Routine and Special Techniques in Toxicologic Pathology

Abstract

Anatomic and clinical pathology assessments are key components of toxicity studies, often providing the pivotal data to determine whether a test article has the appropriate safety and efficacy profile to become a new drug. Standard anatomic pathology assessments that are part of most toxicity studies consist of evaluation of macroscopic observations, organ weights, and microscopic observations; and standard clinical pathology assessments consist of evaluation of hematology, clinical chemistry, coagulation, and urinalysis data. Routine laboratory techniques for standard anatomic pathology assessments include necropsy, with macroscopic observations, organ weight measurements, and tissue collection, and histology to process tissue samples into hematoxylin and eosin (H&E)-stained slides for microscopic evaluation. These routine techniques are part of most toxicity studies. Several special laboratory techniques may be added to studies for cause, either to better characterize changes first observed in the standard assessment or proactively included in the study design to detect or characterize changes anticipated due to the mechanism of action of the test article or changes observed in previous studies with the test article.