The Symptoms of allergen-mediated asthma result from which of the following?

Correct Answer: A

Rationale: The correct answer is A) Increased release of mediators from mast cells. In allergen-mediated asthma, exposure to an allergen triggers an immune response leading to the activation of mast cells. Mast cells release various mediators such as histamine, leukotrienes, and prostaglandins. These mediators cause airway inflammation, bronchoconstriction, mucus production, and edema, resulting in the symptoms of asthma like coughing, wheezing, chest tightness, and shortness of breath. Option B) Increased adrenergic responsiveness of the airways is incorrect because while adrenergic drugs can be used to dilate the airways in asthma treatment, it is not the primary mechanism behind allergen-mediated asthma symptoms. Option C) Increased vascular permeability of bronchial tissue is incorrect as increased vascular permeability can lead to edema but is not the primary cause of asthma symptoms in allergen-mediated asthma. Option D) Decreased calcium influx into the mast cells is incorrect because calcium influx is actually necessary for mast cell degranulation and mediator release in response to allergen exposure. Understanding the mechanisms behind allergen-mediated asthma is crucial for healthcare professionals to effectively manage and treat asthma patients. By knowing how allergens trigger mast cell activation and the subsequent release of inflammatory mediators, healthcare providers can choose appropriate treatment options like anti-inflammatory drugs and bronchodilators to control asthma symptoms and improve patient outcomes.

Correct Answer: D

Rationale: In this scenario, the correct answer is D) Have efficacy in the prevention of motion sickness. Fexofenadine and diphenhydramine are both antihistamines used to treat allergy symptoms, but they differ in their side effects and additional uses. Diphenhydramine, unlike fexofenadine, has anticholinergic properties that make it effective in preventing motion sickness. Option A is incorrect because diphenhydramine is not typically used for the treatment of asthma; bronchodilators and corticosteroids are more commonly prescribed. Option B is also incorrect as diphenhydramine is not indicated for the treatment of gastroesophageal reflux disease; proton pump inhibitors are typically used for this condition. Option C is incorrect as well because while diphenhydramine can cause cardiac arrhythmias in overdose, it is not a characteristic feature that distinguishes it from fexofenadine. Educationally, understanding the differences between antihistamines like fexofenadine and diphenhydramine is crucial for healthcare professionals to make informed decisions when treating patients with allergy and respiratory problems. Recognizing the unique properties of each medication allows for tailored treatment plans that maximize efficacy and minimize potential side effects.

Correct Answer: B

Rationale: In this question, the correct answer is B) Disodium cromolyn. Disodium cromolyn is a medication that is administered by inhalation of powder and is used as a prophylactic (preventative) treatment for asthma. It works by stabilizing mast cells and preventing the release of inflammatory substances that can trigger asthma symptoms. Option A) Ephedrine is a sympathomimetic drug that acts as a bronchodilator, but it is not typically used as a prophylactic treatment for asthma. Option C) Isoproterenol is a beta-adrenergic agonist that is used for acute bronchospasm relief in conditions like asthma or COPD, but it is not typically used as a prophylactic treatment. Option D) Orcytriphylline is a xanthine derivative bronchodilator used in the treatment of asthma and COPD, but it is not typically administered by inhalation of powder as a prophylactic treatment for asthma. Educationally, understanding the different classes of drugs used in the treatment of respiratory conditions like asthma is crucial for healthcare professionals. It is important to know which medications are used for acute relief versus prophylactic treatment to provide optimal care for patients with respiratory problems. Understanding the mechanisms of action and appropriate administration routes of these drugs is essential for effective management of asthma and other respiratory conditions.

Correct Answer: C

Rationale: In the context of drugs for allergy and respiratory problems, understanding the mechanism of action of histamine and its receptors is crucial. Histamine can cause a fall in blood pressure when present in larger doses. The correct answer, option C (Combination of H₁ and H₂ antagonists), is the most appropriate choice because both H₁ and H₂ receptors play a role in regulating blood pressure. H₁ antihistamines primarily target histamine receptors in the respiratory system and are more effective in treating symptoms like sneezing and itching. On the other hand, H₂ antagonists mainly block histamine receptors in the stomach, reducing acid production. Therefore, using H₁ antihistaminics alone (option A) or H₂ antagonists alone (option B) would not effectively block the fall in blood pressure caused by larger doses of histamine because it requires a combination of both H₁ and H₂ antagonists to address the multiple effects of histamine on different receptor types in the body. In an educational context, this question highlights the importance of understanding the specificity of different histamine receptors and the need for a comprehensive approach in managing histamine-related reactions. It also emphasizes the significance of combination therapy in certain situations where multiple receptor pathways are involved in producing physiological responses to a particular mediator like histamine. This knowledge is essential for healthcare professionals involved in treating patients with allergies and respiratory issues to ensure appropriate and effective management strategies.

Correct Answer: B

Rationale: The correct answer is B) Bradycardia. 5-Hydroxytryptamine, also known as serotonin, acts on the 5-HT₃ receptor to induce bradycardia by decreasing heart rate. This is a pharmacological effect commonly seen with activation of the 5-HT₃ receptor. Option A) Vasoconstriction is incorrect because the vasoconstrictive effects of serotonin are primarily mediated by other receptor subtypes, such as 5-HT₁ and 5-HT₂ receptors. Option C) EDRF release is incorrect because EDRF (endothelium-derived relaxing factor) is typically associated with vasodilation rather than bradycardia. Option D) Platelet aggregation is incorrect because serotonin is known to enhance platelet aggregation through other receptor subtypes, such as the 5-HT₂ receptor, not the 5-HT₃ receptor. In an educational context, understanding the specific actions of neurotransmitters like serotonin on different receptor subtypes is crucial in pharmacology. This knowledge helps healthcare professionals predict and manage potential side effects and therapeutic outcomes when prescribing medications that target these receptors. Understanding the effects of serotonin on the 5-HT₃ receptor, in this case, can guide the selection and use of drugs that modulate this pathway in the treatment of various conditions such as nausea and vomiting.