332 VEGETABLE DRUGS 



failure from disease, after operations, and in shock and poisoning. Two other 

 preparations are of value for injection into vein, muscle, or under the skin. (1) 

 Digipuratum, of which 1 tablet or 1 mil = gr. 1% of digitalis, is an extract freed 

 from digitonin and a mixture of digitoxin and true digitalin. (2) Digalen is a 

 solution of digitoxin or digitalein in water, alcohol and glycerin, and is given 

 intramuscularly or intravenously, in the same dose as the tincture by mouth. It 

 is not so reliable as digipuratum. The tincture or fluidextract should not be 

 given under the skin because they are precipitated in the tissues. The action of 

 digitalis being slow, such drugs as alcohol, ammonia and camphor should first be 

 resorted to in heart failure. 



Action of Digitalis. 



External. — None. 



Internal. — Alimentary Canal. — Digitalis in large doses is a gastro- 

 intestinal irritant, and in poisoning causes nausea, colic, purging, and 

 vomiting in animals capable of the act. It has been shown that vomiting 

 is due to irritation of the vomiting center by large doses and occurs when 

 the drug is given under the skin. 



Circulation. — The dominant action of digitalis is expended upon the 

 heart and blood vessels. After medicinal doses we find the pulse becomes: 

 1. Slower. 2. Fuller and stronger. 3. More regular in rhythm, if pre- 

 viously irregular. In poisoning, these phenomena are reversed and the 

 pulse is: 1. Rapid. 2. Weak. 3. Irregular. The therapeutic effects 

 following moderate doses are due to: 1. Stimulation of the heart muscle, 

 and perhaps its contained ganglia (pulse stronger and somewhat less 

 frequent). 2. Excitation of the vagus centre and the vagus cardiac ter- 

 minations (pulse infrequent). 3. Stimulation of the muscular walls of 

 the vessels and vasomotor centres (increased vascular tension). When 

 given by the mouth in therapeutic doses digitalis often does not cause 

 either general vascular constriction or rise in blood pressure. The labora- 

 tory results are obtained by large doses given intravenously. Clinically, 

 digitalis acts by favorably altering an abnormal flow and distribution of 

 blood, owing to venous stasis, without necessarily increasing blood pres- 

 sure. In consequence of the action on the heart the ventricular contrac- 

 tions are complete and forcible (stimulation of the heart muscle) ; and 

 the diastolic period is lengthened (increased dilatation of the ventricle 

 owing to vagus stimulation) ; therefore, more blood enters the viscus and 

 more is squeezed out with each contraction. In poisoning, the symptoms 

 noted above follow: 1. Excessive irritability of the heart muscle (pulse 

 rapid). 2. Insufficient filling of the vessels and paralysis of the vessel 

 walls (pulse weak). 3. Irregularities of rhythm occur (pulse irregular). 

 There may be several systoles with scarcely any diastolic periods ; the 

 heart may beat slowly and weakly at one time, and rapidly and strongly 

 at another. All sorts of indescribable irregularities in rhythm may be 

 seen. At one time the heart beats slowly and weakly; at another time 

 the heart beats rapidly and strongly. The heart, during this irregular 

 toxic period, is seen to be unequally affected, in that one portion (the 

 apex) may be firmly contracted while the rest of the ventricle is dilated. 

 Moreover, the auricles and ventricles do not act synchronously, owing 

 to inhibition of impulses (heart-block) from auricle to ventricle. The 



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