Epilepsy

Question 1

How does Lamotrigine work?

Answer 1

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

Question 2

What is Lamotrigine’s target?

Answer 2

Voltage gated Na+ channels on pre-synaptic glutaminergic neurones.

Question 3

What are Lamotrigine’s main side effects?

Answer 3

Common:
Rash, drowsiness

Less common but serious:
Steven-Johnson’s syndrome (disorder affecting skin, mucous membrane, genitals and eyes), suicidal thoughts

Question 4

How can you reduce the frequency and severity of allergic skin reactions that come with using lamotrigine?

Answer 4

Introducing lamotrigine gradually

Question 5

How does Sodium Valproate work?

Answer 5

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 extra-neuronal metabolism of GABA is slowed which also slows GABA removal from the synapse.

Question 6

What is Sodium Val’s target?

Answer 6

GABA transaminase

Question 7

What are the side effects of Sodium Val?

Answer 7

Common:
Stomach pain and diarrhoea, drowsiness, weight gain, hair loss

Serious:
hepatotoxicity, teratogenicity, pancreatitis

Question 8

How does sodium val increase the serum concentration of many co-administered drugs?

Answer 8

It inhibits the CYP 450 enzyme in the liver which is involved in the breakdown of many drugs.

Question 9

How does Diazepam work?

Answer 9

It 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 10

What is Diazepam’s main target?

Answer 10

Benzodiazepine site on the GABA A receptor

Question 11

What are the side effects associated with Diazepam?

Answer 11

Common:
Drowsiness, respiratory depression (if i.v. or at high dose)

Uncommon but serious:
Haemolytic anaemia, jaundice

Question 12

Why is Diazepam not used for long-term suppression of seizures?

Answer 12

• The body builds tolerance towards Diaezpam over time.

- Addiction prone individuals more likely to become dependent on diazepam

Question 13

How does Levetiracetam work?

Answer 13

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 14

What does Levetiracetam target?

Answer 14

Synaptic vesicle protein SV2A

Question 15

What are the side effects associated with using Levetiracetam?

Answer 15

dizziness, somnolence, fatigue and headache

Question 16

Is Levetiracetam likely to interact with other drugs?

Answer 16

No, the metabolism of levetiracetam has no effect on the cytochrome P450 enzyme system