Module 1 Case Studies

Mr. W. is a 66-year-old technology consultant who makes frequent trips abroad as part of his job in the telecommunications industry. His only medical problem is chronic atrial fibrillation, and his only chronic medication is warfarin. Mr. W. flies to Turkey for a consulting job. On the last night of the trip, he attends a large dinner featuring shish kebabs and other foods he does not often eat. The next day, he develops profuse, watery, foul-smelling diarrhea. A physician makes a diagnosis of traveler's diarrhea and prescribes a 7-day course of trimethoprim–sulfamethoxazole.

Mr. W. feels entirely well 2 days into the course of antibiotics, and 4 days later (while still taking his antibiotics), he entertains some clients at another lavish dinner. Mr. W. and his guests become intoxicated at the dinner, and Mr. W. stumbles and falls on the curb as he is leaving the restaurant. The next day, Mr. W. has a markedly swollen right knee that requires evaluation in a local emergency department. Physical examination and imaging studies are consistent with a moderate-sized hemarthrosis of the right knee, and laboratory studies show a markedly elevated International Normalized Ratio (INR) which is a standardized measure of prothrombin time and, in this clinical setting, a surrogate marker for plasma warfarin level. The emergency physician advises Mr. W. that his warfarin level is in the supratherapeutic (toxic) range and that this effect is likely attributable to adverse drug–drug interactions involving warfarin, antibiotics, and recent alcohol intoxication.

Value: 1

Drugs distribute within the body based on a four-compartment model and each drug's volume of distribution. Which of the following statements regarding the relationship between the administration of a drug and its distribution is correct?

a. Drugs that exhibit high plasma protein binding tend to distribute rapidly into the protein-rich muscle compartment after intravenous administration.
b. Drugs that have a large volume of distribution tend to distribute into all compartments after administration.
c. Drugs tend to distribute into the fat compartment rapidly because it has the highest capacity for drug uptake and binding.
d. Drugs that enter the vessel-rich compartment after administration tend to remain there and redistribute slowly to other compartments.
e. Drugs that have a small volume of distribution tend to rapidly cross the blood–brain barrier.

Value: 1

Case 2

You are working in a local clinic. Your patient, Mr. S, is a 65-year-old man who you have been following closely over the past few weeks for progressively elevated blood pressure readings. You have just confirmed blood pressure readings of 145/105 mm Hg in Mr. S. this morning. You decide to begin a thiazide diuretic and a beta-receptor antagonist as antihypertensive therapy. As you try to choose between atenolol and propranolol for Mr. S., you recall that the thiazide you will prescribe is 98% plasma protein bound in the blood. You also consider the following facts about the two beta-receptor antagonists.

Value: 1

How does the differential plasma protein binding of atenolol versus propranolol affect your decision about therapy in this case?

a. Atenolol is less highly protein bound, so it will have less ability to reach its receptor sites through the circulation.
b. Atenolol is less highly protein bound, so it will be less likely to interfere with the plasma protein binding of thiazide.
c. Propranolol is less highly protein bound, so it will be less likely to displace the thiazide from it plasma protein-binding sites.
d. Propranolol is more highly protein bound, so it will be more likely to compete with the thiazide for binding at its end organ receptor sites.
e. Propranolol is more highly protein bound, so it will require a lower administered dose to achieve an effect similar to that of atenolol.

Value: 1

Mr. S. is 65 years old, and you suspect that he has an age-related decrease in liver function. How does this fact impact your decision about the choice of therapy in this case?

a. Atenolol is more highly metabolized by the liver, and the dose may need to be reduced to prevent drug accumulation and adverse effects.
b. Atenolol is less highly metabolized by the liver, and the dose may need to be increased to be sure that therapeutic concentrations are achieved.
c. Propranolol is less highly metabolized by the liver, and the dose may need to be increased to be sure that therapeutic concentrations are achieved.
d. Propranolol is more highly metabolized by the liver, and the dose may need to be reduced to prevent liver failure.
e. Propranolol is more highly metabolized by the liver, and the dose may need to be reduced to prevent drug accumulation and adverse effects.

Value: 1

You know that some drugs have undesirable CNS adverse effects. As you consider the pharmacokinetic parameters of atenolol versus propranolol, how does this information impact the likelihood of potential CNS adverse effects associated with each drug?

a. Atenolol has a smaller volume of distribution and will not be able to achieve therapeutic concentrations in the CNS.
b. Atenolol has a larger volume of distribution and will be more likely to cause CNS adverse effects.
c. Propranolol has a larger volume of distribution and will be trapped in the fat compartment and less likely to cause CNS adverse effects.
d. Propranolol has a larger volume of distribution and will be more likely to cause CNS adverse effects.
e. Propranolol has a larger volume of distribution and will be more likely to reach therapeutic concentrations in the CNS.

Value: 1

	Atenolol	Propranolol
Plasma protein binding	5%	95%
Urinary excretion of unchanged drug	85%	1%
Volume of distribution	39 L	270 L
β1/β2 selectivity	β1 selective	Nonselective

Module 1 Case Studies

Case 1

Case 2