The therapeutic effect of mesalamine is considered to be dose-dependent; however, no consensus has been reached regarding the optimal doses for individual patients. This study aimed to provide new insight for dose optimization using two doses of pH-dependent release mesalamine for induction of remission of moderately active ulcerative colitis (UC).

In a multicenter, double-blind, randomized study, 110 patients with moderately active UC were assigned to two groups after treatment with a constant dose of mesalamine. Fifty-five patients were treated with a pH-dependent release formulation of 3.6 or 4.8 g/day for 8 weeks. The primary endpoint was a decrease in the UC disease activity index (UCDAI) adjusted by covariates.

In the full analysis set (n=110), the mean decrease in UCDAI was 3.1 in the 3.6 g/day group and 3.4 in the 4.8 g/day group ( P >0.05). In a subgroup analysis, the effectiveness of the 4.8 g/day dose was greater in particular populations, such as those who had been previously treated with a lower dose of mesalamine and those with more severe disease. The safety was comparable between the two groups.

The results suggest that treatment with pH-dependent release mesalamine at either 3.6 or 4.8 g/day was effective and safe for the induction of remission in patients with moderately active UC. However, the patients receiving mesalamine at 2.4 g/day but in whom the therapeutic effect is not sufficient and having more severe symptoms (UCDAI 9-10), benefit from higher doses of mesalamine compared to others.