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1、Epilepsy AgentsObjectives Describe three categories of the mechanisms of antiseizure drugs.Describe the clinical uses of all kinds of antiseizure drugs.EpilepsyChronic,recurrent seizures.(unprovoked)Most cases unknown cause(idiopathic)Finite episodes of brain dysfunction resulting from abnormal disc
2、harge of cerebral neurons.Seizure classificationsimplerepetitive unusual movements,but preservation of consciousness(20-60sec)compleximpaired consciousness(0.5-2min)with purposeless movementPartial seizures(Simple and Complex)Generalized seizuresAbsent Sudden loss of consciousness,no muscle contract
3、ions Most frequent in children/adolescentsTonic-clonic(grand mal)Loss of consciousness,followed by tonic,then clonic phases Most commonly encountered form(status epilepticus)Myoclonic Short episodes of muscle contractionsPharmacotherapy Main method is to take long-term antiepileptic drugs to control
4、 symptomsPrinciple Inhibition of neuronal firing in lesions.Acting on the normal nerve tissue around the lesion to curb the spread of abnormal discharge.Enhancement of brain GABA,Interference of cation channels such as Na+,Ca2+,K+.Grand malPhenytoin sodiumCarbama-zepinePhenobar-bitalBenzodia-zepines
5、Sodium valproateAbsent Ethosuxi-mideSodium valproateBenzodia-zepinesNot suppress firing from the lesion neuronStabilize neuronal membranesBlock voltage-dependent Na+,Ca2+channelSuppress PTP(post tetanic potentiation)Sodium phenytoin（dilantin）Action:Inhibiting the spread of abnormal dischargeAbsorpti
6、on and MetabolismOral slow irregularplasma protein binding 8590%metabolized by the hepatic hydroxylation systemblood concentration 2-3.5 mg/100ml)direct peripheral vasodilationIndications(Different routes of administration can cause different actions)PO.-diarrhoea action (poorly absorbed)im or iv-anticonvulsive actionskeletal muscle relaxationlower blood pressureTherapeutic use:hypertensive crises during pregnancy（eclampsia 子痫）,tetanic 破伤风 convulsionAdverse effect:respiratory depression,BP decrease,cardiac arrestrescue:calcium chloride or calcium gluconate