Pharmacological Evaluation of Respiratory Safety Following a Single Intravenous Administration of Theophylline in Sprague-Dawley Rats

Drinking tea is an important cultural and sensory activity in modern society. However, tea consumption may influence biological functions because of its high polyphenol and methylxanthine content. Theophylline is a methylxanthine that plays a significant role in respiratory physiology and is used clinically as a bronchodilator. In this study, we assessed the pharmacological safety of theophylline by investigating its effects on the respiratory responses of experimental rodents. Six-week-old male Sprague-Dawley rats were intravenously administered 0, 2.5, 5, or 10 mg/kg theophylline. After systemic theophylline exposure, the respiratory rate, tidal volume, and minute volume were monitored and statistically analyzed. There was a significant increase in respiratory rate and minute volume with no change in tidal volume at theophylline doses of >5 mg/kg. Changes in respiratory rate and minute volume peaked at 0.25 h after exposure; the respiratory rate increased by 58.2% and 88.9%, and the minute volume increased by 50.5% and 72.8% with the 5 and 10 mg/kg doses, respectively, compared with the vehicle control. These results provide fundamental scientific data that can be used in clinical applications.