Catechu Nigrum. Black Catechu. Acacia Catechu. Br.

Origin and Properties. Catechu is an extract prepared from the inner wood of Acacia Catechu, a small tree growing in Hindostan, Pegu, and other parts of India. It is in masses or fragments of diversified shape and size, usually rusty-coloured externally, reddish-brown Internally, with a fracture generally smooth and somewhat shining but sometimes rough, inodorous, and of a bitterish very astringent taste, with a sweetish after-taste. It yields its virtues to water and alcohol.

Active Principle. This is tannic acid, of the variety which yields with the salts of sesquioxide of iron a greenish-black or olive-black precipitate, and may be called catechu-tannic acid. Another constituent, to which it probably owes its sweetness, is catechuic acid, which, however, is not known to possess any medical virtues.

Its chemical relations are the same as those of kino.

Effects on the System

So far as the effects of catechu upon the system can be traced, they are almost precisely those of the medicine last described.

Therapeutic Application

Its therapeutic uses are almost the same as those of kino, and need not, therefore, be repeated here. It is, however, I believe, less used internally in this country, probably because less elegant in appearance, and usually less pure. Some writers speak of it as specially advantageous in checking excessive expectoration; but I cannot think that it has much power of this kind. As a topical application, in the form of infusion, it has the advantage over kino of staining less. From its greater hardness, it is better adapted to the treatment of chronic angina, with relaxation or elongation of the uvula, in which it sometimes proves very useful by being held in the mouth between the cheek and teeth, and allowed slowly to dissolve. Its solution in the saliva is thus brought constantly, as it is swallowed, into contact with the diseased parts, and keeps up a steady astringent action upon them. In the same way it is said to be used by professional singers and speakers, to relieve the hoarseness consequent on an excessive use of the voice. In the form of powder, it is also occasionally useful in spongy gums, to which it may be applied by means of a camel's-hair pencil. The tincture is preferable to that of kino, in consequence of being less liable to change by keeping.

The dose of the powder is from ten to thirty grains, that of the officinal Tincture (Tinctura Catechu, U. S.), from thirty minims to three flui-drachms. An infusion (Infusum Catechu Compositum) is directed both by the U. S. and British Pharmacopoeias, made, according to the former, with half an ounce of catechu and a drachm of cinnamon to a pint of boiling water. The dose is one or two fluidounces three or four times daily. The modes of administration, not specially noticed, are precisely the same as those already sufficiently described under kino.

Gambir. Catechu Pallidum. Pale Catechu. Uncaria Gambir (Nauclea Gambir). Br.

This is probably the old terra Japonica. It is usually ranked with the varieties of catechu, which it closely resembles in virtues; but it has a wholly different origin, being an extract from the leaves and young shoots of Nauclea Gambir (Uncaria Gambir, De Candolle), which is a native of Eastern India. It is in the form of cubes, of about an inch in size, light and porous, of a yellowish or reddish-brown colour, lighter within, an earthy fracture, and a strongly astringent, bitter, and sweetish taste. It is closely analogous in composition to catechu, and may bo used for the same purposes, and in the same dose.