13 NONCLINICAL TOXICOLOGY
13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility
Busulfan is a mutagen and a clastogen. In in vitro tests it caused mutations in Salmonella typhimurium and Drosophila melanogaster. Chromosomal aberrations induced by busulfan have been reported in vivo (rats, mice, hamsters, and humans) and in vitro (rodent and human cells). The intravenous administration of busulfan (48 mg/kg given as biweekly doses of 12 mg/kg, or 30% of the total Busulfan Injection dose on a mg/m2 basis) has been shown to increase the incidence of thymic and ovarian tumors in mice.
Busulfan depleted oocytes of female rats and induced sterility in male rats and hamsters. The solvent DMA may also impair fertility. A DMA daily dose of 0.45 g/kg/day given to rats for nine days (equivalent to 44% of the daily dose of DMA contained in the recommended dose of Busulfan Injection on a mg/m2 basis) significantly decreased spermatogenesis in rats. A single subcutaneous dose of 2.2 g/kg (27% of the total DMA dose contained in Busulfan Injection on a mg/m2 basis) four days after insemination terminated pregnancy in 100% of tested hamsters [see Use in Specific Populations (8.3)].