[Toxicity studies of VP 16-213 (III)--Oral six-month chronic toxicity in rats]

VP 16-213 (etoposide, abbr. to VP), an oncostatic drug, was administered orally to Crj : CD (Sprague-Dawley) rats of both sexes at dose levels of 1, 3, 10 and 30 mg/kg/day for six months with the object of examining its chronic toxicity and the reversibility of toxic effects. The summarized results obtained are as follows: VP 30 mg/kg suppressed body weight increase and feed intake, and brought transient diarrhea, anemia and depilation. Some animals receiving this dose died showing systemic debility, emaciation and ataxia. VP 3 mg/kg and higher predominantly decreased red blood cell count as well as white blood cell count accompanied with lowered lymphocyte fraction. VP 30 mg/kg lowered total serum protein content and elevated A/G ratio in males, and lowered serum alkaline phosphatase activity in females. VP 10 and 30 mg/kg predominantly induced thymic atrophy, testicular atrophy with suppression of spermatogenesis and tubular atrophy, a decrease in epididymal weight, and splenic erythropoiesis. Above-described changes excluding the findings on testis and epididymis in VP 30 mg/kg group were shown to be generally reversible. Based on these results, the non-effect dose level of VP under the present experimental condition was estimated to be 1 mg/kg/day against rats of both sexes.