TINCTURE-(Tinctures).

Tinkturen, Germ.; Teintures, Alcoolés, French; Alcoholados, Span.

TINCTURES are alcoholic or partially alcoholic solutions of the useful constituents of drugs, which are usually not wholly soluble in the menstruum. (Tincture of Iodine, Tinct. of Ferric Chloride, and perhaps a few others are included in this class from long custom).

MENSTRUUM.-The strength of the menstruum employed in different tinctures varies according to the nature of the drug. Before a suitable menstruum can be selected, the nature of the active constituents of the drug must be studied, and such a solvent selected as will take up those principles with as little inert matter as possible, and yet yield a permanent and elegant preparation. For this reason, various menstrua are directed by the Pharmacopoeia, and unless for a satisfactory reason, a weaker or stronger menstruum than that directed, should not be employed.

The most common menstruum employed is alcohol diluted to different degrees of strength. The alcohol of the U. S. Pharmacopoeia is directed to be of the specific gravity 0.820; that of the British 0.838; of the German, 0.830 to 0.834; and of the French, 0.819. In a few instances, the U. S. Pharmacopoeia directs the addition of glycerin to the menstruum; this adds to the permanency of tinctures containing tannin-like principles. Such menstrua as aromatic spirit of ammonia and ethereal spirit (ether 7 p., alcohol 3 p.), are also employed, these being known as ammoniated tinctures and ethereal tinctures.*

STRENGTH.-The U. S. Pharmacopoeia directs a certain quantity of the air-dried drug, expressed in grammes, to be employed to make 1000 cubic centimeters of the finished tincture.

The British Pharmacopoeia directs, on an average, one part (by weight) of the drug to be represented by 8 parts by measure of the finished tincture. In the French, German and Austrian Pharmacopoeias, one part of the drug (by weight) is represented by 5 or 10 parts (by weight) of the tincture. The strength of tinctures prepared from potent drugs varies considerably among different foreign Pharmacopoeias. It is therefore well to bear this important point in mind in dispensing U. S. Pharmacopoeia tinctures in foreign prescriptions.

*Teintures éthérées of the French Pharmacopoeia.

PREPARATION. For the preparation of tinctures only the best obtainable quality of a drug should be employed. The use of cheap and second-rate material is a culpable and reprehensible practice. The market affords an abundance of first-class drugs at a reasonable price for the quality.

The various methods employed in the preparation of tinctures are:-first, Solution; second, Maceration; third, Digestion; fourth, Percolation.

1st. Solution. This is applicable in such instances as tinctures of iodine and tolu, where the material is wholly or practically soluble in alcohol.

2d. Maceration.t-This process is preferred by the majority of foreign pharmacopoeias. For this purpose large, strong bottles with a wide mouth are selected, the drug (in coarse powder or particles) and menstruum are introduced, and they are then well corked and set aside for a period of from 7 to 14 days. The temperature of the room should be about 20° C.; the bottles should be conveniently placed, so that they may be shaken once or twice daily. At the end of the period of maceration the fluid portion is drained off, the residue then transferred to the strainer, deprived of as much of the fluid as possible by hand pressure, then enclosed securely in the straining-cloth, and subjected to pressure in a tincture press. The tincture is allowed to settle and is then

This is only approximate for the U. S. P., for the drug is expressed in parts by weight, and the finished product in parts by measure. In the B. P. the quantity of drug is expressed in avoirdupois ounces and fractions thereof, and the finished product in measure (imperial pint).

+ Concerning the comparative advantages and disadvantages of Maceration and Percolation, see page 189.

filtered. No attempt is made to bring the strained liquid to a definite volume by washing the dregs with menstruum.

3d. Digestion. This is maceration between the temperatures of 30° and 40° C. It is employed in such cases where the drug is difficult of extraction, or where rapid exhaustion is desired. In this operation the drug and menstruum should be placed in a large glass flask, which is placed on a water- or sand-bath. The flask is closed with a perforated stopper, into which may be fitted an inverted condenser (Fig. 151), or a long (4-5 ft.) plain glass tube (air cooler), for the purpose of condensing the volatilized solvent. The apparatus is allowed to become cold before the contents are drained off.

4th. Percolation. While the principle of percolation or displacement has been known and applied in chemical and industrial operations for a very long time, it was first applied, officially, to the preparation of tinctures, fluid extracts, etc., in this country, in the Pharmacopoeia of 1840. It is now also recognized to some extent by the pharmacopoeias of England, France, Germany, Switzerland, etc.

Percolation as applied to the preparation of tinctures, although demanding care and close attention, is not fraught with the same difficulties as in the preparation of fluid extracts, since the volume of menstruum is largely in excess of that necessary to insure the exhaustion of the drug. This should not, however, lead to carelessness, for no matter how large the excess of menstruum may be, should the operator have packed the drug carelessly, and not have devoted proper attention to the operation, exhaustion cannot be expected. The U. S. Pharmacopoeia directs a short period of maceration, previous to beginning percolation. This precaution should always be observed, and the time should rather be lengthened than shortened. The British Pharmacopoeia demands a preliminary maceration of forty-eight hours, which is certainly a point in its favor.

The U. S. Pharmacopoeia directs that the drug be percolated until a certain volume (1000 Cc.) is obtained. Hence, the menstruum which is retained by the drug is lost. To avoid this, it has been suggested to adopt the method of the British Pharmacopoeia. According to this, after the whole of the menstruum (equal in volume to the quantity of tincture to be obtained) has been added, and percolation ceases, the marc is to be transferred to a tincture press, the expressed and filtered liquid mixed with the percolate, and the whole then made up to the proper volume by adding more menstruum.

Some operators attempt to recover the menstruum retained by the drug by forcing it out with water. This is not advisable, since the vegetable tissues, on coming in contact with water, swell and often choke the percolator. Besides, water takes up other principles than alcohol, and since the diffusion of the one into the other cannot be prevented, this diluted menstruum, generally

contaminated with inert extractive, flows into the more or less. alcoholic percolate, causing thereby cloudiness or precipitation.

The practice of preparing tinctures by diluting Fluid Extracts should be condemned, particularly so in the case of potent drugs.

PRESERVATION.-Tinctures should be kept in well-stoppered bottles, away from the direct rays of the sun. As a guide to the estimation of the quality and strength of tinctures, the German Pharmacopoeia specifies the limits of specific gravity; the percentage of dry residue left on evaporation on the water-bath; the percentage of ash; or the percentage of acid expressed in milligrammes of KOH, necessary to neutralize 10 Gm. of tincture diluted with 100 Gm. of water. These figures, however, do not give any decisive clue as to the quality of the tincture. When the activity of a drug resides in certain definite proximate principles, the only accurate method of judging the quality of its preparations is by assay. The U. S. Pharmacopoeia has thus standardized two of its tinctures, viz., those of Opium and Nux Vomica.

TINCTURE HERBARUM RECENTIUM.

This class of preparations was introduced many years ago by Hahnemann, and is extensively used at present in homoeopathic and eclectic practice. They were first prepared by the addition of the freshly-expressed juice to twice its weight of alcohol. The United States, as well as French Pharmacopoeias, adopted the process of Soubeiran, which consisted in macerating the fresh, cut or bruised drug with alcohol in definite proportions. As a rule, these are very active preparations, for it is justly claimed that the process of drying, in order to prepare drugs for the process of grinding and powdering, injures or alters many sensitive active principles. On the other hand, uniformity in the strength of these preparations cannot be expected, for the freshly-collected drug contains a variable amount of moisture, according to the time of gathering and the length of subsequent exposure. The U.S. Pharmacopoeiat gives the following directions: "These tinctures, when not otherwise directed, are to be prepared by the following formula: Take of the fresh herb, bruised or crushed, 500 Gm.; alcohol, 1000 Cc.; macerate the herb with the alcohol for fourteen days; then express the liquid and filter." Among the tinctures made by this process and in frequent use are those of Rhus Toxicodendron, Conium, Digitalis, Hyoscyamus, Pulsatilla, Gelsemium, Aconite, Belladonna, etc.

*See "Recovery of Residual Tinctures from Marcs," R. H. Parker, Western Druggist, 1895, p. 51. "Tinctures from Fluid Extracts," J. W. England, Druggists' Circular, 1893, p. 245.

The French Pharmacopoeia directs equal parts of the fresh drug and alcohol of 90 %, and to macerate 10 days.

SUCCI-JUICES.

These are a class of preparations official in the British Pharmacopoeia, made by bruising and expressing fresh, succulent drugs. The juice is then mixed with a definite volume of alcohol (1 vol. alcohol to 3 vols. juice), the mixture set aside for seven days, and filtered. These preparations vary in strength for the same reasons which were just given under Tinctures of Fresh Herbs, which latter were introduced into the U. S. Pharmacopoeia in lieu of the "Succi."

The British Pharmacopoeia recognizes Succus Belladonnæ, Conii, Hyoscyami, Scoparii, and Taraxaci.

EXPLANATORY (TINCTURES).

There are 71 tinctures official in the U. S. Pharmacopoeia. TINCTURA FERRI CHLORIDI.-This preparation should be allowed to stand at least 3 months before being dispensed, as directed by the U. S. Pharmacopoeia. By this time it will have developed an agreeable ethereal odor due to the formation of a small amount of ethyl chloride (C2HCl). Tincture of iron is incompatible with alkalies, alkali earths or carbonates (production of Fe(OH), or FeO3); likewise with preparations containing tannic acid (inky mixtures); also with mercurous salts (forming mercuric compounds); with mucilage of acacia it often produces a jelly.

Assay. See Liquor Ferri Chloridi.

TINCTURA IODI.-Freshly prepared tincture of iodine forms a precipitate upon the addition of water; after long standing, however, it is often found to yield a clear solution with water. This is due to the formation of hydriodic acid produced by the reaction between the iodine and alcohol.

The British Pharmacopoeia adds potassium iodide to its tincture for the purpose of rendering it miscible with water. This is not objectionable when it is intended for internal use; but, as it is exceedingly rare to administer iodine in this form, the advantage of the addition of KI is scarcely apparent.

The tincture should be recently prepared. It is incompatible with salts of the metals (forms insoluble metallic iodides); also alkalies, alkali carbonates, ammonium chloride (iodide of nitrogen, explosive), starch (iodide of starch), sodium hyposulphite (decolorized), and most alkaloids.

The so-called Decolorized Tincture of Iodine is made by digesting 10 parts each of iodine, sodium hyposulphite and water, until solution is effected, then adding 16 parts of spirit of ammonia, shaking, adding 75 parts of alcohol, and filtering after three days. The title of the preparation is very misleading, for it does not contain a trace of free iodine, it having all combined with the