Pharmacology of Quixidix. 



283 



143 (1725) 



Experimental studies of the pharmacology of quinidin. 



By ALFRED E. COHN and ROBERT L. LEVY. 



[From the Hospital of the Rockefeller Institute for 

 Medical Research, New York, N. Y.] 



It has recently been shown that in certain patients suffering 

 from fibrillation of the auricles, the normal cardiac mechanism 

 may be restored by the oral administration of quinidin sulphate. 

 Knowledge concerning the pharmacological action of this drug is 

 desirable for the clinic and is important insofar as it may furnish 

 information concerning the nature of the fibrillatory process. 



Experiments were done on 12 dogs. Anesthesia was accom- 

 plished by intratracheal etherization. The thorax was opened in 

 the median line. A myocardiograph of the Roy and Adami type 

 was sewed into the tip and base of the ventricles and connected 

 with a system of Marey tambours. Changes in the degree of 

 cardiac contraction obtained by this method may be taken to 

 represent alterations in volume output. The blood pressure was 

 recorded from the right femoral artery; injections of the drug were 

 made into the left femoral vein. In eight experiments the thres- 

 hold for the production of transient auricular fibrillation was de- 

 termined by faradization of the right auricle. Electrocardiograms 

 were made at frequent intervals. 



The results may be summarized as follows: 



1. Rate. — No constant effect was noted. There was accelera- 

 tion 4 times, slowing 4 times and fluctuation in the remainder of 

 the animals. 



2. P-R (conduction) Time. — The changes were slight and 

 relatively insignificant. There was prolongation four times and 

 shortening once. 



3. T-ivave. — A change in this portion of the electrocardiogram 

 occurred eight times. This consisted either of reversal in the 

 direction of the deflection, or of increase in the voltage of the 

 original wave. 



