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 B
Explanation
A. To decrease the cost of medication for the patient: While cost may be a consideration in long-term therapy, it is not the primary reason for tapering corticosteroids. The tapering process is necessary to protect the patient’s physiological balance, not driven by cost concerns.
B. To prevent the risk of acute adrenal insufficiency: Long-term prednisone use suppresses the hypothalamic-pituitary-adrenal (HPA) axis. Abrupt discontinuation can lead to adrenal insufficiency, a potentially life-threatening condition characterized by hypotension, fatigue, and electrolyte imbalances. Gradual tapering allows the adrenal glands to resume natural cortisol production.
C. To minimize the potential for drug interactions: Tapering does not reduce drug interactions. Such risks are managed through medication reconciliation and monitoring, not by adjusting steroid taper schedules.
D. To reduce the likelihood of rheumatoid arthritis flare-up: While tapering may reduce flare risk, the primary concern is adrenal suppression. Flare prevention is managed with other disease-modifying agents rather than the tapering schedule alone.
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