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Questions and Answers
Which of the following AEDs primarily acts by potentiating the GABA mechanism?
Which of the following AEDs primarily acts by potentiating the GABA mechanism?
Which of the following AEDs is known to be a potent inducer of its own metabolism?
Which of the following AEDs is known to be a potent inducer of its own metabolism?
Which of the following AEDs is primarily used for the treatment of absence seizures?
Which of the following AEDs is primarily used for the treatment of absence seizures?
Which of the following AEDs exerts its effect by blocking GABA degradation?
Which of the following AEDs exerts its effect by blocking GABA degradation?
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Which of the following AEDs is known to decrease the glucuronidation of lamotrigine?
Which of the following AEDs is known to decrease the glucuronidation of lamotrigine?
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Which of the following AEDs exerts its effect by blocking the AMPA receptor?
Which of the following AEDs exerts its effect by blocking the AMPA receptor?
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Which of the following AEDs is used for long-term treatment of seizures and is administered rectally to children?
Which of the following AEDs is used for long-term treatment of seizures and is administered rectally to children?
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Which of the following AEDs acts by increasing potassium channel permeability?
Which of the following AEDs acts by increasing potassium channel permeability?
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Flashcards
Seizures
Seizures
Sudden excessive synchronous discharges of neurons that lead to loss of consciousness and abnormal movements.
Partial Seizures
Partial Seizures
Seizures that start in one area of the brain; include simple and complex types.
Generalized Seizures
Generalized Seizures
Seizures involving both hemispheres of the brain, typically without an aura.
Volage Gated Sodium Channels
Volage Gated Sodium Channels
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GABA Potentiation
GABA Potentiation
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Calcium Channel Blockers
Calcium Channel Blockers
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Glutamate Antagonism
Glutamate Antagonism
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Exocytosis Antagonism
Exocytosis Antagonism
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Study Notes
Seizures
- Seizures are sudden, excessive, and synchronous neuronal discharges.
- Result in loss of consciousness, abnormal movements, atypical movements, and distorted perceptions.
Types of Seizures
Partial/Focal Seizures
- Simple partial: Partial sensory seizure, often preceded by an aura.
- Complex partial: Temporal lobe seizure.
- Secondarily generalized: Partial seizure that spreads to involve the entire brain.
- Treatment: Most AEDs are effective; ethosuximide is an exception.
Generalized Seizures
- No aura present before the seizure.
- Generalized tonic-clonic: Muscle stiffening (tonic) and jerking (clonic) movements.
- Tonic/atonic: Muscle stiffness followed by loss of muscle tone.
- Absence: Brief loss of awareness.
- Myoclonic: Sudden, brief muscle jerks.
- Treatment: Limited AED options.
Anti-Epileptic Drugs (AEDs) Mechanisms and Interactions
1. Voltage-Gated Sodium Channels
- Phenytoin: Zero-order kinetics, metabolized by P450 enzymes, enzyme inducer.
- Carbamazepine/Oxcarbazepine: Enzyme inducer for their own metabolism, and also induce P450 enzymes.
- Lamotrigine: Major metabolic pathway is glucuronic acid conjugation. Valproic acid decreases glucuronic acid conjugation of lamotrigine; estrogen increases glucuronic acid conjugation of many drugs.
- Phenobarbital: Enzyme inducer.
- Valproic Acid: High protein binding; blocks metabolism; P450 inducers lower levels of Valproic Acid.
2. GABAergic Mechanism Potentiation
- Phenobarbital: Increases the duration of chloride channel opening.
- Benzodiazepines: Increases the frequency of chloride channel opening.
- Felbamate, topiramate, valproate: Similar effects as benzodiazepines, acting on GABAergic mechanisms.
- Vigabatrin: Blocks GABA transaminase (GABA-T), increasing extracellular GABA.
- Tiagabine: Blocks GABA reuptake in neurons and glial cells, increasing extracellular GABA.
- Benzodiazepines: Lorazepam (IV emergency, sublingual at aura), midazolam (IV emergency), rectal diazepam (children). Long-term treatment options include clonazepam and clobazam. Withdrawal can cause seizures in non-epileptic individuals.
3. Calcium Channel Blockade
- Ethosuximide, Valproic Acid: Low-threshold T-type calcium channels in thalamic pacemaker neurons. Ethosuximide, along with Valproic Acid, is an treatment option for absence seizures.
- Gabapentin, Pregabalin: Act on presynaptic voltage-gated calcium channels, reducing calcium influx and subsequent glutamate release. They are not direct GABA agonists, but they affect GABAergic pathways through modulation of calcium influx.
4. Glutamate Antagonism
- Phenobarbital: Antagonizes glutamate effects.
- Felbamate: NMDA receptor antagonist.
- Topiramate: AMPA receptor antagonist.
- Perampanel: AMPA receptor antagonist.
5. Potassium Channel Permeability Enhancement
- Valproic Acid: Enhances potassium channel permeability.
- Ezogabine: Enhances potassium channel permeability.
6. Exocytosis Antagonism
- Levetiracetam: Binds to the SV2A vesicle protein, decreasing neurotransmitter release.
AED Excretion
- Gabapentin, Pregabalin, Vigabatrin, Levetiracetam: Excreted by the kidneys.
Drug Interactions
- Increased potency: Valproic acid increases phenytoin levels.
- Decreased potency: Carbamazepine decreases carbamazepine and other drug levels.
- Vit D & Bone Health: Low vitamin D can lead to osteoporosis, particularly regarding some anticonvulsants. Oral contraceptives may be affected.
- Liver P450 inducers: Phenytoin, phenobarbital, and carbamazepine are P450 inducers.
Pregnancy
- Folate: Folate supplementation (4 mg/day) is crucial during pregnancy.
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Description
This quiz covers various types of seizures, their characteristics, and the role of anti-epileptic drugs in their treatment. It includes information on partial and generalized seizures, along with the mechanisms of action of common AEDs. Test your understanding of seizure pathology and pharmacology.
