CHRYSAROBIN. — This drug, also known as "Goa powder," "Araroba powder," "Po de Bahia," and also (im properly) as "chrysophanic acid," is the metamorphosed heart-wood of the An diva araroba: a leguminous tree indig enous to Brazil. It is a brownish-yellow crystalline powder, permanent in the air, tasteless, odorless, almost insoluble. in water, slightly so in alcohol, completely in ether, containing a variable amount 70 to SO per cent.—of chrysophan, which latter, by oxidation, is readily transformed into chrysophanic acid.
Chrysophanic acid is a neutral sub stance, identical with rhein, the active principle of rhubarb. It is commonly found as a granular, orange-yellow powder, but sometimes takes the form of bright, shining-yellow needles: a transformation that is effected by subli mation. It is odorless, acrid, soluble in alkaline waters, oils and fats, form, petroleum spirit, and glycerin; but is insoluble in water, alcohol, and ether.
Preparations and Doses.—Chrysaro bin, 1/5 to 5 grains.
Chrysophanic acid, 1/8 to 1/., grain; as an emetic and purge, S to 20 grains.
Chrysarobin ointment (acid. chry sophanic., 1; benzoated lard, 24).
Compound chrysarobin o in tm ent (chrysarobin, 5; salicylic acid, 2; ich thyol, 5; vaselin, SS).
Chrysarobin pigment (acid. chryso phanic., 1; solution of gutta-percha, 9).
Araroba ointment (chrysarobin, 6; glacial acetic acid, 1; lard, 14).
Bismuth chrysophanate, external use as an antiseptic only.
Zinc chrysophanate, an antiseptic dusting-powder.
Physiological Action.—In general the action of chrysarobin and chrysophanic acid, when given internally, is not un derstood, but Brunton and Delepine be lieve the latter to be an hepatic stimu lant, and that it, at the same time, pro duces a marked increase in the glycogen of the liver. It may- be added, however,
that chrysarobin is an active irritant poison, and even in minute doses induces gastro-intestinal disturbances, such as vomiting and purg,ing. There is noth ing to the credit of either drup- that should lead to its use as an internal remedy.
Externally, chrysarobin is an irritant to the skin, stainim; it yellow; and, ap plied in excess, produces irritation and inflammation, accompanied by swelling, itching, pain, heat, and sometimes a papular eruption; and the action is not always limited to the part to which it is applied, but extends to the healthy skin in the vicinity.
Chrysophanic acid does not cause dis coloration, but it is much less active than chrysarobin, and does not, in any sense, represent the true principles of the latter.
Therapeutics. — SKIN DISEASES.— There is no doubt that chrysarobin is a remedy of value in parasitic skin dis eases, and especially in psoriasis, but chrysophanic acid is far from upholding the repute of its derivative.
Chrysophanic acid does not stain like chrysarobin, and is scarcely at all irri tating; but comparative experiments made with the two substances in the treatment of psoriasis lead to the con clusion that the former is not an effi cient substitute for the latter in the treatment of this disease. Walter C.. Smith (Brit. Jour. Derm., July, '96).
Though at various times recommended in the management of acne and eczemas, chrysarobin is seldom of value.