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General Pharmacology MCQs ( Part-6 )

General Pharmacology MCQs

Each of the curves in the graph below may be considered a concentration effcct curve or a concentration-binding curve. For each numbered item, select the ONE lettered option that is most closely associated with it.

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30. Describes the percentage binding of a full agonist to its receptors as the concentration of a partial agonist is increased from low to very high levels
A. curve 1
B. curve 2
C. curve 3
D. curve 4
E. curve 5

31. Describes the percentage effect when a full agonist is present throughout the experiment, and the concentration of a partial agonist is increased from low to very high levels
A. curve 1
B. curve 2
C. curve 3
D. curve 4
E. curve 5

32. Describes the percentage binding of the partial agonist whose effect is shown by curve 4. if the system has many spare receptors
A. curve 1
B. curve 2
C. curve 3
D. curve 4
E. curve 5

33. A city clinic is considering the substitution of generic drugs in order to save money. The clinical pharmacologist is asked to advise on the bioavailability of the generic products. She informs the head of the clinic that the bioavailability of drugs is :
A. Established by FDA regulation al 100% for preparations for intramuscular injection
B. 100% for oral preparations that are not metabolized in the liver
C. Calculated from the peak concentration of drug divided by the dose administered
D. Important because bioavailability determines what fraction of the administered dose reaches the systemic circulation
E. Equal to 1 (100%) only for drugs administered by any parenteral route

34. You have diagnosed asthma in a 19-year-old patient with recurrent, episodic attacks of bronchospasm with wheezing. You are concerned about drug interactions caused by changes in drug metabolism in this patient. Drug metabolism usually results in a product that is
A. More likely to distribute intracellulary
B. Less lipid-soluble than the original drug
C. More likely to be reabsorbed by kidney tubules
D. More lipid-soluble than the original drug
E. More likely to produce adverse effects

35. If therapy with multiple drugs causes induction of drug metabolism in your asthma patient, it will
A. Result in increased smooth endoplasmic reticulum
B. Result in increased rough endoplasmic reticulum
C. Result in decreased enzymes in the soluble cytoplasmic fraction
D. Require 3-4 months to reach completion
E. Be irreversible

36. A factor that is likely to increase the duration of action of a drug that is partially metabolized by CYP3A4 in the liver is
A. Chronic administration of phenobarbital prior to and during therapy with the drug in question
B. Chronic therapy with cimetidine prior to and during therapy with the drug in question
C. Displacement from tissue binding sites by another drug
D. Increased cardiac output
E. Chronic administration of rifampin

37. Which of the following is a phase II drug-metabolizing reaction?
A. Acetylation
B. Deamination
C. Hydrolysis
D. Oxidation
E. Reduction

38. Reports of cardiac arrhythmias caused by unusually high blood levels of two antihistamines terfenadine and astemizole, led to their removal from the market. These effects were best explained by
A. Concomitant treatment with phenobarbital
B. Use of these drugs by smokers
C. A genetic predisposition to metabolize succinylcholine slowly
D. Treatment of these patients with ketoconazole, an antifungal agent

39. Which of the following drugs is associated with slower metabolism in Caucasians and African- Americans than in most Asians?
A. Cimetidine
B. Procainamide
C. Quinidine
D. Rifampin
E. Succinylcholine

40. Which of the following drugs may inhibit the hepatic microsomal P450 responsible for warfarin metabolism?
A. Cimetidine
B. Ethanol
C. Phenobarbital
D. Procainamide
E. Rifampin

41. Which of the following drugs is hydrolyzed by a plasma esterase that is abnormally low in activity in about one out of every 2500 humans?
A. Cimetidine
B. Ethanol
C. Procainamide
D. Rifampin
E. Succinylcholine

42. Chronic use of which of the following drugs may increase the toxicity of acetaminophen?
A. Cimetidine
B. Ethanol
C. Ketoconazole
D. Procainanmide
E. Quinidine
F. Ritonavir
G. Succinylcholine
H. Verapmil

43. Which of the following drugs has higher first-pass metabolism in men than in women ?
A. Cimetidine
B. Ethanol
C. Ketoconazole
D. Procainanmide
E. Quinidine
F. Ritonavir
G. Succinylcholine
H. Verapmil

44. Which of the following drugs is an established inhibitor of P-glycoprotein (P-gp) drug transporters ?
A. Cimetidine
B. Ethanol
C. Ketoconazole
D. Procainanmide
E. Quinidine
F. Ritonavir
G. Succinylcholine
H. Verapmil

45. Which of the following agents, when used in combination with other anti-HIV drugs permits dose reduction ?
A. Cimetidine
B. Ethanol
C. Ketoconazole
D. Procainanmide
E. Quinidine
F. Ritonavir
G. Succinylcholine
H. Verapmil
Mr. Jones is admitted to General Hospital with pneumonia due to gram-negative bacteria. The antibiotic tobramycin is ordered. The CL and Vd of tobramycin in Mr. Jones are 80 mL/min and 40 L, respectively.

46. What maintenance dose should be administered intravenously every 6 hours to eventually obtain average steady-state plasma concentrations of 4 mg/L?
A. 0.32 mg
B. 19.2 mg
C. 115 mg
D. 160 mg
E. 230 mg

47. If you wish to give Mr. Jones an IV loading dose to achieve the therapeutic plasma concentration of 4 mg/L rapidly, how much should be given?
A. 0.1 mg
B. 10 mg
C. 115.2 mg
D. 160 mg
E. None of the above

48. Despite your careful adherence to basic pharmacokinetic principles, your padent on digoxin therapy has developed digitalis toxicity. The plasma digoxin level is 4 mg/mL. Renal function is normal, and the plasma t1/2 for digoxin in this patient is 1.6 days. How long should you withhold digoxin in order to reach a safer yet probably therapeutic level of 1 mg/mL?
A. 1.6 days
B. 2.4 days
C. 3.2 days
D. 4.8 days
E. 6.4 days

49. A 60-year-old man enters the hospital with a myocardial infarction and a severe ventricular arrhythmia. The antiarrhythmic drug chosen has a narrow therapeutic window: the minimum toxic plasma concentration is 1.5 times the minimum therapeutic plasma concentration. The half-life is 6 hours. It is essential to maintain the plasma concentration above the minimum therapeutic level to prevent a possibly lethal arrhythmia. Of the following, the most appropriate dosing regimen would be
A. Once a day
B. Twice a day
C. Three times a day
D. Four times a day
E. Constant IV infnsion

50. A 50-year-old woman with metastatic breast cancer has elected to participate in the trial of a new chemotherapeutic agent. It is given by constant 1V infnsion of 8 mg/hour. Plasma concentrations (Cp) are measured with the results shown in the table.

From these data it may be concluded that
A. Volume of distribution is 30 L
B. Clearance is 2 L/h
C. Elimination follows zero-order kinetics
D. Half-life is 8 hours
E. Doubling the rate of infnsion would result in a plasma concentration of 16 mg/L at 40 hours

51. A nineteen-year-old woman is brought to the hospital with severe asthmatic wheezing. You decide to use IV theophylline for treatment. The pharmacokinetics of theophylline include the following average parameters: Vd 35 L; CL 48 mL/min; half-life 8 hours. If an IV infnsion of theophylline is started at a rate of 0.48 mg/min, how long will it take to reach 93.75% of the final steady state concentration?
A. Approximately 48 minutes
B. Approximately 7.4 hours
C. Approximately 8 hours
D. Approximately 24 hours
E. Approximately 32 hours

52. Your 74-year-old patient with a myocardial infarction has a severe cardiac arrhythmia. You have decided to give lidocaine to correct the arrhythmia .A continuous IV infnsion of lidocaine, 1.92 mg/min, is started at 8 am. The average pharmacokinetic parameters of lidocaine are: Vd 77 L: CL 640 mL/min: half-life 1.4 hours. The expected steady-state plasma concentration is approximately
A. 40 mg/L
B. 3.0 mg/L
C. 0.025 mg/L
D. 7.2 mg/L
E. 3.46 mg/L

53. Your patient has been receiving lidocaine for 8 hours and you decide to obtain a plasma concentration measurement. When the results come back, the plasma level is exactly twice of what you expected. The infusion rate should :
A. be changed to 0.48 mg/min
B. be changed to 0.96 mg/min
C. be halted for 1.4 h and then restarted at 0.96 mg/min
D. be halted for 1.4 h and then restarted at 1.92 mg/min
E. not be changed but the plasma level should be measured again

54. A patient requires an infusion of procainamide, lts half-life is 2 hours. The infusion is begun at 9 AM. At 1 PM the same day a blood sample is taken; the drug concentration is found to be 3 mg/L. What is the probable steady-state drug concentration, eg, after 12 hours of infnsion?
A. 3 mg/L
B. 4 mg/L
C. 6 mg/L
D. 9.9 mg/L
E. 15 mg/L

55. A young man is brought to the emergency room in a deep coma. His friends state that he took a large dose of morphine 6 hours earlier. An immediate blood analysis shows a morphine blood level of 0.25 mg/L. Assuming that the pharmacokinetics of morphine in this patient are Vd 200 L and half-life is 3 hours, how much morphine did the patient inject 6 hours earlier ؟
A. 25 mg
B. 50 mg
C. 100 mg
D. 200 mg
E. not enough data to predict

56. A normal volunteer will receive a new drug in a phase 1 clinical trial. The clearance and volume of distribution of the drug in this subject are 1.386 L/h and 80 L, respectively. The half-life of the drug in this subject will be approximately:
A. 83 hours
B. 77 hours
C. 58 hours
D. 40 hours
E. 0.02 hours

57. Gentamicin is often given in intermittent IV bolus doses of 100 mg three times a day to achieve target peak plasma concentration of about 5 mg/L. Gentamicin’s clearance (normally 5.4 L/h/70kg) is almost entirely by glomerular filtration. Your patient, however, is found to have a creatinine clearance one-third of normal. Your initial dosage regimen for this patient would probably be:
A. 20 mg three times a day
B. 33 mg three times a day
C. 72 mg three times a day
D. 100 mg twice a day
E. 150 mg twice a day
A new drug was studied in 20 healthy volunteers to determine basic pharmacokinetic parameters. A dose of 100 mg was administered as an intravenous bolus to each volunteer and blood samples were analyzed at intervals as shown in the graph below. The average plasma concentrations at each time are shown by the solid circles at 10 and 30 minutes and at 1, 2, 3, 4, 6, and 8 hours after administration.

58. The elimination half-life of the new drug is approximately
A. 1.5 hours
B. 2 hours
C. 4 hours
D. 6 hours
E. 8 hours

59. The volume of distribution of the new drug is approximately
A. 0.05 L
B. 0.1L
C. 5 L
D. 10 L
E. 20 L

60. The clearance of the new drug is approximately
A. 0.43 L/h
B. 0.86 L/h
C. 1.15L/h
D. 2.3 L/h
E. Too few data to answer

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