Anti-Convulsants

Question 1

Complex waves on an EEG

Answer 1

are summation of simple waves

Question 2

dx of seizure focus can occur by EEG or____

Answer 2

single photon emission coherence topography (SPECT), measures regional BF in the brain; image shows increases in BF in the area associated with onset of a seizure in the same area

Question 3

seizures secondary to what can cause irreversible brain damage

Answer 3

stroke/trauma

Question 4

partial epilepsy

Answer 4

originates in a small group of neurons that constitute a seizure focus
symptoms depends on site of focus and extent to which electrical activity spreads
subtype: simple, complex
Contained in 1 hemisphere, can spread to generalized

Question 5

generalized epilepsy

Answer 5

seizures spread across both hemispheres (cortical and subcortical), convulsive/non-convulsive, associated with an immediate loss of consciousness; starts as a partial seizure
subtypes: tonic-clonic, absence, myoclonic, febrile seizures in children, status epilepticus

Question 6

simple partial seizure

Answer 6

sym: depend on site of focus and spread, consciousness is unimpaired, little spread (10%)
only a couple EEG waves read abnormally

Question 7

complex partial seizure

Answer 7

consciousness is impaired, may spread across cortex processing to a secondary generalized seizure; spread throughout hemisphere (35%)

Question 8

generalized: tonic-clonic

Answer 8

tonic:

Question 9

generalized: absence

Answer 9

3-5 sec, eyes flutter; 10%

Question 10

generalized myoclonic

Answer 10

brief muscle contractions that may reoccur for several minutes; rare, occurs at any age, often a result of brain damage

Question 11

generalized: febrile

Answer 11

3mo-5yo
typically during illness/high fever
usually benign
rarely req meds

Question 12

generalized: status epilepticus

Answer 12

medical emergency
systemic hypoxia
acidemia
hyperpyrexia
CV collapse
brain damage
1) rapid-acting drugs IV and support of CV and resp systems
2) long acting drugs IV (phenytoin)

Question 13

phenytoin

Answer 13

drug of choice: adult epilepsy (initial)
blocks Na channels (and some Ca channels), suppresses repetitive AP firing
supresses: partial (both) and tonic-clonic, IV for status
NOT USED FOR ABSENCE
-high PRO bound
metabolized by P450 (CYP), saturate at high dosage
Interactions: doxycyline, cyclosporine
SE: gingival hyperplasia, megaloblastic anemia, teratogenic effects

alt: fosphenytoin (prodrug) for IV/IM use

Question 14

Carbamazepine

Answer 14

MOa: blocks Na channels (somewhat Ca channels), suppresses Ap firing and propagation of abnormal waves throughout brain
Drug of choice for simple, partial complex, tonic-clonic
other: trigeminal neuralgia/bipolar d/o
PK: highly lipid soluble: rapid CNS penetration
Metabolized by CYPs –induces CYPs, increases own metabolism
drug interactions: enhances CYPs increasing metabolism of some anti-epileptics (phenytoin)
carbamazepine metabolism inhibit by many drugs
SE: hepatotoxicity, teratogenic effects

Question 15

valproate

Answer 15

MOA: blocks Na and Ca channels, to some extent GABAergic signaling, reduces propagation of abnormal electrical discharge in brain
Drug of choice: myoclonic seizures, second line to tonic-clonic and absence (hepatotox)
PK: high PRO bound, metabolized by CYP

SE: nausea

Question 16

divalproex

Answer 16

combo of sodium valproate and valproic acid, improved GI tolerance

Question 17

ethosuximide

Answer 17

MOA: inhibits T-type Ca channels, controls rhythmic depolarization of thalamic neurons during absence seizures
DOC: absence
PK: not bound to plasma PRO
75% metabolized by CYP, 25% urinated no change

Question 18

phenobarbital

Answer 18

barbiturate
used to rx simple partial, recurrent tonic-clonic, febrile seizures
-used in combo with carbamazepine allows for use of smaller doses
-also used to rx anxiety
MOA: facilitates GABAR activation ot increase inhibit
PK: freely penetrates brain, 75% inactivated by hepatic microsomal system
SE: teratogenic effects, megaloblastic anemia

Question 19

primidone:

Answer 19

prodrug, effects comes from metabolite phenobarb

Question 20

diazepam

Answer 20

benzodiazepine
Drug of choice: emergent Rx of seizure or status
tolerance: after 1-6 mo
-potentiates GABAR activation to increase inhibitory tone

Question 21

lorazepam

Answer 21

benzodiazepine
Drug of choice: emergent Rx of seizure or status
tolerance: after 1-6 mo
-potentiates GABAR activation to increase inhibitory tone

Question 22

clonazepam

Answer 22

benzodiazepine
used for myoclonic and absence seizures
potentiates GABAR activation to increase inhibitory tone
tolerance develops after 1-6 months

Question 23

lamotrigine

Answer 23

possibly inhibits glutamate release by inhib Ca channels, also inhibits Na channels, suppresses repetitive AP firing
rx partial (both) and tonic-clonic
-1/2 life is decreased by enzyme inducing drugs (carbamazepine, phenytoin), increased by valproic acid

Question 24

gabapentin

Answer 24

-unclear MOA: may enhance GABAR activation, inhibits glutamate release by Ca+ channel blockage
-rx partial seizures, generalized tonic-clonic seizures
PK: not metabolized, does not induce CYP
-no PRO binding
-negligible interax

Question 25

pregabalin

Answer 25

MOA: blocks Ca channels and gluamate release
rx partial seizures
SE: thrombocytopenia

Question 26

topiramate

Answer 26

rx partial seizures and tonic-clonic seizures, blocks Na channels and increases post-synaptic GABAR activity

Question 27

levetiracetam

Answer 27

rx partial and tonic-clonic

-modifies glutamate and GABA release by binding to synaptic PRO SV2A