Preparation: Unguentum Chrysarobini (U. S. P.)—Chrysarobin Ointment
Related entry: Araroba.—Goa Powder - Acidum Chrysophanicum.—Chrysophanic Acid
History.—This body is extracted from Goa powder by means of hot benzene. It is largely used in the preparation of chrysophanic acid, which it contains in greater or less quantities, and as a local remedy for parasitic skin diseases. Its composition is mainly C30H26O7. It was differentiated from chrysophanic acid by Liebermann and Seidler, in 1878. This substance, at one time supposed to be chrysophanic acid, is a neutral principle. As a commercial article, it is more or less impure, and is so recognized by the U. S. P., where its use is directed in the preparation of Unguentum Chrysarobini.
Description and Tests.—Chrysarobin is a permanent, pale-yellow, or orange-yellow, warty, micro-crystalline powder. It is without taste or odor, but is an irritant to the conjunctival and Schneiderian membranes. It is "very slightly soluble in cold water, or alcohol; soluble, without leaving more than a small residue, in 150 parts of boiling alcohol; also soluble in 33 parts of boiling benzol, and in solutions of the alkalies. When heated to 151° C. (303.8° F.), it fuses, forming a dark, opaque mass; and, when ignited, it is partly sublimed, and finally consumed without leaving a residue"—(U. S. P.). It dissolves in sulphuric acid with a yellow color when pure (chrysophanic acid dissolves with red color in this acid). It is somewhat soluble in fusel oil, chloroform, and collodion, but nearly insoluble in ammonia and dilute potassium hydroxide solutions, and yields a brown mass when fused with caustic potash. Chrysophanic acid, on the other hand, dissolves with a red color in dilute solution of the potassium hydroxide; fusion with that agent produces a blue compound. If chrysarobin be dissolved in concentrated solution of caustic potash, a yellow color, accompanied by a marked greenish fluorescence results. In contact with air the solution, by oxidation, turns red and changes to chrysophanic acid. Chrysarobin was named by Attfield, who obtained it by treating Goa powder with boiling benzol. It acquires a deeper tint upon exposure to the atmosphere.
"When boiled with about 2000 parts of water (which produces only partial solution), the light, reddish-brown filtrate does not affect litmus paper, and is not altered by ferric chloride T.S. In concentrated sulphuric acid it is soluble with a deep-red color; on pouring this solution into water, the substance is again deposited unchanged. On adding 0.1 Gm. of chrysarobin to 10 Cc. of potassium or sodium hydrate T.S., in a test-tube, and shaking the latter, the solution, which is at first yellow, or yellowish-red, will gradually acquire a deep-red color"—(U. S. P.).
Action, Medical Uses, and Dosage.—The action of this body in certain skin affections is said to be due to its strong reducing powers, its affinity for oxygen being great. It is losing ground as a remedy on account of the occasional recurrence in a more severe form of the maladies that it appears to cure, and also on account of its irritating and staining qualities. Erythema, with swelling and cuticular desquamation, with reddening of the conjunctiva, are the effects of its application to the face or scalp. Intensely painful inflammation may succeed, lasting several weeks, and associated with it may be recurrent crops of boils. It has recently been lauded as a remedy for hemorrhoids, when combined with belladonna and iodoform in ointment and suppository. Its uses in skin affections are precisely those mentioned under araroba and chrysophanic acid (which see). It should not, as formerly, be prescribed under the name chrysophanic acid. Taken internally chrysarobin provokes purgation which, though at first delayed, continues for several days without marked discomfort. Doses of about 5 grains (children) and 25 grains (adults) are likely to first cause emesis. If used internally the 1 x or 2 x trituration should be preferred. Locally, the best ointment for general use may be prepared by incorporating 10 to 20 grains of chrysarobin with 1 ounce of lanoline or lard.
Related Products.—ANTHRAROBIN. Desoxyalizarin (C14H10O3). Anthroarobin.—A reduction product of commercial alizarin, produced by means of nascent hydrogen. A yellowish or yellowish-white powder, readily dissolving in alcohol, cold alkaline solutions, and glycerin; sparingly dissolved by chloroform, ether, and benzol, and practically insoluble in water and acidulous solutions. With fatty bodies it mixes readily to produce ointments. In alkaline solutions it absorbs oxygen from the air, turning to green and blue in color, alizarin being reproduced. When ignited the residue should not amount to more than 2 per cent. It has been used as a substitute for chrysarobinum and pyrogallol, because it is more easily dissolved than the former, and lacks irritant properties. It is weaker in its action than chrysarobin, though its stain is more pronounced upon the skin and linen.
HYDROXYLAMINE HYDROCHLORIDE (NH2.OH.HCI).—Hydroxylamine exists free, only in solution. The salt used is the hydrochloride, which forms in hygroscopic, colorless crystals, dissolving in 1 part of water, 1 part of glycerin, and in 15 parts of alcohol. Its solutions are acid in reaction. The salt must be kept in well-closed bottles. It is a strong reducing agent. On account of its non-staining qualities, it has been recommended to replace anthrarobin, chrysarobin and pyrogallic acid in the treatment of skin affections, particularly scabies, lupus, herpes tonsurans, chronic psoriasis, parasitic sycosis, etc. A solution (1 to 1000) in glycerin and alcohol (equal parts) is preferred, being applied with a brush to small areas at a time. Stronger solutions do much damage to the skin, and many denounce its use at all, stating it to be inferior to the other applications mentioned and to be liable to serious consequences, both to the skin and to the general system through absorption. Constitutionally it induces a lowered blood pressure and destroys the blood corpuscles, rendering the blood brown in color. It is also destructive to plant life.
King's American Dispensatory, 1898, was written by Harvey Wickes Felter, M.D., and John Uri Lloyd, Phr. M., Ph. D.