The lethal dose of digoxin was determined by administering 10 ml of a digoxin-saline solution to 26 nonimmunized rabbits through an ear vein over a 10 min period. Rabbits receiving less than 0.45 mg/kg digoxin showed no toxic effect, whereas all 15 rabbits that received 0.5 mg/kg developed an early arrhythmia and died within 1 hr. Moreover, eight rabbits which had been immunized with antigens unrelated to digoxin or injected with Freund's adjuvant mixture all died after receiving 0.6 mg/kg digoxin. Thus, it was concluded that 0.6 mg/kg digoxin was uniformly lethal in rabbits that had not been immunized or had received antigens unrelated to digoxin.
Donald H. Schmidt, Vincent P. Butler Jr.