Epilepsy

Question 1

Name 4 classes of drugs used to treat epilepsy

Answer 1

• Lamotrigine
• Sodium valproate
• Diazepam
• Levetiracetam

Question 2

What is the primary mechanism of action of lamotrigine?

Answer 2

• Blocks voltage gated Na+ channels preventing Na+ influx

- Prevents depolarisation of glutamatergic neurones and reduces glutamate excitotoxicity

Question 3

What is the primary mechanism of action of sodium valproate?

Answer 3

Inhibits GABA transaminase which prevents GABA breakdown which increases GABA conc.s directly in the synapse presynaptically and also indirectly prolongs GABA in the synapse due to the fact that extraneuronal metabolism of GABA is slowed which also slows GABA removal from the synapse

Question 4

What is the primary mechanism of action of diazepam?

Answer 4

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

Question 5

What is the primary mechanism of action of levetiracetam?

Answer 5

Inhibits the synaptic vesicle protein SV2A and this prevents vesicle exocytosis so there is a reduction in glutamate secretion which reduces glutamate excitotoxicity

Question 6

What are some side effects of lamotrigine?

Answer 6

• Rash
• Drowsiness (somnolence)
• Steven-Johnson’s syndrome
• Suicidal thoughts

Question 7

What are some side effects of sodium valproate?

Answer 7

• Stomach pain
• Diarrhoea
• Drowsiness
• Weight gain
• Hair loss
• Hepatotoxicity
• Teratogenicity
• Pancreatitis
• Broad CYP enzyme inhibitor - increases serum conc. of many co-administered drugs

Question 8

What are some side effects of diazepam?

Answer 8

• Drowsiness
• Respiratory depression (if IV or at high dose)
• Haemolytic anaemia
• Jaundice
• Addiction

Question 9

What are some side effects of levetiracetam?

Answer 9

• Dizziness
• Drowsiness
• Fatigue
• Headache