Introduction to CV Pharmacology - Orlando Health

CV Pharmacology
Isoproterenol
Sometimes called the “cardiac whip”, Isopreterenol (Isuprel) is a potent beta-adrenergic agonist
with essentially no alpha adrenergic activity. Isopreterenol produces large increases in
myocardial contractility, automaticity and conductivity. These actions profoundly increase
myocardial oxygen demand and increase the risk of myocardial ischemia, myocardial infarction,
and dysrhythmias. Because of its severe side effect profile Isopreterenol is now used only for
very specific indications, most commonly in cardiac transplantation. Because it is used so rarely,
Isopreterenol will not be discussed further in this packet. For further information please refer to
Lexicomp and Micromedex.
Sodium Bicarbonate
Sodium bicarbonate is used as a buffering agent in patients with a preexisting metabolic acidosis.
When bicarbonate combines with an acid, it forms carbonic acid, which usually dissociates to
water and carbon dioxide. In the presence of inadequate respiratory function (when carbon
dioxide is not rapidly cleared from the system) carbonic acid does not dissociate to carbon
dioxide and water. Instead, it remains carbonic acid, which can lead to an intracellular acidosis
and result in a decrease in myocardial contractility.
In general, the administration of sodium bicarbonate during a cardiac arrest situation is
associated with poor resuscitation outcomes. For this reason, sodium bicarbonate is no longer
routinely given as part of resuscitation efforts.
Indications
Sodium bicarbonate is indicated for several specific causes of pulseless electrical activity or
asystole within ACLS protocols. It is given to patients with a preexisting metabolic acidosis such
as patients in renal failure or diabetic ketoacidosis. However, it is not given to patients in
respiratory acidosis. It can also be given to patients with hyperkalemia or those who have
overdosed on tricyclic antidepressants or phenobarbital. A continuous infusion of sodium
bicarbonate given immediately prior to and post procedure has been shown to reduce the
incidence of contrast-induced nephropathy for patients undergoing cardiac catheterization,
computed tomography (CT), diagnostic or therapeutic arteriography, or transjugular intrahepatic
portal systemic shunt (TIPS) placement.
Precautions and Interactions
Sodium bicarbonate can lead to metabolic alkalosis if too much is administered. Because of the
high sodium content, it may cause hypernatremia and increase serum osmolality, resulting in
massive diuresis and cellular dehydration.
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