Anti-epileptic drugs Flashcards
How do voltage gated sodium channels treat epilepsy
Bind to Na channels in depolarised neurones to keep them deactivated
Preferentially bind to focal area of increased depolarisation so prevent spread of neuronal hyperactivity
Examples of voltage gated Na channel blockers to treat epilepsy
Carbamazepine
Lamotrigine
Phenytoin
Contraindications for carbamazepine
AVN conduction disorders
Side effects of carbamazepine
Leukopenia Diplopia Blurred vision Impaired balance Erythematous rash (mild)
Drug interactions of carbamazepine
Decreases concentration of: Phenytoin OC pill Warfarin Corticosteroid Antidepressants
What categories of epilepsy carbamazepine and phenytoin treat
Tonic clonic
All partial
What categories of epilepsy do lamotrigine and valproate treat
All generalised (including absence) All partial
What kinetic order does phenytoin follow
0 order at therapeutic dose
Side effects of phenytoin
Dizziness Ataxia Headache Nystagmus Gingival hyperplasia (20%) Stevens johnson syndrome (2-5%)
Drug interactions for phenytoin
Decreases concentration of OC pill
Levels are increased in plasma by NSAIDs and cimetidine
Side effects of lamotrigine
Maculopapular rashes Steven Johnson syndrome Diplopia Blurred vision Photosensitivity (More side effects in children so not first line for paeds)
Drug interactions for lamotrigine
Plasma levels increased by valproate
Plasma levels decreased by OC pill
Examples of drugs that increase GABA to treat epilepsy
Valproate
Benzodiazepines
Role of GABA in treating epilepsy
Binds to GABA receptor so increased Cl influx which causes hyperpolarisation of neurones
MoA of valproate
Inhibits GABA inactivation
Increases GABA synthesis
Side effects of valproate
Nausea very common - have with meal Sedation Tremor Weight gain Increased LFTs (40%) Pancreatitis Hair loss
Drug interactions for valproate
Plasma levels increased by aspirin
Plasma levels decreased by antidepressants and antipsychotics
MoA of benzodiazepines for epilepsy
Positive allosteric effector of GABA receptor
Side effects of benzodiazepines
Sedation Tolerance Dependence/seizure on withdrawel Confusion Aggression Respiratory depression
What can reverse a benzodiazepine overdose
IV flumazenil
What categories of seizures do benzodiazepines treat
Status ellipticus (lorazepam) Absence (clonazepam)
Treatment for status ellipticus
IV lorazepam
IV phenytoin
Propofol
Difficulty with AED prescribing in pregnancy
Risk of seizure = hypoxia
Risk of treatment = birth defects
What should be given to pregnant epileptic women
Lamotrigine
Folate supplements
Vitamin K supplements
