AED drugs Flashcards Preview

neuro final > AED drugs > Flashcards

Flashcards in AED drugs Deck (21):
1

phenytoin

-block Na+ channel by prolonging fast inactivation state
-zero order pharmacokinetics, dose adjustment difficult, doubling dose does not double serum level
-induces CYP450
-gingival hyperplasia, hirsutism, hypocalcemia, osteoporosis
-induce CYP450 dependent Vit D catabolism causing decrease in Ca2+ absorption and osteoporosis

2

carbamazepine

-block Na+ channel by prolonging fast inactivation state
-inducer of CYP450
-induces so much CYP450 it causes an increase of own metabolism -> have to continue to increase does until at steady state
-induce CYP450 dependent Vit D catabolism causing decrease in Ca2+ absorption and osteoporosis
-allergic reaction, stevens-johnson syndrome
-increases clearance of oral contraceptives (estrogen) = 4x increase risk of unplanned pregnancy
-increase Warfin clearance = increase risk of thrombosis
-aplastic anemia - idiosyncratic, leukopenia, neutropenia, thrombocytopneia (bruising, infections)
-hypocalcemia, osteoporosis
-hyponatremia from increase response of collecting tubules to ADH = SIADH
-binds Na channel less effectively, but with much faster rate than phenytoin, making it more effective in blocking high frequency firing
-metabolized to active 10,11 CBZ epoxide = TOXIC

3

lamotrigine

-allergic reaction, life threatening, stevens-johnson syndrome
-block Na+ channel by prolonging fast inactivation state
-also acts on N and P type voltage gated Ca2+ channels in cortical neurons and neocortical potassium currents

4

oxcarbazepine

-block Na+ channel by prolonging fast inactivation state
-uses real/hepatic clearance = decrease in drug interaction
-rash
-hyponatremia from increase response of collecting tubules to ADH = SIADH

5

zonisamide

-blocks voltage gated Na+ channel and T type Ca2+ channel
-sulfonamide derivative
-uses real/hepatic clearance = decrease in drug interaction
-rash, renal calculi, hypohidrosis

6

lacosamide

-block Na+ channel by enhancing slow inactivation state
-used to treat partial seizures
-effective at reducing the amplitudes and frequency of sustained repetitive firing spikes when stimulus was prolonged to 10sec as opposed to less than 1 sec

7

ethosuximide

-used for absence seizures (3Hz spike!, staring blankly)
-non-sedating
-antagonist of T type Ca2+ channels
-only limits excitation (Ca2+ channel)
-use lamotrigine or valproate as 2nd line therapy

8

tiagabine

-inhibits GABA reuptake transporter
-pre-synaptic drug
-stubor

9

vigabatrin

-inhibits GABA metabolism (GABA T) so more can be released from vesicles
-pre-synaptic drug

10

phenobarbital

-bind to distinct GABA receptor site -> increases the DURATION of Cl- channel opening
-powerful, non-specific CNS depression
-can cause significant sedation
-can cause lethal respiratory depression
-has abuse + addiction potential
-high doses of barbiturates are GABA independent, lethality PB > BZD
-induce CYP450 dependent Vit D catabolism causing decrease in Ca2+ absorption and osteoporosis

11

primidone

-phenobarbital pro-drug
-can treat tremors at low dose

12

benzodiazepines (diazepam/lorazapam)

-binds to GABA receptor -> allosteric change -> potentiate GABA binding leading to Cl- channel open with more FREQUENCY
-used for status epilicus = seizures that occur without epilepsy (can also occur from withdraw of AED, alcohol, benzodiazepines, opioids, from poison, stimulant abuse, brain tumor, high fever. (major medical emergency)
-treat status epilepicus with lorazepam/diazapam for IV 5min, if no change, use fosphenytoin IV which is a Na+ channel antagonist.

13

clonazepam

-a benzodiazepine used for myoclonic seizures or subcortical myoclonus
-given IV or rectally

14

valproic acid (valproate)

-voltage gated Na+ channel, T type Ca2+ channel, increase GABA
-induces CYP450 Vit D catabolism = osteoporosis
-weight gain, tremor, hair loss, lethargy

15

topirimate

-voltage gated Na+ channel, ligand gated Na+, increase GABA, potentiates GABAa receptors
-also blocks glutamate, so its a glutamate (AMPA) receptor antagonist, on ligand gated Na+ channel -> decrease Na+
-use hepatic/renal clearance, decreases drug interactions
-nephrolithasis, open angle glaucoma, hypohidrosis

16

gabapentin

-binds voltage dependent Ca2+ channels
-no significant drug interactions
-100% renal clearance

17

leviteracetam

-binds to synaptic vesicle protein SV2A = blunts glutamate release
-well tolerate, no CYP interaction
-uses renal/hepatic clearance, decrease drug interactions

18

pregabalin

-multiple mechanisms of action
-100% renal clearance

19

ezogabine

-opens voltage gated K+ channel
-causes urinary retention

20

combined use of lamotrigine and valproate

-together inhibit conjugation of drugs by inhibiting UGT enzymes, leads to accumulation of parent drugs

21

valproic acid
carbamazepine
phenytoin

-all teratogens
-can cause spina bifida, atrial septal defect, cleft palate, hypospadias, polydactyly