Posology : מינונים

4.2.   Posology and Method of Administration
Posology
Note:
Patients with ventricular arrhythmias require careful cardiological surveillance at the beginning of propafenone treatment. These patients should only be started on the drug if emergency cardiological equipment is available and if the possibility of monitoring is assured.
The individual maintenance dose should be determined under cardiological surveillance including ECG monitoring and repeated blood pressure control (adjustment phase). A decision should be made as to whether to continue treatment if there are ECG changes such as QRS or QT prolongation greater than 25% or PR prolongation greater than 50% or QT prolongation to more than 500 ms, or an increase in the incidence or severity of cardiac arrhythmias.

Elderly patients:
No overall differences in safety or effectiveness were observed in this patient population, but greater sensitivity of some older individuals cannot be ruled out, therefore, these patients should be carefully monitored. The same applies to maintenance therapy. In such patients it is recommended to postpone therapeutically necessary dose increases until steady state plasma concentrations have been reached, usually after around 5 to 8 days. This precaution reduces the risk of inducing proarrhythmic effects in these patients during the initial phase of treatment.

In those patients in whom significant widening of the QRS complex or second or third degree AV block occurs, a dose reduction should be considered.

Note: In patients with flutter, treatment should be initiated with careful monitoring (preferably under hospitalization).

When prescribing propafenone it should be taken into account that there is no evidence that antiarrhythmic treatment with Class I antiarrhythmics improves survival.

It is recommended that therapy be initiated with 150 mg propafenone given every eight hours (450 mg/day). Dosage may be increased at a minimum of 3 to 4 day intervals to 300 mg every 12 hours (600 mg/day). If necessary, 300 mg every 8 hours (900 mg/day) may be administered until optimum clinical response is obtained.

Occasionally, it may be necessary to increase the daily dose to 900 mg of propafenone hydrochloride. The daily dose should be reduced accordingly for patients with a lower body weight.
Dose increases should not be attempted until the patient has been receiving treatment for 3-4 days.

The individual maintenance dose should be determined under cardiological surveillance including ECG monitoring and repeated blood pressure control (titration phase).

The usefulness and safety of dosages exceeding 900 mg per day have not been established.

As with other antiarrhythmic agents, in the elderly or in patients with marked previous myocardial damage, the dose of Rytmonorm should be increased slowly and gradually during the initial phase of treatment, whereby monitoring of plasma concentrations of the drug may be appropriate. The first dose increase should take place after 5 to 8 days at the earliest.

Patients with Hepatic/Renal Impairment
In patients whose liver and/or kidney function is impaired, there may be drug accumulation after standard therapeutic doses. Nonetheless, patients with these conditions can still be titrated on propafenone hydrochloride under ECG and clinical monitoring.
Method of administration
Because of its bitter taste and its surface anaesthetic action, the tablets should be swallowed whole together with some liquid after meals.