AEDs

Question 1

Voltage gated sodium channel blockers- mechanism?

Answer 1

Bind only in depolarisation, increase duration of inactive state -> AP firing rate reduces, drug detaches once membrane potential returns to normal

Question 2

Carbamazepine- PKs

Answer 2

75% protein bound, induces OWN CYP metabolism! (Half life decreases so increase dose gradually measure plasma [drug])

Question 3

Carbamezapine- ADRs

Answer 3

Dizziness, motor/sensory disturbance, vomiting, BP fluctuation

Question 4

Carbamazepine DDI

Answer 4

CYP inducer- decrease [other drug] e.g. Phenytoin, warfarin, steroids,
Competitive protein binding

Question 5

Carbamazepine- uses?

Answer 5

All epilepsy types apart from absense

Question 6

Lamotrigine- ADRs

Answer 6

Less than other AEDs! Dizziness, nausea, skin rashes, don’t use in children as increased ADRs

Question 7

Lamotrigine- DDIs

Answer 7

OCP- decrease lamotrigine

Valproate- increase lamotrigine (competitive binding)

Question 8

Lamotrigine- uses?

Answer 8

All types, 1st line!! Safest in pregnancy

Question 9

Phenytoin- PKs

Answer 9

90% protein bound, CYP inducer, NON-linear elimination kinetics!! (Monitor plasma levels!)

Question 10

Phenytoin- ADRs

Answer 10

Headache, nystagmus, gingival hyperplasia, Stevens-Johnson syndrome

Question 11

Phenytoin- DDIs

Answer 11

Competitive binding- NSAIDs increase phenytoin
CYP induction- decrease OCP etc
Cemetidine (inhibitor)- increase phenytoin

Question 12

Phenytoin- monitoring

Answer 12

Close monitoring of free plasma levels required (use salivary levels)

Question 13

Phenytoin- uses?

Answer 13

Status epilepticus (IV)

Question 14

Benzodiazepine (GABA agonist) mechanism

Answer 14

Activate GABA receptors -> increase Cl- into neurone -> increase threshold for AP generation -> decrease epileptic hyperactivity

Question 15

Benzodiazepines- PKs

Answer 15

Heavily protein bound (85-100%)

Question 16

Benzodiazepines- ADRs

Answer 16

Confusion, aggression, sedation, resp/CNS depression, abrupt withdrawal= induce seizure!

Question 17

Benzodiazepines uses?

Answer 17

Status (IV lorazepam) and absence seizures

Question 18

Sodium valproate- mechanism

Answer 18

Many sites of action- Na channels, Increase GABA (increase synthesis, decrease deactivation)

Question 19

Valproate PKs

Answer 19

Heavily protein bound (90%)

CYP inhibitor

Question 20

Valproate- ADRs

Answer 20

CNS sedation, ataxia, raised liver enzymes, liver failure

Question 21

Valproate DDI

Answer 21

NSAIDs- increase valproate (competitive binding)
Antidepressants- inhibit valproate action
Antipsychotics- decrease seizure threshold

Question 22

Valproate monitoring

Answer 22

Monitor LFTs, check for metabolic, blood disorder