21) Anti-Epileptic Drugs

Question 1

What is epilepsy?

Answer 1

Episodic discharge of abnormal high frequency electrical activity in brain leading to seizure

Question 2

How can a diagnosis of epilepsy be determined?

Answer 2

Evidence of recurrent seizures, unprovoked by identifiable causes

Question 3

How are seizures classified?

Answer 3

Partial (simple and complex)

Generalised

Question 4

What are some dangers of severe epilepsy?

Answer 4

Physical injury
Hypoxia
SUDEP
Brain dysfunction

Question 5

What is primary epilepsy?

Answer 5

No identifiable cuase

Question 6

What is secondary epilepsy?

Answer 6

Medical condition affecting the brain e.g. vascular disease or tumour

Question 7

What are some precipitants to epilepsy?

Answer 7

Sensory stimuli
Brain disease/trauma
Metabolic - hypoglycemia, hypocalcemia, hyponatremia
Infections 
Therapeutics

Question 8

What are the targets of anti-epileptic drugs?

Answer 8

Voltage gated sodium channel blockers
Enhancement of GABA
Inhibition of Ca2+ channel function
Inhibition of glutamate

Question 9

What are some examples of drugs that prolong VG sodium channel inactivation state?

Answer 9

Carbamezepine
Phenytoin
Lamotrigine

Question 10

For what types of seizures is carbamezepine indicated?

Answer 10

Tonic clonic

Partial

Question 11

What are the side effects of carbamezepine?

Answer 11

Dizziness, ataxia, numbness, rashes, hyponatremia, motor disturbance
Rare: neutropenia

Question 12

For what types of seizures is phenytoin indicated?

Answer 12

Tonic clonic

Partial

Question 13

What are the side effects of phenytoin?

Answer 13

Dizziness, ataxia, headache, nystagmus, gingival hyperplasia. Stevens-Johnson

Question 14

How is phenytoin monitored?

Answer 14

Monitor free concentration in plasma

Salivary levels

Question 15

For what types of seizures is lamotrigine indicated?

Answer 15

Partial
Tonic clonic
Absence

Question 16

What are the side effects of lamotrigine?

Answer 16

Dizziness, ataxia, sleepiness, nausea, skin rashes

Question 17

Why does enhancing GABA help in treating seizures?

Answer 17

Post synaptic inhibition and a natural anti-convulsant

Question 18

What is the mechanism of action of valproate?

Answer 18

Inhibits GABA inactivation, stimulates GABA synthesis, VGSCB

Question 19

What are the side effects of valproate?

Answer 19

Sedation, ataxia, tremor, weight gain

Rare: hepatic failure

Question 20

For what types of seizures is valproate indicated?

Answer 20

Partail, tonic clonic and absence

Question 21

What are the side effects of benzodiazepines?

Answer 21

Sedation, tolerance, confusion, aggression, withdrawal, resp and CNS depression

Question 22

How is benzodiazepine overdose treated?

Answer 22

IV flumazenil

Question 23

Give examples of benzodiazepines:

Answer 23

Lorazepam/diazepam - status epilepticus

Clonazepam - absence

Question 24

How can anti-epileptic drugs affect the fetus?

Answer 24

Congenital malformations
Facial and digit hypoplasia
Neural tube defects (valproate)

Question 25

How do anti-epileptic drugs affect contraception?

Answer 25

Failure rate of contraception is 4x as high when using carbamazepine or phenytoin

Question 26

How should anti-epileptics be used in pregnancy?

Answer 26

Single agent at lowest dose
Use lamotrigine
High dose folate supplements and vit K (trimester 3)

Question 27

What is status epilepticus?

Answer 27

Prolonged seizure of any type - single convulsion lasting more than 30 mins or convulsions back to back with no recovery

Question 28

What is the treatment for status epilepticus?

Answer 28

ABCDE, O2, terminate seizure
Lorazepam IV
IV phenytoin
If no response - midazolam, propofol and ITU admission