Anticonvulsants

Question 1

Lamotrigine primary mech

Answer 1

Blocks voltage gated Na+ channels preventing Na+ influx. Prevents depolarisation of glutamatergic neurones and reduces glutamate excitotoxicity

Question 2

Lamotrigine drug target

Answer 2

Voltage gated Na+ channels

Question 3

Lamotrigine side effects

Answer 3

Common: Rash, drowsiness

Less common but serious:
Steven-Johnson’s syndrome, suicidal thoughts

Question 4

Sodium Valproate primary mech

Answer 4

Inhibition of GABA transaminase prevents the breakdown of GABA. This increases GABA concentrations directly in the synapse presynaptically and also indirectly prolongs GABA in the synapse due to the fact that extraneuronal metanolism of GABA is slowed which also slows GABA removal from the synapse.

Question 5

Sodium valproate drug target

Answer 5

GABA transaminase

Question 6

Sodium Valproate Side effect

Answer 6

Side effects (MANY):
Common: Stomach pain and diarrhoea, drowsiness, weight gain, hair loss
Serious:
hepatotoxicity, teratogenicity, pancreatitis

Question 7

Diazepam Primary mech

Answer 7

Increases choride ion influx in response to GABA binding at the GABA A receptor. Increased chloride ion influx associated with hyperpolarisation of excitatory neurones.

Question 8

Diazepam drug target

Answer 8

Benzodiazepine site on GABA A receptor

Question 9

Diazepam side effects

Answer 9

Side effects:
Common: Drowsiness, respiratory depression (if i.v. or at high dose)
Uncommon but serious:
Haemolytic anaemia, jaundice

Question 10

Levetiracetam primary mech

Answer 10

Inhibition of the synaptic vesicle protein SV2A. It inhibits this protein and prevents vesicle exocytosis. A reduction in glutamate secretion is reduces glutamate excitotoxicity

Question 11

Levetiracetam drug target

Answer 11

SV2A synaptic vesicle protein

Question 12

Levetiracetam side effects

Answer 12

Common:

dizziness, somnolence, fatigue and headache