THE EFFECT OF DIGITALIS UPON COAGULATION TIME OF THE BLOOD

¹ From the Department of Pharmacology, Medical College of Virginia, Richmond

1. Continuous intravenous administration of a diluted tincture of digitalis (from U.S.P. XII reference powder) to dogs maintained under Dial anesthesia resulted in a reduction of blood coagulation time by 10.7 per cent after 50 per cent of the fatal dose had been injected, and a reduction of 17 per cent after 90 per cent of the fatal dose had been given; t-values for both of these figures were significant.

2. Continuous intravenous administration of gitalin to dogs under Dial anesthesia resulted in a 24 per cent decrease in coagulation time; the t-value for this decrease was less than significant.

3. Continuous intravenous administration of the diluted tincture of digitalis to dogs maintained under sodium pentobarbital anesthesia resulted in a 15 per cent drop in the coagulation time of the blood; the t-value was less than significant.

4. Continuous intravenous administration of the diluted tincture of digitalis to dogs maintained under ether anesthesia had practically no effect upon the coagulation time of the blood.

5. The fatal dose of the tincture of digitalis for dogs maintained under Dial anesthesia was found to be 1.23 cc. per kg., that for dogs under ether 0.94 cc. per kg., and that for dogs under sodium pentobarbital 1.39 cc. per kg.

6. Administration of a single large dose of the tincture of digitalis intravenously to unanesthetized dogs had no tendency to shorten the coagulation time and in fact tended to lengthen it somewhat several hours after injection of the drug.

7. Daily oral administration of the tincture of digitalis in amounts sufficient to produce mild intoxication to unanesthetized dogs had no effect upon the coagulation time of the blood.

8. Preadministration of heparin to cats did not alter the toxicity of the tincture of digitalis as determined by the usual assay method.

9. In vitro experiments showed no effect of digitalis on the coagulation of whole blood beyond that produced by a solution of equal alcohol content.

10. No antagonism between heparin and digitalis could be demonstrated in vitro.