Comparative Cardiac Effects of Quinidine and N,N-Bis(phenylcarbamoylmethyl) dimethylammonium Chloride (QX-572), A New Antiarrhythmic Agent

¹ Astra Pharmaceutical Products, Inc., Worcester, Mass.
² Worcester, Mass

The effects of N,N-bis(phenylcarbamoylmethyl) dimethyianmmonium chloride (QX-572) 0n the electrophysiologic properties of the isolated papillary muscle of the cat and of the intact dog heart were compared with those of quinidine sulfate. QX-572 increased the threshold of both the isolated papillary muscle and the intact ventricle of the dog. It was also found that this agent could increase the absolute refractory period to a greater extent than it decreased conduction velocity of cardiac muscle. From a theoretical view, this combination of effects would tend to indicate that QX-572 is an effective antiarrhythmic compound. In the hypothermic dog QX-572 did reduce significantly the incidence of ventricular fibrillation when administered 18 to 24 hours prior to cooling. Quinidine, on the other hand, increases threshold but causes a greater decrease in conduction velocity as compared to the increase in refractory period produced. Thus, it would appear that the antiarrhythmic activity of quinidine is based mainly on its ability to depress myocardial excitability. It may be that the potential antiarrhythmic activity of new compounds can be evaluated by determining their effects on the various electrophysiologic properties of an isolated papillary muscle preparation.

Note:

The authors wish to thank Drs. A. P. Truant and H. E. D'Amato of Astra Biological Laboratories for supplying N,N-bis(phenylcarbamoylmethyl) dimethylammonium chloride.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?