Chronic toxicity and carcinogenicity of N-[N-[3-(3-hydroxy-4-methoxyphenyl) propyl]-α-aspartyl]-L-phenylalanine 1-methyl ester, monohydrate (advantame) in the rat.

Groups of 55 male and 55 female Han Wistar rats were administered advantame (98.9-99.8% purity) in the diet at concentrations of 0, 2000, 10,000, or 50,000 ppm for 104 weeks, following parental exposure to the same levels from prior to mating and throughout gestation. Additional groups of 20 rats/sex and 10 rats/sex were dosed for a period of 52 weeks and constituted the toxicity and reversibility phases of the study. Achieved doses of advantame over the carcinogenicity study were 0, 97, 488, and 2621 mg/kg body weight/day in males and 0, 125, 630, and 3454 mg/kg body weight/day in females, respectively. A high incidence of a pale and swollen anus and changes in fecal composition were observed in the high-dose groups. There was no effect of treatment on mortality. Body weight gain in the high-dose males (50,000 ppm) was slightly reduced compared to controls after 52 and 104 weeks of treatment; the decrease was not considered to be of toxicological significance, but due to the non-nutritive nature of the high dietary concentration of advantame. During the toxicity phase, food conversion efficiency was slightly decreased in both sexes, at the 50,000 ppm dose level. Given the non-nutritive content of the diet, this finding was not considered biologically significant. There were no relationships between treatment and the results of hematological or urinalysis investigations. Clinical chemistry evaluations showed consistently lower plasma urea concentrations in both sexes treated at 50,000 ppm, which was reversed during the 6-week recovery phase following 52 weeks of treatment, indicating a lack of permanent effects. Terminal investigations at both the 52 and 104-week revealed a number of intergroup differences in absolute and/or relative organ weights; however, the differences did not show dose-response relationships, were minor in nature, and/or occurred only in one sex, and were not associated with any pathological findings, and they were considered not to be treatment-related. Evaluation of the histopathology of the carcinogenicity phase animals revealed an increased incidence of pancreatic islet cell carcinomas in males (incidence rates of 0/55, 1/55, 2/55, and 3/55 in the 0, 2000, 10,000, or 50,000 ppm groups, respectively) and of mammary gland adenomas in the high-dose females (incidence rates of 0 in the control through 10,000 ppm dose groups and 4/41 in the 50,000 ppm dose group). The incidence rates of these tumors did not attain statistical significance and/or remained within background historical control values, and they were considered to be unrelated to advantame treatment. The no-observed-adverse-effect level was considered to be 50,000 ppm in the diet, the highest concentration tested, equivalent to 2621 and 3454 mg/kg body weight/day in males and females, respectively. Advantame was concluded to be without carcinogenic activity.