A COMPARATIVE EVALUATION OF SUBCUTANEOUSLY ADMINISTERED PYRETIC AGENTS IN SPRAGUE-DAWLEY
BABATUNDE ABISOYE LAWAL1, FINIAN KELECHI ODOALA1,2, PASCHAL NNABUGWU WOKOTA1, ABRAHAM GODWIN IDAGU1, JOAN AGBO BULLEY3
1. Department of Pharmacology and Toxicology, Faculty of Pharmacy, University of Calabar, P.M.B 1115, Calabar, Nigeria.
2. Department of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, Veritas University, Abuja
3. Department of Pharmacology, Faculty of Basic Medical Sciences, University of Calabar, Calabar, Nigeria.
Afr. J Pharm Res Dev; Volume 18(1): . 689-698 ; 2026
ABSTRACT
Selecting an appropriate pyrexia model is a critical first step in screening novel antipyretic compounds. While several agents are known, a direct comparison of their efficacy and time-course profiles is lacking, leading to potential inefficiencies in research design. This study aimed to compare the pyretic activities of four agents—turpentine, formalin, carrageenan, and brewer’s yeast—in a rat model to determine the most suitable agent for antipyretic evaluation studies. A total of 25 Sprague-Dawley rats were randomly assigned to 5 groups, with 5 rats per group. Fever was induced by administering a subcutaneous injection of 2mL/Kg turpentine (100%), formalin (5%), carrageenan (1%), brewer’s yeast (15%), and normal saline (control), at the nape of the neck. Body temperature was measured non-invasively at the nape, ear, and abdomen over 540 minutes. All pyrogenic treatments induced a significant increase in temperature above baseline, peaking around 350 minutes. Formalin elicited a significant (p < 0.05) pyretic response at all measurement sites (nape, ear, abdomen). Turpentine induced significant pyrexia at the nape and abdomen, while carrageenan and brewer’s yeast showed significant effects only at the administration site (nape). Notably, the control group also exhibited a gradual temperature rise, attributed to stress from sleep deprivation. Formalin injection also caused significant localized tissue damage. While all tested agents can induce fever, their efficacy and site of action vary. Formalin and turpentine are the most robust systemic pyrogens. However, formalin’s significant tissue toxicity may limit its utility. The observed stress-induced hyperthermia in controls underscores the necessity for carefully controlled experimental conditions. Researchers should select pyretic models based on the desired systemic versus localized response and consider animal welfare implications.
Keywords: Pyrexia, Antipyretic screening, Pyrogenic agents, Sprague-Dawley rats, Stress-induced hyperthermia.
Email of correspondence: fodoala@gmail.com;
https://doi.org/10.59493/ajopred/2026.1.27 ISSN: 0794-800X (print); 1596-2431 (online)