A client frequently takes diphenhydramine (Benadryl) to alleviate his upper respiratory symptoms associated with allergies. Which of the following mechanism of actions applies to diphenhydramine (Benadryl)?
stimulates effects of histamine by occupying all H receptor sites.
blocks effects of histamine by competing and occupying H1 receptor sites.
blocks effects of histamine by competing and occupying H2 receptor sites.
stimulates effects of histamine by increasing amount of H2 receptor sites.
The Correct Answer is B
A. Stimulates effects of histamine by occupying all H receptor sites: This statement inaccurately describes the action of diphenhydramine. Instead of stimulating histamine effects, diphenhydramine actually blocks them, particularly at H1 receptors, which are involved in allergic responses.
B. Blocks effects of histamine by competing and occupying H1 receptor sites: This accurately describes the mechanism of action of diphenhydramine. As an antihistamine, it competes with histamine for binding to H1 receptor sites, effectively reducing symptoms of allergies, such as sneezing, itching, and nasal congestion.
C. Blocks effects of histamine by competing and occupying H2 receptor sites: This option is incorrect because H2 receptor antagonists are used primarily to reduce gastric acid secretion, not to treat allergic reactions. Diphenhydramine specifically targets H1 receptors, not H2 receptors.
D. Stimulates effects of histamine by increasing the amount of H2 receptor sites: This statement is also incorrect. Diphenhydramine does not stimulate histamine activity or increase receptor sites. Instead, it functions to inhibit the action of histamine at H1 receptors, which is fundamental in alleviating allergy symptoms.
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Correct Answer is ["C","E"]
Explanation
A. This medication (Benadryl) targets H2 receptors to alleviate symptoms: This statement is incorrect. Diphenhydramine is an H1 receptor antagonist, not an H2 antagonist. H1 receptors are primarily involved in allergic reactions, whereas H2 receptors are related to gastric acid secretion.
B. Take this medication on an empty stomach before breakfast. Drowsiness is a common side effect of diphenhydramine (Benadryl): While drowsiness is indeed a common side effect, taking diphenhydramine on an empty stomach is not necessarily required and may lead to gastrointestinal discomfort. It can be taken with food if preferred.
C. Avoid CNS depressants while taking diphenhydramine (Benadryl): This is an important teaching point. Diphenhydramine can cause sedation, and the use of other CNS depressants (like alcohol or sedatives) can enhance this effect, increasing the risk of excessive drowsiness or other complications.
D. This medication is a 2nd generation antihistamine: This statement is incorrect. Diphenhydramine is actually a first-generation antihistamine. First-generation antihistamines tend to cause more sedation and other side effects compared to second-generation antihistamines, which are less sedating.
E. Paradoxical reactions can be seen with this medication: This is true. In some individuals, particularly children, diphenhydramine can cause paradoxical reactions, such as increased excitability or hyperactivity, rather than the expected sedation. This is an important consideration to discuss with clients.
Correct Answer is B
Explanation
A. Stimulates effects of histamine by occupying all H receptor sites: This statement inaccurately describes the action of diphenhydramine. Instead of stimulating histamine effects, diphenhydramine actually blocks them, particularly at H1 receptors, which areinvolved in allergic responses.
B. Blocks effects of histamine by competing and occupying H1 receptor sites: This accurately describes the mechanism of action of diphenhydramine. As an antihistamine, it competes with histamine for binding to H1 receptor sites, effectively reducing symptoms of allergies, such as sneezing, itching, and nasal congestion.
C. Blocks effects of histamine by competing and occupying H2 receptor sites: This option is incorrect because H2 receptor antagonists are used primarily to reduce gastric acid secretion, not to treat allergic reactions. Diphenhydramine specifically targets H1 receptors, not H2 receptors.
D. Stimulates effects of histamine by increasing the amount of H2 receptor sites: This statement is also incorrect. Diphenhydramine does not stimulate histamine activity or increase receptor sites. Instead, it functions to inhibit the action of histamine at H1 receptors, which is fundamental in alleviating allergy symptoms.