Download Chapter 10 Principles of Pharmacology Case PowerPoint Answers

Nancy Caroline’s Emergency Care in the Streets, Seventh Edition
Chapter 10: Principles of Pharmacology
Chapter 10
Principles of Pharmacology
Case PowerPoint Answers
1. What is your potential differential diagnosis?
Answer: Your patient presents with a combination of symptoms: palpitations, mild
shortness of breath, and visual disturbances. Looking at this trio of symptoms, cardiac
problems such as a silent MI, high blood pressure, and abnormal heart rate or rhythm are
good possibilities. The mention that he has a history of “heart problems” also helps to tip
the scale in this direction.
2. What types of medications might your patient be taking?
Answer: There are a variety of different types of medications that he could be taking for
heart problems—including a diuretic, a beta blocker, a calcium channel blocker, or an
ACE inhibitor.
3. What type of drug is Cardizem, and how does it work?
Answer: Cardizem is a calcium channel blocker. This drug lowers blood pressure by
decreasing peripheral vascular resistance. It helps decrease the work load of the heart by
diminishing myocardial and smooth muscle contraction. Calcium channel blockers are
also effective in the management of fast cardiac rhythm disturbances because of their
ability to decrease the conduction of electrical impulses through the heart.
4. Does the patient present with signs and symptoms of possible drug toxicity? If so, which
medications are in question?
Answer: Yes, drug toxicity, specifically digoxin and Cardizem, is a possibility. When
taken in excess, either medication can cause a significant drop in a patient’s
hemodynamic status, which explains the problems with the heart rate and blood pressure,
but what about the vision disturbances? One of the other side effects of digoxin toxicity is
visual disturbances, including the presence of a yellow-green halo around objects and
blurred vision.
5. What treatment will increase the patient’s blood pressure?
Answer: In this case the best treatment is to reverse the effects of the calcium channel
blocker, Cardizem, by administering calcium chloride or calcium gluconate. If this
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Nancy Caroline’s Emergency Care in the Streets, Seventh Edition
Chapter 10: Principles of Pharmacology
patient was experiencing cardiogenic shock, transcutaneous pacing and
sympathomimetics such as dopamine would also be an option.
6. What does it mean when a medication has a low therapeutic index?
Answer: The therapeutic index measures the safety of the drug. It is calculated by
dividing the lethal dose 50 (LD50) by the effective dose 50 (ED50). The closer the
answer is to 1, the more harmful the drug is. Since the therapeutic index for digoxin is
close to one, the amount of medication between a normal dose and a toxic dose is very
small, making it easy for toxic levels to develop. Because of this, patients who take
digoxin frequently have their blood levels checked to make sure that they are within the
therapeutic range.
7. What occurs when one drug potentiates a second drug?
Answer: When potentiation occurs, the effect of one drug increases the effect of another.
In your patient, the administration of Cardizem increased the amount of digoxin in the
blood, leading to the increased effects of digoxin and an increased chance of toxicity.
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