26-WEEK ORAL TOXICITY STUDY OF BENZALAZINE IN RATS

A 26-week toxicity study by oral gavage administration was performed i n Sprague-Dawley rats with benzalazine (2-hydroxy-5-[(4-carboxyphenyl) azo] benzoic acid, CAS 64896-26-0), a new agent for the treatment of ulcerative colitis and Crohn's disease of the large intestine, as a pa rt of a safety evaluation program. Dosages of 0 (control), 300, 900 an d 2700 mg/kg b.w./d were selected for this study. Except slight change s in the urinary status (decreased pH value and increased specific gra vity) from 900 mg/kg b.w./d p.o. onwards, which were probably substanc e related, no further intolerance reactions were observed. The urine h ad a dark-yellow colour which was probably an indication of metabolite s of benzalazine or benzalazine itself which were excreted via the uri ne. Behaviour external appearance, body weight gain, food and water co nsumption, haematology, clinical biochemistry, organ weight analysis, macroscopic and microscopic examinations revealed no substance-related influence. Therefore, on the basis of the results obtained it is conc luded that the non-toxic dose level in this study is considered to be 300 mg benzalazine/kg b.w./d p.o. following daily administration for 2 6 weeks.