Drugs for Epilepsy

Epilepsy

A group of disorders characterized by excessive excitation of neurons within the CNS.

Seizure

General term aplied to all types of epieptic events

Convulsion

Abnormal motor phenomena (jerking movements)

1. head trauma

2. hypoxia at birth

3. cancer (braint tumor)

4. congenital defects

Seizure etiology [4]

Synchronous high frequency discharges from a group of hyperexcitable neurons

Seizures are initiated by:

Focal seizure

Seizure activity begins in cerebral cotex. Spreads minimally to cortical areas

Generalized seizure

Focal seizure activity is conducted widely throughout both hemispheres

Status epilepticus

Seizure lasting longer than 30 minutes. Is a major medical emergency because muscles are taking al available oxygen, oxygen is limited to the brain

IV valium

Status epilepticus treatment

To reduce seizures to an extent that enables a person to live a (near) normal life

Goal of epilepsy treatment

Seizure frequency chart

How are epilepsy meds evaluated?

LObectomy

Surgery for epilsepy

Ketogenic: high fat, low carbsDr

Diet for epilespy

1. barbiturates (phenobarbital)

2. benzodiazepines (lorazepam, clonazepam)

3. miscellaneous drugs (gabapentin)

Drugs that potentiate GABa [3]

1. hydratoins (Phenytoin, dilantin)

2. Phenytoin-like agents (carbamazepine/Tegretol)

Drugs that suppress sodium influx

Reversibly binds t sodium channels while they are still n the inactivated state

prolongs Na channel inactivation

decreases ability of neuronns to fire at high frequencies

reduces seizures that depend on high-frequency neural discharge

Pheytoin and tegretol MOA

Succinimides (valproic acid/ Depakene)

Drugs that suppress calcium influx

Delaying calcium influx into euronal membranes

Succinimide MOA

Depakene

Drug that can be used for all seizure types

1. carbamazepine (Tegretol)

2. Phenytoin (Dilantin)

3. Depakene

Drugs for simple/complex partial

Secondarily generalized

generalized: grand mal seixures [3]

1. ethosuximade

2. depakene

Absensce seizure drugs [2]

1. clonazepam

2. depakene

Myoclonic seizure medications [2]

1. absoprtion varies with different formulations

2. can overwhelm liver

3. very narrow therapeutic range

Why is phenytoin (Dilantin) difficult to establish at effective and safe dosage

liver disease. Can overwhelm liver

Contraindication for phenytoin (dilantin)

1. sedation

2. Nystagmus (wobbly vision)

3. Diplopia (double vision)

4. Ataxia (uncoordinated little to no movement)

5. Gingival hyperplasia (Gum tissue overgrowth)

6. Skin rash

Adverse effects of phenytoin (dilantin) [6]

1. warfarin

2. glucocorticoids

3. oral contraceptives

Dilantin can decrease the effects of [3]

1. diazepam

2. alcohol

3. cimetidine

Drugs that increase dilantin plasma levels and risk of toxicity [3]

1. Carbamazepine

2. phenobarbital

Drugs that decrease Dilantin o sub-therapeutic plasma levels [2]

1. alcohol

2. CNS depressants

3. barbiturates

Drugs that amplify the CNS depression effects of dilantin [3]

1. oral and IV route

2. initially BID dose, maintained on OD

3. Short half-life, higher dose increases half life

Dilantin pharmacokinetics [3]

Tegretol

Mainstay of epilepsy treatment

Delays recovery of Na+ channels from inactivated state. Induces drug metabolizing enzymes to increase its own metabolism

Tegretol MOA

half life decreases as therapy progresses (40 to 15 hours)H

relative tegretol half-life

1. less sideeffects

2. wider therapeutic range

How is tegretol safer than dilantin?

can cause birth defects. If pregnant, put on a different drug

Tegretol and pregnancy

1. vertigo, nystagus, blurred vision, unsteadiness

2. leukopenia, anemia, thrombocytopenia

Adverse effects of tegretol

Can inhibit metabolism of Tegretol

GRapefruit juice and tegretol

1. oral contraceptives

2. warfarin

Tegretol causes accelerated inactivation of: [2]

1. Dilantin

2. Phenobarbital

Drugs that can acceerate the metabolism of Tegretol so it becomes sub therapeutic [2]New epile

Lamotrigine (Lamictal)

New epilespy drug that blocks sodium channels and some blockage of calcium channels

Oxcarbazepine (Trileptal)

Drug that blocks voltage-sentisive sodium channels, stabilizes yperexcitable neurons, suppresses seizure spread

Gabapentin (neurontin)

Precise mechanism of drug is unknown, but may enhance GABA release, increasing Gaba-medicated inhibition of neuron firing.

1. seizure record keeping

2. avoid grapefruit juice on tegretol

3. complete blood counts

4. visually monitor for absent seizures

5. avoid operating heavy machinery and driving (especially starting off)

6. good dental hygiene

Nursing interventions for epilepsy [6]