DRUGS ACTING ON THE DIGESTIVE ORGANS 19 



lies inhibit not only the secretion of acid gastric juice, but also all the 

 other digestive secretions, i.e., the secretions of the intestines, liver (bile), 

 and pancreas (pancreatic juice). Antacids (as sodium bicarbonate and 

 magnesia) are, however, indicated in gastric hypersecretion and hyper- 

 chlorhydria. 



If administered several hours after eatin.g, antacids counteract acid- 

 ity due to fermentation and relieve pain caused by this condition. Since 

 fermentation is frequently the cause of tympanites, the antacids are con- 

 joined to advantage with carminatives (sodium bicarbonate and ginger). 

 The alkaline carbonates allay pain by means of the carbonic dioxide set 

 free, which is locally sedative and also stimulates peristalsis, and the 

 antacids are also beneficial in dissolving mucus in catarrhal conditions 

 of the alimentary canal. 



The antacids are synonymous with alkalies, with the exception of the 

 neutral vegetable salts — acetates, citrates and tartrates — of potassium 

 and sodium, which are sometimes classed under this head. These do not 

 alkalize the contents of the stomach, but nevertheless are broken up in 

 the body and transformed into carbonates and thus render the urine 

 more alkaline during their elimination. Among those included in the 

 following list the sodium compounds are much less active in alkalizing 

 the urine than the potassium salts. Sodium bicarbonate is in most fre- 

 quent use in digestive disorders, but ammonium carbonate is particularly 

 appropriate in flatulence, because it possesses more power in stimulating 

 peristaltic action and expelling flatus. 



ANTACIDS. 



Sodium carbonate Ammonium carbonate 



Sodium bicarbonate Magnesia 



Potassium carbonate Magnesium carbonate 



Potassium bicarbonate Calcium carbonate (chalk) 



Solution of potash Solution of lime (lime water) 



Ammonia 



Acids. — Contrary to accepted ideas, Pawlow's and Starling's experi- 

 ments show that mineral acids directly stimulate the secretion of acid in 

 the stomach, and, indirectly, the secretions of the intestines, liver and 

 pancreas. The first part of gastric secretion is caused by vagal stimula- 

 tion through reflex action produced by the desire, sight, and smell of 

 food, and is further increased by the taking of food. In the latter part 

 of gastric digestion, the acid product of the first part of digestion acts 

 on the mucosa to cause the formation of a chemical body, or hormone 

 (Greek, to excite), known as gastrin. This is absorbed into the blood 

 and stimulates the activity of the secretory glands of the fundus of the 

 stomach. In the intestines, acid chyme likewise leads to the formation of 

 another hormone, secretin, which likewise is absorbed and stimulates the 

 secretion of the intestines, liver and pancreas. 



Carminatives include the same drugs which were mentioned as stom- 

 achics/ and valerian, asafetida and the volatile oils ; but the term as gen- 



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