This section is from the book "A Practitioner's Handbook Of Materia Medica And Therapeutics", by Thos. S. Blair. Also available from Amazon: A Practitioner's handbook of Materia Medica and Therapeutics.
Pepsinum, Pepsin. An active proteolytic agent employed in several forms of dyspepsia and in peptonizing milk. In cases of malnutrition in infants, pepsin in small doses triturated with milk-sugar is often of most direct benefit. It should also be remembered that following shock or severe disease a deficiency of pepsin in the gastric secretion is ofttimes a marked factor in the case. It combines rationally with hydrochloric acid and the bitter tonics. Dose, 3 to 10 gr. A few makers extract direct from the hog's stomach the pepsin therein. These essences of pepsin are probably the most active form of the drug, and are utterly free of decomposition products.