Antiepileptic Agents

7/30/2019 Antiepileptic Agents

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Known as Anticonvulsants Goal of tx: control or prevent seizures while

maintaining a reasonable quality of life Many patients must take for life Abrupt discontinuation can cause withdrawal

seizures If 1st agent not effective, must be tapered slowly

while 2nd is introduced Depending on agent, therapeutic drug

monitoring of serum levels must be done toassess effectiveness of therapy and avoidtoxicities or under treatment


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Classified into

Traditional AED

Newer AED Classes

Barbiturates

Hydantoins Iminostilbenes plus valproic acid


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Phenobarbital [generic] oldest Sch IV- B Carbamazepine [Tegretol]- I

Phenytoin [Dilantin]-H Pimidone [Mysoline]-B Valproic acid [Depakene, Depakote,

Depakote ER]-unspecified Exthosuximide [Zarontin]-Succinimide


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Gabapentin [Neurontin]-used to treat neuropathicpain also

Lamotrigene [Lamictal]

Levetiracetam [Keppra]-**sleepiness Pregabalin [Lyrica]-Schedule V; also for

neuropathic pain & postherpetic pain Tiagabine [Gabitril] Topiramate [Topamax] Zonisamide [Zonegram] Lacosamide [Vimpat] Banzel [rufinamide] Onfi [Clobazam] 2011 U.S.


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Oxacarbazepine-TrileptalGabapentin-NeurontinLamotrigine-LamictalLevetiracetam-Keppra

TopamaxGabitril, Zonegram, pregbalin-Lyrica


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1. increase threshold activity in area of braincalled motor cortex

2. limit spread of seizure discharge from itsorigin

3. decrease speed of nerve impulseconduction within a given neuron


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Pheno: sedation/drowsiness [most common],lethargy, depression, learning impairment,

physical dependence, poryphyria Valporic acid-hepatoxicity, pancreatitis Phenytoin-gingival hyperplasia,

sedation/drowsiness,nystagmus, diplopia,ataxia, cognitive impairment, skin rash,dyrsrhythmias [IV]


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Topiramate [Topamax]-met. Acidosis,hypohidrosis [reduced sweating], close-angleglaucoma

Zonisamide [Zonegram]- nephrolithiasis, psycheffects Pregabalin [Lyrica]-blurred vision, somnolence,

rhabdomyolysis [rare], dependence Lamotrigine [Lamictal]-life threatening rashes-

SJS, toxic epidermal necrolysis Oxcarbazepine [Trileptal]- hyponatremia [less

125 mEq/L], fatal skin rashes, mult-iorganhypersensitivities


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Pregnancy: AEDS: teratogenic BUT

Benefits must outweigh the risks Common malformations

Valproic acid-spina bifida & other neural tubedefects

Uncontrolled seizures Safety concern

Induce labor

Injury to baby during last month


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Carbamazepine [Tegretol]- Traditional/first generation Uses: partial and general tonic-clonic; trigeminal

neuralgia DO NOT GIVE w/GRAPEFRUIT-increased

toxicity of antiepileptic medication Instruct patient to report visual abnormalities. Instruct patient that abrupt withdrawal after

long-term use may precipitate seizures Must monitor drug levels: 4-12 mcg/mL A/E: bone marrow suppression, fatal aplastic

anemia


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1st line drug-Protypical-HYDANTOIN Used: tonic-clonic/partial seizures Most common adverse effects are lethargy, abnormal

movements, mental confusion, and cognitive changes. Gingival hyperplasia is a well-known adverse effect of long-

term oral phenytoin therapy.

Scrupulous dental care can help prevent gingivalhypertrophy.

Long-term=gingival hyperplasia, acne, hirsutism, andhypertrophy of subcutaneous facial tissue resulting in anappearance known as Dilantin facies.

Another long-term consequence of phenytoin therapy is

osteoporosis. Need Vitamin D su lements


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Therapeutic drug levels are usually 10 to 20mcg/mL.

Above 20 mcg/mL: Toxic levels: nystagmus,

ataxia, dysarthria, and encephalopathy. Phenytoin can interact with other medications

for two main reasons. First, it is highly bound to plasma proteins and

competes with other highly protein-boundmedications for binding sites.

Second, it induces hepatic microsomal enzymes,mainly cytochrome P-450


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Route: PO, IV Should be given slow IVP [not to exceed 50

mg/min in adults] Must be diluted in NORMAL SALINE for IV

infusion & a filter must be used. Follow each dose by saline flush to avoid local

venous irritation Loading dose: 1 gram IV: pt needs to be on a

CARDIAC monitor.


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Gingival inflammation


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injectable prodrug of phenytoin [Dilantin] Route: intramuscularly or intravenouslyby IV push or

continuous infusionwithout causing burning on injectionFosphenytoin is dosed in phenytoin equivalents (PE)

Fosphenytoin is given at a rate of 150 mg PE/min or less to avoidhypotension or cardiorespiratory depression.

If dysrhythmias or hypotension occur, discontinue the infusion.

Implement fall prevention measures after infusion of either

phenytoin or fosphenytoin because of possible ataxia anddizziness.

Take vital signs up to 2 hours after infusion.


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two of the most commonly used antiepilepticdrugs were the barbiturates phenobarbital andprimidone (Mysoline)

Phenobarbital-Schedule IV used for the management of status epilepticus and

is an effective prophylactic drug for the control offebrile seizures

Most common effect: sedation Therapeutic serum drug levels: 10-40 mcg/mL.

Long half-life-50-120 hours

Route: PO, Injectible


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Benzodiazepines-Status epilepticus Lorazepam [Ativan]-preferred

Phenytoin [Dilantin] loading 1 gram IV Diazepam [Valium]

Phenobarbital [rarely used]


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SAFETY ALERT

During a seizure, you should do the following:

Maintain a patent airway.

Protect the patient's head, turn the patient to the side,loosen constrictive clothing, ease patient to the floor, if

seated.

Do not restrain the patient.

Do not place any objects in the mouth.


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When a seizure occurs, you should carefullyobserve and record details of the eventbecause the diagnosis and subsequenttreatment often rest solely on the seizuredescription.

All aspects of the seizure should be noted.

What events preceded the seizure? When didthe seizure occur? How long did each phase(aural [if any], ictal, postictal) last? Whatoccurred during each phase?


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Monitor serum drug levels Baseline and periodic lab studies as ordered

O2 as ordered IV access essential Maintain seizure precautions Through neuro/respiratory assessment Instruct patient not to abruptly stop Instruct patient regarding worsening effects Instruct to administer same time each day


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IV pump for IV infusions Follow agency protocol for dilantin

Cardiac monitoring as indicated esp.w/dilantin loading [1 gram IV] Instruct to check whether driving is allowed-

most states driving is not allowed for aspecific period of time

All safety precautions

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Antiepileptic Agents