Diastase is the starch-digesting agent of barley malt, changing hydrolized or cooked starch to dextrin and maltose. It has also some power to hydrolyze raw starch. The Pharmacopoeia requires that it be able to convert not less than 50 times its own weight of potato starch into sugars. It acts in a neutral or slightly acid medium, is retarded in its activity by alkalies (Chittenden and Ely, and Kellerman), and is destroyed by strong acids. Its digestive power is seldom needed in therapeutics, except possibly in pancreatic disease, or where for some obscure reason starch digestion is definitely defective.

The extract of malt is prepared by extracting barley malt with water and evaporating to a thick, honey-like consistence. It contains much maltose and other nutritive matter and a little diastase. As its diastatic activity is not very great, it is really nothing but a form of carbohydrate food (see Nutrients). Owing to its sweetness and thick consistence it is a good vehicle for cod-liver oil, cascara, and other strong-tasting drugs.

There are also marketed some "extract of malt" preparations which are really malt liquors of the nature of beer. They contain about 2 per cent. of alcohol, by volume, and much nutritive extractive. In some cases they are made bitter with hops. They have very feeble digestant power for starch.

Taka-diastase, a ferment with diastatic properties, is obtained from a mold, Aspergillus oryzae, which grows in Japan upon the rice plant.

Papain is an enzyme obtained from the juice of the unripe fruit of Carica papaya, a South American papaw plant. It can digest albumin in a medium that is alkaline, neutral, or acid, but acts best in one that is slightly acid. It has no special indications.

Ingluvin is the dried lining membrane of the chicken's crop. Its digestive power is not very great. It has been given in doses of 5 grains (0.3 gm.) after each meal in the nausea and vomiting of pregnancy, but its use is purely empiric.

Secretin, owing to its unstable nature, has not as yet come into general therapeutic use. It is quickly destroyed by gastric juice and by trypsin (Carlson).

Hormonal is a preparation from the spleen of the rabbit. It is said to contain the same peristaltic hormone as the gastric mucous membrane. Reports as to its value differ widely, but a number of authorities have obtained good and continued action of the bowels in postoperative tympanites and obstinate chronic constipation. It tends to cause headache and a marked fall in blood-pressure, and anaphylaxis has occurred. It is given in doses of 15 to 40 c.c. intravenously or intramuscularly, the latter being painful.