Anticonvulsants Veterinary Pharmacology PDF

ANTICONVULSANTS VPM 61 - Basic Veterinary Pharmacology Philip John S. Sajol Assistant Professor I Department of Anatomy, Physiology, and Pharmacology College of Veterinary Medicine Anticonvulsants Introduction phenobarbital, phenytoin, primidone, diazepam, potassium bromide, clonazepam, valpro...

ANTICONVULSANTS VPM 61 - Basic Veterinary Pharmacology Philip John S. Sajol Assistant Professor I Department of Anatomy, Physiology, and Pharmacology College of Veterinary Medicine Anticonvulsants Introduction phenobarbital, phenytoin, primidone, diazepam, potassium bromide, clonazepam, valproic acid Epilepsy is a disorder of the brain chrarcterized by recurring seizures Seizures, ts and convulsions are synonymous terms to describe the manifestations of abnormal brain function that are characterized by paroxysmal stereotyped alterations in behavior Seizures can be caused by numerous abnormalities that a ect neuronal function of the brain fi ff  Anticonvulsants Phenobarbital Drug of choice for control of seizures in dogs and cats; should be used rst in all cases E ective in controlling seizures in 60-80% of epileptic dogs, provided the serum concentration of the drug is maintained within the recommended therapeutic range (15-45 microgram/ml) Depresses the motor center of the cerebral cortex by inhibiting initiation of seizures, raising seizure threshold, but does not prevent spread of seizure activity given IV or orally, onset of action 12 hours after oral administration ff fi Anticonvulsants Phenytoin Also known as diphenylhydantoin Depresses motor centers without depressing sensory areas Inhibits the spread of seizure activity from focus to adjacent neural tissues Not a general anticonvulsant like Phenobarbital Given orally or IV, poor absorption from gut of dogs Anticonvulsants Primidone No hypnotic e ect when used as anticonvulsant in dogs Toxic to cats Metabolized to Phenobarbital and phenylethylmalonamide which have anticonvulsant e ects Toxic reactions: hepatotoxicity, polyphagia, polydipsia, sedation, and behavioral change ff ff Anticonvulsants Diazepam A benzodiazepine Used to control status epilepticus; not used for maintenance Good choice for control of seizures in cats, but not in dogs  Anticonvulsants Potassium bromide An e ective addition to phenobarbital therapy in dogs especially if cluster of seizures occur Since KBr is not available in pharmaceutical grade, crystals may be obtained and mixed by pharmacist Can be absorbed through the skin and can be toxic to humans ff Anticonvulsants Clonazepam A broad-spectrum anticonvulsant May be used in combination with anti-epileptic drugs Causes drowsiness and dose-dependent ataxia Anticonvulsants Valproic acid Also broad-spectrum anticonvulsant Absorbed rapidly Able to displace bound phenytoin or phenobarbital, and is metabolized to metabolites that are not anticonvulsants With relatively short half life