P760 Differences in persistence of oral mesalazine preparations as monotherapy in patients with ulcerative colitis

Abstract

Abstract Background Oral mesalazine is the mainstay treatment of ulcerative colitis (UC). Mesalazine exerts its anti-inflammatory effect locally in the colonic mucosa. The mucosal mesalazine concentration is inversely correlated with the degree of inflammation and previous studies have found that mucosal drug concentrations differ between various oral mesalazine preparations. In the current study we have examined the drug persistence of oral mesalazine preparations in a national cohort of UC patients. Methods Patients with newly diagnosed UC from 2010 to 2014 using oral mesalazine as anti-inflammatory monotherapy 3 months after the time of diagnosis were identified by combining data from the Norwegian Patient Registry and the Norwegian Prescription Database. The patients were retrospectively followed through 2017, median follow-up time was 1029 days. Treatment failure was defined as start of topical mesalazine or glucocorticoid preparations, systemic glucocorticoids, immunomodulators and biologic treatment or a change to another oral mesalazine preparation. Drug persistence was defined as duration of oral mesalazine preparation in monotherapy. Disease was categorised as more severe in patients who had dispensed systemic glucocorticoids the first three months after diagnosis. Drug persistence at national and regional level was stratified by mesalazine preparation (Mezavant (MEZ), Asacol (ASA), Pentasa (PEN), Salofalk (SAL)) and disease severity. Consumption was estimated based on defined daily doses (DDD = 1.5 g) of mesalazine dispensed from pharmacies. Results A total of 3421 patients were identified. Overall median mesalazine drug persistence was 311 days. The persistence differed between the preparations in descending order: MEZ (398 days), SAL (374 days), PEN (273 days), ASA (266 days), and the order was similar in the four regions. Patients with more severe disease at diagnosis had shorter drug persistence (193 vs. 407 days). Systemic glucocorticoids were given to similar proportion of patients for ASA (0.60) and PEN (0.61), while this proportion of MEZ users was lower (0.52) and even lower for SAL users (0.43). The number of prescribed DDD the first year after diagnosis was slightly higher in MEZ users (MEZ 1.75, ASA 1.36, PEN 1.42, SAL 1.40). Conclusion There were significant differences in drug persistence between oral preparations that were not explained by differences in prescription at regional level, but could partially be related to differences in disease severity. These differences could have clinical implications and bear further investigations.