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General Pharmacology MCQs ( Part-5 )

General Pharmacology MCQs

1. A 3-year-old child is brought to the emergency department having just ingested a large over-dose of promethazine, an antihistaminic drug. Promethazine is a weak base with a pK a of 9.1 .It is capable of entering most tissues, including the brain. On physical examination, the heart rate is 100/rain, blood pressure 110/60 mm Hg, and respiratory rate 20/min. In this case of promethazine overdose:
A. Urinary excretion would be accelerated by administration of NH4C1
B. Urinary excretion would be accelerated by giving NaHCO 3
C. More of the drug would be ionized at blood pH than at stomach pH
D. Absorption of the drug would be faster from the stomach than from the small intestine
E. Hemodialysis is the only effective therapy

2. All of the following are general mechanisms of drug permeation EXCEPT
A. Aqueous diffusion
B. Aqueous hydrolysis
C. Lipid diffusion
D. Pinocytosis or endocytosis
E. Special carrier transport

3. Which one of the following processes is best suited for permeation of very large protein molecules into cells ?
A. Aqueous diffusion
B. Aqueous hydrolysis
C. Lipid diffusion
D. Endocytosis
E. Special carrier transport

4. A patient with a history of episodic attacks of coughing, wheezing, and shortness of breath is being evaluated in the asthma clinic. Several drug treatments with different routes of administration are under consideration. Which of the following statements about routes of administration is MOST correct?
A. Blood levels often rise more slowly after intramuscular injection than after oral dosing
B. The “first-pass” effect is the result of metabolism of a drug after administration and before it enters the systemic circulation
C. Administration of antiasthmatic drugs by inhaled aerosol is usually associated with more adverse effects than is administration of these drugs by mouth
D. Bioavailability of most drugs is greater with rectal (suppository) administration than with sublingual administration.
E. Administration of a drug by transdermal patch is often faster but is associated with more first-pass metabolism than oral administration

5. Aspirin is a weak organic acid with a pKa of 3.5. What percentage of a given dose will be in the lipid-soluble form in the duodenum at a pH of 4.5?
A. About 1%
B. About 10%
C. About 50%
D. About 90%
E. About 99%

6. If the plasma concentration of a drag declines with “first-order kinetics,” this means that
A. There is only one metabolic path for drug disposition
B. The half-life is the same regardless of the plasma concentration
C. The drug is largely metabolized in the liver after oral administration and has low bioavailability
D. The rate of elimination is proportionate to the rate of administration at all times
E. The drug is not distributed outside the vascular system

7. Regarding termination of drug action ،
A. Drugs must be excreted from the body to terminate their action
B. Metabolism of drugs always increases their water solubility
C. Metabolism of drugs always abolishes their pharmacologic activity
D. Hepatic metabolism and renal excretion are the two most important mechanisms involved
E. Distribution of a drug out of the bloodstream terminates the drug’s effects

8. Distribution of drugs to specific tissues
A. Is independent of blood flow to the organ
B. Is independent of the solubility of the drug in that tissue
C. Depends on the unbound drug concentration gradient between blood and the tissue
D. Is increased for drugs that are strongly bound to plasma proteins
E. Has no effect on the half-life of the drug

9. Timolol is being considered for the treatment of glaucoma in a 58-year-old patient. Except for elevated intraocular pressure, the patient’s history and physical exam are unremarkable. Timlol is a weak base of pKa 9.2 .Which of the following statements is FALSE ?
A. After parenteral administration, the concentration of timolol in the aqueous humor (pH 7.8) will be lower than the concentration in the duodenum (pH 5.5)
B. When administered as eye drops, the rate of absorption into the eye will be slower if the drops are alkaline (pH 8.0) than if they are acidic (pH 5.0)
C. Excretion in the urine will be slower if urine pH is alkaline (.pH 8.0) than if the urine pH is acidic (pH 5.8)
D. The proportion of timolol in the protonated form will be approximately 10% at pH 8.2
E. The proportion of timolol in the more lipid soluble form will be approximately 10% at pH 10.2

10. For which of the following drugs will excretion be most significantly accelerated by acidification of the urine ?
A. Weak acid with pK of 5.5
B. Weak base with pK of 3.5
C. Weak acid with pK of 7.5
D. Weak base with pK of 6.5

11. A physical process by which a weak acid becomes less water-soluble and more lipid-soluble at low pH is :
A. Distribution
B. Elimination
C. First-pass effect
D. Permeation
E. Protonation

12. The set of properties that characterize the effect of a drug on the body is called :
A. distribution
B. permeation
C. pharmacodynamics
D. pharmacokinetics
E. protonation

13. The set of properties that characterize the effect of the body on a drug is called :
A. absorption
B. distribution
C. elimination
D. first order kinetics
E. pharmacokinetics

14. The most general term for the process by which the amount of active drug in the body is reduced after absorption into the systemic circulation :
A. distribution
B. elimination
C. excretion
D. first-order elimination
E. metabolism

15. The process by which the amount of drug in the body is reduced after administration but before entering the systemic circulation :
A. excretion
B. first-order elimination
C. first-pass effect
D. metabolism
E. pharmacokinetics

16. The kinetics that is characteristic of the elimination of ethanol and high doses of phenytoin and aspirin are called :
A. distribution
B. excretion
C. first-pass effect
D. first-order elimination
E. zero-order elimination

17. A 55-year-old woman with heart failure is to be treated with a diuretic drug. Drugs X and Y have the same mechanism of diuretic action. Drug X in a dose of 5 mg produces the same magnitude of diuresis as 500 mg of drug Y. This suggests that
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 is a safer drug than drug Y
E. Drug X will have a shorter duration of action than drug Y because less of drug X is present for a given effect

18. Dose-response curves are used for drug evaluation in the animal laboratory and in the clinic. Quantal dose-response curves are
A. Used for determining the therapeutic index of a drug
B. Used for determining the maximal efficacy of a drug
C. more precisely quantitated than ordinary graded dose-response curves
D. Obtainable from the study of intact subjects but not from isolated tissue preparations
E. Used to determine the statistical variation (standard deviation) of the maximal response to the drug

19. The results shown in the graph below were obtained in a comparison of positive inotropic agents. Which of the following statements is MOST correct ?

 

 

 

 

A. Drug A is most effective
B. Drug B is least potent
C. Drug C is most potent
D. Drug B is more potent than drug C and more effective than drug A
E. Drug A is more potent than drug B and more effective than drug C

20. In the absence of other drugs, pindolol causes an increase in heart rate by activating beta adrenoceptors. In the presence of highly effective beta stimulants, however, pindolol causes a dose-dependent, reversible decrease in hearl rate. Therefore. pindolol should be classified as
A. An irreversible antagonist
B. A physiologic antagonist
C. A chemical antagonist
D. A partial agonist
E. A spare receptor agonist

21. 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 will be detected if the intracellular effect of drug-receptor interaction lasts longer than the drug-receptor interaction itself
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 greater than the Kd for the agonist

22. Two drugs, “A'” and “B,'” were studied in a large group of patients and the percentages of the group showing a specific therapeutic effect were determined. The results are shown in the table:

 

 

 

 

 

Which of the following statements about these results is MOST correct ?
A. Drug A is safer than drug B
B. Drug B is more effective than drug A
C. The two drugs act on the same receptors
D. Drug A is less potent than drug B
E. The therapeutic index of drug B is 10

23. Which of the following terms best describes the antagonism of leukotriene’s bronchoconstrictor effect (mediated at leukotriene receptors) by terbutaline (acting at adrenoceptors) in a patient with asthma?
A. Pharmacologic antagonist
B. Partial agonist
C. Physiologic antagonist
D. Chemical antagonist
E. Noncompetitive antagonist

24. Which of the following terms best describes an antagonist that interacts directly with the agonist and not at all, or only incidentally, with the receptor?
A. Pharmacologic antagonist
B. Partial agonist
C. Physiologic antagonist
D. Chemical antagonist
E. Noncompetitive antagonist

25. Which of the following terms best describes a drug that blocks the action of epinephrine at its receptors by occupying those receptors without activating them?
A. Pharmacologic antagonist
B. Partial agonist
C. Physiologic antagonist
D. Chemical antagonist
E. Noncompetitive antagonist

26. Which of the following provides information about the variation in sensitivity to the drug within the population studied ?
A. Maximal efficacy
B. Therapeutic index
C. Drug potency
D. Graded dose-response curve
E. Quantal dose-response curve

27. Which of the following most accurately describes the transmembrane signaling process involved in steroid hormone action ?
A. Action on a membrane-spanning tyrosine kinase
B. Activation of a G protein, which activates or inhibits adenylyl cyclase
C. Diffusion into the cytoplasm and binding to an intracellular receptor
D. Diffusion of “STAT” molecules across the membrane
E. Opening of transmembrane ion channels

28. Which of the following provides information about the largest response a drug can produce, regardless of dose ?
A. Drug potency
B. Maximal efficacy
C. Mechanism of receptor action
D. Therapeutic index
E. Therapeutic window

29. Verapamil and phenytoin are both eliminated from the body by metabolism in the liver. Verapamil has a clearance of 1.5 L/min, approximately equal to liver blood flow, whereas phenytoin has a clearance of 0.1 L/min. When these compounds are administered along with rifampin, a drug that increases hepatic drug-metabolizing enzymes, which of the following is most likely?
A. The clearance of both verapamil and phenytoin will be increased
B. The clearance of both verapamil and phenytoin will be decreased
C. The clearance of verapamil will be unchanged, whereas the clearance of phenytoin will be increased
D. The clearance of phenytoin will be unchanged, whereas the clearance of verapamil will be increased
E. The clearance of both drugs will be unchanged

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