Araroba, B.P. Araroba.
Synonyms.—Crude Chrysarobin; Goa Powder.
Araroba is a substance found in the trunk of Andira Araroba, Aguiar (N.O. Leguminosae), a large tree growing in the damp forests of Bahia (Brazil). It is scraped out of the cavities together with woody debris, and is exported in a crude and moist condition as an umber-brown powder, containing numerous fragments of wood. It is roughly freed from the moisture and much of the woody debris by drying and sifting, and may be further purified by exhausting with hot chloroform or benzene, evaporating the solution to dryness, and powdering the residue. It is stated, however, that by this method an active constituent insoluble in chloroform and benzene is left in the drug. Another method of purification is to boil the crude drug with solution of caustic potash, filter, and reprecipitate by acidifying the dark coloured solution with hydrochloric acid. The drug occurs as a brownish-yellow to dark brown powder, which should yield not less than 50 per cent. to hot chloroform, while as much as 75 per cent. is sometimes obtained.
Constituents.—Purified araroba consists largely of chrysarobin, but also contains dichrysarobin, the methyl ether of dichrysarobin, and a fourth substance which awaits further investigation; all of these are soluble in chloroform. Crude araroba contains in addition to these substances from 15 to 30 per cent. of moisture and varying quantities of woody debris.
Action and Uses.—Araroba resembles chrysarobin in its properties; in India, crude araroba is preferred to chrysarobin. For its action in psoriasis see under Chrysarobinum. In tropical countries it is applied mixed with lime juice or with vinegar. Araroba is used officially as the source of chrysarobin, but it has been asserted to be more efficacious than the latter, owing to the presence of an unknown active substance, which is not extracted by chloroform.
- Unguentum Ararobae, B.P.C.—ARAROBA OINTMENT.
- Araroba, 1; glacial acetic acid, 1; lard, 14. Used as a stimulant and parasiticide in psoriasis, acne rosacea, and ringworm. It may be diluted with an equal quantity of lard when used for tender skins.
Chrysarobin, as generally found in pharmacy, is a mixture of substances obtained from araroba by extracting with hot chloroform, evaporating to dryness, and powdering. The synonym chrysophanic acid, a name by which it is very generally known, is a misnomer, since the substance consists of chrysarobin (C30H26O7), (Chrysarobinum, U.S.P.), dichrysarobin, and dichrysarobin methyl-ether. Chrysarobin occurs as a yellow micro-crystalline, odourless, tasteless powder, which has an irritating effect on the mucous membranes and especially the conjunctiva. On heating it melts, giving off yellow vapours, and on complete ignition leaves not more than 1 per cent. of ash.
Slightly soluble in water and in ether; entirely soluble in hot chloroform and fats, and almost entirely in hot alcohol; partially soluble in petroleum spirit, and in solutions of alkalies with brown colouration.
Action and Uses.—Chrysarobin has been given internally in psoriasis and chronic skin diseases, but is rarely so employed, since it readily causes gastroenteritis. A small quantity is absorbed and colours the urine yellow, which changes to red on the addition of an alkali. It is best administered in a pill made with glycerin of tragacanth. Externally Pigmentum Chrysarobini and Unguentum Chrysarobini are commonly used in psoriasis, alopecia, ringworm of the scalp, and other parasitic affections of the skin. The former is a cleanly application by which the drug is brought into close contact with the skin over a long period. The ointment, which should not be applied over a large surface, is often required to be diluted. It stains the skin and linen; such stains may be removed by a solution of chlorinated lime. Plasters are prepared of various strengths. Oxidised chrysarobin was formerly recommended by Unna for use in ointments as a substitute for chrysarobin; it is darker in colour and is much less irritating. Recent researches seem to show that the action of chrysarobin is dependent upon an oxidising process taking place upon the skin in which the oleic acid secreted by the sweat and sebum glands is concerned. Ointment of lead oleate is suggested as the best basis. Derivatives of chrysarobin similarly used are anthrarobin, a reduction product of alizarin, chrysarobin triacetate (Eurobin), and chrysarobin tetra-acetate (Lenirobin).
Dose.—1/2 to 6 centigrams (1/10 to 1 grain).
- Pigmentum Chrysarobini, B.P.C.—CHRYSAROBIN PAINT. 1 in 10.
- Applied to the skin with a stiff brush in chronic psoriasis. It has the advantage over chrysarobin ointments of not staining the linen.
- Unguentum Chrysarobini, B.P.—CHRYSAROBIN OINTMENT.
- Chrysarobin, 4; benzoated lard, 96. Mix the chrysarobin gradually with the previously melted lard, heat gently until it is dissolved, and stir till cold. The chrysarobin is not usually entirely soluble, and the insoluble portion should be strained out. Chrysarobin ointment is applied to the patches in chronic psoriasis. Diluted with 2 to 4 parts of benzoated lard it is used in chronic eczema, acne, and other skin affections. Chrysarobin ointment stains the hair, skin, and linen. It should not be applied over large surfaces.
- Unguentum Chrysarobini, U.S.P.—CHRYSAROBIN OINTMENT.
- Chrysarobin, 6; benzoinated lard, 94.
- Unguentum Chrysarobini Compositum, B.P.C.—COMPOUND CHRYSAROBIN OINTMENT.
- Chrysarobin, 5; ammonium ichthosulphonate, 5; salicylic acid, 2; soft paraffin, yellow, 88.
The British Pharmaceutical Codex, 1911, was published by direction of the Council of the Pharmaceutical Society of Great Britain.