SPECIFIC ANTIARRHYTHMIC DRUGS
a. Quinidine (Quiniglute, Quinidex). Quinidine is an antiarrhythmic agent
used in the treatment of atrial fibrillation and ventricular arrhythmias. It is given orally in
a usual dose of 200 to 400 milligrams every 6-8 hours. The side effects associated with
quinidine include hypersensitivity reactions, gastrointestinal (GI) disturbances (nausea,
vomiting, and diarrhea) and a group of symptoms known as cinchonism. Some
symptoms associated with cinchonism are tinnitus (ringing in the ears), vertigo
(dizziness), and headaches.
b. Procainamide (Pronestyl). Procainamide is used in the treatment of atrial
and ventricular arrhythmias in an oral dosage range of from 250 to 500 milligrams four
times daily. Procainamide is similar in chemical structure to procaine. It retains the
quinidine like actions of procaine, but it is not rapidly hydrolyzed and its action persists
long enough so that it is active even after oral as well as parenteral administration.
Pharmacologically, procainamide is equivalent to quinidine. Procainamide may cause
anorexia, nausea and vomiting, and drug hypersensitivity.
c. Propranolol (Inderal). Propranolol is an agent that is used in the treatment
of hypertension, angina pectoris, and cardiac arrhythmias. It is especially useful in the
treatment of ventricular arrhythmias. The normal dosage of this drug for antiarrhythmic
purposes is 10 to 40 milligrams given three or four times daily. As you might expect, the
dose of the drug can be adjusted to meet the individual needs of the patient. The side
effects associated with propranolol include bradycardia, bronchoconstriction, and
congestive heart failure (CHF). These arise because of the beta blocking effects of the
drug. The drug should be used with caution in persons who have asthma. Other beta
blocking agents commonly used include Metoprolol (Lopressor) and Atenolol
(Tenormin) and Sotalol (Betapace).
d. Phenytoin (Dilantin). Phenytoin is an agent that may be administered
intravenously to reverse digitalis-induced arrhythmias. Rapid intravenous administration
may cause bradycardia, hypotension, and cardiac arrest (rarely).
e. Lidocaine (Xylocaine). Lidocaine is an agent that may be given
intravenously in the treatment of ventricular arrhythmias. Large intravenous doses may
produce convulsions, coma, and respiratory depression. You should be aware that not
all lidocaine solutions are to be administered intravenously. Lidocaine for intravenous
use is clearly marked as such on the container.
f. Amiodarone (Cordarone). Amiodarone is an agent that is used to treat
life- threatening ventricular arrhythmias and occassionally atrial arrhythmias. It is
administered as an IV loading dose over 24 hours followed by oral maintenance. Use of
amiodarone is associated with hepatic, ophthalmic, thyroid, and pulmonary side effects.
g. Diltiazem (Cardizem). Diltiazem is used intravenously (5-20 mg/hr) to
control ventricular rate in atrial flutter or fibrillation. The oral dosage is 240 mg to 320