Anti-convulsants Flashcards
- Define seizure
a. Sudden changes in behaviour caused by electrical hyper synchronization of neuronal networks in the cerebral cortex
- What are general seizures
a. Begins simultaneously in both hemispheres of brain
- What are partial/focal seizures
Begins within a particular area of brain and may spread out
What are the types of general seizures
a. Tonic-clonic = loss of consciousness, muscle stiffening , jerking twitching, deep sleep , wake up
b. Absence = brief staring episodes with behavioural arrest
c. Tonic/atonic = sudden muscle stiffening/sudden loss of muscle control
d. Myoclonic = sudden, brief muscle contractions
e. Status epilepticus = >5 min continuous seizure activity
- What are the types of partial seizures
a. Simple = retained awareness/consciousness
b. Complex = impaired awareness/consciousness
- Describe neurotransmission at a glutamergic synapse
a. VGSC opens -> membrane depolarisation
b. VGKC opens -> membrane repolarisation
c. Calcium influx through VGCCs -> vesicle exocytosis
d. Synaptic vesicle associated (SV2A) protein allows vesicle attachment to presynaptic membrane
e. Glutamate activates excitatory post-synaptic receptors such as NMDA, AMPA, kainate)
- What are the pharmacokinetics of all anticonvulsants
a. Fast onset
b. Long duration of action
- How does carbamazepine work and when is it given
a. Stabilises inactive state of sodium channel-> reduces neuronal activity
b. Enzyme inducer
c. Tonic-clonic seizures, partial seizures
d. Potential severe skin side effects in individuals of HLA-B 1502 allele
How does lamotrigine work and when is it given
a. Inactivates sodium channels which reduces glutamate neural activity
b. Tonic-clonic seizures, absence seizures
- How does Ethosuximide work and when is it given
a. T-type calcium channel antagonist -> reduces activity in relay thalamic neurones
b. Absence seizures
- How does levetiracetam work and when is it given
a. Binds to synaptic vesicle associated protein which prevents glutamate release
b. Myoclonic seizures
How does topiramate work and when is it given
a. Inhibits NMDA and kainate receptors
b. Also affects VGSCs and GABA receptors
c. Partial seizures
- How does a GABAergic synapse work
a. GABA can be released tonically and also following neuronal stimulation
b. GABA activates inhibitory post-synaptic GABAa receptors
c. GABAa receptors are chloride channels which lead to membrane hyperpolarization
d. GABA is taken up by GAT and metabolised by GABA transaminase (GABA-T)
- How does diazepam work and when is it given
a. Positive allosteric modulator at PAM (GABA receptor)
b. Rectal gel
c. Status epilepticus
- How does sodium valproate work and when is it given
a. Inhibits GABA transaminase which inc GABA mediated inhibition
b. All forms of epilepsy
