Papain is an amorphous substance, perfectly white, soluble in water, insipid, odorless. An aqueous solution, if shaken violently, foams like a solution of soap. Boiling makes it turbid and when concentrated it has a slightly astringent taste. It is precipitated by hydrochloric, nitric, picric and the metaphosphoric acids. Trommer’s test gives it a beautiful blue violet color which, on boiling, changes to a red violet.
It is an extremely active digestive ferment, comparable with pepsin, but superior to the latter because it does not require an acid medium, as its digestive action takes place even in the presence of an alkaline medium and of antiseptic substances such as boric acid, phenol, etc. It is given in doses of 10–40 centigrams in different vehicles such as water, wine, etc. It should be given after meals carefully and properly diluted, in order that its action may not be exerted upon the gastric mucous membrane itself. Its use is contraindicated in gastric ulcer.
A watery solution prepared by macerating the green fruit has been used effectively to remove blemishes from the face, leaving the skin clean and smooth. The natives use little pieces of the green fruit to remove freckles (which they call pecas). The ripe fruit is edible and its taste quite agreeable; in some of the Malay Islands it is given for dysentery, but it must be remembered that the ripe fruit does not contain papain.
The pure exudate is given to children as an anthelmintic in doses of 2–6 grams with a little molasses, but it is not so harmless that it may be used with impunity in this form, Moncorvo and others having reported cases of peritonitis with symptoms suggestive of cholera following its use. It is drastic and digestive in addition to its anthelmintic action, but according to Rabuteau, boiling destroys the first property without affecting the others. Dr. Lemarchand of the island of Mauritius gives the following anthelmintic prescription:
| Juice of papaya and molasses | āā 1 tablespoon. |
Add gradually while shaking the mixture.
| Boiling water | 4 tablespoons. |
Cool and administer in one dose followed immediately by 30 grams of castor oil. For a child, one-half dose.
This treatment frequently causes colic, for the relief of which the author advises an injection of sweetened water. Sir O’Shaughnessy’s prescription is preferable:
| 20–60 drops of the exudate in a little sweetened water. |