Thread: Case : Adrenergic Pharmacology

Case : Adrenergic Pharmacology

Case report:

A 35 yr. old, overweight female purchased a
weight-reduction product which contained ephedrine. She is the
product in accordance with directions on the label for one-month,
then stopped using it during a vacation week, and then started
again upon her return to work. Two days after restarting, she was
awakened by anterior chest pain, which radiated to her left
shoulder and arm. She experienced numbness in the left arm,
shortness of breath, and sweating (diaphoresis).



At the emergency department, she was treated with
morphine and nitroglycerin. Cardiac catherization revealed 60%
narrowing of the left anterior descending coronary vessel and a
50 percent narrowing of the circumflex coronary artery. There was
no evidence of completely occluded coronary vessels. ECG tracings
indicated T-wave changes indicative of an acute myocardial
infarction -- later confirmed by elevated cardiac enzymes.



Recovery was uneventful; the patient was discharged
with instructions to avoid using the weight loss product or
similar weight loss products in the future.

1.Primary mechanism of ephedrine (orally administered) cardiovascular action:
A. direct alpha receptor agonist
B. direct beta-1 receptor agonist
C. release of stored catecholamines (indirect action)
D. ephedrine not active following oral administration
E. release of stored histamine (indirect action)

2.Properties of ephedrine:
A. orally active
B. catecholamine
C. weak base
D. A & C
E. A, B & C

3.Possible explanations why ephedrine might cause myocardial infarction:
A. ephedrine may increase myocardial oxygen requirements
B. promotes coronary vasospasm
C. both
D. neither

4.In this patient, if it were concluded that coronary vasospasm was responsible for acute myocardial infarction, what drugs might reduce the likelihood of a recurrence.
A. propranolol
B. metoprolol
C. diltiazem
D. ergonovine
E. all the above

5.For what reason(s) was/were morphine used in the management of this patient?
A. pain relief
B. bradycardic effects
C. increases cardiac output

6.What is the major rationale for administration of nitroglycerin to this patient?

A. decrease myocardial oxygen demand
B. increase blood pressure
C. must be administered following morphine

7.What physiological factors might contraindicate the use of nitroglycerin in a patient with acute myocardial infarction?

A. low systolic arterial pressure (< 100 mm Hg)
B. clinical suspicion of right ventricular infarction
C. both
D. neither

8.In this patient, if acute myocardial infarction was caused by ephedrine-induced increased myocardial oxygen demand and if nitroglycerin were unable to reverse this effect, what alternative drug(s) might be effective?

A. alpha adrenergic blocker
B. beta-adrenergic blocker
C. both
D. neither


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Correct Answers

[HIDE]
1.Primary mechanism of ephedrine (orally administered) cardiovascular action:
A. direct alpha receptor agonist
B. direct beta-1 receptor agonist
C. release of stored catecholamines (indirect action)
D. ephedrine not active following oral administration
E. release of stored histamine (indirect action)

2.Properties of ephedrine:
A. orally active
B. catecholamine
C. weak base
D. A & C
E.X A, B & C

3.Possible explanations why ephedrine might cause myocardial infarction:

A. ephedrine may increase myocardial oxygen requirements
B. promotes coronary vasospasm
C. both
D. neither

4.In this patient, if it were concluded that coronary vasospasm was responsible for acute myocardial infarction, what drugs might reduce the likelihood of a recurrence.
A. propranolol
B. metoprolol
C. diltiazem
D. ergonovine
E. all the above

5.For what reason(s) was/were morphine used in the management of this patient?

A. pain relief
B. bradycardic effects
C. increases cardiac output

6.What is the major rationale for administration of nitroglycerin to this patient?
A. decrease myocardial oxygen demand
B. increase blood pressure
C. must be administered following morphine

7.What physiological factors might contraindicate the use of nitroglycerin in a patient with acute myocardial infarction?
A. low systolic arterial pressure (< 100 mm Hg)
B. clinical suspicion of right ventricular infarction
C. both
D. neither

8.In this patient, if acute myocardial infarction was caused by ephedrine-induced increased myocardial oxygen demand and if nitroglycerin were unable to reverse this effect, what alternative drug(s) might be effective?
A. alpha adrenergic blocker
B. beta-adrenergic blocker
C. both
D. neither

[/HIDE]

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Case: Sympathomimetic Drug

A ten-year old boy was referred to the asthma clinic
for workup. History: consistent with asthma; on pulmonary
function testing, a marked reduction of FEV1 was noted.

1.Autonomic drug: beneficial in treating asthma:
A. bethanechol (Urecholine)
B. acetylcholine
C. ipratropium (Atrovent)
D. scopolamine
E. mecamylamine (Inversine)

2.Drug category most likely to be effective in treating asthma:
A. beta-1 antagonists
B. nonselective beta antagonists
C. beta-2 agonists
D. muscarinic agonists
E. none of the above


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Answers:

[HIDE]
1.Autonomic drug: beneficial in treating asthma:
A. bethanechol (Urecholine)(would promote bronchoconstriction)
B. acetylcholine (not appropriate; would promote bronchoconstriction)
C. ipratropium (Atrovent)
antimuscarinic; anticholinergic --quaternary atropine derivative; may be effective in blocking parasympathetic-mediated bronchoconstriction

D. scopolamine (anticholinergic; significant CNS side effects)

E. mecamylamine (Inversine) (ganglionic blocker -- no role in asthma management)


2.Drug category most likely to be effective in treating asthma:
A. beta-1 antagonists
B. nonselective beta antagonists
C. beta-2 agonists (effective in promoting bronchodilation; examples:terbutaline, metaproterenol, albuterol)
D. muscarinic agonists
E. none of the above
[/HIDE]

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