A nurse is preparing to administer valproic acid (Depakote) to a client who has absence seizures. The client asks the nurse why this medication is prescribed. What is an appropriate response by the nurse?
"This medication works by inhibiting the breakdown of a neurotransmitter that prevents seizures."
"This medication works by enhancing the activity of a neurotransmitter that inhibits seizures."
"This medication works by blocking sodium channels that trigger seizures."
"This medication works by suppressing calcium influx that causes seizures."
The Correct Answer is B
Valproic acid is an anticonvulsant that is used to treat absence seizures, which are brief episodes of staring or blanking out. Valproic acid is believed to increase the concentration of gamma-aminobutyric acid (GABA) in the brain, which is a neurotransmitter that reduces the excitability of neurons and prevents seizures¹².
Choice A is wrong because valproic acid does not inhibit the breakdown of a neurotransmitter, but rather increases its availability. The neurotransmitter that is inhibited by valproic acid is not known to prevent seizures, but rather to cause them. This neurotransmitter is glutamate, which is the main excitatory neurotransmitter in the brain³.
Choice C is wrong because valproic acid does not block sodium channels that trigger seizures, but rather calcium channels that are involved in neuronal signaling. Blocking sodium channels is the mechanism of action of another class of anticonvulsants, such as phenytoin and carbamazepine⁴.
Choice D is wrong because valproic acid does not suppress calcium influx that causes seizures, but rather inhibits calcium channels that regulate calcium influx. Suppressing calcium influx is the mechanism of action of another anticonvulsant, ethosuximide, which is also used to treat absence seizures⁵.
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Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Phenytoin is an anticonvulsant that works by stabilizing the neuronal membrane and preventing the spread of seizure activity¹. The therapeutic range of phenytoin is **10-20 mcg/mL**²³⁴⁵. A serum phenytoin level of **25 mcg/mL** is above the therapeutic range and indicates toxicity. The nurse should hold the next dose and notify the provider to prevent further adverse effects, such as nystagmus, ataxia, confusion, and coma¹.
Choice A. Administer the next dose as scheduled is wrong because it would increase the risk of phenytoin toxicity and worsen the client's condition.
Choice C. Increase the next dose by 25% is wrong because it would also increase the risk of phenytoin toxicity and worsen the client's condition.
Choice D. Decrease the next dose by 25% is wrong because it may not be enough to lower the phenytoin level to the therapeutic range. The nurse should consult with the provider before making any dose adjustments.
Correct Answer is B
Explanation
Valproic acid is an anticonvulsant that is used to treat absence seizures, which are brief episodes of staring or blanking out. Valproic acid is believed to increase the concentration of gamma-aminobutyric acid (GABA) in the brain, which is a neurotransmitter that reduces the excitability of neurons and prevents seizures¹².
Choice A is wrong because valproic acid does not inhibit the breakdown of a neurotransmitter, but rather increases its availability. The neurotransmitter that is inhibited by valproic acid is not known to prevent seizures, but rather to cause them. This neurotransmitter is glutamate, which is the main excitatory neurotransmitter in the brain³.
Choice C is wrong because valproic acid does not block sodium channels that trigger seizures, but rather calcium channels that are involved in neuronal signaling. Blocking sodium channels is the mechanism of action of another class of anticonvulsants, such as phenytoin and carbamazepine⁴.
Choice D is wrong because valproic acid does not suppress calcium influx that causes seizures, but rather inhibits calcium channels that regulate calcium influx. Suppressing calcium influx is the mechanism of action of another anticonvulsant, ethosuximide, which is also used to treat absence seizures⁵.
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