficacy of treatment with corticosteroids. Additionally, further study is required to determine whether corticosteroids are more effective in patients with certain phenotypes or when administered intravenously.

Traditional corticosteroids for induction of remission in Crohn's disease

BACKGROUND

Historically, corticosteroids have been the most commonly used class of medication for induction of remission in Crohn's disease (CD). Corticosteroids down regulate production of inflammatory cytokines and interfere with NF-kappaB production, thereby blunting inflammatory response.

OBJECTIVES

The primary objective was to systematically review the efficacy and safety of traditional corticosteroids (given orally or intravenously) for induction of remission in CD.

SEARCH STRATEGY

The following electronic databases were searched: MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, the Cochrane Inflammatory Bowel Disease and Functional Bowel Disorders (IBD/FBD) Group Specialized Trial Register, and ClinicalTrials.gov. No language restrictions were applied. Reference lists of trials and review articles, as well as recent proceedings from major gastroenterology meetings were manually searched.

SELECTION CRITERIA

Randomized, controlled clinical trials of traditional, systemic corticosteroids for the induction of remission of active CD were included in this review. Control groups included patients receiving either placebo or 5-aminosalicylates (5-ASA). The study population included patients of any age with active CD (as defined by the study authors or validated clinical activity indices), receiving any formulation of systemically available corticosteroid by any oral or parenteral methods of delivery. The primary outcome was induction of remission of CD. Secondary outcomes included clinical response, change in mean CDAI, adverse events and the proportion of patients withdrawing due to adverse events.

DATA COLLECTION AND ANALYSIS

Two independent investigators reviewed studies for eligibility, extracted the data and assessed study quality using Jadad's criteria. A random or fixed effects model was chosen based on an assessment of heterogeneity, and studies were weighted using the DerSimonian & Laird or the Mantel-Haenszel method accordingly. Meta-analysis was performed using RevMan 4.2.10 software.

MAIN RESULTS

Two studies compared corticosteroids to placebo and six studies compared corticosteroids to 5-ASA. Corticosteroids were found to be significantly more effective than placebo at inducing remission in CD (RR 1.99; 95% CI 1.51 to 2.64; P < 0.00001). Corticosteroids were found to be more effective than 5-ASA at inducing remission in studies with long follow-up duration (i.e. > 15 weeks; RR 1.65; 95% CI 1.33 to 2.03; P < 0.00001). Corticosteroids induced adverse events in a higher proportion of patients than placebo (RR 4.89; 95% CI 1.98 to 12.07; P = 0.0006), or low-dose 5-ASA (RR 2.38; 95% CI 1.34 to 4.25; P = 0.003). No difference existed in the proportion of patients experiencing adverse events when steroids were compared to high-dose 5-ASA. Steroids did not induce more study withdrawals due to adverse events than either placebo or 5-ASA.

AUTHORS' CONCLUSIONS

Corticosteroids are effective for induction of remission in patients with CD, particularly when used for more than 15 weeks. Although corticosteroids cause more adverse events than either placebo or low-dose 5-ASA, these adverse events did not lead to increased study withdrawal in the included studies. Further information is required to determine the optimal duration of treatment and tapering protocol to maximize the efficacy of treatment with corticosteroids. Additionally, further study is required to determine whether corticosteroids are more effective in patients with certain phenotypes or when administered intravenously.

Balsalazide disodium for the treatment of ulcerative colitis

5-aminosalicylates remain the first-line treatment for patients with ulcerative colitis. A number of formulations are available for the treatment of active ulcerative colitis, including encapsulated mesalazine and mesalazine in combination with other molecules. Balsalazide is an aminosalicylate prodrug that releases mesalazine in the colon, thus exerting its multiple anti-inflammatory effects in areas of colitis. This review will examine the pharmacological and therapeutic features of balsalazide as an anti-inflammatory agent in ulcerative colitis. The introduction of novel aminosalicylate formulations and an appreciation of their molecular mode of action, has renewed interest in these agents in both maintenance of disease remission and cancer prevention.

Delayed-release oral mesalamine 4.8 g/day (800 mg tablets) compared to 2.4 g/day (400 mg tablets) for the treatment of mildly to moderately active ulcerative colitis: The ASCEND I trial

BACKGROUND

Delayed-release oral mesalamine 2.4 g/day to 4.8 g/day has been shown to be effective in treating mildly to moderately active ulcerative colitis (UC), but it is unknown whether an initial dose of 4.8 g/day is more effective than 2.4 g/day in patients with mildly to moderately active UC and in the subgroup with moderate disease.

PATIENTS AND METHODS

A six-week, multicentre, randomized, double-blind, controlled trial assessing the safety and clinical efficacy of a new dose (ASCEND I) of medication randomly assigned 301 adults with mildly to moderately active UC to delayed-release oral mesalamine 2.4 g/day (400 mg tablet [n=154]) or 4.8 g/day (800 mg tablet [n=147]). The primary efficacy end point was overall improvement (ie, treatment success), defined as complete remission or response to therapy from baseline to week 6. Primary safety end points were adverse events and laboratory evaluations. Data were also analyzed separately for the prespecified subgroup of patients with moderate UC at baseline.

RESULTS

Treatment success was not statistically different between the treatment groups at week 6; 51% of the group (77 of 150) who received delayed-release oral mesalamine 2.4 g/day and 56% of the group (76 of 136) who received 4.8 g/day reached the efficacy end point (P=0.441). Among the moderate disease subgroup, however, the higher initial dose was more effective; 57% of patients (53 of 93) given delayed-release oral mesalamine 2.4 g/day and 72% of patients (55 of 76) given 4.8 g/day achieved treatment success (P=0.0384). Both regimens were well tolerated.

CONCLUSIONS

Delayed-release oral mesalamine is an effective and well-tolerated initial therapy in patients with mildly to moderately active UC, and a 4.8 g/day dose may enhance treatment success rates in patients with moderate disease compared with mesalamine 2.4 g/day.

Review article: evolving concepts in treatment and disease modification in ulcerative colitis

BACKGROUND

More than two-thirds of ulcerative colitis patients experience at least one relapse over a period of 10 years. Treatments that reduce the likelihood of relapses also reduce the risk of long-term complications.

AIM

To review three topics: the current standard of treatment for ulcerative colitis, evolving concepts in treatment, and disease modification as a treatment goal of the future.

RESULTS

Currently, 5-aminosalicylates are the standard treatment for the induction and maintenance of remission in mild-to-moderate ulcerative colitis patients. Evidence suggests that patients who take oral 5-aminosalicylates regularly are nearly six times more likely to experience regression in disease severity than those who do not. Additional treatment options such as corticosteroids, immunomodulators, biological therapies and ciclosporin are available for moderate-to-severe ulcerative colitis patients, or those who do not respond to 5-aminosalicylate. Surgery becomes pertinent for more than one-third of ulcerative colitis patients during the course of their disease. With the availability of a variety of therapies, advances in surgery and improved management strategies, a better understanding of patient treatment expectations can help improve the quality of care for ulcerative colitis patients.

CONCLUSIONS

Disease modification is increasingly becoming a treatment goal in the management of ulcerative colitis. However, long-term studies are needed to examine further the disease modifying role of 5-aminosalicylates.

The involvement of heme oxygenase-1 activity in the therapeutic actions of 5-aminosalicylic acid in rat colitis

The mechanism of action of 5-aminosalicylic acid (5-ASA), the active therapeutic moiety of a number of clinically used anti-colitic agents, is unclear. The present study investigates whether the beneficial effects in vivo could involve induction of the heat shock protein, heme oxygenase-1 (HO-1), known to provide endogenous anti-oxidant and anti-inflammatory moieties which can modulate colonic inflammation. The effects of 5-ASA on the colonic expression and activity of HO-1 along with its effect on the inflammatory damage have been evaluated in the colitis provoked by instillation of trinitrobenzene sulphonic acid (TNBS) over 48 h in the rat. Intracolonic administration of 5-ASA (8, 25 and 75 mg/kg/day) dose-dependently reduced the TNBS-provoked macroscopic colonic inflammatory injury, myeloperoxidase (MPO) activity and TNF-alpha levels, while also dose-dependently increasing colonic heme oxygenase enzyme activity. Colonic HO-1 protein expression, determined by Western blot analysis in this colitis model, was likewise further induced by 5-ASA. Intracolonic administration of 5-ASA alone under unchallenged conditions also induced colonic HO-1 protein expression and stimulated heme oxygenase enzyme activity. Administration of zinc protoporphyrin (50 micromol/kg/day, s.c.), which prevented the increase in colonic heme oxygenase activity, abolished the anti-colitic effect of 5-ASA. These results suggest that 5-ASA may exert its colonic anti-oxidant and anti-inflammatory effects in vivo in part through the up-regulation of HO-1 enzyme expression and activity.

Optimizing drug therapy in inflammatory bowel disease

This article reviews current data to optimize the use of both older and newer drugs in inflammatory bowel disease. For patients with severe ulcerative colitis (UC), steroid dosing has been clarified, and a mega-analysis of steroid outcomes and toxicities has been reported. In regard to mesalamine, recent information has suggested benefit of a higher dose of pH-dependent release mesalamine for patients with moderate UC. Also, a once-daily formulation with Multi-Matrix System (MMX) technology (Shire Pharmaceuticals, Wayne, PA), has been approved. In regard to cyclosporine, two centers have reported an increased rate of colectomy over a long-duration follow-up of a cyclosporin A course given for UC. Additional information regarding thiopurines has been published, including the use of metabolite testing and duration of therapy for these drugs. Lastly, additional information regarding the optimal method for using anti-tumor necrosis factor therapy continues to accumulate.

Colon-specific delivery of 5-aminosalicylic acid from chitosan-Ca-alginate microparticles

Chitosan-Ca-alginate microparticles for colon-specific delivery and controlled release of 5-aminosalicylic acid after peroral administration were prepared using spray drying method followed by ionotropic gelation/polyelectrolyte complexation. Physicochemical characterization pointed to the negatively charged particles with spherical morphology having a mean diameter less than 9 microm. Chitosan was localized dominantly in the particle wall, while for alginate, a homogeneous distribution throughout the particles was observed. (1)H NMR, FTIR, X-ray and DSC studies indicated molecularly dispersed drug within the particles with preserved stability during microencapsulation and in simulated in vivo drug release conditions. In vitro drug release studies carried out in simulated in vivo conditions in respect to pH, enzymatic and salt content confirmed the potential of the particles to release the drug in a controlled manner. The diffusional exponents according to the general exponential release equation indicated anomalous (non-Fickian) transport in 5-ASA release controlled by a polymer relaxation, erosion and degradation. Biodistribution studies of [(131)I]-5-ASA loaded chitosan-Ca-alginate microparticles, carried out within 2 days after peroral administration to Wistar male rats in which TNBS colitis was induced, confirmed the dominant localization of 5-ASA in the colon with low systemic bioavailability.

MMX Multi Matrix System mesalazine for the induction of remission in patients with mild-to-moderate ulcerative colitis: a combined analysis of two randomized, double-blind, placebo-controlled trials

MMX mesalazine [LIALDA (US), MEZAVANT XL (UK and Ireland) MEZAVANT (elsewhere)] utilizes MMX Multi Matrix System (MMX) technology which delivers mesalazine throughout the colon. Two phase III studies have already evaluated MMX mesalazine in patients with active, mild-to-moderate ulcerative colitis. Aim To provide more precise estimates of the efficacy of MMX mesalazine over placebo by combining the patient populations from the two phase III studies. Methods Combined data from two 8-week, double-blind, placebo-controlled trials were analyzed. Patients randomized to MMX mesalazine 2.4 g/day (once daily or 1.2 g twice daily), 4.8 g/day (once daily) or placebo were reviewed. The primary end point was clinical and endoscopic remission (modified Ulcerative Colitis-Disease Activity Index of </=1 calculated as: rectal bleeding and stool frequency scores of 0, a combined Physician's Global Assessment and sigmoidoscopy score of </=1, no mucosal friability and a >/=1-point reduction in sigmoidoscopy score from week 0). Results Data from 517 patients were analysed. 8-week remission rates were 37.2% and 35.1% in the MMX mesalazine 2.4 g/day and 4.8 g/day groups, vs. 17.5% on placebo (P < 0.001, both comparisons). 8-week complete mucosal healing rates were 32% in both MMX mesalazine groups compared with 16% on placebo. Adverse event frequency was similar in all groups. Conclusion MMX mesalazine is effective and generally well tolerated for inducing clinical and endoscopic remission of active, mild-to-moderate ulcerative colitis.

Inflammatory bowel disease: clinical aspects and established and evolving therapies

Crohn's disease and ulcerative colitis are two idiopathic inflammatory bowel disorders. In this paper we discuss the current diagnostic approach, their pathology, natural course, and common complications, the assessment of disease activity, extraintestinal manifestations, and medical and surgical management, and provide diagnostic and therapeutic algorithms. We critically review the evidence for established (5-aminosalicylic acid compounds, corticosteroids, immunomodulators, calcineurin inhibitors) and emerging novel therapies--including biological therapies--directed at cytokines (eg, infliximab, adalimumab, certolizumab pegol) and receptors (eg, visilizumab, abatacept) involved in T-cell activation, selective adhesion molecule blockers (eg, natalizumab, MLN-02, alicaforsen), anti-inflammatory cytokines (eg, interleukin 10), modulation of the intestinal flora (eg, antibiotics, prebiotics, probiotics), leucocyte apheresis and many more monoclonal antibodies, small molecules, recombinant growth factors, and MAP kinase inhibitors targeting various inflammatory cells and pathways. Finally, we summarise the practical aspects of standard therapies including dosing, precautions, and side-effects.

Immunochemical method for sulfasalazine determination in human plasma

Sulfasalazine is an antibiotic used in the treatment of inflammatory bowel diseases. For the assessment of sulfasalazine in several biological matrices, an Enzyme-Linked Immunosorbent Assay (ELISA) method based on polyclonal antibodies was developed and characterized. The immunoassay showed a high sensitivity (IC50=0.51 ng mL(-1)) and specificity, a detection limit of 0.02 ng mL(-1) and a dynamic range of 0.06-3.75 ng mL(-1) (80-20% inhibition). The immunoassay performed well when it was applied to spiked plasma samples (from 0.5 to 2.0 ng mL(-1)) previously cleaned up by protein precipitation with methanol. Recoveries ranged from 83 to 119%, with a mean value of 99% (CV=13%). Since sulfasalazine remaining of a treatment reaches the systemic circulation in unchanged form, the immunoassay can be applied to the determination of this pharmaceutical in human plasma in order to facilitate the control of the patients through the application of personal doses.

Indications for 5-aminosalicylate in inflammatory bowel disease: is the body of evidence complete?

Mesalazine is a safe drug, although adverse events may be seen in a minority of patients. This applies also to pregnant women and children. The role of mesalazine in combination therapy to improve efficacy and concomitant drug pharmacokinetics, or in chemoprevention against inflammatory bowel disease (IBD)-related colonic carcinoma has not yet been completely elucidated. Therapeutic success of mesalazine may be optimized by a combination of high dose and low frequency of dosage to improve compliance. Therefore, due to its superior safety profile and pharmacokinetic characteristics, mesalazine is preferable to sulphasalazine. This paper reviews the literature concerning mechanisms of action, indications and off-label use, pharmacokinetic properties and formulations, therapeutic efficacy, compliance, paediatric indications, chemoprevention, and safety issues and adverse event profile of mesalazine treatment versus sulphasalazine. It also highlights these controversies in order to clarify the potential benefits of mesalazines in IBD therapy and evidence for its use.

Review article: high-dose aminosalicylates to induce and maintain remissions in ulcerative colitis

Sulfasalazine was the first aminosalicylate to be used for induction and maintenance therapy of ulcerative colitis (UC). Initial trials demonstrated a dose response that was compromised by dose-related intolerance. Recognition that the 5-aminosalicylic acid moiety (5-ASA, mesalazine) is the active ingredient of sulfasalazine has allowed the development of sulpha-free formulations of mesalazine and alternative azo-bond derivatives (olsalazine, balsalazide) that substantially reduce the dose-related (and allergic) consequences of the sulfapyridine moiety of sulfasalazine. Dose-ranging studies of mesalazine formulations for induction of remission have demonstrated increased efficacy of oral mesalazine up to 4-4.8 g/day, particularly in patients with more moderate disease activity. Combination therapy with oral and rectal mesalazine provide additional efficacy for patients with both distal and extensive colitis. The mesalazine formulations have dose-related benefits without dose-related side effects. In contrast, the azo-bond formulations are compromised by secretory diarrhoea at doses providing greater than 2-2.4 g/day of mesalazine. There are less data regarding dose-related benefits of aminosalicylates to maintain remissions in UC greater than 1.6 g/day of mesalazine, although the absence of dose-related side effects allows continuation of the same inductive dose through maintenance treatment without dose-related toxicity.

The metabolism of mesalamine and its possible use in colonic diverticulitis as an anti-inflammatory agent

5-Aminosalicylic acid (5-ASA) is the mainstay of therapy for inflammatory bowel disease (IBD), particularly ulcerative colitis. 5-ASA is the active moiety in sulfasalazine, which was initially developed for the treatment of rheumatoid arthritis more than 60 years ago, by linking 5-ASA with sulfapyridine Because many of the side effects related to sulfasalazine were found to be due to sulfapyridine, several drugs that contain 5-ASA, and lack the side-effect profile of sulfasalazine, have been developed during the last 2 decades. These drugs have proven to be quite effective in treating mild-to-moderate symptoms of IBD, as well as inducing and maintaining remission. Although they exert anti-inflammatory effects, their exact mechanism of action remains elusive. Nonetheless, their success in treating IBD has led to studies using this class of drugs for novel indications. Several recent studies have evaluated the use of 5-ASA drugs (mesalamine) for the treatment of uncomplicated acute diverticulitis. In this review, we will briefly discuss the development of 5-ASA releasing drugs, their metabolism, side effects, indications, mechanisms of action, and the rationale for the clinical use of mesalamine in colonic diverticulitis.

Review article: evolutionary advances in the delivery of aminosalicylates for the treatment of ulcerative colitis

Ulcerative colitis is a chronic and debilitating disease that involves inflammation of the colonic mucosa. Current therapies aim to reduce the symptom burden of ulcerative colitis and maintain disease quiescence. The standard first-line treatment for mild-to-moderate ulcerative colitis is 5-aminosalicylate therapy, which is available in oral and rectal (topical) formulations. While current 5-aminosalicylate formulations are effective in the majority of patients, they are associated with a number of limitations including inconvenient dosing regimens and poor patient acceptability, which may lead to non-compliance with prescribed therapy. A variety of improved delivery mechanisms have been developed in an effort to overcome these limitations. Micropellet formulations and high-dose tablets appear to offer comparable efficacy and tolerability to conventional formulations, although any benefit in terms of long-term patient compliance remains to be proven. Novel methods of delivery, such as those using a combination of hydrophilic and lipophilic matrices, designed to provide once-daily dosing in a high-strength tablet, may offer a significant improvement in the therapy of active and quiescent ulcerative colitis. This review examines the limitations of current 5-aminosalicylate formulations and reports on the evolution of novel oral formulations designed to overcome these limitations, maximize patient compliance during both induction and maintenance of quiescence, and optimize overall clinical outcomes.

Use of mesalazine in diverticular disease

Diverticular disease includes a spectrum of conditions sharing the underlying pathology of acquired diverticula of the colon: symptomatic uncomplicated diverticular disease, recurrent symptomatic uncomplicated diverticular disease, and complicated diverticular disease. Goals of therapy in diverticular disease should be to improve symptoms and to prevent recurrent attacks in symptomatic uncomplicated diverticular disease, and to prevent the complications of disease such as diverticulitis. Inflammation seems to play a key role in all forms of the disease. This is the rationale for the use of anti-inflammatory drugs such as mesalazine. Inflammation in such diseases seems to be generated by a heightened production of proinflammatory cytokines, reduced anti-inflammatory cytokines, and enhanced intramucosal synthesis of nitric oxide. The mechanisms of action of mesalazine are not yet well understood. It is an anti-inflammatory drug that inhibits factors of the inflammatory cascade (such as cyclooxygenase) and free radicals, and has an intrinsic antioxidant effect. Some recent studies confirm the efficacy of mesalazine in diverticular disease both in relief of symptoms in symptomatic uncomplicated forms and in prevention of recurrence of symptoms and main complications.

Mesalazine for diverticular disease of the colon--a new role for an old drug

Colonic diverticulosis is among the most common diseases of developed countries. Its prevalence is approximately 5 - 10% of the population by age 50, and 30, 50 and 66% of those > 50, > 70 and > 85years of age, respectively. Antibiotics have been successfully used in the treatment of uncomplicated diverticular disease; however, the use of mesalazine (alone or in combination with antibiotics) in treating uncomplicated diverticulitis has been successfully developed in recent years. Indeed, mesalazine (with or without antibiotics) showed significant superiority in improving the severity of symptoms, bowel habits, and in preventing symptomatic recurrence of diverticulitis over antibiotics alone. More-over, in light of some preliminary results, it is probable that the association of mesalazine with probiotics may in the future be the first-choice treatment for mild-to-moderate uncomplicated attacks of acute diverticulitis.

5-aminosalicylate therapy is associated with higher 6-thioguanine levels in adults and children with inflammatory bowel disease in remission on 6-mercaptopurine or azathioprine

BACKGROUND

Small uncontrolled trials have suggested that 5-aminosalicylate (5-ASA) medications increase 6-thioguanine nucleotide (6-TGn) levels in adults with Crohn's disease (CD) on azathioprine (AZA) or 6-mercaptopurine (6-MP), presumably through the inhibition of thiopurine methyltransferase (TPMT). We tested the theory that coadministration of 5-ASA agents with AZA/6-MP results in higher 6-TGn levels in a large cohort of children and adults with CD or ulcerative colitis (UC).

METHODS

A retrospective cohort study identified all children and adults treated for IBD with AZA/6-MP at 2 tertiary medical centers. Patients were included if their TPMT genotype was known and 6-TGn and 6-methymercaptopurine (6-MMP) levels had been obtained after 3 months of clinical remission at a stable dose of AZA/6-MP. 6-TGn and 6-MMP levels were compared between patients taking and those not taking 5-ASA medications through the use of linear regression models to identify and adjust for potentially confounding variables.

RESULTS

Of the 126 patients included, 88 were taking 5-ASA medications. Patients on 5-ASA agents had higher mean 6-TGn levels after adjustment for confounding variables (Delta6-TGn, 47.6 +/- 21.8 pmol/8 x 10 red blood cells; P = 0.03). CD and TPMT heterozygosity was independently associated with higher 6-TGn levels (P = 0.01 and P = 0.03, respectively). 5-ASA exposure was not associated with a change in 6-MMP levels.

CONCLUSIONS

We found that 5-ASA therapy is associated with higher 6-TGn levels in children and adults with IBD on 6-MP/AZA. TPMT inhibition may not explain this effect because 5-ASA exposure did not affect 6-MMP levels. The observed association of CD with higher 6-TGn levels is novel and needs to be verified in prospective studies.

Comparison of the efficacy and safety of Eudragit-L-coated mesalazine tablets with ethylcellulose-coated mesalazine tablets in patients with mild to moderately active ulcerative colitis

BACKGROUND

There are no comparative studies of coated mesalazine.

AIM

To compare the efficacy and tolerability of Eudragit-L- and ethylcellulose-coated mesalazine tablets in patients with mild to moderately active ulcerative colitis.

METHODS

A double-blind, double-dummy, randomized parallel group trial was performed across 18 centres in Australia, and 20 in Eastern Europe. Patients were treated with 3 g mesalazine for 8 weeks with the primary efficacy end point being clinical remission.

RESULTS

Of 215 patients, 69% achieved clinical remission in both treatment groups (P < 0.001; chi-square test) with no differences in frequency of adverse events. In the Australian cohort (n = 63), the Eudragit-L group had a higher remission rate (73% vs. 36%) and responded 13 days faster, compared with those in the European group (67% vs. 84%, and 2 days respectively). No clear reasons for differences in treatment responses were identified.

CONCLUSIONS

Eudragit-L and ethylcellulose-coated mesalazine tablets are well tolerated and equally effective in achieving remission in mild-moderately active ulcerative colitis over 8 weeks.

How important is onset of action in ulcerative colitis therapy?

Pharmacotherapy is the cornerstone of management in ulcerative colitis. However, controversy remains over optimal medical strategies. Specifically, differences in the onset of action of various drug therapies are thought to influence the achievement and maintenance of remission of disease, yet this is poorly characterised. There is a wide range of recent data concerning aminosalicylates, with much debate as to the relative merits of the various formulations and delivery systems. Meta-analyses confirm the efficacy of aminosalicylates for the induction and maintenance of remission and suggest that the newer agents are comparable in efficacy to sulfasalazine. Among aminosalicylates, data from clinical trials reveal that the onset of action is earlier with balsalazide than mesalazine. Although the efficacy of the newer 5-aminosalicylate agents is no greater than that of sulfasalazine, they have better adverse effect profiles. Factors such as tolerability and adherence appear more important than onset of action in long-term maintenance. Corticosteroids have long been used in the treatment of ulcerative colitis, yet there is a paucity of data regarding this. They have a rapid onset of action but considerable systemic adverse effects. Therefore, corticosteroids are reserved for disease that fails to respond to other agents or for primary therapy in patients with severe disease, although there is no universal acceptance of a threshold at which to initiate corticosteroid treatment.Rectal preparations of both aminosalicylates and corticosteroids have been developed in an attempt to exert a more rapid and direct onset of action while minimising adverse systemic effects. In clinical trials, topical preparations of both aminosalicylates and corticosteroids are effective in inducing remission. However, patient acceptability and proximal extent of disease dictate selection of a topical agent more than concern with rate of onset.A wide range of immunomodulators have been investigated in patients with steroid-refractory ulcerative colitis. The thioguanine derivatives are the most widely used but have a limited evidence base to support this use with controlled trials providing equivocal results regarding efficacy in severe ulcerative colitis. In addition, the thioguanine derivatives have a protracted onset of action and a considerable serious adverse effect profile. Calcineurin inhibitors and methotrexate have a more rapid onset of action than the thiopurines but have even less data to support their widespread use. They are widely regarded as salvage therapy and further data are required. Regarding biological agents, infliximab revolutionised the treatment of Crohn's disease, yet results in ulcerative colitis have been disappointing. Further trials are ongoing with great anticipation for more favourable data. The practical clinical implications of any differences between the agents depend on patient satisfaction with various therapies. Noncompliance is a major concern in maintenance therapy and is probably associated with relapse. Dose administration schedules and acceptability of therapy appear to be important factors in adherence. Overall, it is not clear that onset of action has a major influence on patient adherence and addressing issues of compliance may have more direct clinical impact.