Mitchell et al., "Mortality and morbidity in patients receiving
encainide, flecainide, or placebo--the Cardiac Arrhythmia Suppression Trial," The New England Journal of Medicine, vol.
Investigators, Preliminary Report: Effect of
Encainide and Flecainide on
One frequently cited case involves the anti-arrhythmia drugs
encainide and flecainide.
In the US, dogs failed to predict heart problems caused by the cardiovascular drugs
encainide and flecainide which led to an estimated 3,000 deaths.
Among the drugs of particular importance in this regard are those with a narrow therapeutic index including flecainide,
encainide, vinblastine, carbamazepine, and TCAs.
The trial was halted because it clearly showed that the three sodium channel blockers being studied (
encainide, flecainide, and morizicine) increased mortality--even though they had effectively corrected the arrhythmia.
Nonetheless, on October 31, 1985 - only three months later - FDA approved Tambocor for patients with less severe as well as life-threatening arrhythmias.(35) After approval, clinical trials sponsored by the National Heart, Lung, and Blood Institute revealed a two-and-a-half-fold increase in mortality among patients treated with Tambocor or Enkaid (
encainide HCl) - another antiarrthythmic agent - compared to patients receiving a placebo.
Drugs which could be affected by poor metabolism include metoprolol, a 13-blocker, and recently
Encainide, scheme 5, a potent drug which suppresses irregular heart beats and which has been examined in patients by Laganiere in collaboration with the Ottawa Heart Institute and other North American centres.
Study patients taking
encainide (marketed as Enkaid by Bristol Laboratories in Evansville, Ind.) and flecainide (marketed as Tambocor by 3M Riker in St.
(12) Similarly,
encainide and flecainide reduce the incidence of arrhythmias after acute myocardial infarction, but they also increase mortality.
Increased risk of death and cardiac arrest from
encainide and flecainide in patients after non-Q-wave acute myocardial infarction in the Cardiac Arrhythmia Suppression Trial.
Mortality in patients treated with flecainide and
encainide for supraventricular arrhythmias.
Encainide was provided by Bristol-Myers, Princeton, NJ.
The widespread use of
encainide and flecainide before POEMs were available led to more than 50,000 premature deaths, more than all the Americans killed during the Vietnam War.[5]
