269. Guaiacum.—Guaiac. Gum Guaiac.
The resin from the wood of Gua'iacum. officina'le Linné and of G. sanctum.
SOURCE.—Obtained from natural exudation or from incisions into the trunk, occasionally by boring longitudinally through a billet, placing one end in the fire, and catching the melted resin as it exudes from the hole in the other end; more commonly, however, by extracting the chips or raspings with a boiling solution of common salt.
DESCRIPTION OF DRUG.—Greenish-brown, irregular masses, containing fragments of wood and bark; brittle, breaking with a glossy fracture; in thin pieces, transparent. The powder is gray when fresh, but becomes green on exposure, and blue when in contact with oxidizing agents. Odor slight, balsamic, when heated resembling benzoin; taste slightly irritating.
CONSTITUENTS.—Guaiacic acid, β-resin (11.75 per cent.), and guaiac yellow, C20H20O7, soluble in milk of lime; guaiaretic acid, C20H24O4, 11.15 per cent.; guaiaconic acid, 50 per cent., and gum and ash in small quantity. Guaiacene, guaiacol, cresol, and pyroguaiacin are obtained by dry distillation. The coloring matter crystallizes in pale yellow or quadratic octahedra having a bitter taste. Ash, not exceeding 4 per cent.
The so-called "guaiacum oil" is obtained by boiling guaiacum resin with solution of sodium carbonate, allowing to cool, filtering, saturating the filtrate with carbon dioxide, again filtering, extracting the oil with ether, and allowing the solvent to evaporate. The product is soluble in water, alcohol, and ether. From the alkaline liquid acids precipitate the yellow coloring matter ("guaiacum yellow"), which imparts a blue color to strong sulphuric acid.
The blue color which guaiacum resin produces with certain oxidizing agents is due to an oxidation product of guaiaconic acid.
ACTION AND USES.—Stimulant, diaphoretic, and alterative; also a mild purgative. Dose: 5 to 30 gr. (0.3 to 2 Gm.).
- Tinctura Guaiaci (20 per cent.), Dose: 30 to 60 minims (2 to 4 mils).
- Tinctura Guaiaci Ammoniata (20 per cent), 30 to 60 minims (2 to 4 mils).