Dose range finding approach for rodent preweaning juvenile animal studies

Area of Science:

• Pharmacology
• Toxicology
• Pediatric Drug Development

Background:

• Juvenile animal studies (JAS) are crucial for pediatric medicine development.
• Dose selection in juvenile rodents presents challenges due to significant organ development during preweaning stages.
• Extrapolating adult data for juvenile dosing is unreliable due to differing systemic exposures.

Purpose of the Study:

• To establish robust strategies for juvenile dose ranging studies.
• To ensure consistent systemic exposure and adequate dose separation in JAS.
• To optimize animal use and study design for pediatric drug development.

Main Methods:

• Conducted over 45 rodent juvenile studies over 20 years.
• Implemented a phased dose-range-finding approach: tolerability and dose range phases.
• Incorporated toxicokinetics and age-based dose adjustments.

Main Results:

• Preweaning rodents (86%) required lower test article doses than adults.
• Increased systemic exposure in immature animals (83%) necessitated dose adjustments.
• Exposure decreased as animals matured postweaning, supporting age-based dose strategies.

Conclusions:

• A phased dose-ranging approach with toxicokinetics is effective for juvenile studies.
• Age-based dose adjustments are critical for accurate exposure assessment in juvenile rodents.
• Well-designed juvenile dose range studies are essential and should not be replaced by adult data extrapolation.