Teratogenicity of cyclophosphamide in New Zealand white rabbits

Pregnant rabbit does received daily oral doses of 6.2 or 18.6 mg/kg cyclophosphamide (CP) on days 6-20 of gestation. On day 29, shortly before term, the uterine content was removed by Caesarean section. At the dose of 6.2 mg/kg CP maternal mortality was 2/9 does and at 18.6 mg/kg CP one abortion was recorded. Body weight gain of pregnant females was essentially unaffected by CP treatment. Both doses of CP elicited significant dose-dependent decrease of fetal body, organ (heart, lung, liver, kidney) as well as placental weight. After treatment with 18.6 mg/kg CP, gross examination of fetuses revealed significantly increased incidence of exophthalmos, cleft palate/lip, syndactyly, and brachycardia. Skeletal anomalies and malformations, significantly increased after the higher CP dose, included sternebrae, back-bone and limb defects. Oral administration of CP to rabbits in the dose of 18.6 mg/kg during organogenesis resulted in pronounced embryotoxic and teratogenic changes.