Respiratory Responses to a Single Oral Dose of Caffeine in Male Sprague–Dawley Rats

Caffeine is a key component of beverages such as coffee and tea and has effects on the cardiovascular and respiratory systems, prompting a variety of physiological changes. In our previous study, intravenously administered caffeine at high concentrations significantly influenced respiratory rates. However, comparative research on the potential adverse effects of caffeine consumption on the respiratory system is limited. To address this issue, in this study, we focused on evaluating the effects of orally administered caffeine (0, 2, 6, and 20 mg/kg) on the respiratory system of 6-week-old male Sprague-Dawley rats. We measured the respiratory rate, tidal volume, and minute volume following the guidelines set forth by the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use, specifically adhering to Harmonized Tripartite Guideline S7A for Safety Pharmacology Studies for Human Pharmaceuticals. Caffeine administration led to a notable increase in both the respiratory rate and the tidal volume. Conversely, a marked reduction in minute volume was recorded between 0.5 and 2 h following caffeine administration in doses exceeding 6 mg/kg.