KNOLL'S RYTHMOL BACKED BY FDA PANEL

Knoll's Rythmol (propafenone) should be approved for symptomatic treatment of supraventricular arrhythmias with a warning similar to that included on the labeling of 3M Pharmaceuticals' Tambocor (flecainide), according to the Cardiovascular & Renal Drugs Advisory Committee of the US Food and Drug Administration. The drug is already on the market in Europe under the trade name Rytmonorm.

The committee agreed that propafenone should be approved for prophylaxis of paroxysmal supraventricular tachycardia (PSVT) and paroxysmal atrial fibrillation and flutter (PAF), but the proarrhythmic properties of the drug necessitated a statement on the label warning of increased mortality, similar to that seen with Tambocor. The proarrhythmic properties of flecainide and other Class I anti-arrhythmic agents, such as encainide, were uncovered in the Cardiac Arrhythmia Suppression Trial (CAST), reported in 1992 (Marketletters passim).

Tambocor's labeling asks physicians to consider the potential risks when prescribing the drug for PSVT, and makes reference to the excess mortality seen in CAST.