DRUGS ACTING ON THE CIRCULATION 29 



Medicated irrigations are most serviceable in catarrhal disorders of 

 the bowels (dysentery, etc.), i.e., the fluid is allowed to flow in and out 

 again till the solution returns clear. 



, DRUGS ACTING ON THE CIRCULATION. 

 I- — ^Acting Upon the Blood. 



(a) Blood plasma. — The alkalinity of the blood plasma can be in- 

 creased by the use of the salts of the alkaline and earth metals; i.e., 

 potassium, sodium, lithium, ammonium, magnesium and calcium com- 

 pounds. This effect is of value therapeutically in rheumatism, hemo- 

 globinemia and uric-acidemia. In the former two disorders, increasing 

 the alkalinity of the blood plasma appears to assist in the elimination of 

 toxic material, while in the latter condition the excretion of uric acid — 

 existing in the blood as urates — is thought to be favored by potassium and 

 lithium salts. These salts also alkalize the urine and increase its secre- 

 tion. Drugs which remove considerable fluid from the body, as purga- 

 tives, diaphoretics and diuretics, necessarily alter the composition of the 

 blood plasma. By removing fluid from the plasma, these agents are use- 

 ful in aiding absorption of inflammatory exudations, dropsies and edemas, 

 since the mass of fluid removed is soon replaced from that contained in 

 the food and tissues. In the various infectious and constitutional diseases 

 treatment is largely directed to exciting the secretions and excretions 

 with the purpose of eliminating products of tissue waste and bacterial 

 action from the blood, which prove detrimental to the system. This line 

 of treatment is pursued in uremia, hemoglobinemia and lymphangitis. 

 Venesection, saline infusions, hypodermoclysis and enteroclysis alter the 

 character of the plasma and often have a life-saving value. (See p. 514.) 



(b) The red corpuscles. — The so-called blood tonics, or hematinics, 

 influence the red corpuscles, increasing their number and content of hemo- 

 globin when there is a deficiency of either. The effect upon the augmenta- 

 tion of hemoglobin is more marked. 



HEMATINICS. 



Iron and i1;s salts Corrosive sublimate 



Arsenic Potassium permanganate 



Copper salts Manganese dioxide 



The first two are immensely superior to the others in blood-making 

 properties. Iron especially favors the formation of hemoglobin; arsenic 

 increases the number of red corpuscles. Certain agents possess toxicolog- 

 ical significance by destroying the composition of hemoglobin. Large 

 doses of the coal tar products, as acetanilid, antipyrin and phenacetin, 

 nitrites and potassium chlorate, convert hemoglobin into methemoglobin, 

 a mixture, probably, of hematin and soluble albumin; while carbonic 

 oxide, phosphorus, sulphur, arsenic, iodine, hydrogen sulphide and tur- 

 pentine, in large doses, reduce oxyhemoglobin and prevent its combination 



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