Comparative Analyses of the Influences of Vehicles on Selected Biological Parameters Following Single-Dose Oral Administration in Sprague-Dawley Rats

Various types of vehicles are used in non-clinical studies to administer treatment substances to experimental animals. It is recognized that these vehicle substances can influence animal physiology to some extent. Studies are designed to minimize the effects of vehicle substances to ensure reliable results. However, research on the biological effects of these vehicles is still inadequate. This study aims to assess the effects of vehicles on selected biological parameters (body weight, food consumpton, water consumption, functional observational battery, clinical pathology, and organ weights) and to establish reference ranges for these parameters to aid in historical control data. A total of 1,528 Sprague-Dawley rats were used in this study, exposed to commonly utilized vehicles such as distilled water, corn oil, dimethyl sulfoxide (DMSO), polyethylene glycol 400, carboxymethyl cellulose, and methyl cellulose via oral dosing at 5 mL/kg body weight per day, consistent with the dosing regimen employed in the toxicity tests included in this study. Significant changes were observed in the red blood cell counts and organ weights with DMSO treatment, whereas other vehicles induced only minor changes. This study highlights the importance of careful vehicle selection in non-clinical trials to eliminate their biological impact.