Medications and Drugs
GENERIC NAME: propafenone
BRAND NAME: Rythmol
DRUG CLASS AND MECHANISM: Propafenone is used to treat
heart
rhythm abnormalities (antiarrhythmic agent). The primary
mechanism of
action is blocking channels which transport sodium across cell
borders,
which prolongs the beginning of the phase during which heart
muscle cells
become electrically stimulated (action potential).
Propafenone slows conduction throughout the heart and is
referred to as
a type IC antiarrhythmic. Propafenone also has some beta
adrenergic
receptor blocking properties, and, to a lesser extent, calcium
channel
blocking effect. These are class II and class IV properties ,
respectively. Propafenone also blocks electrical conduction
through
accessory pathways, such as seen in WPW syndrome.
PRESCRIPTION: yes
GENERIC AVAILABLE: yes
PREPARATIONS: Propafenone triangular tablets (150, 225,
300 mg).
STORAGE: Tablets should be stored at room temperature
in a
tightly closed, light-resistant container.
PRESCRIBED FOR: Propafenone is an antiarrhythmic agent
and is
only approved for use in patients with life-threatening
ventricular
arrhythmias, such as ventricular tachycardia. Propafenone is
also
effective in suppressing the recurrence of atrial fibrillation
once sinus
rhythm has been restored. Propafenone is at least as effective
as any
other type I agent in converting atrial fibrillation to sinus
rhythm.
Propafenone is effective in atrial tachycardia, AV nodal
tachycardia, and
bypass tract tachycardias.
DOSING: Propafenone is given with or without food every
eight
hours. In most patients propafenone is metabolized, primarily
by the
liver, and excreted in the urine over 2 to 10 hours. In up to
10% of
patients this metabolism is slow and occurs over 12 to 32
hours. Doses may
need to be lowered in these patients, and those with reduced
liver and
kidney function.
DRUG INTERACTIONS: Because of its beta blocking
activity,
propafenone must be used with caution in patients with weak
heart muscle
(congestive heart failure), slow heart rate, any form of heart
electrical
conduction block, low blood pressure, or asthma. The most
serious side
effect of propafenone is the causing of serious life-
threatening irregular
heart rhythms (ventricular arrhythmias or proarrhythmia). It is
for this
reason that propafenone is started and doses increased while
patients are
hospitalized in a monitored setting.
Quinidine inhibits the metabolism of propafenone and,
therefore, their
combined use should be avoided. Propafenone increases the
levels of
digoxin (Lanoxin), warfarin (Coumadin), and beta blockers which
may
require dose reductions. The electrical safety margins of
artificial
pacemakers can be compromised by the effects of propafenone and
should be
closely monitored. Safety and efficacy in children has not been
established.
PREGNANCY: Safety and efficacy in pregnant women has
not been
established.
NURSING MOTHERS: It is not known whether propafenone
enters breast milk.
SIDE EFFECTS: Common side effects include dizziness,
blurred
vision, anorexia, unusual taste, fatigue, nausea and vomiting.
Reference: FDA Prescribing Information
Last Editorial Review: 12/31/1997
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
- Drug Interactions - Learn about potential drug interactions you may be exposed to. Drug interactions can occur with prescription drugs, OTC medication, vitamins, herbs, and supplements.
- Atrial Fibrillation - Learn about atrial fibrillation including what it is, what happens during atrial fibrillation, symptoms, risk factors, how it is diagnosed, and how it is treated
- Drugs: What You Should Know About Your Drugs - Find out what you should know about your drugs such as side effects, warnings and precautions, storage information, and if a generic version is as good as the brand name.
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