Aqua Laurocerasi. Br. Cherry-Laurel Water.
Related entries: Laurocerasi Folia
Eau distillee de Laurier-cerise, Fr. Cod.; Kirschlorbeer-wasser, G; Agua destilada de laurel-cerezo, Sp.
"Cherry-Laurel Leaves, crushed, 800 grammes; Water, 2500 millilitres. Distil one thousand millilitres; shake the product; filter, if necessary; adjust the strength of the finished product either by adding hydrocyanic acid or Distilled Water, so that, when tested as described under 'Acidum Hydrocyanicum Dilutum' it contains 0.1 per cent. by weight of hydrocyanic acid, HCN." Br.
The International Protocol (1906) fixed the strength of Cherry-Laurel Water at 0.1 per cent. of hydrocyanic acid which corresponds with the strength of the Br. Pharm, 1898 and 1914.
It is greatly to be regretted that this uncertain, dangerous, and troublesome preparation should retain a place in European pharmacopoeias, inasmuch as it could easily be replaced by a flavored water containing a definite amount of a soluble cyanide. See S. W. P., 1909, No. 10, 147, and 1909, No. 36, 542.
As the cherry-laurel is little cultivated in the United States, the water is not official; but from several experiments by William Procter there is little or no room to doubt that a preparation identical in its effects might be made from the leaves of our common wild cherry, Prunus serotina. The imported cherry-laurel water, as found in commerce, is generally impaired by age, and not to be relied on.
Cherry-laurel leaves contain 65 per cent. of water, sufficient to provoke the reaction which results in the formation of a volatile oil and hydrocyanic acid. Water is very prone to hasten the conversion of the benzaldehyde, contained in the volatile oil, into benzoic acid by oxidation, and it has been found by C. Umney (P. J., x, 467) and by Moore (Ibid., 604) that the water distilled without previous maceration is somewhat stronger in hydrocyanic acid and decidedly stronger in oil (Umney) than the official product. The strength of cherry-laurel water was formerly very variable, but the present Pharmacopoeias require 0.1 per cent. of hydrocyanic acid. The proportion of hydrocyanic acid in the water diminishes with time. It has been ascertained by Deschamps that if a drop of sulphuric acid be added to a pint of the preparation it will keep unchanged for at least a year. It is best preserved by the entire exclusion of air and light. Lepage found that, preserved in full and perfectly air-tight bottles, both this and bitter almond water remained unchanged at the end of a year; while if freely exposed to the air, they lost all their hydrocyanic acid and essential oil in two or three months. (J. P. C., xvi, 346.) For Deniges's method of assaying the water, see Proc. A. Ph. A., 1894, 556.
Uses.—Cherry-laurel water is employed in, Europe as a sedative narcotic, identical in its properties with a diluted solution of hydrocyanic acid; but it is of uncertain strength, and should not be allowed to supersede the preparation of the acid now in use.
Dose, twenty minims to a fluidrachm (1.3-3.75 mils).