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DIGITALIS. 



DIGITALIS. 



Digitalis is the dried leaves of the second year's growth of Foxglove, Digitalis 

 purpurea. 



Pharmacodynamics. 



Central Nervous System. Stimulation in the medulla of the cardio-inhibitory 

 (and vasoconstrictor) centers; later, respiratory and vomiting centers, and reflexes to 

 motor tracts. 



Muscular system is not affected in mammals. 



Respiration is slowed in toxic conditions. 



Heart. Vagus action prolongs diastole, while direct action irritates heart muscle, 

 extending and energizing systole. 



Blood-pressure is increased, partly by the increased force of the heart-beat, partly 

 by irritation contraction of the vessel walls, partly by centric vasoconstriction. 



Alimentary tract tends to be irritated. 



Secretory Glands. Kidneys manifest increased activity, due in part to local epi- 

 thelial irritation, and in part to augmented blood-pressure; most evident in cardiac 

 dropsy. 



Metabolism. Effect inappreciable. 



Temperature is lowered when fever exists. 



Absorption takes place slowly from the alimentary canal. 



Excretion. Probably oxidized in the body. 



Local Action. Digitalis is very irritant to the eye and to mucosa; abscesses have 

 followed when used hypodermically. 



Tolerance. Not acquirable by man. 



Symptoms. 



Therapeutic Doses. 



Slowing and strengthening of 

 heart rhythm. 



Toxic Doses. 



Uneasiness and giddiness. 



Nausea and vomiting. 



Great muscular weakness. 



Very slow intermittent pulse; or, 

 if cumulative, racing, flutter- 

 ing pulse with great precor- 

 dial anxiety. 



Mental distress. 



Therapeutics. 



Digitalis is employed in cardiac incompetency, whether due to simple dilatation 

 or to valvular lesions ; and is seemingly a specific in auricular fibrillation. 



Dosage. 



Fluidextractum Digitalis, 0.05 mil. 



Tinctura Digitalis, 0.3 to I mil, repeated very cautiously. 



Digitalis is slowly absorbed, but its effect is prolonged. A single dose will keep 

 the heart slowed for several days. Therefore, repeated doses are liable to produce a 

 cumulative effect, with severe toxic symptoms. 



