Antiseizure

Question 1

Carbamazepine

Answer 1

Uses: focal seizures
MOA: voltage gated Na+ channel blocker
PK: autoinduces it’s own metabolism (3A4, 2C8, 3A5)
ADE: Hyponatremia, SJS (HLA-B*1502; asians)
DI: COCs
Other: useful in comorbid bipolar disorder & trigeminal neuralgia
- Carbamyl @ 5 essential for antiseizure activity

Question 2

Oxcarbazepine

Answer 2

Uses: focal seizures
MOA: enhances fast inactivation of VG Na+ channels
PK: no hepatic metabolism
ADE: hyponatremia more common than carbamazepine

Question 3

Lacosamide (C-IV)

Answer 3

Uses: focal seizures
MOA: inactivation of VG Na+ channels
PK: uses 3A4, 2C9, 2C19
ADE: BBW suicidality
DI: Drugs prolonging QT interval

Question 4

Phenytoin

Answer 4

Uses: focal, generalized or status epilepticus
PK: CYP inducer (2C9, 2C19); First –> Zero order PK
ADE: nystagmus, gingival hyperplasia, hirsutism, PN, osteomalcia, diplopia, IV use & purple glove syndrome

Question 5

Lamotrigine

Answer 5

Uses: focal, generalized, absence
MOA: enhances fast inactivation of VG Na+ channels
PK: glucuronidation
ADE: SJS***, paradoxical insomnia,
Other: preferred in absence seizures in females of childbearing age

Question 6

Ethosuximide

Answer 6

Uses: 1st line tx of absence
MOA: blockage of Ca+ T-Type in thalamus
PK: M via 3A4; t1/2 ~ 40 hrs
ADE: GI upset, fatigue, HA, hiccup euphoria, + behavioral changes

Question 7

Ezogabine

Answer 7

Uses: 3rd line tx focal
MOA: opens/stabilizes KCNQ K+ ion channels
ADE: pigment discoloration of retina skin, dizziness, somnolence, blurred vision

Question 8

Phenobarbital

Answer 8

Uses: focal & generalized (myoclonic)
MOA: GABAa allosteric agonist (increase duration of channel opening)
PK: M via 2C19; t1/2 ~4-5 days; INDUCES CYPS
ADE: physical dependence, less sedation @ seizure doses
Other: may worsen absence & infantile seizures; used to be dosed in grains

Question 9

Primidone

Answer 9

Uses: focal, generalized
MOA: maybe GABAa allosteric agonist (same as phenobarb)
PK: converted to phenobarb & PEMA
ADE: sedation & GI upset 
Other: can be used for essential tremor

Question 10

BZDs

Answer 10

Uses: status epilepticus, cluster seizures
MOA: GABAa allosteric agonist (increase frequency of channel opening)
ADE: physical dependence, tolerance, sedative effects
Other: Diazepam & lorazepam most common

Question 11

Vigabatrin

Answer 11

Uses: focal
MOA: irreversible GABA-T inhibitor
ADE: irrversible retinal dysfunction, weight gain, psychiatric issues

Question 12

Tiagabine

Answer 12

Uses: focal
MOA: inhibits GAT-1 to decrease GABA reuptake)
PK: M via 3A4
ADE: nervousness, dizziness, tremor, depression, ataxia
CI: generalized seizures

Question 13

Bromides

Answer 13

Uses: VET ONLY! epilepsy in dogs
MOA: competes/supplies GABARs with another negative ion (Br-) to hyperpolarize
ADE: Bromism (mental dullness, memory loss, slurred speech, tremors, ataxia, mucular weakness, transient paranoid schizophrenia)
Other: must be specially ordered/supplied (KBr, NaBr)

Question 14

Levetiracetam

Answer 14

Uses: focal, generalized
MOA: binds SV2A to modify release of NT
PK: M in blood
ADE: minimal

Question 15

Brivacetam

Answer 15

Uses: focal
MOA: binds SV2A
ADE: abolishes photoparoxysmal repsonse d/t photosensitivation

Question 16

Gabapentin

Answer 16

Uses: add on therapy for focal
MOA: binds subunit of a2ẟ VG Ca2+ channel
PK: A is saturable; no CYP interactions
ADE: sedation, ataxia, weight gain
Other: more commonly used for PN; CS in some states

Question 17

Perampanel

Answer 17

Uses: focal
MOA: allosteric, noncompetitive AMPAR antagonist (prevents cortical spread)
PK: M via 3A4; t1/2 ~70-110 hrs
ADE: behavioral changes (agression, anger)

Question 18

Valproate

Answer 18

Uses: focal, generalized, absence (+ bipolar, migraines)
MOA: ??? might block Na+ & Ca2+ channels or GABARs
PK: affects M of many drugs
ADE: GI, tremor, weight gain, hair loss, hepatotoxic; TERATOGENIC
Other: aka divalproex, valproic acid; all strengths expressed in [] of valproic acid

Question 19

Felbamate

Answer 19

Uses: Focal, Lennox-Gastaut
MOA: blocks NMDARs; barbiturate-like potentiation of GABAaRs
PK: M via 3A4. 2E1
ADE: improved alertness, aplastic anemia, severe hepatitis
Other: ADEs limit use to refractory pts
NMDA & AMPA = excitatory NTs

Question 20

Topiramate

Answer 20

Uses: focal, generalized, Lennox-Gastaut (+ migraines)
MOA: posulated sites = VG Na+ channels, GABAaRs, AMPARs
ADE: cognitive effects, paesthesias, somnolence, faitgue, nervousness, confusion, glaucoma, urolithiasis, weight loss; TERATOGENIC
Other: weak CAI (could cause met. acidosis)
Acetazolamide = prototypical CAI but no longer used

Question 21

Zonisamide

Answer 21

Uses: focal, generalized
MOA: blocks VG Na+ channels but other actions likely
PK: M via 3A4
ADE: drowsiness, cognitive impairment, renal stones, skin rashes, weight loss
Other: contains sulfur (look for allergic rxn)

Question 22

Rulfinamide

Answer 22

Uses: Lennox-Gastaut, focal
MOA: multiple; VG Na+ channel bloackade related to antiseizure activity
PK: no CYP M
ADE: HA, dizziness, somnolence, fatigue, N