Pepsin is one of the normal constituents of the gastric juice, and, with the aid of hydrochloric acid, changes albumins into peptones, in which form they are readily diffusible and capable of being absorbed into the blood.

Pepsin, as used in medicine, is a preparation made from the mucous membrane which lines the stomach of the pig.

It is made by cleaning the mucous lining, scraping it, drying the pulp at a temperature of 100° F., and pulverizing it. The power is a light yellow-brown, almost insoluble in water, and of slightly salty taste. It may be taken dry on the tongue or given in milk.

Average dose, gr. viii.-0.5 Gm., with meals or immediately after.