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
Explanation
A) Montelukast (Singulair): This medication is a leukotriene receptor antagonist used to manage asthma and allergic rhinitis. It does not contain soy or soy-derived ingredients, making it a safe option for a client with a soybean allergy. There are no known contraindications related to soy in this medication.
B) Methylprednisolone (Solumedrol): This is a corticosteroid used to reduce inflammation. It is not contraindicated for clients with a soybean allergy, as it does not contain soy-derived components. The medication primarily poses risks related to long-term use, but not specifically regarding soybean allergies.
C) Ipratropium bromide (Atrovent): This medication is an anticholinergic used to relieve bronchospasm. Ipratropium bromide is formulated with soy lecithin, which is derived from soybeans. Therefore, it is contraindicated for clients with a known allergy to soybeans, as it may trigger an allergic reaction.
D) Albuterol (Ventolin): This medication is a short-acting beta-agonist used for quick relief of bronchospasm. It does not contain any soy components and is generally safe for patients with soybean allergies. While there may be other considerations for its use, the allergy to soy is not a concern with this medication.
Correct Answer is D
Explanation
A. Stimulate alpha-adrenergic receptors, thus producing vascular constriction of capillaries in nasal mucosa: This describes the action of decongestants, not guaifenesin. Guaifenesin does not work by constricting blood vessels; rather, its primary function is to help manage mucus production.
B. Compete with histamine for receptor sites, thus preventing a histamine response and overall congestion: This mechanism is associated with antihistamines, which are used to relieve symptoms of allergic reactions, not with guaifenesin. Guaifenesin does not block histamine but focuses on mucus management.
C. Treat allergic rhinitis and prevent motion sickness: While these are common uses for antihistamines, they do not apply to guaifenesin. Guaifenesin is primarily an expectorant and is not indicated for treating allergic rhinitis or motion sickness.
D. Loosen bronchial secretion to assist in elimination: Guaifenesin acts as an expectorant, promoting the clearance of mucus from the airways by loosening bronchial secretions. This facilitates easier expectoration of mucus, helping to relieve chest congestion associated with upper respiratory infections.