Anti-epileptics Flashcards
Drugs used for antiepileptics (4)
Phenytoin, Carbamazepine, Phenobarbitone, Valproate
Mechanism of action for phenytoin and carbamazepine
Increase brain GABA, decrease membrane excitability, hyperpolarise membrane potential
Phenobarbitone mechanism of action
Low dose: increase frequency of GABA gated CL- channel opening
High dose: increase duration of GABA gated Cl- channel
> prolonged opening could lead to death
Valproate mechanism of action
Increase GABA by inhibiting GABA breakdown
Hyperpolarise membrane potential
Which antiepileptic drug is a hepatic enzyme inhibitor
Valproate > decrease metabolism of other drugs
> displaces diazepam from binding proteins
Other drugs are inducers > increases their metabolism
Phenytoin metabolism and excretion
Dependent on plasma concentration
-Low: 1st order kinetics
-Higher than therapeutic range: zero order kinetics
Phenytoin dose dependent adverse effects
Gum hypertrophy
Carbamazepine dose dependent adverse effect
Nystagmus
Phenobarbitone adverse effects
Sedation, drowsiness, diplopia, behaviour disturbances, depression
Valproate adverse effect
Sedation
