Maintenance of remission of ulcerative colitis: a comparison between balsalazide 3 g daily and mesalazine 1.2 g daily over 12 months. ABACUS Investigator group

Aliment Pharmacol Ther. 1998 Dec;12(12):1207-16. doi: 10.1046/j.1365-2036.1998.00427.x.


Background: Despite widespread use of aminosalicylates as maintenance treatment for ulcerative colitis (UC), patients still report troublesome symptoms, often nocturnally.

Aim: To compare the efficacy and safety of balsalazide (Colazide) with mesalazine (Asacol) in maintaining UC remission.

Methods: A randomized, double-blind comparison of balsalazide 3 g daily (1.04 g 5-ASA) and mesalazine 1.2 g daily for 12 months, in 99 (95 evaluable) patients in UC remission.

Results: Balsalazide patients experienced more asymptomatic nights (90% vs. 77%, P=0.0011) and days (58% vs. 50%, N.S.) during the first 3 months. Balsalazide patients experienced more symptom-free nights per week (6.4+/-1.7 vs. 4.7+/-2.8; P=0.0006) and fewer nights per week with blood on their stools or on the toilet paper, mucus with their stools or with sleep disturbance resulting from symptoms or lavatory visits (each P < 0.05). Fewer balsalazide patients relapsed within 3 months (10% vs. 28%; P=0.0354). Remission at 12 months was 58%, in both groups. Similar proportions of patients reported adverse events (61% balsalazide vs. 65% mesalazine). There were five serious adverse events (two balsalazide, three mesalazine) and four withdrawals due to unacceptable adverse events (three balsalazide, one mesalazine), of which one in each group was also a serious adverse event.

Conclusions: Balsalazide 3 g/day and mesalazine 1.2 g/ day effectively maintain UC remission and are equally well tolerated over 12 months. At this dose balsalazide prevents more relapses during the first 3 months of treatment and controls nocturnal symptoms more effectively.

Publication types

  • Clinical Trial
  • Comparative Study
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aminosalicylic Acids / administration & dosage
  • Aminosalicylic Acids / adverse effects
  • Aminosalicylic Acids / therapeutic use*
  • Anti-Ulcer Agents / therapeutic use*
  • Colitis, Ulcerative / drug therapy*
  • Delayed-Action Preparations / pharmacokinetics
  • Double-Blind Method
  • Female
  • Headache / chemically induced
  • Humans
  • Male
  • Mesalamine / administration & dosage
  • Mesalamine / adverse effects
  • Mesalamine / therapeutic use*
  • Middle Aged
  • Phenylhydrazines
  • Secondary Prevention
  • Time Factors
  • Treatment Failure


  • Aminosalicylic Acids
  • Anti-Ulcer Agents
  • Delayed-Action Preparations
  • Phenylhydrazines
  • Mesalamine
  • balsalazide