Ingvast‐Larsson, C, Paalzow, G., Paalzow, L., Ottosson, T., Lindholm, A.&Appelgren, L.E. Pharmacokinetic studies of theophylline in horses.J. vet. Pharmacol. Therap.8, 76–81.The pharmacokinetics of theophylline were determined in Standardised trotters after single intravenous and oral administration. A bi‐exponential equation was fitted to the intravenous data and a tri‐exponential equation to the oral data. The biological half‐life of theophylline was found to be 14.8 h, the volume of distribution 1.02 l/kg and the total plasma clearance 0.86 ml/kg/min. The oral absorption of the drug was complete (bioavailability 108%) and rapid (absorption half‐life 0.4 h).Professor L. E. Appelgren, Department of Pharmacology and Toxicology, Biomedicum. Box 573, S‐75J 23 X'p