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Cordarone
amiodarone
This product is to be used only by a registered medical practitioner with
experience in cardiology
COMPOSITION
Per tab
Amiodarone (INN) hydrochloride ......... 200mg
CLINICAL PARTICULARS
Cordarone is indicated only for the treatment of severe rhythm disorders,
not responding to therapy or when other treatments cannot be used:
• Atrial rhythm disorders (conversion of fibrillation of flutter, and
maintenance of sinus rhythm following conversion)
• Nodal rhythm disorders
•
Ventricular rhythm disorders (life-threatening ventricular premature
contractions, ventricular tachycardia salves, prevention of ventricular
tachycardia attacks or ventricular fibrillation episodes)
•
Rhythm disorders associated with Wolff-Parkinson-White syndrome
In view of its pharmaceutical properties, amiodarone is indicated in the
above rhythm disorders especially when they are associated with an
underlying heart disease (coronary insufficiency, heart failure).
PHARMACOLOGICAL PROPERTIES
Pharmacodynamic properties
Class III Antiarrhythmic
ATC Code: C01BD01 (C: cardiovascular system)
Anti-arrhythmic properties:
•
Prolongation of phase 3 of the action potential of cardiac fiber essentially
resulting from a reduction in the potassium channel (Vaughan Williams class
III);
•
Bradycardiac effect due to reduction of sinus automatism. This effect is not
antagonized by atropine;
• Non-competitive alpha- and beta anti-adrenergic antagonist properties;
•
Slowing down of sino-atrial, atrial and nodal conduction, which is more
marked the higher the rhythm;
• No modification in intraventricular
conduction;
• Increase in refractory period and reduction in myocardial
excitability at the atrial, nodal and ventricular stage;
•
Slowing in conduction and prolongation of refractory periods in accessory
atrioventricular pathways;
Other properties:
•
Reduction in oxygen consumption due to moderate decrease in peripheral
resistance and reduction in heart rate;
• Increase of coronary output due to a direct effect on myocardial arteries
smooth muscle
• Maintenance of cardiac output due to a decrease in aortic pressure and
peripheral resistance
A meta-analysis of thirteen controlled, randomized, prospective studies
including 6553 patients with recent myocardial infarction (78%) or chronic
heart failure (22%) was conducted.
The average follow-up period for the patients ranged from 0.4 to 2.5 years.
The daily maintenance dosage was, on average, between 200 and 400mg.
This meta-analysis demonstrated a significant reduction in favour of
amiodarone by 13% for total mortality (CL95% 0.78 - 0.99; P = 0.030) and by
29% for rhythm-related mortality (CL95% 0.59 - 0.85; p = 00003).
However, these results must be interpreted cautiously, taking into account
the heterogeneity of the studies included (heterogeneity related mainly to
the population selected, the duration of followup, the methodology used and
the results of the studies).
The percentage of treatment withdrawals was
higher in the amiodarone group (41%) than in the placebo group (27%).
Seven
percent of the patients taking amiodarone presented hypothyroidism, versus
1% in the placebo group. Hyperthyroidism was diagnosed in 1.4% of patients
taking amiodarone, versus 0.5% in the placebo group.
Interstitial pneumopathy occurred in 1.6% of patients taking amiodarone,
versus 0.5% in the placebo group.
Pharmacokinetic properties
Amiodarone is a compound which is slowly absorbed and has a high tissue
affinity.
Its bioavailability following oral administration varies between individuals
from 30 to 80% (mean value, 50%). Following a single dose, peak plasma
levels are reached in 3 to 7 hours. Therapeutic activity is usually achieved
within one week (a few days to two weeks). Amiodarone has a long half-life
with great inter-individual variations (20 to 100 days). During the first
days of treatment, the compound accumulates in most tissues in the body, and
particularly in adipose tissue. Excretion starts after a few days and
output/input equilibrium is reached after one or several months, depending
on subjects.
These characteristics justify the use of loading doses intended to ensure
the rapid tissue impregnation necessary for therapeutic activity.
A certain proportion of the iodine breaks away from the compound and is
found in an iodide form in the urine; this corresponds to 6mg/24 hours at a
daily dose of 200mg of amiodarone. The remainder of the compound, and thus
the majority of the iodine, is eliminated in the faeces following passage
through the liver.
The negligible urinary excretion enables the use of this
compound at standard doses in renal failure patients.
Following treatment
discontinuation, elimination of the product continues for several months.
The persistence of residual activity over 10 days to one month should be
taken into account.
Posology and Method of Administration
Initial treatment
The usual dosage regimen is 3 tablets per day, for 8 to 10 days. In some
cases, the initial treatment has used higher doses (4 to 5 tablets per day),
always for short periods and under electrocardiographic monitoring.
Maintenance treatment
Seek the minimum effective dose, which varies depending on the patient,
ranging from 1/2 tablet per day (1 tablet every 2 days) to 2 tablets every
day.
Contraindications
This medicine is contraindicated in the following situations:
• Sinus bradycardia and sino-atrial heart blocks not corrected by a
pacemaker; Sinus disease not corrected by a pacemaker (risk of sinus
arrest); High-degree conduction disorders not corrected by a pacemaker;
• Hyperthyroidism due to its possible exacerbation by amiodarone;
•
Known hypersensitivity to iodine or to amiodarone
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The last 6 months of pregnancy;
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Breast-feeding;
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Combination with medicines that can induce torsades de
pointes:
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Class la antiarrhythmics (quinidine, hydroquinidine, disopyramide, etc.),
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Class III antiarrhythmics (sotalol, dofetilide, ibutilide, etc.),
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Sultopride
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Other medicines, such as bepridil, cisapride, diphemanil, erythromycin IV,
mizolastine, sparfloxacin, etc. (see Interactions with other medicinal
products and other forms of interaction),
This medicine IS NOT GENERALLY RECOMMENDED in combination
with:
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injectable diltiazem
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Halofantrine, pentamidine, moxifloxacine,
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Certain neuroleptics (thioridazine, chlorpromazine, levomepromazine,
trifluoperazine, cyamemazine, sulpiride, amisulpride, tiapride, primozide,
haloperidol, droperidol),
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And with beta-blockers other than sotalol and Esmolol (see Interactions
with other medicinal products and other forms of interaction).
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