Answer to Question 1
Correct Answer: 3
Rationale 1: Antihistamines are not very effective at relieving headaches.
Rationale 2: Antihistamines do not ease coughing.
Rationale 3: Antihistamines are histamine blockers (H-1 blockers). Histamines are responsible for sneezing, itching, and watery eyes.
Rationale 4: Antihistamines do not relieve wheezing.
Global Rationale: H1-receptor antagonists, also called antihistamines, are drugs that selectively block histamine from reaching its H1 receptors, thus alleviating allergic symptoms. Antihistamines are not very effective at relieving headaches and do not relieve coughing or wheezing.
Answer to Question 2
Correct Answer: 3
Rationale 1: Antihistamines block cholinergic receptors; they have anticholinergic effects and adverse effects.
Rationale 2: Antihistamines block just H-1 receptors.
Rationale 3: Antihistamines are most effective when taken prophylactically for the symptoms of nasal allergies.
Rationale 4: Antihistamines have only limited usefulness during acute attacks.
Global Rationale: Antihistamines are most effective when taken prophylactically to prevent allergic symptoms. Their effectiveness in reversing allergic symptoms that have already manifested is limited. This is because antihistamines block the effect of histamine at its receptor sites. They do not prevent the release of histamine from mast cells. Their effectiveness may diminish with long-term use. Antihistamines block cholinergic receptors; they have anticholinergic effects and adverse effects.