Clinical pharmacology in gastroenterology: development of new forms of treatment of inflammatory bowel disease

Algorithms to facilitate shared decision-making for the management of mild-to-moderate ulcerative colitis

Nonadherence has been a key barrier to the efficacy of medical treatments in ulcerative colitis (UC). Engaging patients in their IBD care via shared decision-making (SDM) to facilitate self-management may improve adherence to therapy. Areas covered: This review aims to summarize the most recent trial evidence from 2012 to 2017 for mild-to-moderate UC in order to develop clinical algorithms that guide SDM to facilitate self-management. A structured literature search via multiple electronic databases was performed using the search terms 'ulcerative colitis,' 'treatment,' 'management,' 'medication,' 'maintenance,' 'remission,' '5-ASA,' and 'inflammatory bowel disease. Expert commentary: Novel formulations of existing oral and topical medications have expanded the treatment options available for the induction and maintenance therapy for mild-to-moderate UC. Daily dosing of 5-ASA therapy is equivalent to twice daily dosing. The combination therapies of oral plus topical 5-ASA therapy and 5-ASA plus corticosteroid therapy are more effective than monotherapy. Budesonide MMX now plays a role in the management of mild-to-moderate UC. This review collates the evidence on drug efficacy and safety, adherence and tolerability, and noninvasive monitoring of mild-to-moderate UC into SDM-orientated algorithms to facilitate self-management.

Mesalazine in left-sided ulcerative colitis: efficacy analyses from the PODIUM trial on maintenance of remission and mucosal healing

BACKGROUND AND AIM

Left-sided colitis is the most prevalent subtype of ulcerative colitis, a chronic inflammatory disease of the colon. The standard of care for mild-to-moderate ulcerative colitis is mesalazine. The PODIUM study compared a once daily to a twice daily dosing regimen of a slow-release mesalazine (Pentasa®); here we assess the efficacy, in terms of maintenance of remission and mucosal healing, of both regimens in patients with left-sided disease.

PATIENTS AND METHODS

Eligible patients were randomised to once daily (1×2 g) or twice daily (2×1 g) oral treatment with mesalazine, for 12 months. Disease activity was assessed clinically and endoscopically at baseline and at 12 months using the Ulcerative Colitis Disease Activity Index, without endoscopic assessment at months 4 and 8.

RESULTS

The study met the primary endpoint of non-inferiority in terms of remission, for once daily versus twice daily dosing, in patients with left-sided ulcerative colitis; an 8% difference was reported in the 12-month clinical and endoscopic remission rates (69% [95% CI: 59.5-76.5] and 61% [95% CI: 51.4-69.6] with once daily and twice daily dosing, respectively; p=0.310). Mucosal healing scores after 12 months were 0 or 1 for 84.4% of the once daily and 78.8% of the twice daily population. Slow-release mesalazine was well tolerated in both dosing regimens, with no difference in reported adverse events.

CONCLUSIONS

Once daily slow-release mesalazine is similarly effective to the standard twice daily schedule in patients with left-sided ulcerative colitis for the maintenance of remission in mild-to-moderate disease.

Clinical pharmacokinetics of slow release mesalazine

Slow release oral mesalazine (Pentasa) contains microgranules covered by a semipermeable ethylcellulose membrane. The microgranules continuously release their content from duodenum to ileum in a pH- and time-dependent way. About 75% of the microgranules pass into the colon, where further release is slower. This release pattern does not appear to be affected by food, diarrhoea or the simultaneous use of H2 antagonists. Rectal forms of mesalazine deliver active drug directly to the rectum and left colon. Plasma concentrations of mesalazine and its metabolite acetyl-5-aminosalicylic acid after oral or local administration are the result of systemic absorption and hepatic metabolism by N-acetyltransferase. Most studies report maximal plasma concentrations of less than 1 mg/L after oral administration of slow release mesalazine, much lower than those observed after uncoated mesalazine but generally higher than after azo-bound drugs such as sulfasalazine. Urinary recovery is an indicator of absorption and metabolism, and is lower after rectal administration (10 to 30%) than after oral administration (30 to 40%). Faecal recovery after oral administration of slow or delayed release mesalazine is lower than with azo-bound drugs. Mesalazine acts locally after absorption by colonic and ileal mucosa. Mean steady-state concentrations of 25.7+/-2.2 microg/kg wet weight are found in ileocolonic biopsy specimens from patients with irritable bowel syndrome treated for 1 week with slow release mesalazine 1.5 g/day. Intramucosal concentrations after slow release mesalazine differ little between healthy individuals and patients with inflammatory bowel disease. Although significant differences are found between the various aminosalicylates in release patterns and the resulting pharmacokinetic parameters, no differences in therapeutic effects have been found in comparative studies. High doses of oral mesalazine (2 to 4 g/day) are more effective than lower doses in the treatment of patients with mild to moderate active ulcerative colitis. High doses (4 g/day) are also effective in the treatment of Crohn's disease, predominantly in patients with ileitis. In contrast, no dose ranging effects were demonstrated with local treatment forms: mesalazine 1g enema seems sufficient for patients with distal colitis. Higher serum concentrations and urinary recoveries after the administration of slow or delayed release mesalazine compared with azo-bound drugs suggest a higher risk for renal adverse effects, although the reported occurrence is extremely low. Although preliminary data support an association between mucosal concentrations of mesalazine and its clinical activity, further studies are needed to correlate the effects of this drug with its pharmacokinetic parameters.

Prolonged-release mesalazine: a review of its therapeutic potential in ulcerative colitis and Crohn's disease

Prolonged-release mesalazine (Pentasa) consists of ethylcellulose-coated microgranules from which mesalazine (known in the US as mesalamine) is released in the small and large intestine in a diffusion-dependent manner. Dose-dependent improvements in clinical and endoscopic parameters have been reported with prolonged-release mesalazine 2 and 4 g/day in clinical trials in patients with mild to moderately active ulcerative colitis. Induction of clinical and endoscopic remission was achieved in more patients receiving a daily dosage of 4 g/day than in those receiving placebo. In patients with ulcerative colitis in remission, prolonged-release mesalazine is effective in reducing the rate of relapse. Higher dosages tend to be more effective, and a 12-month remission rate of 64% has been reported for patients treated with a 4 g daily dosage of this formulation. Comparative data indicate that prolonged-release mesalazine has similar efficacy in maintaining remission to molar equivalent doses of sulfasalazine. Data from a study in patients with mild to moderately active Crohn's disease indicates that higher dosages (4 g/day) of prolonged-release mesalazine are more effective than placebo in reducing disease activity. After 16 weeks' treatment, 64% of patients receiving a 4 g/day dosage experienced clinical improvement and 43% attained remission. In studies of patients in remission of Crohn's disease, the formulation appears to be more effective in preventing relapse in patients with isolated small bowel disease than in those with colonic involvement. The tolerability profile of oral prolonged-release mesalazine is similar to that of placebo and the incidence of adverse events does not appear to be dose-related. Nausea/vomiting, diarrhoea, abdominal pain and dyspepsia occur most frequently, although their incidence is low. Reports of nephrotoxicity during prolonged-release mesalazine treatment are rare.

CONCLUSIONS

Oral prolonged-release mesalazine is effective for maintenance and induction of remission of mild to moderately active colitis, both in patients with distal disease and in those with pancolitis. The formulation has similar efficacy to that of equimolar concentrations of sulfasalazine. Prolonged-release mesalazine also appears to be effective in the treatment of Crohn's disease, and maintenance therapy is of particular value in patients with isolated small bowel involvement. Evidence suggests that higher dosages (3 to 4 g/day) of prolonged-release mesalazine have additional therapeutic benefits over lower dosages in patients with inflammatory bowel disease without increasing the incidence of adverse events.

[Significance of galenic preparations for luminal release of 5-aminosalicylic acid in human small intestinal lumen]

BACKGROUND

Sufficient intraluminal concentrations of 5-aminosalicylic acid (ASA) within inflamed regions of the intestine are required for therapeutic efficacy in inflammatory bowel disease. Various oral delayed release preparations have been developed to ensure that 5-ASA is set free in those parts of the gut, which are most frequently affected. However, resulting intraluminal concentrations within the small bowel are unknown. Therefore, we determined and compared 5-ASA release within different segments of the small bowel from an Eudragit L coated 5-ASA preparation (Salofalk) and from an ethylcellulose coated microsphere preparation (Pentasa).

METHODS

Twelve healthy subjects were intubated with an oro-ileal multilumen-tube for marker perfusion, duodenal, jejunal and ileal aspiration of chyme and intestinal manometry. Each subject received 500 mg 5-ASA (Salofalk, n = 6, or Pentasa, n = 6) together with a semiliquid test meal. Intestinal aspirates, blood and urine samples were obtained in regular intervals for 7 to 10 hours and were analysed for 5-ASA and its main metabolite acetyl-5-ASA by HPLC.

RESULTS

With Salofalk, gastric emptying of 5-ASA did not take place in the digestive, but in the subsequent interdigestive period. Luminal delivery of 5-ASA and acetyl-5-ASA increased from the duodenum (3% of dose) to the ileum (30% of dose). 10% of the dose administered were excreted in urine and about 90% reached the colon unreleased or solubilised. By contrast, with Pentasa, 5-ASA was delivered to the duodenum together with the test meal and released continuously throughout the small intestine (about 20% of dose solubilised at each intestinal site). Only 3.5% of the dose administered were excreted in urine. Deliver of 5-ASA to the colon was equal to Salofalk.

CONCLUSIONS

From both preparations, considerable amounts of 5-ASA are released during small intestinal transit thus explaining therapeutic efficacy in small intestinal Crohn's disease. Because of specific release patterns, Salofalk may be of use especially in terminal ileal disease, where as patients with extensive small intestinal disease including the proximal small intestine might benefit from Pentasa.