Related entries: Tinctures of fresh herbs - Alcohol.—Alcohol - Extracta et Extracta Fluida.—Extracts and Fluid Extracts.
Other tomes: King's (percolating) - USDisp - AJP1881 - AJP1883 (percolator) - AJP1883 (filtering) - AJP1883 (more tinc)
History.—Tinctures are obtained by subjecting certain medicinal substances to the action of alcohol, ether, etc., for the purpose of extracting their active principles. Some are prepared by simple maceration, or by percolation, at ordinary temperature, while others require certain degrees of temperature. When alcohol, or diluted alcohol, is employed as a solvent, the preparation is termed simply a Tincture; though sometimes a small portion of acid or alkali is added to facilitate its solvent action. Occasionally, spirit of ammonia or ether are employed as the solvents, furnishing Ammoniated tinctures and Ethereal tinctures. Tinctures are also prepared by means of gin, brandy, wine, etc., as the solvent. The former are termed Spirituous tinctures, and those with wine, Vinous tinctures, or Medicated wines. When the substance to be dissolved is insoluble in water, rectified spirit (alcohol of specific gravity 0.820) is preferred as the menstruum; when it is soluble in both alcohol and water, diluted or proof-spirit is preferred. The former is applicable to resins, volatile oils, oleoresins, camphor, etc., in which the addition of water would diminish or entirely prevent the solvent power of the alcohol. The latter is proper where the drugs contain gum-resins, tannates, extractive, saline matters, etc. A Simple tincture contains the active principles of a single substance; a Compound tincture contains the active principles of several articles. The term Saturated tincture is a misnomer, the supposition once being that the resultant products were saturated with the active constituents of the drugs. Essential or Concentrated tinctures are terms once given to Alcoholic fluid extracts. The term Hydro-alcoholic tincture is applied to those prepared with dilute, or even weaker, alcohol. Alcoolatures, or Preserved juices, are mixtures of expressed plant juices with alcohol. Succi of the British Pharmacopoeia, are prepared with 3 parts, by measure, of the juice of the plant to 1 of spirit. The action of light, as well as of air, sometimes has a deleterious influence upon tinctures. In order to preserve them from evaporation, and thereby maintaining a uniform degree of strength, and also from decomposition or deterioration, all tinctures should be kept in bottles well closed with accurately-fitting stoppers, and in a cool place not exposed to sunlight.
Preparation.—I. BY MACERATION. The article or articles should be reduced to a powder of a proper degree of fineness, or, where this can not be done, should be sliced or bruised, and then be placed in alcohol or diluted alcohol, as may be required, and allowed to macerate, in a close glass bottle, usually for 14 days, with occasional agitation, after which they are expressed, if necessary, and the tincture filtered through paper. Tinctures of drugs rich in oleoresins, the majority of gum-resins, resins, and balsams, are best prepared by this method.
II. BY PERCOLATION.—The article or articles should be reduced to a powder of a proper degree of fineness, or, where this can not be done, should be sliced, bruised, or rasped, etc. They are then to be first covered with the menstruum with which the tincture is to be made, and allowed to stand until they are moistened throughout, which step generally requires from 24 to 36 hours. The whole is then transferred to a percolator, and the menstruum gradually poured on, and allowed to percolate or filter until the requisite amount has passed (see section on Percolation, under Fluid Extracts). The preparation of tinctures by percolation is, with a few exceptions, the method now generally pursued by all pharmacists of this country. The National Formulary gives the following directions for preparing unofficial tinctures:
TINCTURAE (N. F.), Tinctures.—GENERAL PROCESS. "All tinctures, for which no working formula is provided by the United States Pharmacopoeia, the National Formulary, or some other work of authority, and the strength of which is not otherwise specified by the prescriber, should be prepared in the following proportions: The drug, properly comminuted, one hundred and twenty-five grammes (125 Gm.) [4 ozs. av., 179 grs.]; the menstruum, enough to make one thousand cubic centimeters (1000 Cc.) [33 fl℥, 391♏]. Note.—The choice of the menstruum will depend upon the nature of the drug, and, in some cases, upon the uses to which the tincture is to be applied. In general, it may be stated that, if the useful constituents are soluble in alcohol, and but slightly or not at all soluble in water, strong alcohol should be used as a menstruum. Whenever it is possible, and consistent with the intended use of the preparation, the alcoholic strength of the menstruum should be made to approach that of diluted alcohol, the object being not only to exhaust the drug of all its useful constituents, but also to retain them in solution. If the drug is fibrous, and can be dried or powdered without injury or loss of useful constituents, percolation is preferable. If the drug is resinous, and partly or almost wholly soluble in the menstruum, or if it is fibrous and can not well be powdered without undergoing injury, maceration should be resorted to. In the latter case, the drug, comminuted as much as possible, should be kept in contact with the full quantity of the menstruum for two weeks, or until the soluble matters are extracted, the liquid portion strained off, and the remainder of the tincture contained in the residue on the strainer carefully displaced by washing with a fresh portion of the menstruum until one thousand cubic centimeters (1000 Cc.) [33 fl℥, 391♏] of tincture are obtained for every one hundred and twenty-five grammes (125 Gm.) [4 ozs. av., 179 grs.] of drug used in the operation. The preparation of tinctures from fluid extracts, instead of from the original drugs themselves, is not recommended. In some special cases, however, when the crude drug is not accessible, or when a tincture, which is not at hand and otherwise unobtainable, is required for immediate use, it may be prepared, extemporaneously, from the corresponding fluid extract, provided that the latter is known to fully represent the active constituents of the drug which are intended to be contained in the tincture"—(Nat. Form.). The following general directions are given by the National Formulary for the preparation of Ethereal tinctures:
TINCTURAE AETHEREAE (N. F.), Ethereal tinctures.—GENERAL FORMULA. "The drug, properly comminuted, one hundred and twenty-five grammes (125 Gm.) [4 ozs. av., 179 grs.]; alcohol, ether (U. S. P), of each a sufficient quantity to make one thousand cubic centimeters (1000 Cc.) [33 fl℥, 391♏]. Percolate the drug in the usual manner, but with proper precautions to avoid loss of menstruum by evaporation, with a mixture of one (1) volume of ether, and two (2) volumes of alcohol, until one thousand cubic centimeters (1000 Cc.) [33 fl℥, 391♏] of percolate are obtained. Note.—This formula is to be used, when ethereal tinctures of belladonna, castor, digitalis, lobelia, valerian, or of other drugs, are to be prepared"—(Nat. Form.).
(For extensive systematic work on the standardization of tinctures, see Messrs. Farr and Wright, Pharm. Jour. Trans., Vol. XXIV, 1893-94, pp. 177-180; and Proc. Amer. Pharm. Assoc., 1891 to 1895).