4: Anti-Epileptic Drugs

Question 1

two major mechanisms causing epileptic events

Answer 1

increased glutamate/aspartate + decreased GABA

Question 2

two major mechanisms AEDs use to treat epilepsy

Answer 2

suppress excitatory glutamate + enhance inhibitor GABA

Question 3

four drugs that induce CYP450***

Answer 3

1. Carbamazepine
2. Phenytoin
3. Phenobarbital
4. Valproic acid

Question 4

the four drugs that induce CYP450 also cause osteoporosis when used chronically - explain

Answer 4

induce CYP450-dependent vitamin D catabolism -> reduced vitamin D circulating -> decreased intestinal Ca absorption -> PTH increases -> bone demineralization

Question 5

why is Oxcarbazepine better than carbazepine

Answer 5

uses an alternative active metabolite that causes fewer CNS/heme side effects + is a less potent CYP450 inducer

Question 6

what to do if pt is not responding to Vigabatrin

Answer 6

discontinue after 3 months of use bc of potential vision loss

Question 7

the four AEDs that induce CYP40 increase clearance of which three important drugs?**

Answer 7

1. oral contraceptives
2. warfarin
3. antivirals, like HIV ART

Question 8

which two AEDs inhibit conjugation of drugs by UGT, causing accumulation of the parent drug?

Answer 8

Valproid acid, lamotrigine

Question 9

which three AEDs induce conjugation of drugs by UGT, causing reduction of parent drug?

Answer 9

1. phenytoin
2. carbamazepine
3. phenobarbital

Question 10

renal clearance of newer AEDs tends to minimize drug interactions. Which six drugs are notable for this helpful new feature?

Answer 10

1. Levetiracetam
2. Topiramate
3. Oxcarbazepine
4. Gabapentin
5. Pregabalin
6. VIgabatrin

Question 11

status epilepticus

Answer 11

a seizure that persists for a sufficient length of time or is repeated frequently enough that recovery between attacks does not occur

Question 12

example causes of status epilepticus

Answer 12

abrupt withdrawal from AEDs, BZDs, opioids, alcohol, brain mass, brain trauma, infection, fever