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 A
Explanation
A) Liver injury: Zafirlukast (Accolate) has been associated with the risk of liver injury. It is important for clients to be informed about this potential adverse effect, as it may require monitoring of liver function tests during treatment. Symptoms of liver injury, such as jaundice, dark urine, or severe fatigue, should prompt clients to seek medical attention.
B) Bradycardia: Bradycardia is not a commonly associated adverse effect of zafirlukast. This medication primarily works as a leukotriene receptor antagonist and does not typically affect heart rate significantly. Clients should be aware of other more relevant side effects rather than bradycardia.
C) Renal failure: Renal failure is not a known adverse effect of zafirlukast. While kidney function should always be monitored in patients taking various medications, zafirlukast specifically does not have a direct association with renal failure.
D) Bronchoconstriction: While bronchoconstriction is a concern in asthma management, zafirlukast is designed to prevent bronchoconstriction by blocking leukotriene receptors. Therefore, it is not an adverse effect of the medication. In fact, its purpose is to help reduce the incidence of bronchoconstriction and improve asthma control.
Correct Answer is C
Explanation
A) Palpitations: While palpitations can be concerning for many medications, they are not a commonly reported side effect of dextromethorphan. This medication primarily acts as a cough suppressant and does not typically have cardiovascular effects that would lead to palpitations. Therefore, clients should not primarily monitor for this side effect when taking dextromethorphan.
B) Hypertension: Dextromethorphan is not generally associated with causing hypertension. Its main action is to suppress the cough reflex, and it does not typically influence blood pressure levels. Patients taking this medication should focus on other side effects rather than worrying about hypertension.
C) Ataxia: Ataxia, or impaired coordination, is a notable adverse effect associated with dextromethorphan, especially at higher doses or when combined with other central nervous system depressants like alcohol. This side effect can lead to dizziness and increased risk of falls or accidents, making it important for clients to be aware of their coordination and alertness levels while on this medication. Advising patients to avoid driving or operating heavy machinery if they experience ataxia is essential for their safety.
D) Diarrhea: Diarrhea is not a common adverse effect of dextromethorphan. The medication is primarily used for its antitussive properties, and gastrointestinal disturbances like diarrhea are generally not associated with its use. If patients experience gastrointestinal symptoms while taking this medication, they may need to consider other factors or medications that could be contributing to those symptoms.