CHRONIC ORAL TOXICITY OF A HIGH GEL POINT METHYLCELLULOSE (METHOCEL HG) IN RATS AND DOGS

¹ Division of Pharmacology and Toxicology, University of Rochester School of Medicine and Dentistry, Rochester 20, New York

1. Groups of 50 male and 50 female rats were fed for a period of two years diets containing the following percentages of Methocel HG:0 (control groups), 1, 5 and 20. Growth retardation was exhibited only by the male rats maintained on the 20 per cent diet. The addition of Methocel HG up to 20 per cent of the diet did not influence the life span adversely. At two years, the males averaged around 82 per cent mortality, the females around 66 per cent, regardless of diet. Urine analyses and hematological examinations gave mostly normal values. No significant variation in organ weights existed from group to group. From histological examinations, no evidence of tissue injury was found.

2. Two dogs each were given for one year the following doses of Methocel HG by mouth: 0 (a control group), 0.1, 0.3, 1.0 and 3.0 gm./kgm./day. The dogs maintained body weights or gained slightly. There were no deaths. Urine analyses for sugar and protein gave uniformly negative results. Periodic hematological examinations gave mostly normal values. Gross autopsy and histological examinations revealed scattered abnormalities but no evidence of any tissue change ascribable to the administration of Methocel HG.