Combined Repeat Dose and Reproductive/Developmental Toxicity Screening Test (OECD): familiarization using...

Area of Science:

• Toxicology
• Pharmacology
• Chemical Safety

Background:

• The Organisation for Economic Co-operation and Development (OECD) proposed the Combined Repeat Dose and Reproductive/Developmental Toxicity Screening Test (ReproTox).
• Cyclophosphamide (CP) is a known toxicant with established effects on multiple organ systems.

Purpose of the Study:

• To conduct a familiarization study on the proposed OECD ReproTox test.
• To evaluate the utility of ReproTox in identifying known toxicological properties of cyclophosphamide.

Main Methods:

• Groups of Sprague-Dawley rats (12 males, 12 females) received daily oral doses of cyclophosphamide (0, 2, 3, 4.5, or 6.7 mg/kg body weight).
• Assessed hematological parameters, organ weights (thymus, spleen), and performed histopathological examinations.
• Evaluated reproductive and developmental toxicity endpoints, including postimplantation loss, pup survival, and pup body weight.

Main Results:

• Cyclophosphamide induced anemia and leukopenia in male rats.
• Significant decreases in absolute and relative thymus and spleen weights were observed in treated rats.
• Histopathology revealed thymus, spleen, and bone marrow atrophy.
• Dose-dependent increases in postimplantation fetal loss and postnatal pup death were noted.
• CP treatment resulted in a dose-related decrease in pup body weight.

Conclusions:

• The ReproTox test successfully identified most known toxicological effects of cyclophosphamide.
• The test demonstrated sensitivity to repeat-dose toxicity (hematological and organ weight changes, histopathological findings).
• Reproductive/developmental toxicity was indicated by increased fetal loss and pup mortality/reduced growth.
• The ReproTox test shows promise as a screening tool for assessing the toxicity of high-production volume chemicals.