A 21-year-old man is brought to the emergency department by his mother after she found him violently shaking on the kitchen floor of her home. The patient urinated on himself and bit his tongue during the incident. He has a past medical history of posttraumatic epilepsy and is noncompliant with his antiseizure medications. In the hospital, he has several brief, back-to-back generalized tonic-clonic seizures and never fully regains consciousness between episodes. Intravenous lorazepam 2 mg is administered, and the seizures stop. Intravenous infusion of another drug is started simultaneously to prevent seizure recurrence. Which of the following is the most likely mechanism of action of the second drug infused in this patient?

Question

A 21-year-old man is brought to the emergency department by his mother after she found him violently shaking on the kitchen floor of her home.  The patient urinated on himself and bit his tongue during the incident.  He has a past medical history of posttraumatic epilepsy and is noncompliant with his antiseizure medications.  In the hospital, he has several brief, back-to-back generalized tonic-clonic seizures and never fully regains consciousness between episodes.  Intravenous lorazepam 2 mg is administered, and the seizures stop.  Intravenous infusion of another drug is started simultaneously to prevent seizure recurrence.  Which of the following is the most likely mechanism of action of the second drug infused in this patient?

Quizplus · Accepted Answer

11ec160b_3c1a_98ee_9249_7f2dbb5f0b73_MD0001_00 Status epilepticus is a single seizure lasting >5 minutes or the occurrence of multiple discrete seizures with incomplete recovery of consciousness between episodes. Common causes include structural brain injury (eg, stroke, tumor, head trauma), infection, metabolic abnormalities (eg, hypoglycemia), and medication noncompliance in individuals with known epilepsy. Prompt evaluation and treatment is necessary as the condition is life-threatening and associated with a number of systemic complications (eg, cardiac arrhythmias, hypoventilation/hypoxia, disabling neurologic deficits). Intravenous lorazepam is a benzodiazepine that potentiates the effects of the inhibitory neurotransmitter GABA in the central nervous system. It is the initial drug of choice for treatment of status epilepticus due to its efficacy and rapid onset of action. Intravenous phenytoin (or fosphenytoin) is a long-acting anticonvulsant that is administered concurrently to prevent the recurrence of seizure activity, regardless of patient responsiveness to lorazepam. Phenytoin inhibits neuronal high-frequency firing in the cortex by reducing the ability of sodium channels to recover from inactivation. (Choice A) Ethosuximide blocks T-type calcium channels in thalamic neurons. It is a first-line treatment for absence seizures. (Choices C and D) Benzodiazepines and barbiturates (eg, phenobarbital) bind to the ligand-gated chloride channel of the GABA_A receptor. These substances enhance the inhibitory effect of GABA by increasing postsynaptic chloride influx. (Choice E) Vigabatrin is an irreversible inhibitor of GABA transaminase, the enzyme responsible for GABA catabolism in the central nervous system. Vigabatrin is one of several drugs that can be used in cases of treatment-resistant epilepsy. Educational objective: Status epilepticus is a single seizure lasting >5 minutes or the occurrence of multiple discrete seizures with incomplete recovery of consciousness between episodes. The initial treatment includes intravenous lorazepam and phenytoin given concurrently. Phenytoin is a long-acting anticonvulsant that inhibits neuronal high-frequency firing by reducing the ability of sodium channels to recover from inactivation. __________ References: The management of status epilepticus. (http://www.ncbi.nlm.nih.gov/pubmed/11385046) Basis of the antiseizure action of phenytoin. (http://www.ncbi.nlm.nih.gov/pubmed/8981053)

A 21-Year-Old Man Is Brought to the Emergency Department by His