Which of the following drugs should be used only in situations in which the client can be very closely monitored, such as a critical care unit?
A. bretylium (Bretylol)
B. digoxin (Lanoxin)
C. quinidine (Cardioquin)
D. inderal (Propranolol)
Correct Answer: A. bretylium (Bretylol)
Among the choices, this is the only agent that must be monitored closely. Bretylium (bretylium tosylate injection ) tosylate injection is an anti fibrillatory and antiarrhythmic agent; intended for intravenous or intramuscular use. Bretylium (bretylium tosylate injection ) Tosylate is indicated in the prophylaxis and therapy of ventricular fibrillation. Use of bretylium (bretylium tosylate injection) should be limited to intensive care units, coronary care units, or other facilities where equipment and personnel for constant monitoring of cardiac arrhythmias and blood pressure are available. Digoxin, quinidine, and Inderal are given to outpatients as oral preparations.
Option B: Digoxin comes from the foxgloves plant known as Digitalis purpurea. It is a cardiotonic glycoside and belongs to the digitalis class. It increases the force of contraction of the heart by reversibly inhibiting the activity of the myocardial Na-K ATPase pump, an enzyme that controls the movement of ions into the heart. Digoxin has vagomimetic effects on the AV node. By stimulating the parasympathetic nervous system, it slows electrical conduction in the atrioventricular node, therefore, decreases the heart rate.
Option C: Quinidine is used in selected patients with Brugada syndrome as an alternative to the implantable cardioverter-defibrillator placement (ICD). Treatment with quinidine can be useful in patients with short QT syndrome and recurrent ventricular arrhythmias (VA). In patients with short QT syndrome who undergo ICD placement, therapy with quinidine may reduce the number of shocks.
Option D: Propranolol is a competitive beta-adrenergic receptor antagonist, devoid of agonist activity, making it the prototype for comparison to the other beta-antagonists. Propranolol is a nonselective beta-adrenoceptor antagonist, also classified as a class II antiarrhythmic. It exerts its response by competitively blocking beta-1 and beta-2 adrenergic stimulation in the heart, which is typically induced by epinephrine and norepinephrine.