Catechu, B.P. Catechu.

Related entry: Acacia catechu

Synonym.—Catechu Pallidum.

Catechu, Gambier, or Terra Japonica (Gambir, U.S.P.), is an extract prepared from the leaves and young shoots of Uncaria Gambier, Roxb. (N.O. Rubiaceae), a climbing shrub indigenous to the Malay Archipelago, and cultivated in many of the surrounding islands. The leaves and twigs are boiled with water, the resulting decoction evaporated to a syrupy consistence in copper pans and cooled, crystallisation being induced by agitation. The mass is then drained and cut into small cubes, less frequently into strips or buttons, and dried. Much is imported in large blocks, but these are not official. The cubes measure about 25 millimetres each way, are very light, fairly regular in shape, dark red-brown externally, pale cinnamon-brown internally, porous, and friable. They have no odour, the taste is at first bitter and astringent, then sweetish. Catechu should not leave more than 5 per cent. of ash on incineration, and not more than 30 per cent. of the drug should be insoluble in boiling alcohol; usually the proportion insoluble in alcohol is considerably less. If 3 grammes of catechu be mixed with 25 mils of normal solution of potassium hydroxide, and shaken a few times in a separator with 50 mils of petroleum spirit, the separated spirit should exhibit a marked green fluorescence (distinction from black catechu). Catechu is liable to be adulterated with starch, with inorganic matter, and possibly with other extracts. Starch is best detected by exhausting the drug with cold water and examining the residue microscopically. Inorganic matter is detected by increase in the percentage of ash.

Constituents.—Catechu consists chiefly of catechin (7 to 33 per cent.), and catechu-tannic acid (22 to 50 per cent.). In addition to these, quercetin, wax, oil, catechu red, and a fluorescent body, named gambier-fluorescein, occur in small quantities; the drug also contains moisture (about 10 per cent.), vegetable debris, and mineral matter (about 3 to 4 per cent.). Catechin, which is not identical with the acacatechin of cutch, occurs in white, silky needles with the formula C₁₅H14O6,4H₂O (melting at 175° to 177°), or anhydrous, C₁₅H14O₆ (melting at 235° to 237°). It is sparingly soluble in cold water (1 in 1100 to 1200), but freely in boiling water and alcohol, and produces with ferric salts a deep green colour. Catechu-tannic acid is a reddish amorphous astringent substance, which precipitates gelatin, and is coloured dirty green by ferric salts. On boiling the aqueous solution with or without a mineral acid, it is converted into a reddish-brown amorphous substance.

Action and Uses.—Catechu is a powerful astringent. It is used internally, in association with other astringents as Pulvis Catechu Compositus, and as Tinctura Catechu in diarrhoea and haemorrhage from the alimentary canal. The compound powder may be administered in cachets, in capsules prepared to dissolve only in the bowel, or in a mixture with sedatives; the tincture is generally used in conjunction with aromatic confection or compound chalk mixture, opium, ginger, or coto. Tincture or infusion of catechu is occasionally an ingredient of astringent injections (1 in 50), with zinc or alum salts, for gonorrhoea and gleet. Catechu lozenges are prepared for their astringent action in the mouth and throat: gargles may contain the tincture (1 in 25). Preparations of catechu are incompatible with gelatin, iron salts, and alkalies.

Dose.—3 to 10 decigrams (5 to 15 grains).

PREPARATIONS.

Mistura Haematoxyli cum Catechu, B.P.C. Logwood Mixture with Catechu. - Mistura Cretae Composita, B.P.C. Compound Chalk Mixture.

Infusum Catechu, B.P., 1885.—INFUSION OF CATECHU.

Catechu, in coarse powder, 5.3; cinnamon bark, bruised, 1; distilled water, boiling, 149. Infuse the drugs in the water for thirty minutes, in a covered vessel, and strain. Used as a vehicle for astringent diarrhoea mixtures. Dose.—15 to 30 mils (½ to 1 fluid ounce).

Mistura Catechu et Cretae, B.P.C.—CATECHU AND CHALK MIXTURE.

Each fluid ounce contains 20 minims of tincture of catechu, with chalk mixture. Dose.—15 to 30 mils (½ to 1 fluid ounce).

Pulvis Catechu Compositus, B.P.—COMPOUND POWDER OF CATECHU.

Catechu, 40; kino, 20; krameria root, 20; cinnamon bark, 10; nutmeg, 10; all in powder. Mix intimately. Employed in diarrhoea, given in powders, cachets, or capsules. Dose.—½ to 2 ½ grammes (10 to 40 grains).

Tinctura Catechu, B.P.—TINCTURE OF CATECHU.

Catechu, in coarse powder, 20; cinnamon bark, bruised, 5; alcohol (60 per cent.), 100. Prepared by maceration. Used as an astringent in diarrhoea. Dose.—2 to 4 mils (½ to 1 fluid drachm).

Tinctura Gambir Composita, U.S.P.—COMPOUND TINCTURE OF GAMBIR.

Gambir, in No. 50 powder, 5; Saigon cinnamon, in No. 50 powder, 2.5; alcohol (49 per cent.), sufficient to produce 100. Average dose.—4 mils (1 fluid drachm).

Trochisci Catechu Compressi, B.P.C.—COMPRESSED CATECHU LOZENGES.

Each lozenge contains catechu, 1 grain, with gum acacia and refined sugar. Used in inflamed and ulcerated throats.

Trochisci Gambir, U.S.P.—TROCHES OF GAMBIR.

Gambir, 6 grammes; sugar, 65 grammes; tragacanth, 2 grammes; orange-flower water (undiluted), a sufficient quantity. To make 100 lozenges.

Trochiscus Catechu, B.P.—CATECHU LOZENGE.

Each lozenge contains catechu, 1 grain; with simple basis. Useful as a local astringent for the throat.

The British Pharmaceutical Codex, 1911, was published by direction of the Council of the Pharmaceutical Society of Great Britain.