2004 Volume 29 Issue 5 Pages 555-569
Single- and 13-week repeated-dose toxicities of Geranti Bio-Ge Yeast®, organic germanium fortified yeasts, were investigated in dogs. Both sexes of Beagle dogs were orally administered once at a dose of 2,000 mg/kg in single-dose toxicity or daily for 13 weeks at doses of 500, 1,000 or 2,000 mg/kg in repeated-dose toxicity tests. In single-dose toxicity test, no animal dead, moribund, or showing clinical signs or changes in body weight gain was found. In repeated-dose toxicity study, there were no considerable changes in ophthalmoscopy and urinalysis. Several alterations were observed in electrocardiography, hematology and blood biochemistry, including heart rate, R-R interval, QT correcting, reticulocytes, activated partial thromboplastin time and albumin/globulin ratio in only male dogs, but not in females, administered with Geranti Bio-Ge Yeast® in a dose-independent manner. In gross findings, several cases of abnormal findings were observed in both control and treatment groups, showing diffuse dark brown to black discoloration of liver, in a dose-independent manner. In microscopic examination, mild lesions, including cholestasis and inflammatory cell foci in liver, kidneys and prostate, were found sporadically in both control and treatment groups. In spite of some alterations in electrocardiography, hematology, blood biochemistry, gross and microscopic findings, such effects were not considered to include toxicopathological significance, based on the marginal changes within normal ranges and lack of dose-dependency, consistent time-course and gender relationship. Taken together, it is suggested that no observed adverse effect level (NOAEL) of Geranti Bio-Ge Yeast® is considered to be 2,000 mg/kg in dogs, and that long-term treatment in clinical trials might not exert adverse effects.