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 B
Explanation
A. Instruct the patient to limit their fluid intake: Limiting fluids can worsen secretion thickness and impair mucociliary clearance. Hydration is essential for thinning secretions and supporting the action of mucolytics like Acetylcysteine.
B. Perform chest physiotherapy: Chest physiotherapy, including percussion and postural drainage, helps mobilize loosened secretions following Acetylcysteine administration. This facilitates airway clearance and improves ventilation and oxygenation.
C. Instruct the patient to avoid coughing to prevent airway irritation: Coughing is a natural and beneficial response that helps expel mucus after mucolytic therapy. Inhibiting the cough reflex can lead to secretion retention and airway obstruction.
D. Administer a bronchodilator: While bronchodilators may be helpful in patients with bronchospasm, they are not required after every dose of Acetylcysteine. Chest physiotherapy is more directly effective in clearing mucus after mucolytic administration.
Correct Answer is ["4"]
Explanation
Desired dose = 8 mg
The medication label for Perphenazine Tablets, USP states: 2 mg per tablet.
- Determine the number of tablets needed:
Number of tablets = Desired dose / Dose per tablet
= 8 mg / 2 mg/tablet
= 4 tablets.
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