The medical profession has become greatly interested in intravenous therapy in recent years, and although no particular evidence of this enthusiasm has been reflected in the treatment of heart disorders, the work of Eggleston,1 introducing the administration of large single doses of digitalis by mouth, might well lead others to try the effect of similar preparations intravenously. In the past, intravenous cardiac therapy has been essentially limited to preparations of strophanthin, which is generally considered to be a dangerous procedure. With this in mind, an attempt was made to determine whether the introduction into the blood stream of digitalis in its more complete and less potent form would prove to be a safe method for obtaining a therapeutic effect.
The margin of safety has been taken as the difference between the minimum lethal dose (M.L.D.) and the minimum toxic dose (M.T.D.). We introduce the concept of the margin of safety