Which of the following statements correctly differentiates first-generation and second-generation antihistamines?
Second-generation antihistamines have shorter half-lives and require more frequent dosing compared to first-generation antihistamines.
First-generation antihistamines block both histamine and muscarinic receptors, while second-generation antihistamines primarily block histamine receptors.
First-generation antihistamines are less likely to cause sedation compared to second-generation antihistamines.
Second-generation antihistamines cross the blood-brain barrier, causing significant central nervous system effects.
The Correct Answer is B
A. Second-generation antihistamines have shorter half-lives and require more frequent dosing compared to first-generation antihistamines: Second-generation antihistamines typically have longer half-lives, allowing once-daily dosing. They are designed for sustained action with improved compliance and fewer side effects.
B. First-generation antihistamines block both histamine and muscarinic receptors, while second-generation antihistamines primarily block histamine receptors: First-generation agents, such as diphenhydramine, cross the blood-brain barrier and exert anticholinergic effects by blocking muscarinic receptors. Second-generation antihistamines are more selective for peripheral H1 receptors, resulting in fewer CNS and anticholinergic side effects.
C. First-generation antihistamines are less likely to cause sedation compared to second-generation antihistamines: First-generation antihistamines are more likely to cause sedation because they easily penetrate the blood-brain barrier and affect central H1 receptors, unlike second-generation agents.
D. Second-generation antihistamines cross the blood-brain barrier, causing significant central nervous system effects: These medications are designed not to cross the blood-brain barrier significantly, which is why they are much less sedating and have minimal CNS effects compared to first-generation antihistamines.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is ["12.5"]
Explanation
Desired dose = 25 mg
Available concentration = 10 mg per 5 mL
- Calculate the concentration in mg/mL:
Concentration (mg/mL) = Available dose / Available volume
= 10 mg / 5 mL
= 2 mg/mL
Volume to administer = Desired dose / Available concentration
= 25 mg / 2 mg/mL
= 12.5 mL
Correct Answer is ["150"]
Explanation
Total volume to be infused = 1200 mL
Total infusion time = 8 hours
- Calculate the flow rate in mL per hour (mL/hr):
Flow rate (mL/hr) = Total volume (mL) / Total infusion time (hours)
= 1200 mL / 8 hours
= 150 mL/hr
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