This section is from the "A Handbook of Useful Drugs" book, by State Medical Examining and Licensing Boards.
A proteolytic ferment or enzyme obtained from the glandular layer of the fresh stomach of the hog, Sus scrofa.
Properties : Pepsin occurs as pale yellow, transparent or translucent scales or grains, or as a cream-colored, amorphous powder, free from any offensive odor and having a slightly acid or saline taste. It is soluble, or almost entirely soluble in water, the solution having more or less opalescence; it is practically insoluble in alcohol.
Action and Uses: Pepsin acts only in an acid medium. It is useful to secure the digestion of protein food in the stomach. It is seldom indicated, because the gastric juice usually contains sufficient pepsin to perform gastric digestion. It may be given in conjunction with hydrochloric acid in those cases of acute dyspepsia in which there is an absence of free hydrochloric acid in the stomach contents. In chronic cases it should be given only when the acid and pepsin are both lacking. As a rule, even when acid is absent, the pepsin is still secreted and digestion will occur normally if hydrochloric acid is given without pepsin. In achylia gastrica. pepsin is a valuable addition to the hydrochloric acid, which is usually prescribed.
Dosage: 0.25 gm. or 4 grains.