Drug choice and therapeutic drug monitoring in the management of canine primary epilepsy : continuing education

Abstract

Therapeutic drug monitoring is an underutilised resource in the management of canine primary epilepsy. Many of the anti-epileptic drugs, including phenobarbitone, have variable pharmacokinetic profiles in different dogs, with each individual animal showing variable rates of absorption, distribution, metabolism and excretion. This results in variable serumdrug concentrations with the same oral dose. Many clinicians interpret this situation as therapeutic failure and classify these patients as refractory to treatment. By measuring blood concentrations of drugs at appropriate times, it is possible to explain the efficacy or failure of treatment, and also to prevent serum concentrations from reaching toxic levels. By analysing paired samples, key pharmacokinetic parameters may be calculated for each patient and a profile for the disposition of the drug obtained. Individual optimal drug dosage can be calculated for each patient at little cost to the pet owner

Therapie epileptischer Anfälle bei Hund und Katze

“…Die therapeutische Wirkung von Kaliumbromid beruht auf dem Umstand, dass der Organismus nicht zwischen Chlorid-und Bromidionen differenziert, weshalb durch die gesteigerte Zufuhr an Bromidionen eine Hyperpolarisation neuronaler Zellmembranen hervorgerufen wird [15].…”

Determination of bromide in canine plasma using ion chromatography

“…It is defined as an imbalance in excitatory and inhibitory neurotransmission with no discernible underlying disease. Epileptic seizures are thought to arise from neurons with an increase in cell membrane excitability or imbalance of inhibitory and excitatory neurotransmitters [1]. Estimates of the incidence of canine epilepsy range from 2 to 3% of total referral teaching hospital admissions.…”

Pharmacokinetics of potassium bromide in adult horses

“…As bromide concentrations in the brain rise, electrical activity in the central nervous system is inhibited, thus making the initiation of a seizure more difficult. Potassium bromide is currently enjoying a resurgence of use in the management of canine epilepsy, 1–7 because of the long half‐life in this species and the lack of hepatotoxicity that may be associated with phenobarbitone. There are also reports of the efficacy of this drug as part of combination therapy for the management of certain types of refractory epilepsy in children 8–10 and dogs.…”

“…Appropriate dosage regimens and therapeutic serum concentrations have been reported for humans 9,10 and dogs 5,11 . In other species, drug uptake and response are highly variable 3,7 . Therapeutic drug monitoring is recommended to ensure serum concentrations within the therapeutic range and below toxic concentrations 5,7,11 .…”

“…In other species, drug uptake and response are highly variable 3,7 . Therapeutic drug monitoring is recommended to ensure serum concentrations within the therapeutic range and below toxic concentrations 5,7,11 . Adverse effects are often dose dependent 11,12 and include central nervous system effects (such as depression, drowsiness, sedation, stupor, recumbency, ataxia, paresis and, in people, confusion, auditory and visual hallucinations), gastrointestinal tract problems (such as nausea, inappetence, weight loss, pancreatitis), increased water consumption and urination, muscle pain and skin disorders 8,9,12–17 .…”