12. Epilepsy And Antiepileptic Drugs Flashcards
What is a seizure?
Transient occurrence of signs or symptoms due to abnormal electrical activity in the brain, leading to disturbance of consciousness, behaviour, emotion, motor function or sensation
what can cause an imbalance in inhibitory and excitatory receptors?
Genetic differences in brain chemistry/receptor structure (epilepsy)
By exogenous activation of receptors (drugs)
Acquired changes in brain chemistry (drug withdrawal)
Damage to any of these networks (stroke, tumours)
What are the signs and symptoms of a seizure?
Loss of consciousness with changes in muscle tone, tongue biting
Initial hypertonic phase, followed by rapid clonus of the limbs
Post-ictal period present
Often an aura prior to seizure
What can bring on a reflex seizure?
Photogenic Musicogenic Thinking Eating Hot water immersion Reading
What are the 3 types of seizures?
Focal onset
Generalised onset
Unknown onset
What can cause provoked seizures?
Drug use or withdrawal Alcohol withdrawal Head trauma and intracranial bleeding Metabolic disturbances CNS infections Febrile seizures in infants Uncontrolled hypertension
What is status epilepticus?
A seizure lasting more tan 5 minutes or more, or multiple seizures without a complete recovery between them
What are the pharmacological treatment for status epilepticus?
0-5mins - full dose of benzodiazepine
0-15mins - 2nd full dose of benzodiazepine
15-45mins - 2nd line antiepileptic (phenytoin/levetiracetam)
45+ mins - thiopentone/anaesthesia
What is the class of benzodiazepine?
GABAa agonists
What is the action of benzodiazepines?
Increase Cl- conductance = more negative resting potential, less likely to fire
What are the benzodiazepine options for status epilepticus?
IV lorazepam
Diazepam rectally
Buccaneers or intranasal midazolam
What are the investigations for epilepsy?
Electroencephalography
MRI
What class of drug is carbamazepine?
Sodium channel blockers
What are the side effects of carbamazepine?
Suicidal thoughts
Joint pain
Bone marrow failure
What class of drug is phenytoin?
Sodium channel blocker
When is phenytoin mainly used?
Status epilepticus
Or as an adjunct in generalised seizures
What are the side effects of phenytoin?
Bone marrow suppression
Hypotension
Arrhythmias
What are the actions of sodium valproate?
Mix of GABAa effects and sodium channel blockade
What are the side effects of sodium valproate?
Liver failure
Pancreatitis
Lethargy
What is the first line drug for generalised epilepsies?
Sodium valproate
Where does lamotrigine act?
Primarily sodium channel blocker
May also affect calcium channels
What is lamotrigine good for?
Focal epilepsy
What is the action of levetiracetam?
Synaptic vesicle glycoprotein binder, stops release of neurotransmitters into synapse and reduces neuronal activity
Which antiepileptic drug is safe in pregnancy?
Levetiracetam
What is levetiracetam used in?
Focal seizures and generalise seizures
What are some general side effects of AEDs?
Tiredness/drowsiness Nausea and vomiting Mood changes and suicidal ideation Osteoporosis Rashes - Steven Johnson syndrome Can cause anaemia, thrombocytopenia or bone marrow failure
Which patients need particular monitoring when on AEDs?
Those that are also on warfarin
Which of the AEDs are CYP enzyme inducers?
Phenytoin
Carbamazepine
Barbituates
Which of the AEDs is a CYP enzyme inhibitor?
Valproate
Which AED should not be prescribed to any woman of childbearing age unless on pregnancy prevention programme?
Valproate
