Sustained-release theophylline pharmacokinetics in the cat

Area of Science:

• Veterinary Pharmacology
• Pharmacokinetics
• Drug Formulation

Background:

• Theophylline is a bronchodilator used in veterinary medicine.
• Optimal dosing strategies for sustained-release theophylline in cats require further investigation.
• Understanding the pharmacokinetic differences between oral formulations is crucial for effective therapeutic management.

Purpose of the Study:

• To compare the pharmacokinetic profiles of two sustained-release theophylline formulations (Slo-bid Gyrocaps and Theo-Dur Tablets) in cats.
• To evaluate the suitability of these formulations for once-daily administration.
• To determine key pharmacokinetic parameters including mean residence time, mean absorption time, absolute bioavailability, and time to peak plasma concentrations.

Main Methods:

• A three-way crossover study design was employed with six cats.
• Theophylline was administered intravenously and orally using two sustained-release formulations.
• Pharmacokinetic parameters were determined through plasma concentration analysis.

Main Results:

• Slo-bid Gyrocaps exhibited a longer mean residence time (19.4 h) compared to Theo-Dur Tablets (15.8 h).
• Absolute bioavailability was comparable between Slo-bid (82%) and Theo-Dur (76%).
• Slo-bid was predicted to have less fluctuation between peak and trough plasma concentrations.

Conclusions:

• Both Slo-bid Gyrocaps and Theo-Dur Tablets demonstrate pharmacokinetic characteristics suitable for once-daily theophylline dosing in cats.
• Slo-bid may offer more stable plasma concentrations, potentially improving therapeutic outcomes.
• These findings support the use of these sustained-release formulations for managing feline respiratory conditions.