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31 Cards in this Set
- Front
- Back
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Epilepsy |
A group of disorders characterized by excessive excitation of neurons within the CNS Usually a chronic condition |
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Seizure |
A general term applied to all types of epileptic events |
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Convulsion |
Abnormal motor phenomena (i.e. jerking movement) |
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Pathophysiology of Seizures |
Seizures initiated by synchronous high frequency discharges from a group of hyper-excitable neurons (focus) |
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Partial (Focus) Seizures |
Activity begins focally in Cerebral cortex areas - Simple, Complex, Secondary Generalized |
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Simple Seizure |
Discrete symptoms, depends on area of brain affected S&S: twitching, numbness, hallucinations, salivation, incontinence, feelings of unreality Lasts 20-60 seconds No loss of consciousness |
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Complex Seizures |
Impaired consciousness and lack of responsiveness S&S: motionless, fixed gaze, repetitive purposeless movements Lasts 45-90 seconds |
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Secondary Generalized |
Begins as simple or complex and evolves to tonic-clonic (grand mal), lasts 1-2 minutes |
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Generalized Seizures |
Focal seizure activity is conducted widely throughout both hemispheres - Tonic-clonic, Absence (petit-mal), myoclonic, febrile |
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Tonic- Clonic (Grand Mal) Seizures |
Neuronal discharge spreads throughout entire cerebral cortex S&S: major convulsions, muscle rigidity, jerking, incontinence, loud cry, CNS depression (postictal state) |
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Absence (Petit Mal) Seizures |
Brief loss of consciousness (10-30 seconds) May or may not have motor activity |
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Myoclonic Seizures |
Sudden muscle contractions 1 limb or whole body (1 sec) |
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Febrile Seziure |
6mths- 5yo from increased fever Does not increase risk of developing epilepsy later in life |
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Status Epilepticus (SE) |
Seizures lasting 30 minutes or more; may be of various types; must go to ER; IV valium; O2 is limited to brain |
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Goal of Epilepsy Treatment |
To reduce seizures to an extent that enables a person to live Meds benefit 60-70% of pts with epilepsy Evaluation of drug effect: seizures frequency chart |
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Drugs that potentiate GABA |
- Barbiturates (Phenobarbital) - Benzodiazepines (Lorazepam, Clonazepam) - Misc. drugs (Gabapentin) |
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Drugs that suppress sodium influx |
Decrease CNS activity by delaying the influx of sodium ions across neuronal membranes - Hydontoins- Phenytoin (DIlantin) - Hyentoin- like agents- Carbamozepine (Tegretol) |
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Drugs that suppress calcium influx |
Delaying calcium influx into neuronal membranes - Succinimides- Valproic Acid (Depakene) |
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Carbamazapine (Tegretol) treats... |
Simple, complex partial seizures |
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Phenytoin (Dilantin) treats... |
Secondary generalized seizures |
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Valproic Acid treats... |
Tonic-clonic (grand mal) seizures Absence seizures Myoclonic seizures |
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Sodium Channel Physiology |
Neuronal action potentials are moved along by Na moving into Na channels (gated pores in cell membrane) For Na influx to occur, channel must be active After Na entry, channel becomes inactivated, blocking further Na influx Normally the channel recharges quickly to become active again |
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Phenytoin (Dilantin)/ Carbomazepine (Tegretol) MOA |
Suppression of sodium influx Reversibly bind to sodium channels while they are in the inactivated state - Prolong Na channel inactivation - Decrease ability of neurons to fire at high frequencies - Decrease seizures that depend on high frequency neuronal discharge |
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Phenytoin (Dilantin) |
Effective and safe dosage is difficult to establish- narrow therapeutic range Absorption varies with formulation of drug (suspension, IV, tablets, capsules) Overwhelms liver, ensure correct dosage Contraindication: liver disease |
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Phenytoin (Dilantin) Adverse Effects |
Sedation Nystagmus Diplopia Skin rash Ataxia Gingival hyperplasia (gum tissue overgrowth) |
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Phenytoin (Dilantin) Drug Interactions |
Warfarin, glucocorticoids, oral contraceptives (taking Dilantin may cause decrease effects) Diazepam, alcohol, cimotidine (these increase Phenytoin plasma levels, toxicity) Carbamozepine, Phenobarb (decrease Dilantin plasma levels to subtherapeutic levels) Alcohol, CNS depressants, barbiturates (amplify the CNS depressant effects Phenytoin creates) |
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Phenytoin (DIlantin) Pharmacokinetics |
Route: PO, IV Initially doses even BID, maintained on OD doses Very short half life, higher doses increase half-life (there is more drug present than the liver can process, can last up to 60 hrs as opposed to 8hr half life) Serum levels: desired between 10-20 mcg |
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Carbamezepine (Tegretol) MOA |
Delays recovery of Na channels from inactivated state |
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Carbamezepine (Tegretol) Pharmacokinetics |
Half-life decreases as therapy progresses (40-->15hrs) Induces drug metabolizing enzymes- increase metabolism Fewer side effects than Dilantin Mood stabilizing effects- Bipolar disorder |
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Carbamezepine (Tegretol) Adverse Effects |
Vertigo, nystagmus, blurred vision, diplopia, unsteadiness Leukopenia, anemia, thrombocytopenia Birth defects |
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Carbamezepine (Tegretol) Interactions |
Oral contraceptives, Warfarin Dilantin and Phenobarb Grapefruit |
