Synonym.—American Pennyroyal Oil.
Oil of hedeoma is obtained by distillation from the herb Hedeoma pulegioides, Pers. (N.O. Labiatae), indigenous to North America. It is official in the U.S.P. It occurs as a pale yellow, limpid liquid, having a characteristic sweetish, mint-like odour, and an aromatic taste. Specific gravity, 0.925 to 0.940 (0.920 to 0.935 at 25°). Optical rotation, +18° to +22°. Adulteration with petroleum, oil of turpentine, and other essential oils can be detected by the solubility in alcohol.
Soluble in 70 per cent. alcohol (1 in 2).
Constituents.—The chief constituent of the oil is pulegone, C10H16O, a liquid ketone identical with that from the oil of Mentha Pulegium, boiling at 221°, and having a specific gravity of 0.936. It also contains two ketones, C10H18O, one boiling at 168° to 171°, the other at 206° to 209°, the latter possibly identical with menthone. Formic, acetic, and isoheptoic acids are also found in the oil. Oil of hedeoma is so similar to the oil obtained from Mentha Pulegium, Linn., that it is frequently substituted for it.
Action and Uses.—Oil of hedeoma has properties resembling those of Oleum Pulegii. It is administered on sugar, or in hot water, as an emmenagogue.
Dose.—1/4 to 2 decimils (0.025 to 0.2 milliliters) (1 to 3 minims).