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37 Cards in this Set

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What drugs treat Tonic-Clonic and Partial Seizures
DOC: Carbamazepine, Phenytoin, Valproic Acid (Valproate)

Alternatives: Phenobarbital/Primidone (infants), Lamotrigine, Gabapentin, Topiramate, Vigabatrin, Tiagabine
What drugs treat Absence Seizures?
DOC: Ethosuximide, Valproic Acid, Clonazepam

Alternatives: Clonazepam, Lamotrigine, Topiramate
What drugs treat Myoclonic seizures?
DOC: Valproic Acid, Clonazepam

Alternatives: Felbamate, Iamotigine, Levetiracetam, Zonisamide
What drugs are Back-up Adjunctive drugs?
Felbamate
Gabapentin
Lamotrigine
Tiagabine
topiramate
vigabatrin
Zonisamide
Classes of Antiseizure Drugs
Barbiturate -- Phenobarbital
Benzodiazepine -- Diazepam
Carboxylic Acids -- Valproic Acid
Hydantoins -- Phenytoin
Succinimides -- Ethosuzimide
Tricyclics -- Carbamazepine
Newer Agents -- many
General info about Antiseizure Drugs
Anticonvulsants and Antiepileptics
-Well absorbed orally
-Good bioavailability
-Most drugs metabolized by hepatic enzymes --> active metabolites
-Adjust dose with liver disease
Drug Interactions

-Antiseizure drugs are the largest type of drug that with interact with other drugs
Drugs that inhibit antiseizure drug metabolism (CYP inhibitors) --> Toxic levels of drug in body

Drugs that induce hepatic enzymes (Rifampicin) --> inadequate levels of drug in body
Phenytoin
Hydantoin type Antiseizure drug
-Blocks sodium channels --> blocks action potential
-Non-sedating = advantage
-High doses --> toxic
-Treats tonic-clonic and partial seizures and bipolar disorder
Phenytoin Drug Interactions
Drug interactions:
Sulfonamides and Valproic Acid - both displace phenytoin from its protein binding site (where its inactive) --> toxic levels

Decrease phenytoin levels by inducing liver metabolism: Phenobarbital, Rifampicin

Increase Phenytoin levels by inhibiting liver metabolism: Cimetidine, Isoniazid
Phenytoin Toxic Effects
Gingival hyperplasia (gums swelling) - clear indicator of toxic levels
Diplopia, Ataxia, hirsutism, rash, hematologic complications
Carbamazepine
Tricyclic type Antiseizure drug
-Blocks sodium channels
-Used for tonic-clonic and partial seizures

-Non-sedating
It's a liver enzyme inducer so it increases its own metabolism. As you give it you have to keep increasing the dose.
Drug interactions:
Increases metabolism of many other anticonvulsants
Propoxyphene and Valproic Acid inhibit its metabolism

Toxic Effects:Diplopia, Ataxia, Rashes, Blood dyscrasia
Valproic Acid

(Valproate)
Carboxylic Acid type Antiseizure
-Activates potassium channels --> maintains the resting potential more --> makes it harder for neuron to fire

-Used specifically for tonic-clonic seizures (best) but also used for absence and myoclonic seizures
Competes for phenytoin plasma protein binding sites so increases levels of phenytoin

Drug interactions: inhibits metabolism of Phenytoin, Phenobarbital, Lamotrigine

Toxic Effects: Hepatoxicity in kids <2
Ethosuximide
Succinimide type Antiseizure drug
-Inhibits calcium channels --> block action potential

-Used for Absence seizures
Valproic acid increases level of drug
Toxic effects: Gastric issues (lose weight, not eating), hematological abnormalities, Skin rashes
Phenobarbital
Barbiturate type Antiseizure
-Mechanism = sedation
-enhances the inhibitory actions of GABA. Increased duratin of chloride channel opening
Being replaced by Primidone
Primidone
Barbiturate type Antiseizure
-Replacing Phenobarbital
-mechanism = sedation
Prodrug metabolized into phenobarbital
-Used often for Infants!!
Benzodiazepines
Lorazepam --> Xanax
Clonazepam --> used as alternative drug in absence seizures and myoclonic seizures. Can cause drowsiness
Clorazepate
Nitrazepam

-Mechanism: Interact with specific GABA receptor-chloride ion channel macromolecular complex. Frequency of Cl- channel opening increases --> facilitates the inhibitory effects of GABA.

Gives a calming effect. Used as an antianxiety med

All Benzodiazepines can be used for Status Epilepticus and infantile spasms
Gabapentin
Newer Antiseizure drug
-Structural analog of GABA. How is works is unknown
-Uses: used when nothing else is working. In generalized tonic-clonic and partial seizures if refractory cases.

Drug of choice for Trigeminal neuralgia ***** know for test
Vigabatrin
Newer Antiseizure Drug
-Irreversibly inactivates GABA transaminase so GABA is not degraded --> inhibitory effects of GABA

-Used as a back-up drug in tonic-clonic and partial seizures
Lamotrigine
Newer Antiseizure Drug
-Block voltage gated sodium channels
-Used as alternative in generalized tonic-clonic and partial seizures, absence and myoclonic seizures
-Usefulness is limited by its toxic potential --> skin rashes and Steven-Johnson Syndrome
Topiramate
Newer Antiseizure Drug
-Blocks sodium channels and potentiates the action of GABA
-Used as back up drug for tonic-clonic and partial and absence seizures.
Mechanism of Action: Sodium Channel Blockade
Phenytoin, Carbamazepine, Lamotrigine
Mechanism: Inhibits GABA transaminase
Vigabatrin
Valproic acid also does but only at very high doses
Tiagabine
Newer Antiseizure drug
-Inhibits reuptake of GABA transporters in neurons and glia

-Used for partial seizures
Felbamate
Newer Antiseizure Drug
-Blocks glutamate NMDA receptors

-Used as adjunct drug in myoclonic seizures

-Toxic effects: aplastic anemia and acute hepatic failure
Simple Partial Seizure
Consciousness preserved

Convulsive jerking, paresthesia, psychic symptoms (altered sensory perceptoin, illusions, hallucinations), autonomic dysfunction
Complex Partial Seizure
Impaired consciousness

Preceded, accompanied or followed by psychological symptoms (aura)
Generalized Tonic-Clonic Seizure
Tonic Phase: very rapid (< 1min), Abrupt loss of consciousness, Muscle rididity (arched back), respiratory arrest

Clonic Phase: 2-3 min, Jerking of body muscles, lip or tongue biting, fecal and urinary incontinence
Absence Seizure
Impaired consciousness
-Often abrupt onset and brief
-sometimes with automatism
-Loss of postural tone
-Enuresis (pee pants)
-Begin in childhood. Usually stop by 20 yo.
Myoclonic Seizure
Single or multiple myoclonic muscle jerks
Status Epilepticus
Series of seizures
-usually tonic-clonic
-Without recovery of consciousness between attacks
-Life threatening emergency
What treats Status Epilepticus?
IV diazepam or Lorazepam
-effective in terminating attacks
-Short-term control

IV Phenytoin
-prolonged therapy
-Very effective, less sedating
-May cause cardiotoxicity
-Fosphenytoin much safer in emergency situation

Phenobarbital - in children

General Anesthesia - very severe status epilepticus.
Infantile spasms treatment
Corticotropin and corticosteroids
-cushingoid side effect

Benzodiazepines
Migraine treatment
Phenytoin
Trigeminal Neuralgia treatment
Gabapentin
Bipolar disorder treatment
Valproic acid, carbamazepine, phenytoin and gabapentin
Teratogenicity of Antiseizure drugs
Phenytoin --> fetal hydantoin syndrome

Valproic acid --> Neural tube defect (spina bifida)
Antiseizure drug Overdose Effects
Respiratory depression
CNS depression

Give Flumazenil for bendodiazepine overdose