ASDs Flashcards
List the voltage gated Na+ Channel Blockers
Phenytoin, Fosphenytoin Carbamazepine, Oxcarbazepine Valproic Acid Lamotrigine Topiramate Zonisamide Lacosamine
Which state is are the Na+ channels blocked during
Inactivated state
Phenytoin (Dilantin)
Indication
Focal seizures
Generalized tonic-clonic seizures
Phenytoin (Dilantin)
PK
Non-linear
- With change in dose, t1/2 changes
- Induces metabolic enzymes, different time to steady state based on dose
t 1/2 15-20 hrs
Phenytoin (Dilantin)
Metabolism
CYP2C9/19
Forms: Arene Oxide Active metabolite with ADRs
Phenytoin ADRs
Nystagmus Diplopia Sedation Gingival Hyperplasia** Hirsutism**
Long term:
Choreoathetosis, peripheral neuropathy
Severe:
Toxic epidermal necrolysis
SJS
**Common
Phenytoin (Dilantin)
Teratogenicity
Fetal Hydantoin Syndrome
Phenytoin (Dilantin)
DDIs
-High Plasma Protein Binding (Displacement issues)
-CYP2C9/19 inhibitors
(Cimetidine, Isoniazid, Sulfonamides, Valproic Acid)
-CYP2C9/19 Inducers
(Barbiturates, ChronicEtOH, Carbamazepine, Rifampin)
-Drugs that decrease absorption (Antacids)
-Phenytoin induces CYP3A4, CYP2C, CYP2D
Carbamazepine (Tegretol, Carbatrol)
MOA
Na+ channel blocker
Phenytoin (Dilantin)
MOA
Voltage dependent Na+ channel blocker
Carbamazepine (Tegretol, Carbatrol)
PK: t1/2 and metabolism
t 1/2: 12-30 h (~15 for long term)
Metabolized by CYP3A4 (auto induction), CYP2C9/19
Carbamazepine (Tegretol, Carbatrol)
Indication
- All seizure types except absence seizures
- Temperal lobe epilepsy
Carbamazepine (Tegretol, Carbatrol)
ADRs
BBW, Dose Related, Dose Unrelated, and Long-term Use
BBW: Leukopenia
Dose related: Fatigue, sedation Nystagmus Dilopia Nausea Ataxia
Dose Unrelated:
Rash & SJS
Teratogenicity
Longterm:
Seizure freq. increased
Aplastic anemia
Hypersensitivity
Carbamazepine (Tegretol, Carbatrol)
DDIs
-Strong CYP3A4 inducer
Other ASDs, Oral Contraceptives, Warfarin, Corticosteroids.
-CYP3A4 inhibitors
Valproate, Cimetidine, Erythromycin
-CYP3A4 inducers
Phenytoin, Carbamazepine, primidone, phenobarbital, Ethosuximide
Oxcarbazepine (Trileptal)
MOA and Indication
Same as Carbamazepine
Oxcarbazepine (Trileptal) PK t1/2 t1/2 metabolites Elimination
Oxcarbazepine : 1-2 h
Active metabolites : 8-12 h
Glucuronide (Urinary)
Oxcarbazepine (Trileptal)
ADRs
Dose related
Dose un-related
Less common, less severe
Dose related: Somnolence, dilopia, ataxia
Dose-unrelated: Rash, hyponatremia
Oxcarbazepine (Trileptal)
DDIs
WeakCYP3A4 induction:
Less affected by CYP3A4 modulation
Valproic Acid (Depakote, Depakene) MOAs (3)
- Na channel blocker
- Stimulates GABA synthesis
- Inhibits GABA transaminase
Valproic Acid (Depakote, Depakene) Indication
Most seizure types INCLUDING absence seizures
Lamotrigine (Lamictal)
MOA
Na+ Channel Blocker
Lamotrigine (Lamictal)
Indication
All seizure types
Generalized seizures in children with absence attacks
Lamotrigine (Lamictal)
PK
t1/2
Elimination
25 h
Glucuronide conjugation
Lamotrigine (Lamictal)
ADRs
Headache, nausea, vomiting
Rash (SJS)
Lamotrigine (Lamictal)
DDIs
Hepatic inducers increase glucuronidation (Clearance)
Topiramate (Topamax)
MOAs (3)
- Na+ blocker
- Augments GABA at GABAaR
- Blockatde of Glutamate receptors (Kainate, AMPA)
Topiramate (Topamax)
Indications
Focal Seizures
Generalized tonic-clonic seizures
Topiramate (Topamax)
PK
t1/2
20-30 h
Topiramate (Topamax)
ADRs
Sedation, cognitive slowing, confusion
Fetal malformations
Topiramate (Topamax)
DDIs
Carbamazepine, Phenytoin increase topiramate metabolism
Zonisamide (Zonegran)
MOAs (2)
Na+ channel blocker
T-type Ca2+ channel blocker
Zonisamide (Zonegran)
Indication
Focal Seizures
Zonisamide (Zonegran)
PK
t1/2
metabolism
> 60 h
Partially by CYP3A4
Zonisamide (Zonegran)
ADRs
Dizzienes, ataxia
Somnolence/Insomnia
Cognitive problems
Rash (fatal)
Zonisamide (Zonegran)
DDIs
-Phenytoin, Carbamazepine (CYP3A4 inducers)
Valproic Acid, Cimetidine, Erythromycin (CYP3A4 inhibitors)
Sufonamide hypersensitivity (contraindicated)
Lacosamide (Vimpat)
MOA
Enhances slow inactivation of Na+ channels
Lacosamide (vimpat)
Indication
Adjunctive therapy for focal-onset seizures
Lacosamide (Vimpat)
PK
t1/2
metabolism
12-16 h
CYP2C19
Lacosamide (Vimpat)
DDIs
N/a?
CYP2C19 Inducers?
Phenytoin and Carbamazepine?
Gabapentin (Neurontin, Gralise)
MOAs(2)
Ca2+ Channel Blocker –> Decrease glutamate release
GABAergic –> Increases release of GABA
Gabapentin (Neurontin, Gralise)
Indication
Focal Seizures
Gabapentin (Neurontin, Gralise) PK t1/2 PPB Metabolism
~6 h
0%
hardly metabolized
Gabapentin (Neurontin, Gralise)
ADRs
Sedation, Somnolence, Dizziness, Fatigue
Nystagmus
Ataxia
Gabapentin (Neurontin, Gralise)
DDIs
None (Based on PK)
Pregabalin (Lyica)
MOA
Ca++ channel blocker –> decreased Glu release
Pregabalin (Lyrica)
Indication
Focal seizures
Pregabalin (Lyrica) PK t1/2 PPB Metabolism
~6 h
0%
hardly metabolized
Pregabalin (Lyrica)
SEDATION, somnolence, dizziness Headache WEIGHT GAIN Dry mouth Blurred vision
Pregabalin (Lyrica)
DDIs
N/a
Tiagabine (Gabitril)
MOA
GABA reuptake inhibitor
Tiagabine (Gabitril)
Indication
Focal seizures (Mainly Ad on, no longer 1st line)
Tiagabine (Gabitril)
PK
t1/2
metabolism
7h
CYP3A
Tiagabine (Gabitril)
ADRs
Sedation, dizzines, somnolence
Difficulty with concentration
abdominal Pain
**Can actually induce status epilepticus!! (rare)
Tiagabine (Gabitril)
DDIs
CYP3A inducers/inhibitors
Vigabatrin (Sabril)
MOA
GABA Transaminase Inhibitor
Transaminase converts GABA to glutamate (in the synaptic cleft) which then is converted to glutamine in the glia to be recycled to glutamate in glutaminergic neurons
Vigabatrin (Sabril)
Indication
Adjunct for infantile spasms,
Frefractory complex focal seizures,
West Syndrome
Vigabatriin (Sabril) PK t1/2 PPB Elimination
5-7 h
0%
Renal
Vigabatrin (Sabril)
ADRs
Sedation, fatigue
- Depresion, psychotic disurbances
- WHITE MATTTER LESIONS (30%)
- PROGRESSIVE PERMANENT BILATERAL VISION LOSS (30-50%!!!!!)
–> Only available through “SHARE”
Vigabatrin (Sabril)
DDIs
Decreases phenytoinn Cp by 20-30%
Minimal due to PK
Phenobarbital (Luminal)
MOA
GABAa Receptor agonist
Phenobarbital (Luminal)
Indication
All seizure types except absence seizures
Phenobarbital (Luminal) PK t1/2 PPB Elimination
> 60 h
40-60%
Renal excretion of non-metabolized drug
*Strong induction of CYP2C and CYP3A (DDIs)
Phenobarbital (Luminal)
ADRs
Sedation, tolerance develops
Nystagmus, Ataxia
Learning Difficulties (Don’t give to children)
Phenobarbital (Luminal)
DDIs
Induces CYP2C and CYP3A, induces metabolism of other drugs
Benzodiazepines
Drugs
Diazepam (Valium, Diastat)
Clonazepam (Klonopin)
Lorazepam (Ativan)
Clobazam (Onfi)
Benzodiazepines
MOA
GABAa Receptor
Benzodiazepines
Indications (Drugs specific)
Diazepam - Status Epilepticus Clonazepam - Long-term (also absence) Lorazepam - Status Epilepticus Clorazepate - Long term Clobazam Lennox-Gastaut Syndrome (Adjunct)
Benzodiazepines
PK
t1/2
PPB
20-50 h
85-99%
Benzodiazepines
ADRs
Tolerance (50%, 1-6 months)!!
CNS depression, STRONG Sedation, Lethargy
Aggressiveness (25%)
Withdrawal Syndrom
Benzodiazepines
DDIs
GABAa Acting substances
ASDs for for focal seizures and generalized tonic-clonic seizures
Carbamazepine
Phenytoin
Valproic Acid
Phenobarbital
Lamotrigine, Oxcarbazepine, Felbamate, Gabapentin, Pregabalin, Vigabatrin, Lacosamide, Levitiracetam, Tiagabine, Topiramate
ASDs for Gernalized absence, myclonic, or atonic seizures
Valproic Acid
Ethosuximide
Clonazepam
Lamotrigene
ASDs for status epilepticus
Diazepam
Lorazepam
ASDs with weight gain
Valproate (common) Carbamazepine Gabapentin Pregabalin Perampanel
ASDs with weight los
Topiramate
Felbamate
Zonisamide
ASDs that are weight neutral
Phenytoin
Lamotrigine
Lacosamide
Levetiraetam
Hormonal contraception DDIs
CYP3A4
Carbamazepine Oxcarbazepine Felbamate Topiramate Phenytoin Phenobarbital
ASDs with Teratogenic effects
Phenytoin
Phenobarbital
Valproic Acid
Carbamazepine
Which ASD probably transfers to breast milk
Levetiracetam