It is as a solvent of albuminous substances, as a digestive, that papäin comes into consideration. As compared with pepsin its range is far wider. While pepsin is active only in acid solutions, papäin is active in neutral or alkaline, and in slightly acid solutions (Finkler, Hirsch, Sittmann, and others). Papäin is also more effective and lasting as a solvent of albuminous matters than pepsin. Strongly acid and strongly alkaline solutions are rather inimical to the digestive function of papain, although it still preserves some degree of activity under these conditions; but in neutral and feebly alkaline solutions it is at its best working power. Too great extent of dilution impairs its effect; on the other hand, a certain degree of concentration favors its action. From these data it is obvious that papäin is more useful as a digestive ferment for all the conditions present than is pepsin, although the latter has greater energy in the presence of dilute or strongly acid solutions.

For promoting stomach digestion, in the state of apepsia, papäin may be utilized in place of pepsin. Sittmann finds papain to have remarkable power to dissolve albumin, oz of a grain of this substance bringing about the solution of 150 grains of albumin in the course of two hours. In acute gastritis, he found 8 grains, taken after meals, relieve the pain and in a few days effect a cure. It has proved equally beneficial in gastric ulcer and chronic gastric catarrh by the same authority. The author has found it useful in that troublesome disorder, membranous enteritis. In the treatment of this disease, doses of 10 to 20 grains given after meals, at a time when stomach digestion is ended, are highly effective. For lumbricoid worms it has proved active in securing their expulsion. Cases of taenia have been reported cured, and the author has met with one in which daily exhibitions of papain after meals seemed to be the effective agent in securing its discharge.

In intestinal indigestion due to insufficient production of pancreatic juice and consequent imperfect digestion of fats and formation of peptones, papäin is useful in a high degree. When catarrhal jaundice succeeds to duodenitis, it is one of the best remedies to bring about a return to the normal state. In all cases of intestinal disorder, and when coincident affections of the pancreas occur, papäin should be given in full doses, an hour or two after meals, and with a moderate quantity of sodium bicarbonate to neutralize any acid present.

One of the most important applications of papain is in the treatment of false membrane, chiefly the false membrane of diphtheria. Bouchut was the first to conceive the idea that papäin, having an extraordinary digestive power of albumin and fibrin, must act as a solvent of a croupous exudation, and he found it true on actual trial. Jacobi, of New York, has been one of the most conspicuous advocates of this practice. He reports several cases in which the solvent action of papäin was pronounced. The solution employed by him had the strength of 1 to 8, or 1 part of papayotin to 4 each of water and glycerin, applied freely by a mop or in spray. Probably a much stronger solution would be more effective. Papain has also been used successfully as a vermifuge—against the round worm and taenia. It has been supposed to act as a digestive, attacking the soft albuminous material of which these parasites are composed; but, in the case of the tape worm, certainly the action seems to be stupefying, the worm being expelled in its entirety. Considerable doses must be given night and morning until the expulsion of the worm takes place. The author found this method successful, aided by a brisk cathartic, when the passage of numerous segments indicated an uneasy state of the parasite. The dose ranges from 10 to 30 grains for this purpose. There is reason to believe that much of the papäin of commerce is not genuine, or, if genuine, much diluted. Care should be exercised to procure only genuine material in prescribing.

Authorities referred to:

Bouchut et Wurz. Sur le Ferment. Digestif du Carica Papaya. Annuaire de Thérap. for 1881.

Finkler, Dr. Comparative Experiments between Papoid and Pepsin. Therapeutic Gazette, 1887, p. 518.

Hirsch, Dr. A. Ueber Papain und Seiner Werth als Digestivum. Therapeutische Monatshefte, December, 1894.

Roberts, Dr. William. Lumleian Lectures, April and May, 1880.

Sittmann, Dr. Ueber Papain bei Erkrankungen des Magens. Munch, med. Woch~ enschrift, 1893. Quoted by Hirsch, supra.