The pharmacokinetics of phenobarbitone in fasting and non-fasting dogs.
Practicing clinical veterinarians in large companion animal practices are often faced with the phenomena of epileptic seizures which occur commonly in dogs. The high incidence of non-responsive cases is often frustrating, and the literature offers incomplete, conflicting and often inaccurate information. The concept of therapeutic anti-epileptic drug concentration monitoring, as applied in man as an aid to treatment, appears attractive in order to provide an improved service to the patient and client. An investigation into the pharmacokinetics of phenobarbitone, particularly at steady state, became necessary in order to interpret the application of drug serum concentration monitoring. The trend of veterinarians to extrapolate human kinetics to dogs is common and unsound. This study was an attempt to identify the similarities and dissimilarities between the pharmacokinetics of dogs and humans. No literature was available, both for man or animal, on the effect of food on the absorption of phenobarbitone. As dog owners frequently have to administer oral medication in food, this was an important factor to examine. The kinetics of the drug was determined in a group of epileptic dogs in order to provide a possible base-line therapeutic regime on commencement of treatment, and the practical application of therapeutic drug monitoring in order to individualize and improve response to treatment was explored.