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.
Papaya. Several proprietary digestants, among which are "Papain," "Papoid," "Caroid," and "Papaotin," are prepared from the fruit of the carica papaya, which contains ferments and nitrogeneous principles rather remarkable in plant life. These proprietaries are of considerable value, but they do not digest everything, as is claimed by some enthusiasts, and they are very feebly active in an acid medium. In a weak, alkaline solution they are powerfully digestant, taking the place of pancreatin more than that of pepsin, but these agents are not without utility in gastric digestion, and, in their several combinations, are of frequent value in dyspepsia. Unfortunately, the high price has induced some so-called pharmaceutic houses to market tablets only pretending to contain this agent. It is best to buy direct from the makers of these articles under their trade names as herein given.
In my own experience, they possess a peculiar value in dissolving and digesting mucus that I take advantage of in cases of gastric ulcer, gastric catarrh, intestinal troubles with an excess of mucus, and where intestinal parasites lodge in mucous secretions. These agents clear away the mucus and permit the local action upon mucous membranes or the absorption of remedies administered. Dose, 2 to 5 gr. with sodium bicarbonate. A 5% solution in equal parts of glycerine and water dissolves false membrane in diphtheria and croup.