Ch 15 Drugs for Seizures

Causes of seizures

Infectious diseases
Trauma
Metabolic disorders
Vascular diseases
Pediatric disorders
Neoplastic disease
Medications
High doses of local anesthetics
Eclampsia
Drug abuse
Withdrawal syndromes from alcohol or sedative-hypnotic drugs

Convulsion

Involuntary violent spasm of large muscles of face, neck, arms, and legs
Not synonymous with seizure

Pregnancy and Epilepsy

Several antiseizure drugs decrease effectiveness of oral contraceptives.
Most antiseizure drugs are pregnancy category D.
Eclampsia: Severe hypertensive disorder of pregnancy, characterized by seizures, coma, and perinatal mortality

Epilepsy

Seizures occurring chronically
International Classification of Epileptic Seizures:
Partial (focal)
Generalized
Special epileptic syndromes

Partial Seizures = 2

Simple partial: olfactory, auditory, visual hallucinations, intense emotions, twitching(arms legs face)
Complex partial: Aura preceeding, postictal confusion, fumbling w/ or attempt remove clothing, no response to verbal commands

Generalized = 3

Absence: lasts a few seconds, seen most in kids, often misdiagnosed
Atonic: fall or stumble for no reason, lasts few seconds
Tonic-clonic: preceding aura, intense muscle contract, followed by alternating contract and relax, crying at beginning as air leav

Special syndromes = 3

febrile: tonic-clonic (lasting 1-2 min), rapid returns to consciousness, usually in kids 3mo-5yrs
myoclonic: large jerking movements of major muscle groups (ie: arm), falling from sitting position or dropping what is held
status elipticus: medical emergen

Drugs for Absence seizures: 5

YES:
diazepam
lamotrigine
valproic acid
zonisimide
ethosuximide

Drugs not for partial seizures: 3

NO:
diazepam
lorazepam
ethosuximide

Drugs not for tonic-clonic seizures: 6

NO:
gabapentin
pregabalin
tiagabine
vigabatrin
levetiracetam
ethosuximide

Drugs for myoclonic seizures: 5

YES:
diazepam
topiramate
lamotrigine
valproic acid
zonisamide

Once Medication Is Selected

Patient placed on low initial dose
Amount gradually increased
If seizure activity remains, different medication is added in small increments.
Newer antiseizure drugs have less adverse side effects than older drugs.
Most cases require only a single drug.

Antiseizure Pharmacotherapy

Goal: suppress neuronal activity enough to prevent abnormal or repetitive firing
Drugs act through three mechanisms:
-Stimulating an influx of chloride ions
-Delaying an influx of sodium
-Delaying an influx of calcium
Directed at controlling movement of e

Drugs that Potentiate GABA Action

Act by changing the action of gamma-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the brain
Predominant effect of GABA potentiation is CNS depression.

Drugs That Potentiate GABA Action

Barbiturates
Benzodiazepines
Miscellaneous GABA agents
Suppress the firing ability of neurons

Barbiturates and GABA Agents

Monitor patient's condition
Liver and kidney function
Pregnancy Category D
Common side effects

Treating Seizures with Barbiturates

Low margin for safety
High potential for dependence
Cause profound CNS depression
Overall effective against all major seizure types except absence seizures

Examples of Barbiturates

Phenobarbital (Luminal)
Mephobarbital (Membral)
Primidone (Mysoline)

Other GABA-Related Drugs

Gabapentin (Neurontin)
Pregabalin (Lyrica)
Tiagabine (Gabitril)
Topiramate (Topamax)

Patient Teaching: barbs and GABA-related drugs

Use reliable contraception
Immediately report pregnancy
Report excessive signs of bleeding
Report drowsiness and bone pain

Treating Seizures with Benzodiazepines

Indications include absence seizures and myoclonic seizures.
Tolerance may develop quickly.
One of the most widely prescribed classes, used also for anxiety, skeletal muscle spasms, and alcohol withdrawal symptoms.

Examples of Benzodiazepines

Clonazepam (Klonopin)
Clorazepate (Tranxene)
Lorazepam (Ativan)
Diazepam (Valium)

Benzodiazepines�Schedule IV Drug

Monitor for drug-abuse potential
Pregnancy risk�pregnancy Category D
Contraindicated in narrow-angle glaucoma
Respiratory depression may result with other CNS depressants.
Common side effects include dizziness, drowsiness.
Overdose�give flumazenil (Romazi

Patient Teaching: Benzodiazapine

Avoid alcohol, OTC drugs, and herbal medications
Avoid nicotine
Avoid driving and hazardous activities
Rebound seizures if discontinued abruptly
Take with food
Drug often used illegally

Hydantoin and Newer Drugs

Delay an influx of sodium ions across neuronal membranes
Sodium movement is the factor that determines whether neuron will undergo an action potential.
Sodium channels are not blocked; they are just desensitized.

Treating Seizures with Hydantoins and Related Drugs

Useful in treating all types of epilepsy except absence seizures
Provides effective seizure suppression, without the abuse potential or CNS depression associated with barbiturates
Phenytoin-related drugs used less frequently

Examples of Hydantoins

Phenytoin (Dilantin)�most common
Fosphenytoin (Cerebyx)
Ethotoin (Peganone)

Examples of Phenytoin-like Drugs

Carbamazepine (Tegretol)�tonic-clonic and partial seizures
Felbamate (Felbatol)
Lamotrigine (Lamictal)
Valproic acid (Depakene, Depakote)�absence seizures
Zonisamide (Zonegran)

what to monitor with Hydantoin and Phenytoin-like Drugs

serum-drug levels
signs of toxicity
blood dyscrasias and bleeding disorders
liver and kidney function
Fatal hepatotoxicity can occur

Contraindications: Hydantoin and Phenytoin-like Drugs

Patients with hypersensitivity to hydantoin products should be cautious.
Rash, seizures due to hypoglycemia, sinus bradycardia, and heart block

Patient Teaching: Hydantoin and Phenytoin-like Drugs

-Routine labs for serum level
-Routine labs for liver and kidney function
-Immediately report signs of toxicity
-Immediately report unusual bleeding
-Immediately report liver or brain disease
-Immediately report heart block, hypoglycemia, or pregnancy

Succinimides

Do not abruptly withdraw medication
Use with caution with antiseizure medications, phenothiazines, and antidepressants
pregnancy Category C

Succinimides: Common Adverse Reactions

Drowsiness, headache, fatigue, dizziness
Depression or euphoria
Nausea, vomiting, weight loss
Abdominal pain

Succinimides: Life-Threatening Reactions

Severe mental depression with suicide intent
Stevens-Johnson syndrome
Blood dyscrasias

Succinimides: Patient Teaching

-Immediately report mood changes or suicidal thoughts
-Avoid driving and hazardous activities
-Do not suddenly stop taking
-Take with food
-Report symptoms of fever or sore throat
-Report weight loss and anorexia

Dosage Procedure

Start with smallest initial dose
Add additional drugs, if necessary
Ensure compatibility with other medications
Monitor serum-drug levels

Withdrawal of Antiseizure Medications

Should be seizure-free at least three years
Withdraw gradually over several months
Resume medications if seizures return
Be aware of rebound seizures