CORRECT USE OF PROPAFENONE

USE IN CHILDREN

In a study⁽⁶¹⁾ involving 60 patients (mean age: 4.5 years, range 1 day - 17 years), Propafenone was employed in the following forms of arrhythmia: supraventricular re-entrant tachycardia (42 cases, 14 of whom with WPW) post-operative junctional tachycardia (8 cases), atrial flutter (4 cases), and ventricular tachycardia (4 cases).
The overall efficacy of Propafenone in interrupting the arrhythmias was 76%, whereas the drug prevented the arrhythmia recurrence in 63% of the cases. The best results were obtained in supraventricular re-entrant tachycardias.
The overall incidence of side effects was 14% and it was necessary to discontinue therapy in only 6% of the cases.

In one sample of 18 patients⁽⁶²⁾ (age: 10.1 ± 4.5 years) with recurrent paroxysmal supraventricular tachycardia due to atrioventricular accessory pathways (manifest in 11, and concealed in 7), who were followed for 26 ± 10 months, Propafenone, given orally (14.3 ± 3.8 mg/kg/day in 2 - 3 divided doses), was able to prevent the tachycardia recurrence in 83% of the cases (15/18 patients).

PREGNANCY

Very little information is available concerning the use of Propafenone during pregnancy.
No adverse effect on the foetus,⁽⁶³⁾ nor alterations in neonatal development⁽⁶⁴⁾ were observed in a pregnant woman who was taking Propafenone during the second and third trimester. No information exists concerning the first trimester. Thus the drug has to be avoided during this period.

CHILDBED

A case has been reported of a patient with recurrent paroxysmal supraventricular tachycardia and non-sustained ventricular tachycardia which has arose during pregnancy. Since then the patient received Propafenone 900 mg/day.

Concentrations of Propafenone and its principal metabolite in the mother’s milk were not such as to determine the ingestion of a dose greater than 16 and 24 µg/day respectively in the suckling infant. Such values are certainly subtherapeutic and equivalent to only 0.03% of the dose taken by the mother. ⁽⁶⁵⁾

USE IN GERIATRIC PATIENTS

In the elderly patient the pharmacokinetics of Propafenone is slower and therefore greater care in dosage titration is advisable.
In a study carried out on 199 patients, 75 of whom were >65 years old and 124 were aged <65 years, it emerged that the effects of Propafenone were not affected by the patient’s age. ⁽⁶⁶⁾

CARDIAC SURGERY

Atrial fibrillation is a common complication of open heart surgery, and affects about 25 - 30% of patients. Although the arrhythmia is shortlasting and usually disappears spontaneously, the rapid ventricular response and the loss of atrial contraction can be particularly dangerous in the initial post-operative phase.
Consequently, a rapid conversion to normal sinus rhythm is generally desirable.
In a study,⁽²⁰⁾ Propafenone administered intravenously (2 mg/Kg in 10 min) allowed conversion to sinus rhythm in 70% of patients after an average time of 22 ± 6 minutes.
Conversion was obtained in 88% of patients who had coronary by-pass surgery, and 39% in those who had valve replacement or repair of the inter-atrial septum. In patients who did not convert, the average ventricular rate decreased from 142 ± 14 to 108 ± 10 beats per minute (p<0.001).

Pulmonary artery pressure was reduced and the cardiac index increased in patients who converted to sinus rhythm, while both parameters remained unchanged in the patients remaining in atrial fibrillation.

PACEMAKER

The results of two clinical studies suggest that it may be necessary to increase the stimulation energy in patients with pacemakers who receive Propafenone.
One of these studies⁽⁶⁷⁾ showed an increase in ventricular stimulation threshold at 2.5 V from 0.15 ± 0.04 ms (before treatment) to 0.26 ± 0.09 ms (during treatment).
The second study⁽⁶⁸⁾ was carried out in 35 patients with different pacemakers: VVI (9 patients), AAI (15 patients) and DDD (12 patients). After administering Propafenone for seven days at a dosage of 450 and 900 mg/day, an increase in the ventricular stimulation threshold, from 0.10 ± 0.08 to 0.15 ± 0.09 and to 0.23 ± 0.17 msec respectively, was demonstrated. The increase in the duration of the stimulated QRS complexes produced by Propafenone correlated significantly with the increase in the ventricular threshold: in fact, the latter was greater in patients with a stimulated QRS broadening >= 25% with respect to basal values. The atrial stimulation threshold was also increased by Propafenone, although to a lesser degree.

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