131 Questions
Which mechanism is involved in the action of some anti-seizure drugs that prolong the inactivation of Na+ channels?
Enhancing GABA-mediated neuronal inhibition
What is the role of NMDA receptor antagonists in the context of anti-seizure drugs?
Increasing glutamate synaptic activity
How do some AEDs act on voltage-gated Na+ and Ca++ currents?
By blocking both currents
What effect do AEDs that inhibit brain carbonic anhydrase enzyme have on neurons?
Increase Na+ channel inactivation
Which combination of mechanisms do some anti-seizure drugs act through?
Enhancing GABA-mediated inhibition and increasing glutamate activity
What is the initial therapy of choice for status epilepticus?
Lorazepam IV
Which medication is recommended as the second therapy of choice for status epilepticus?
Fosphenytoin IV
Why do neuromuscular blocking agents not stop seizures in status epilepticus?
They only affect the muscular response, not the brain's electrical activity
What can happen when patients on chronic anticonvulsant therapy take drugs that are highly protein bound?
Increased plasma concentrations of AED medications
Which side effects are considered dose-related in antiepileptic drugs?
Dizziness and ataxia
How do antiepileptic drugs exert their anticonvulsant activity?
By modulating the brain's electrical activity
What is the primary mechanism of action for oxcarbazepine?
It is primarily converted to its pharmacologically active 10-monohydroxy metabolite (MHD)
What is a common adverse effect associated with chronic valproate therapy?
Weight gain
What is the recommended monitoring for patients on valproate therapy?
Liver function tests
Which of the following is a non-dose-related adverse effect of valproate?
Rash
Why is valproate contraindicated in pregnancy?
It can increase the risk of neural tube defects in the fetus
Which of the following is NOT a common side effect associated with chronic administration of phenobarbital?
Increased appetite
What is the mechanism of action of ethosuximide in treating absence seizures?
It acts as a T-type calcium channel blocker in thalamic neurons.
Which of the following is NOT a clinical use of valproate sodium or valproic acid?
Treatment of generalized anxiety disorder
What is the primary route of metabolism for valproate sodium or valproic acid?
Hepatic UGT enzymes
Which of the following statements about primidone is TRUE?
It is metabolized into phenobarbital and phenylethylmalonamide (PEMA).
What is the primary mechanism of action of valproate sodium or valproic acid in treating seizures?
Increasing GABA production and inhibiting GABA metabolism
Which of the following statements about the pharmacokinetics of ethosuximide is TRUE?
It has a bioavailability of 100% and is not protein bound.
Which of the following is a potential drug-drug interaction associated with valproate sodium or valproic acid?
It may decrease the metabolism of drugs metabolized by UGT and CYP450 enzymes.
What is the approximate half-life of valproate sodium or valproic acid?
8-17 hours
Which of the following statements about the absorption of valproate sodium or valproic acid is TRUE?
It is a gastrointestinal irritant and enteric-coated dosage forms help decrease GI side effects.
What is the mechanism of action for phenobarbital?
It binds to GABAA receptors and increases GABA-mediated chloride influx
Which of the following is NOT a common adverse effect of phenytoin (Dilantin®)?
Agranulocytosis
What is the primary advantage of fosphenytoin (Cerebyx®) over phenytoin?
All of the above
Which of the following statements about carbamazepine (Tegretol®) is FALSE?
It is available as an oral and injectable formulation
Which of the following statements about the interaction between phenytoin/carbamazepine and nondepolarizing neuromuscular blockers is TRUE?
All of the above
Which of the following statements about phenobarbital is FALSE?
It has a short half-life of approximately 12 hours
Which of the following statements about phenobarbital is TRUE?
All of the above
Which of the following adverse effects is NOT associated with carbamazepine (Tegretol®)?
Fetal hydantoin syndrome
What is the recommended rate of administration for the fosphenytoin loading dose?
No faster than 150 mg PE/min
Which of the following statements about the pharmacokinetics of carbamazepine is TRUE?
All of the above
Oxcarbazepine undergoes auto-induction like carbamazepine.
False
Lamotrigine is an inducer or inhibitor of the CYP450 enzyme system.
False
Hyponatremia (SIADH) is more common with oxcarbazepine compared to carbamazepine.
True
Levetiracetam belongs to the 'racetam' class of compounds and is available in both intravenous and oral formulations.
True
Lamotrigine decreases the presynaptic release of inhibitory amino acids like GABA.
False
Carbamazepine and oxcarbazepine are both sodium channel blockers with similar mechanisms of action.
True
Valproic acid increases the metabolism and decreases the serum concentration of lamotrigine.
False
The primary route of metabolism for valproate is via the liver's CYP450 enzymes.
False
Oxcarbazepine is both an enzyme inducer of CYP3A4/5 and UGT, as well as an inhibitor of some CYP450 enzymes.
True
Which mechanism of action involves enhancing GABA-mediated neuronal inhibition?
Inhibition of brain carbonic anhydrase enzyme
What is the primary effect of agents that prolong the inactivation of Na+ channels?
Enhancing GABA-mediated neuronal inhibition
Which type of drug is more likely to act through a combination of mechanisms?
AEDs inhibiting brain carbonic anhydrase enzyme
What is the effect of inactivating either voltage-gated Na+ or Ca++ currents via blockade?
Reducing the ability of neurons to fire
Which action is associated with AEDs that enhance Na+ channel inactivation?
Decreasing the likelihood of firing at high frequencies
How do AEDs inhibiting brain carbonic anhydrase enzyme impact neuronal activity?
Reduction in neuronal excitability
What is the primary mechanism of action of valproate sodium or valproic acid in treating seizures?
Increases GABA synthesis and inhibits GABA metabolism
What is a common adverse effect associated with chronic valproate therapy?
Bone marrow suppression
How do antiepileptic drugs exert their anticonvulsant activity?
By enhancing the activity of inhibitory neurotransmitters like GABA
Which side effects are considered dose-related in antiepileptic drugs?
All of the above
What will happen to the plasma concentrations of medications metabolized by UGT and CYP450 enzymes when co-administered with valproate sodium or valproic acid?
The plasma concentrations will increase due to enzyme inhibition
Which of the following statements about the pharmacokinetics of ethosuximide is TRUE?
Ethosuximide is primarily eliminated unchanged in the urine
What is the mechanism of action of ethosuximide in treating absence seizures?
Reducing the flow of Ca2+ through T-type Ca2+ channels
Which of the following statements about primidone is TRUE?
Primidone acts similarly to phenobarbital in its mechanism of action
Which adverse effect is MORE COMMON with oxcarbazepine compared to carbamazepine?
Hyponatremia
What is a potential cross-reactivity percentage of patients with hypersensitivity to carbamazepine that will have hypersensitivity to oxcarbazepine?
25-30%
Which enzyme system is oxcarbazepine an inducer of?
3A4/5 and UGT
What is the primary clinical use of lamotrigine?
Monotherapy in partial seizures
Which drug decreases the serum concentration and half-life of lamotrigine?
Valproic acid
Which anti-seizure drug is known for causing fatal or life-threatening hypersensitivity reactions like Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)?
Lamotrigine
What is the main adverse effect associated with levetiracetam at high doses?
Tremor
What is the mechanism responsible for the nonlinear (Michaelis-Menten) pharmacokinetics of phenytoin at higher plasma concentrations?
Saturation of the enzymes involved in phenytoin metabolism
Which of the following patient populations is likely to have a higher free (unbound) fraction of phenytoin in the plasma?
Patients with hypoalbuminemia
Which of the following statements regarding phenytoin's pharmacokinetics is correct?
It exhibits saturable metabolism at plasma concentrations above 10 mcg/mL
Which of the following adverse effects of phenytoin is most likely to be dose-related?
Ataxia
What is the primary reason for phenytoin's potent enzyme-inducing effects?
It induces the synthesis of CYP450 enzymes
Which of the following statements regarding the excretion of phenytoin is correct?
Only a small fraction (<2%) of unchanged phenytoin appears in the urine
Which of the following factors is least likely to affect the therapeutic range of phenytoin?
Renal function
Which of the following statements regarding the pharmacokinetics of phenytoin is false?
Its half-life is dose-independent at all plasma concentrations
Which statement about benzodiazepines is correct?
They potentiate GABA-mediated neuronal inhibition by binding to the benzodiazepine receptor site on GABAA receptors
What is the primary mechanism of action for phenytoin (Dilantin®)?
Blocking fast sodium channels
Which of the following statements about lorazepam is true?
It has a longer elimination half-life and longer duration of antiepileptic action than diazepam
Which statement about the teratogenic effects of antiepileptic drugs (AEDs) is correct?
VPA is generally considered to have the highest incidence of teratogenic malformations and should be avoided during the first trimester of pregnancy
Which statement about the classification of antiepileptic drugs (AEDs) is correct?
First generation agents include phenobarbital, primidone, phenytoin, valproate, and carbamazepine
Which statement about diazepam is true?
It is more lipophilic than lorazepam
How do some anti-seizure drugs enhance GABA synaptic transmission?
By reducing the metabolism of GABA while others act at the GABA-A receptor enhancing chloride influx
Which statement about the metabolism of benzodiazepines is correct?
Lorazepam is metabolized in the liver but does not have active metabolites
What is the duration criterion for a seizure to be classified as status epilepticus?
More than 30 minutes of either continuous seizure activity OR two or more sequential seizures without full recovery of consciousness between seizures
What is considered a neurologic emergency that requires prompt treatment to prevent permanent neurologic damage?
Status epilepticus
Which organ system can be significantly impacted when status epilepticus occurs due to its effect on ventilation?
Respiratory system
What is the potential consequence when seizures last more than 30 to 60 minutes?
CNS damage
Why is status epilepticus considered a neurologic emergency?
Due to the risks of permanent neurologic damage with prolonged seizures
In what timeframe should treatment be initiated for status epilepticus?
Immediately to prevent permanent neurologic damage
What is the mechanism by which some anti-seizure drugs enhance Na+ channel inactivation?
They prolong the inactivation of the Na+ channels, reducing the ability of neurons to fire at high frequencies.
Which of the following statements accurately describes the mechanism of action of NMDA receptor antagonists?
They decrease glutamate synaptic activity.
Which of the following mechanisms is NOT mentioned as a mode of action for anti-seizure drugs?
Inhibition of the brain's sodium-potassium ATPase pump.
Which class of anti-seizure drugs acts by enhancing GABA reuptake?
GABA reuptake inhibitors
What is the significance of the inactivated Na+ channel remaining open but blocked by the inactivation gate?
It allows for faster recovery of the channel once the drug is removed.
Which of the following statements accurately describes the mechanism of action of AMPA/kainate receptor antagonists?
They decrease glutamate synaptic activity.
What will happen to the plasma concentrations of medications metabolized by UGT and CYP450 enzymes when co-administered with valproate sodium or valproic acid?
Their plasma concentrations will increase due to enzyme inhibition
Which anti-seizure drug has been associated with potentially fatal hypersensitivity reactions like Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)?
Carbamazepine
How does valproate sodium or valproic acid enhance GABA-mediated neuronal inhibition?
By stimulating GABA synthesis and inhibiting GABA metabolism
Which mechanism allows ethosuximide to specifically treat absence seizures?
Blockade of T-type calcium channels in thalamic neurons
Which statement about the pharmacokinetics of primidone is TRUE?
It is metabolized to the active metabolites phenobarbital and PEMA
What adverse effect is considered a serious but extremely rare side effect of ethosuximide?
Bone marrow suppression
Which statement about the metabolism of oxcarbazepine is correct?
It is metabolized by the UGT enzyme system, which is a non-CYP450 pathway
Which of the following adverse effects is more likely to occur with lamotrigine compared to carbamazepine?
Rash
Which statement regarding the pharmacokinetics of lamotrigine is correct?
Its metabolism is decreased by carbamazepine, phenytoin, primidone, and phenobarbital
Which of the following statements about levetiracetam (Keppra®) is correct?
It belongs to the 'racetam' class of compounds
Which of the following adverse effects is NOT associated with oxcarbazepine (Trileptal®)?
Hepatotoxicity
Which of the following statements about the pharmacokinetics of lamotrigine is correct?
Its plasma protein binding is approximately 55%
Which mechanism is associated with some anti-seizure drugs in enhancing GABA synaptic transmission?
Reducing the metabolism of GABA
Which of the following statements regarding the teratogenic effects of antiepileptic drugs (AEDs) is correct?
Neural tube defects and cleft lip/palate can occur with certain AEDs during pregnancy.
What is the primary mechanism of action for benzodiazepines in their anticonvulsant effects?
Potentiating GABA-mediated neuronal inhibition
Which statement accurately describes the difference between diazepam and lorazepam in the treatment of status epilepticus?
Diazepam is more lipophilic than lorazepam, leading to a faster onset and shorter duration of action.
What is the primary mechanism of action for phenytoin (Dilantin®) in its anticonvulsant effects?
Blocking voltage-gated sodium channels
Which of the following statements accurately describes the classification of antiepileptic drugs (AEDs)?
First-generation AEDs include phenobarbital, primidone, phenytoin, valproate, carbamazepine, and ethosuximide, while second-generation AEDs are newer agents like lamotrigine and topiramate.
What will happen to the plasma concentrations of medications metabolized by UGT and CYP450 enzymes when co-administered with valproate sodium or valproic acid?
The plasma concentrations will increase due to enzyme inhibition.
What is the potential consequence when seizures last more than 30 to 60 minutes?
Increased risk of permanent neurological damage.
Which adverse effect is considered a serious but extremely rare side effect of ethosuximide?
Bone marrow suppression.
Which mechanism allows ethosuximide to specifically treat absence seizures?
Blocking T-type calcium channels in thalamic neurons.
Which of the following is NOT a clinical use of valproate sodium or valproic acid?
Partial seizures.
Which statement about the teratogenic effects of antiepileptic drugs (AEDs) is correct?
Phenobarbital may cause major fetal malformations.
Which of the following statements about the pharmacokinetics of primidone is TRUE?
Primidone is metabolized into two active metabolites, phenobarbital and PEMA.
How do some AEDs act on voltage-gated Na+ and Ca++ currents?
They enhance the inactivation of voltage-gated Na+ and Ca++ channels.
Which medication is recommended as the second therapy of choice for status epilepticus?
Phenytoin.
Which organ system can be significantly impacted when status epilepticus occurs due to its effect on ventilation?
Respiratory system.
What is a potential life-threatening adverse effect associated with valproate sodium or valproic acid?
Hepatotoxicity
Which of the following is a dose-related adverse effect of chronic valproate therapy?
Alopecia
Why is valproate contraindicated during pregnancy?
Potential neural tube defects
What is the primary pharmacologically active metabolite of Oxcarbazepine (Trileptal®)?
MHD
Which of the following is a non-dose related adverse effect of Valproate Sodium or Valproic Acid?
Aplastic anemia
What is a serious but extremely rare adverse effect associated with ethosuximide?
Hepatotoxicity
Which enzyme system is affected by valproate sodium or valproic acid leading to potential interactions with other medications?
UGT inhibitor
What is the main adverse effect that has been fatal in some cases associated with Oxcarbazepine (Trileptal®)?
Hepatotoxicity
What are the CNS-related adverse effects associated with Valproate Sodium or Valproic Acid?
Sedation/drowsiness, fine distal tremor, ataxia
Study Notes
- Tolerance can develop with chronic administration of anti-epileptic drugs like Primidone, leading to side effects like nystagmus, ataxia, cognitive impairment, and respiratory depression.
- Phenobarbital, a metabolite of Primidone, can cause major fetal malformations.
- Ethosuximide, a succinimide class anti-epileptic drug, is primarily used for absence seizures and acts as a T-type Ca2+ channel blocker in thalamic neurons.
- Valproate Sodium or Valproic Acid, a broad-spectrum anti-seizure medication, is effective against various seizure types and is available in different formulations.
- Valproate Sodium increases GABA production, inhibits GABA metabolism, and has numerous drug interactions due to its enzyme inhibition properties.
- Benzodiazepines like Diazepam and Lorazepam potentiate GABA-mediated neuronal inhibition and are used for treating status epilepticus with different onset and duration of action.
- Phenytoin, an anti-epileptic agent, acts as a fast Na+ channel blocker and regulates neuronal excitability to prevent seizure spread.
Test your knowledge on the medications used for status epilepticus. Learn about the fast-acting and longer-acting agents to manage seizures effectively. Explore the initial and second-line therapies for status epilepticus.
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