Oil of juniper is obtained by distillation from the full-grown, unripe, green fruit or "berries" of Juniperus communis, Linn. (N.O. Coniferae), a tree which is indigenous to Great Britain, and distributed widely over Europe. It is also official in the U.S.P. The oil distilled in England consists of the entire distillate from the. fruit, but there is reason to believe that foreign distilled oil consists of the lighter portions only. The oil occurs as a colourless or pale greenish-yellow, limpid liquid, possessing a peculiar terebinthinate odour when fresh, and a balsamic, burning, somewhat bitter taste. Old oil is somewhat viscid, has an acid reaction, and a more or, less rancid odour. Specific gravity, 0.862 to 0.890 (0.860 to 0.885 at 25°, these figures being raised by exposure owing to gradual resinification. Rotation, rarely exceeding -12°, is almost invariably laevorotatory, and usually about -4° to -6°. The optical rotation of oil distilled from the leaves and branches of Juniperus communis is about +8.5°, but in other respects the oil closely resembles that obtained from the fruit. Alcohol as an adulterant lowers the specific gravity, and may be detected by collecting the first few drops on distillation, and applying the iodoform test. Other possible adulterants of the oil are oil of turpentine, juniper wood oil, and oil of turpentine distilled with juniper berries. Commercial oil of juniper is obtained chiefly from the ripe fruit, and is stated to be in all essential qualities superior to the oil from the unripe green berries.
Soluble with slight turbidity in alcohol (1 in 20), also in 95 per cent. alcohol (1 in 4), and miscible with an equal volume of absolute alcohol, but becoming opalescent if more be added. The solubility decreases with age. Soluble in all proportions of chloroform, carbon bisulphide, benzene, or amyl alcohol.
Constituents.—The chief constituents of the oil are the terpene pinene, C10H16, and the sesquiterpene cadinene, C15H24; juniper camphor, a crystalline body, probably belonging to the series of terpene alcohols; and an ester, boiling about 180°. The peculiar odour of the oil is not due to esters, since the oil retains its characteristic odour after saponification. The relative proportions of pinene and cadinene may be ascertained by fractionation. Pinene boils at 156°, cadinene at 274°. From 25 to 35 per cent. of pinene is obtained between 155° and 160°, and 10 to 20 per cent. of cadinene between 270° and 280°.
Action and Uses.—Oil of juniper has properties resembling those of oil of turpentine. It is employed chiefly as a stimulating diuretic in cardiac and hepatic dropsy, but it should not be given when there is disease of the kidneys. Its irritant properties during excretion cause reflex contractions of the uterus, and the drug has some reputation as an emmenagogue. It is administered on sugar, or as Spiritus Juniperi.
Dose.—1/2 to 2 decimils (0.05 to 0.2 milliliters) (1. to 3 minims).
- Spiritus Juniperi, B.P.—SPIRIT OF JUNIPER.
- Oil of juniper, 5; alcohol, sufficient to produce 100. Dissolve the oil of juniper in the alcohol, and filter, if necessary, through powdered talc. Spirit of juniper is used as an antispasmodic in flatulence and colic, and as a diuretic; it gives the urine an odour of violets. Dose.—1 1/2 to 4 mils (20 to 60 minims).
- Spiritus Juniperi, U.S.P.—Similar to B.P., but made with alcohol (95 percent.).
- Spiritus Juniperi Compositus, U.S.P.—COMPOUND SPIRIT OF JUNIPER.
- Oil of juniper, 0.40; oil of caraway, 0.05; oil of fennel, 0.05; alcohol (95 per cent.), 70; distilled water, to 100. Dose.—4 to 12 mils (1 to 3 fluid drachms).
The British Pharmaceutical Codex, 1911, was published by direction of the Council of the Pharmaceutical Society of Great Britain.