ABSORPTION AND DOSAGE OF THEOPHYLLINE IN THE HORSE AFTER SINGLE AND REPEATED ADMINISTRATION OF A MICROENCAPSULATED PREPARATION

The kinetics of 2 formulations of theophylline were studied in horses. In an initial cross-over study (Phase I) serum concentration-time cur ves were determined for granulated and microencapsulated theophylline after a single oral administration (5 mg/kg bwt). In Phase II microenc apsulated theophylline was administered at 5 mg/kg bwt/12 h for 10 day s at feeding time, as in normal clinical practice. Although no signifi cant differences between the 2 preparations were found with respect to the main kinetic parameters, the microencapsulated form was more even ly and completely absorbed from the digestive tract; furthermore, afte r the repeated treatment, its trough-peak serum concentrations were al ways within the therapeutic window and no toxic effects were observed in treated animals.