Katzung Pharmacology Exam 1 Questions With Verified Answers.

Katzung Pharmacology Exam 1 Questions With Verified Answers. 1. A55-year-old woman with hypertension is to be treated with a vasodilator drug. Drugs X and Y have the same mechanism of action. Drug X in a dose of 5 mg produces the same decrease in blood pressure as 500 mg of drug Y. Which of the following statements best describes these results? (A)Drug Y is less efficacious than drug X (B)Drug X is about 100 times more potent than drug Y (C)Toxicity of drug X is less than that of drug Y (D)Drug X has a wider therapeutic window than drug Y (E) Drug X will have a shorter duration of action than drug Y because less of drug X is present over the time course of drug action - answerNo information is given regarding the maximal antihyperten-sive response to either drug. Similarly, no information about toxicity is provided. The fact that a given response is achieved with a smaller dose of drug X indicates that X is more potent than Y in the ratio of 500:5. The answer is B. 2. Graded and quantal dose-response curves are being used for evaluation of a new antiasthmatic drug in the animal laboratory and in clinical trials. Which of the following statements best describes quantal dose-response curves? (A)More precisely quantitated than graded dose-response curves (B)Obtainable from the study of intact subjects but not from isolated tissue preparations (C)Used to determine the maximal efficacy of the drug (D) Used to determine the statistical variation (standard deviation) of the maximal response to the drug (E)Used to determine the variation in sensitivity of subjects to the drug - answerPrecise quantitation is possible with both types of dose-response curves. Quantal dose-response curves show the frequency of occurrence of a specified response, which may be therapeutically effective (ED) or toxic (TD). Thus, quantal studies are used to determine the therapeutic index and the variation in sensitivity to the drug. Graded (not quantal) dose-response curves are used to determine maximal efficacy (maximal response). The answer is C. 4. A study was carried out in isolated, perfused animal hearts. In the absence of other drugs, pindolol, a β-adrenoceptor ligand, caused an increase in heart rate. In the presence of highly EXAM STUDY MATERIALS July 23, 2024 4:26 PM effective β stimulants, however, pindolol caused a dose-dependent, reversible decrease in heart rate. Which of the following expressions best describes pindolol? (A)A chemical antagonist (B)An irreversible antagonist (C)A partial agonist (D)A physiologic antagonist (E)A spare receptor agonist - answerChoices involving chemical or physiologic antagonism are incorrect because pindolol is said to act at β receptors and to blockβ stimulants. The drug effect is reversible, so choice Bis incorrect. "Spare receptor agonist" is a nonsense distracter. The answer is C. 5. Beta adrenoceptors in the heartregulate cardiac rate and contractile strength. Several studies have indicated that in humans and experimental animals, about 90% of β adrenoceptors in the heart are spare receptors. Which of the following statements about spare receptors is most correct? (A)Spare receptors, in the absence of drug, are sequestered in the cytoplasm (B)Spare receptors may be detected by finding that the drugreceptor interaction lasts longer than the intracellular effect (C)Spare receptors influence the maximal efficacy of the drug-receptor system (D)Spare receptors activate the effector machinery of the cell without the need for a drug (E)Spare receptors may be detected by the finding that the EC50 is smaller than the Kd for the agonist - answerThere is no difference in location between "spare" and other receptors. Spare receptors may be defined as those that are not needed for binding drug to achieve the maximal effect. Spare receptors influence the sensitivity of the system to an agonist because the statistical probability of a drug-receptor interac-tion increases with the total number of receptors. They do not alter the maximal efficacy. If they do not bind an agonist molecule, spare receptors do not activate an effector molecule. EC50less than Kd is an indication of the presence of spare receptors. The answer is E. 7. Sugammadex is a new drug that reverses the action of rocuronium and certain other skeletal muscle-relaxing agents. It appears to interact directly with the rocuronium molecule and not at all with the rocuronium receptor. Which of the following terms best describes sugammadex? (A)Chemical antagonist (B)Noncompetitive antagonist (C)Partial agonist (D)Pharmacologic antagoni