Oleum Eucalypti. U. S., Br. Oil of Eucalyptus.

Ol. Eucalypt. [Eucalyptus Oil]

Related entry: Eucalyptus

"A volatile oil distilled from the fresh leaves of Eucalyptus Globulus Labillardiere (Fam. Myrtaceae) or from some other species oi Eucalyptus, and yielding not less than 70 per cent., by volume, of eucalyptol (cineol) [C10H180 = 154.14]. Preserve it in well-stoppered, amber-colored bottles, in a cool place, protected from light." U. S. "Oil of Eucalyptus is the oil distilled from the fresh leaves of Eucalyptus Globulus, Labill., Eucalyptus dumosa, A. Cunn., and other species of Eucalyptus, and rectified." Br.

Oil of Eucalyptus Globulus; Huile volatile (Essence) de Eucalyptus, Fr. Cod.; Eucalyptusöl, G.; Esencia de eucalipto, Sp.

Various species of the genus Eucalyptus, grown in Australia and Algeria, yield volatile oils in sufficient quantity to be commercial products. Probably the most important of these plants is E. Globulus, on account of its high cineol (eucalyptol) content. Large quantities of oil are also distilled from other species, viz., E. odorata, E. oleosa, E. cuenfolia (?) and E. dumosa.

Oil of eucalyptus is officially described as "a colorless or pale yellow liquid, having a characteristic, aromatic, somewhat camphoraceous odor, and a pungent, spicy, and cooling taste. It is soluble in 4 volumes of 70 per cent. alcohol. Specific gravity: 0.905 to 0.925 at 25° C. (77° F.). Mix 2 mils of the Oil with 4 mils of glacial acetic acid and gradually add 3 mils of a saturated solution of sodium nitrite. When gently stirred, the mixture does not form crystals of phellandrene nitrite (other eucalyptus oils containing large amounts of phellandrene)." U. S.

"Colorless or pale yellow. Aromatic, camphoraceous odor; taste pungent, leaving a sensation of cold. Specific gravity 0.910 to 0.930; optical rotation -10" to +10°. Soluble in 5 parts of alcohol (70 per cent.). Contains not less than 55 per cent. by volume of cineol as determined by the process described under 'Oleum Cajuputi' When 1 millilitre is mixed with 2 millilitres of glacial acetic acid and 5 millilitres of petroleum spirit, 2 millilitres of a saturated aqueous solution of sodium nitrite being added, and the mixture gently shaken, no crystalline precipitate forms in the upper layer (absence of oils containing much phellandrene)." Br.

The valuation of eucalyptus oil being based upon its cineol (eucalyptol) content the commercial oils from other species of eucalyptus are regarded with much less favor for medicinal purposes, because of their variable quality in this respect, and the fact that the other oils contain such constituents as phellandrene, cymene, citronellal, citral and other less known constituents. Cineol being optically inactive and high in its specific gravity communicates specific properties to such oils as contain it in large amounts by which their approximate value or their genuineness may be determined irrespective of the assay for cineol, which, of course, must be the ultimate deciding factor. There is much variation in the physical constants found in the literature of the eucalyptus oils as determined by different observers, and much work yet remains to be done upon the subject.

Eudesmol, C10H16O (possibly a ketone), is the name given to a crystalline camphor obtained from the oil from E. piperita; H. G. Smith and R. T. Baker isolated this product, and later H. G. Smith read a paper upon it before the Royal Society of New South Wales. It proved to be isomeric with camphor, but chemically it is shown to have its oxygen atom combined in a different way.

Uses.—In the belief that the medicinal properties of oil of eucalyptus depend upon cineol, the Pharmacopoeia rejects those oils which contain chiefly phellandrene, but as a matter of fact, we have no definite knowledge concerning the physiological action of phellandrene. Whether or not the medicinal virtues of the official oil are due entirely to its cineol is uncertain, but many prefer to use the pure eucalyptol to the oil itself.

Oil of eucalyptus is an active germicide, although surpassed in power by many of the other volatile oils. Cineol is probably a less efficient antibacterial agent than oil of eucalyptus. When taken in overdose it causes rapidity of the pulse with general excitement and restlessness, nausea, vomiting, frequently dilatation of the pupils, and symptoms of collapse. In the lower animals it reduces the arterial pressure and the bodily temperature, causes muscular weakness, irregular respiration and death from respiratory failure. It is absorbed from the intestinal tract, eliminated partially through the breath to which it imparts its odor, and also, as an oxidation product, through the urine to which it gives an odor resembling that of violets.

The oil of eucalyptus is used locally as an antiseptic, especially in the treatment of infections of the upper respiratory tract and in certain forms of skin disease. Internally it is used as a stimulating expectorant in chronic bronchitis and tuberculosis. In these conditions it is also frequently given by inhalation; a few drops of the oil may be added to boiling water and the mixed vapors and steam inhaled. It has been specially praised in asthma, given internally or preferably by inhalation by means of cigarettes, which may be made by rolling up the dried leaves, or the vapor from boiling water containing the oil may be inhaled. It is also used as a remedy against the hookworm, but is probably of inferior value. It possesses also some antiperiodic power and may be used in malarial fever when for any reason quinine or methylthionine are not available.

Dose, three to ten minims (0.2-0.6 mil), best administered in emulsion.

Off. Prep.—Unguentum Eucalypti, Br.

The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.