Drug-induced Physeal Abnormalities in Preclinical Toxicity Studies

Area of Science:

• Toxicologic Pathology
• Skeletal Biology
• Pharmacology

Background:

• Toxic physeal changes result from drug interactions with chondrocyte development in the growth plate.
• Physeal dysplasia is linked to various drug classes, including receptor inhibitors and vascular targeting agents.
• Morphologic features of toxic physeal injury are often similar across different drug classes.

Purpose of the Study:

• To review the mechanisms and common features of drug-induced toxic physeal injury.
• To highlight the importance of understanding genetic and nutritional bone diseases in identifying drug targets.
• To discuss the complex signaling pathways involved in chondrocyte maturation and their disruption by toxicants.

Main Methods:

• Microscopic examination of physeal changes.
• Review of preclinical toxicologic pathology data.
• Analysis of drug-induced effects on chondrocytic differentiation and maturation pathways.

Main Results:

• Toxic physeal changes include altered chondrocyte development, disordered bone growth, and specific morphologic features like hypertrophic layer thickening.
• Several drug classes can induce similar physeal lesions, complicating identification of specific drug effects.
• Simultaneous disruption of multiple growth factor pathways occurs due to signaling crosstalk.

Conclusions:

• Toxic physeal injury is an emerging concern in preclinical toxicology due to targeted drug therapies.
• Understanding the pathophysiology of physeal toxicants is essential for drug safety evaluation.
• The intricate regulation of chondrocyte maturation means inhibiting one pathway can affect others, leading to complex toxic effects.