Questions and Answers
Which mechanism of action is NOT commonly associated with antiseizure drugs?
What is a significant adverse effect commonly associated with the use of carbamazepine?
Which antiseizure drug is specifically noted for its use in controlling absence seizures?
Which of the following antiseizure drugs is primarily eliminated by hepatic metabolism?
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What interaction should be a major concern when prescribing valproic acid and lamotrigine together?
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Which antiseizure drug class is most likely to cause cognitive impairment as a side effect?
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What is the primary mechanism of action for benzodiazepines in the treatment of seizures?
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Which of the following is a common adverse effect associated with the use of phenytoin?
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What is the primary mechanism of action of the drug used in the prophylaxis of absence seizures?
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Which of the following is an appropriate clinical use for Primidone?
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Which adverse effect is associated with long-term use of Primidone?
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What is the main pharmacokinetic characteristic of the drug used as the drug of choice for absence seizures?
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Which mechanism of action involves blocking sodium channels and leaving them in an inactive state?
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Which mechanism of action is shared by both the drug used for absence seizures and Primidone?
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Which of the following drugs primarily increases inhibitory neurotransmitter activity by binding to the GABAA-BZD-Cl channel complex?
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What is the effect of valproate on excitatory neurotransmission in the CNS?
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What is a common CNS adverse effect of Primidone?
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Which drug is primarily used in the treatment of absence seizures by inhibiting T-type Ca2+ channels?
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Which of the following drug interactions is noted with Primidone?
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Which of the following represents an action that results in decreased metabolism of GABA at the neuro-effector junction?
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Which of the following adverse effects is specific to the drug used for absence seizures?
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What common side effect might occur with the inhibition of Na channels by antiseizure medications?
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The action of topiramate primarily results in a decrease of which neurotransmitter's activity?
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Which drug among the following is not typically associated with GABAergic activity enhancement?
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Study Notes
Introduction
- Seizures result from abnormal electrical activity in the brain, characterized by rhythmic firing of neurons.
- Epilepsy is a chronic condition marked by recurrent seizures.
Classification of Seizures & Antiseizure Drugs
- Seizures categorized into two main types:
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Partial Seizures:
- Simple partial seizures.
- Complex partial seizures.
- Secondarily generalized partial seizures.
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Generalized Seizures:
- Tonic-clonic (Grand Mal) seizures.
- Absence seizures (Petit Mal).
- Other types include tonic, atonic, clonic, myoclonic, and infantile spasms.
-
Partial Seizures:
Classification of Antiseizure Drugs
- Antiseizure drugs typically have heterocyclic ring structures that define their chemical groups.
- Major chemical groups include:
- Acetyl ureas: e.g., phenacemide.
- Barbiturates: e.g., phenobarbital, primidone.
- Benzodiazepines: e.g., clonazepam, diazepam.
- Hydantoins: e.g., phenytoin, mephenytoin.
- Oxazolidinediones: e.g., dimethadione, trimethadione.
- Succinimides: e.g., ethosuximide, phensuximide.
- Iminostilbenes: e.g., carbamazepine.
- Aliphatic carboxylic acid: e.g., valproic acid.
- Newer agents: e.g., progabide, vigabatrin, gabapentin, lamotrigine, felbamate, topiramate, tiagabine.
- Miscellaneous: e.g., acetazolamide, dexamphetamine.
Mechanisms of Action of Antiseizure Drugs
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Inhibition of Na Channels:
- Drugs block sodium channels, prolonging their inactive state and preventing stimulation.
- Examples: phenytoin, carbamazepine, valproate, topiramate, lamotrigine.
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Increase in Inhibitory Neurotransmitter Activity:
- Drugs enhance GABA activity by binding to GABAA-BZD-Cl channel complexes.
- Examples: diazepam, clonazepam, phenobarbital.
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Increase GABA Release:
- Enhance GABA release or inhibit its breakdown or reuptake.
- Examples: gabapentin increases release; vigabatrine decreases metabolism; tiagabine decreases reuptake.
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Decreased Excitatory Neurotransmitter Activity:
- Glutamate and aspartate are major excitatory neurotransmitters.
- Valproate and topiramate inhibit excitatory activity at NMDA and kainate receptors respectively.
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Inhibition of Ca2+ Channels:
- Drugs inhibit T-type Ca2+ channels, crucial for absence seizures.
- Examples: ethosuximide, phensuximide, valproate, lamotrigine.
Pharmacology of Specific Agents & Their Clinical Uses
-
Phenytoin:
- A diphenylhydantoin with a half-life of approximately 40 hours.
- Mechanism includes blocking T-type Ca2+ current and inhibiting Na+/K+ ATPase.
- Used primarily for absence seizures, alongside valproate and others.
- Adverse effects: GIT discomfort, CNS effects (e.g., fatigue, headache), hematological issues, hypersensitivity reactions.
-
Primidone:
- A barbiturate effective for partial and generalized tonic-clonic seizures.
- Pharmacokinetics: complete oral bioavailability, 25% protein binding, t-half of 5-8 hours.
- Mechanism includes altering Na/Cl transport and enhancing GABAA-Cl complex activity.
- Adverse effects: CNS depression, GIT disturbances, potential vitamin D deficiency leading to rickets or osteomalacia.
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Description
Explore the classifications of seizures and antiseizure drugs in this quiz. Understand the differences between partial and generalized seizures, along with the major chemical groups of antiseizure medications. Test your knowledge on this important neurological topic.
