Oleum Gaultheriae, I.C.A. Oil of Gaultheria.
Related entries: Methyl salicylate - Birch Tar Oil - Oil of Betula
Synonym.—Oil of Wintergreen.
Oil of gaultheria is obtained by distillation from the leaves of Gaultheria procumbens, Linn. (N.O. Ericaceae). It is also official in the U.S.P. It occurs as a colourless or yellowish liquid, having a characteristic and strongly aromatic odour, which is slightly different from that of the nearly identical oil obtained from Betula lenta, Linn., and a sweetish, aromatic taste. It should yield a perfectly clear solution with 6 parts of 70 per cent. alcohol at 20°. Specific gravity, 1.180 to 1.187 (1.172 to 1.180 at 25°); boiling-point, 218° to 221°. It rotates the plane of polarised light slightly to the left, viz., -0° 25' to -1° (oil of betula is optically inactive). Admixture with the otherwise almost identical betula oil, or with artificial methyl salicylate, can therefore be detected by depression of the rotatory power below -0° 25', and by the odour.
Readily soluble in alcohol, ether, chloroform, or glacial acetic acid.
Constituents.—The oil consists almost entirely of methyl salicylate, with about 1 per cent. of other bodies, including an alcohol or ketone, and an ester, to the presence of which is due the very characteristic odour by which oil of gaultheria is distinguished from artificial methyl salicylate.
Action and Uses.—Oil of gaultheria has the properties of the salicylates. It is administered in acute rheumatism, usually in capsules on account of its pungent taste. Applied to the skin, it is readily absorbed; it may, however, give rise to an eruption, and pure methyl salicylate is therefore preferred for external application. It is an invaluable application for all chronic rheumatic affections, chronic joint troubles, muscle affections and lumbago (see Methylis Salicylas). Oil of gaultheria is much used to flavour tooth powders, pastes, and liquid dentifrices, often with menthol and oil of eucalyptus.
Dose.—3 to 9 decimils (0.3 to 0.9 milliliters) (5 to 15 minims).
PREPARATION.
- Spiritus Gaultheriae, B.P.C. and U.S.P.—SPIRIT OF GAULTHERIA. Syn.—Essence of Wintergreen. 1 in 20.
- Used principally as a flavouring agent. Dose.—1 to 3 mils (15 to 45 minims).
