Related entry: Garcinia morella
Gamboge is a gum-resin obtained from Garcinia Hanburyi, Hook. f. (N.O. Guttiferae), a tree growing in Siam, Cambodia, and the southern part of Cochin China. It is also official in the U.S.P. In the cortex and bast of the tree are secretory ducts filled with a yellow, milky, gum-resinous juice. This is obtained by making spiral cuts in the bark to a height of about 3 metres above the ground. The gum-resin as it exudes is received in hollow bamboos, and from these it is transferred to smaller bamboos, in which it is allowed to harden. It occurs in solid or hollow rolls, sticks, or cylinders (pipe gamboge), 2.5 to 5 centimetres thick, and 10 to 20 centimetres in length, exhibiting longitudinal striations derived from the inner surface of the bamboo in which the drug has been dried; the fractured surface is smooth, glossy, and of a uniform brownish-orange colour. It has no odour, but an acrid taste. Sometimes a very pure form occurs in tears. Pure gamboge yields about 1 per cent. of ash, the B.P. limit being 3 per cent. Gamboge is sometimes imported in cakes of varying size and appearance, but these are often adulterated with sand, starch, etc., and are not official. Saigon gamboge is frequently imported in oval cakes wrapped in palm leaves. The appearance of the fractured surface, the solubility in ammonia and the amount of ash readily indicate the quality of gamboge. The chief adulterants are starch, inorganic matter and vegetable debris; these are insoluble in alcohol and water (used successively) or in dilute solution of ammonia. Starch may be detected by the iodine test, and inorganic substances, if present, will increase the percentage of ash.
Constituents.—The drug contains about 70 to 80 per cent. of resin, 15 to 25 per cent. of gum and small quantities of vegetable debris. The resin contains α-, β- and γ-garanolic acids, and forms readily soluble compounds with alkalies; the gum is analogous to gum acacia, and contains an oxydase.
Action and Uses.—Gamboge is a powerful hydragogue cathartic, causing in large doses much irritation and griping. It is employed in dropsical conditions, and in cerebral congestion when it is desirable to lower blood-pressure rapidly, but is rarely used alone on account of its drastic action. It is a constituent of Pilula Cambogiae Composita, in which form it is most usually administered. An ammoniated tincture can be prepared with ammoniated alcohol this is miscible with water without precipitation.
Dose.—3 to 12 centigrams (1 to 2 grains).
- Pilula Cambogiae Composita, B.P.—COMPOUND PILL OF GAMBOGE.
- Each 4-grain pill contains about 2/3 grain each of gamboge, Barbados aloes, and compound powder of cinnamon; 1 1/3 grains of hard soap; and a sufficient quantity of syrup of glucose. Dose.—1 to 2 pills.