DIGITALIS 335 



tion from a therapeutic to a toxic effect. This may be due to three 

 causes. 1. Tardy absorption. 2. Increasing susceptibility. 3. Delayed 

 elimination and accumulation of the drug in the system. The cumulative 

 action of digitalis is chiefly due to the latter cause. It should never be 

 administered in full medicinal doses uninterruptedly for any considerable 

 length of time. 



Toxicology. — Poisoning may occur from large single doses within 3 

 to 10 hours of their ingestion, and last for 16 or more hours with a. fatal 

 result; or may appear suddenly after the administration for several days 

 of large medicinal doses (cumulative action). A minimum fatal dose for 

 the horse is about 3vi of digitalis, or gr.iss of Homolle's digitalin. 

 For dogs, 3i of digitalis, or gr. I/4 of digitalin. Cattle take enormous 

 doses of digitalis by the mouth without toxic effect, 



Large doses may, however, induce abortion and a dose of two and 

 a half drams is said to have caused premature labor in a cow. 



The symptoms exhibited are chiefly concerned with the dijgestion 

 and circulation. They consist in dullness, lassitude, loss of appetite, 

 nausea, flatulence, diarrhea, infrequent, full pulse (reduced 6-10 beats 

 in the horse), and contracted pupils. There is vomiting in dogs. In 

 fatal cases these symptoms are followed by severe colic and tympanites; 

 rapid, feeble, dicrotic, irregular or intermittent pulse (120-140 in horses), 

 while the heart may be heard and felt beating wildly and strongly, and 

 a systolic blowing murmur can frequently be detected. This is due to 

 mitral or tricuspid regurgitation caused by irregular contraction of the 

 columnse carnas. The pulse is imperceptible because of the failure of 

 the heart to fill the vessels. The extremities are cold, the eye is pro- 

 truding, and salivation occurs. Bloody diarrhea is very often present and 

 the urine may be suppressed. The breathing finally becomes difficult 

 and death ensues within a few hours, or as late as several days. 



Treatment. — Evacuation of the stomach and bowels. Tannic acid, 

 as a chemical antidote, alcohol, opium, and aconite, which is the physio- 

 logical antagonist in depressing the action of the heart and lowering 

 blood tension. In addition, external heat should be applied and com- 

 plete quiet and rest secured. 



Administration. — In view of its slow absorption and elimination full 

 doses of digitalis should not be given by the mouth oftener than twice 

 daily or once in twenty-four hours, after its effect has been secured. 

 Very large doses may be given, however, repeatedly, in case of threatened 

 heart failure, by the subcutaneous method. The appearan'fce of indi- 

 gestion, nausea or dullness, and a decided fall in the pulse rate, should 

 be a warning to stop the administration at once. The best preparations 

 are the tincture, infusion, and fluid-extract. 



Uses External. — Digitalis is occasionally emploj'ed as a poultice of 

 the leaves, applied over the loins to promote diuresis, or in local inflam- 

 mation, to contract vessels. 



Uses Internal. — Among all other drugs digitalis stands out pre- 

 eminently as the heart stimulant. None may take its place. Yet it has 

 even been classified as a heart depressant. It may, however, exert a 



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