Table 3Important characteristics of antiepileptic medications1,2,7-9

Drug NameMechanism of ActionSeizure Types TreatedAdverse EffectsDrug InteractionsGeneric Available
CarbamazepineInhibition of Na+ channelPartial
Tonic–Clonic
Neurological: dizziness, diplopia, ataxia, vertigo
Non-neurological: aplastic anemia, leucopenia, gastrointestinal irritation, hepatotoxicity, hyponatremia, skin rash*
Enzyme Substrate: CYP 3A4, 2C8
Enzyme Inducer: CYP 1A2, 2B6, 2C8, 2C9, 2C19, 3A4
Enzyme Inhibitor: None
Yes
EthosuximideInhibition of T-type Ca2+ channel in thalamusAbsenceNeurological: ataxia, lethargy, headache
Non-neurological: gastrointestinal irritation, skin rash, bone marrow suppression
Enzyme Substrate: CYP 3A4
Enzyme inducer: None
Enzyme Inhibitor: None
Yes, only Available in Generic
FelbamateAntagonism of NMDA receptor and increase of GABA availabilityPartial
Lennox-Gastaut
Neurological: insomnia, dizziness, sedation, headache
Non-neurological: aplastic anemia, hepatic failure, weight loss, gastrointestinal irritation
Enzyme Substrate: CYP 2E1, 3A4
Enzyme inducer: CYP 3A4
Enzyme Inhibitor: CYP 2C19
No, but patent expired 9/26/09
GabapentinGABA analogue for alpha-2 delta subunitPartialNeurological: sedation, dizziness, ataxia, fatigue
Non-neurological: gastrointestinal irritation, weight gain, edema
Enzyme Substrate: None
Enzyme Inducer: None
Enzyme Inhibitor: None
Yes
LacosamideSelective enhancement of slow inactivation of voltage-gated Na+ channelsPartialNeurological: headache, dizziness, diplopia, ataxia, fatigue, tremor, somnolence, blurred vision
Non-neurological: Nausea, vomiting, diarrhea
Enzyme Substrate: CYP 2C19
Enzyme inducer: None
Enzyme Inhibitor: CYP 2C19
No
LamotrigineDecrease of glutamate releasePartial
Tonic–Clonic
Atypical
Absence
Myoclonic
Lennox-Gastaut
Neurological: dizziness, diplopia, sedation, ataxia, headache
Non-neurological: skin rash*
Enzyme Substrate: UGT1A4
Enzyme inducer: None
Enzyme Inhibitor: None
Yes
OxcarbazepineInhibition of Na+ channelPartialNeurological: fatigue, ataxia, dizziness, diplopia
Non-neurological: aplastic anemia, leucopenia, gastrointestinal irritation, hepatotoxicity, hyponatremia, skin rash
Enzyme Substrate: CYP
Enzyme Inducer: CYP 3A4
Enzyme Inhibitor: CYP 2C19
Yes
PhenobarbitalPotentiation of GABA receptor functionPartial
Tonic–Clonic
Neurological: sedation, ataxia, confusion, dizziness, decreased libido, depression
Non-neurological: Skin rash, hepatotoxicity
Enzyme Substrate: CYP 2C9, 2C19, 2E1
Enzyme Inducer: CYP 1A2, 2A6, 2B6, 2C8, 2C9, 3A4
Enzyme Inhibitor: None
Yes, only available in generic
PhenytoinInhibition of Na+ and Ca2+ channelPartial
Tonic–Clonic
Neurological: dizziness, diplopia, ataxia, confusion
Non-neurological: gingival hyperplasia, peripheral neuropathy, lymphadenopathy, hirsutism, osteomalacia, hepatotoxicity, facial coarsening, skin rash*
Enzyme Substrate: CYP 2C9, 2C19, 3A4
Enzyme Inducer: CYP 2B6, 2C8, 2C9, 2C19, 3A4 and UDPGT
Enzyme Inhibitor: None
Yes
PregabalinGABA analogue for alpha-2 delta subunitPartialNeurological: ataxia, somnolence, dizziness, blurred vision, diplopia
Non-neurological: peripheral edema, increased appetite
Enzyme Substrate: None
Enzyme Inducer: None
Enzyme Inhibitor: None
No
PrimidoneInhibition of neuronal firingPartial
Tonic–Clonic
Neurological: sedation, ataxia, confusion, dizziness, decreased libido, depression
Non-neurological: Skin rash
Enzyme Substrate: None
Enzyme inducer: CYP 1A2, 2B6, 2C8, 2C9, 3A4
Enzyme Inhibitor: None
Yes
TiagabineIncrease of GABA availabilityPartial
Tonic–Clonic
Neurological: confusion, sedation, depression, speech problems, paresthesias, psychosis
Non-neurological: gastrointestinal irritation
Enzyme Substrate: CYP 3A4
Enzyme inducer: None
Enzyme Inhibitor: None
No
TopiramateInhibition of Na+ channelPartial
Tonic–Clonic
Lennox-Gastaut
Neurological: psychomotor slowing, sedation, speech problems, fatigue, paresthesias
Non-neurological: kidney stones, glaucoma, weight loss, hypohidrosis
Enzyme Substrate: None
Enzyme inducer: CYP 3A4
Enzyme Inhibitor: CYP 2C19
Yes
Valproic AcidInhibition of T-type Ca++ channel in thalamus Increase of GABA availabilityPartial
Tonic–Clonic
Absence
Atypical
Absence
Myoclonic
Neurological: ataxia, sedation, tremor
Non-neurological: Hepatotoxicity, thrombocytopenia, gastrointestinal irritation, weight gain, hyperammonemia
Enzyme Substrate: UGT 1A6, 1A9, 2B7, beta-oxidation
Enzyme Inducer: CYP 2A6
Enzyme Inhibitor: CYP 2C9, 2C19, 2D6, 3A4
Yes
VigabatrinAnalog of GABA Inhibition of GABA catabolismComplex PartialNeurological: headache, fatigue, drowsiness, dizziness, tremor, agitation, visual field defects, abnormal vision, diplopia
Non-neurological: nausea, vomiting, diarrhea, weight gain, skin rash
Enzyme Substrate: None
Enzyme inducer: None
Enzyme Inhibitor: None
No
ZonisamideInhibition of Na+ channelPartialNeurological: sedation, dizziness, confusion, headache, psychosis
Non-neurological: Anorexia, renal stones, hypohidrosis
Enzyme Substrate: CYP 2C19, 3A4
Enzyme Inducer: None
Enzyme Inhibitor: None
Yes

Ca2+ = calcium ion; CYP = cytochrome P enzyme; GABA = gamma amino butyric acid; Na+ = sodium ion; NMDA= N-methyl D-aspartic acid

*

Ddenotes skin rash risk (Steven's Johnson syndrome and toxic epidermal necrolysis) related to human leukocyte antigen (HLA)-phenotype.

From: Introduction

Cover of Effectiveness and Safety of Antiepileptic Medications in Patients With Epilepsy
Effectiveness and Safety of Antiepileptic Medications in Patients With Epilepsy [Internet].
Comparative Effectiveness Reviews, No. 40.
Talati R, Scholle JM, Phung OJ, et al.

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