A search for the optimal duration of treatment with 6-mercaptopurine for ulcerative colitis

6-mercaptopurine has proven to be effective in the treatment and maintenance of remission of ulcerative colitis (UC). The optimal duration of treatment with 6-MP is unknown. The intention of this study was to determine the best duration of treatment with 6-MP in terms of maintenance efficacy once remission has been achieved.

We reviewed the records from the inflammatory bowel disease (IBD) center at Lenox Hill Hospital and one large IBD practice in New York City of 334 patients treated with 6-MP for UC. These patients were followed from 4 months to 28.7 yr. Sixty-one patients were treated with 6-MP for at least 6 months and had at least a 3-month disease-free interval off steroids while on the medication. These patients were divided into two groups: Group 1 continued 6-MP and group 2 discontinued the drug at various times for reasons other than relapse. Time to relapse was calculated for both groups.

A Kaplan-Meier survival analysis was employed and differences between the two groups were analyzed using the log-rank test. The median time to relapse in group 2 was 24 wk and in group 1 was 58 wk (p < 0.05). There were no significant differences between the two groups in age, gender, extent of disease, use of concomitant 5-ASA products, dose of 6-MP during remission, duration of UC, and duration of treatment with 6-MP before remission was achieved.

Discontinuation of treatment with 6-MP while UC is in remission leads to a higher relapse rate than maintenance on 6-MP. Therefore, we favor the indefinite treatment with 6-MP in most patients.