Medicines which have no nauseous or unpleasant taste, no acrid or destructive action, which are not deliquescent, and which can be given in not too bulky doses, are usually more advantageously administered in fine powder. When an article is reduced to powder, it has a much greater surface exposed to the influence of light and of the atmosphere than when in the crude, aggregate mass; and as most, if not all vegetable powders, are injured by the action of these agents, it is always better to keep them in well-closed tin cans, or in well-stoppered bottles, which are covered externally with a coat of black paint, varnish, or black paper. Some agents become damp or lose their virtues rapidly when in the state of powder; such should be pulverized in small quantities at a time, and only as they are required. As a general rule, the finer the powder, or the longer it is triturated, the more active it becomes.
M. Dorvault thinks that the operation of pulverization effects an actual change in the chemical and therapeutical properties of many agents. Sugar is less soluble in water, and less sweet, when long pulverized or triturated, and, he inquires, is this to be referred to an altered electrical condition of the sugar, as the phosphorescence developed during the act of pulverization in the dark would lead us to suppose? Gum Arabic, powdered, has not the same taste, nor the same solubility as when in the entire state. If a given quantity of water may be made to dissolve 40 parts of arsenous acid in the vitreous state, the same quantity of water can be made to dissolve only 14 parts after pulverization (Annals of Pharmacy, May, 1852). Changes of this kind may ensue from the action of light, the oxygen of the atmosphere, its nitrogen, or its electricity, etc., upon matter reduced to a state of great fineness.
When but one article is reduced to powder, it is termed a simple powder, when several articles in powder are rubbed together, the mixture is termed a compound powder. As the substances entering into the formation of a compound powder may be of various textures and densities, it is generally preferable to reduce each, separately, to a powder, and then mix and triturate them thoroughly together.
Some articles, however, require the intervention of another before they can be reduced to powder, as camphor, which is pulverized by the addition of a few drops of alcohol; others, again, are powdered with facility by the aid of a harder substance. Medicines that contain considerable fixed oil, or which are deliquescent, should never be prescribed in the form of powders, more especially when they are to be retained for any length of time, as the former may injure the powder in consequence of rancidity, while the latter may render it damp, moldy, and inert. Articles which are incompatible should never be united together, unless the decomposition product is required. When volatile or deliquescent substances are prescribed in powders, as camphor, carbonate of ammonium, or carbonate of potassium, they should be wrapped in wax papers, and enclosed in tin-foil, a tin box, or a wide-mouth vial. The paper used for powders of ordinary character, should be very smooth, or glazed, to prevent the powder from adhering to it, and sufficiently soft and yielding to be opened and closed readily, without springing, so as to throw out any portion of the powder. Some apothecaries fold their powders in foolscap paper, and these, when opened by the patient, in consequence of their stiffness, spill or throw out a very material proportion of the medicine. When a powder is prescribed in bulk, leaving it to the patient to apportion the dose, unless otherwise desired, it should always be put into a wide-mouthed vial.
The old absurd and unscientific style of combining eight or ten articles in one preparation is fortunately becoming unpopular, and, though a few preparations of the kind are retained, yet the major amount of our present compounds consist of but two or three, and rarely exceeding four substances. In the former the articles were too frequently thrown together without any guide or rule, or any regard to compatibilities, and, though benefit might have been, haphazardly, derived from these heterogeneous mixtures, it was always difficult to ascertain upon which article or articles the effect depended, or whether it was owing to a third agent, the result of decomposition.
In preparing powders, it will be best to dry the article, beat it in an iron or brass mortar for a time, then sift it through a fine sieve; again beat the coarser parts in a mortar for a short time, sift again; and so continue alternately pulverizing and sifting until the whole is reduced to fine powder, the product being well mixed. When very active articles, such as strychnine, chloride of gold, atropine, etc., are to be given in the form of powders, gum, sugar, sugar of milk, starch, or marsh-mallow should be triturated with them, in order to facilitate their reduction to minute division. Milk sugar is the most desirable diluent.
The usual vehicle for taking the lighter powders is an agreeable, thin liquid, as water, gruel, milk, etc. Heavy powders require a more consistent vehicle, as syrup, molasses, thick mucilage, etc.; always bearing in mind whether the vehicle be compatible with the active ingredients of the powder. Small amounts of powders of a disagreeable taste, may be conveniently administered in gelatin capsules. An elegant form of administration is that proposed, in 1862, by Limousin. This is by means of wafer capsules, or Cachets de Pain. These are wafers of unleavened bread, into which has been pressed a concavity. One wafer is filled with the powder, and the second wafer, wetted upon the inner surface, is pressed down upon the first with sufficient force to cause them to adhere. To administer, wet the capsule, place it upon the tongue posteriorly, and wash it down with a drink of water or other desired fluid. Similar receptacles are also made of rice flour.
Granular Powders.—Many methods have been suggested for the preparation of granular powders. Granules of vegetable and like powders were introduced by Dr. Thomas Skinner, in 1862. They were prepared by rubbing the desired powder with mucilage to form a non-adhesive, crummy mass, which, after drying and bruising, could be passed through sieves of any desired size. These granules were sometimes coated. Granular effervescent powders, now popular, may be prepared by pulverizing separately the acids, alkaline compounds, and sugar, mixing, and passing them through sieves, moistening with a little alcohol, to cause the particles to adhere, and then passing them with slight pressure through a sieve having suitable sized meshes. After drying, the granules are again passed through sieves of different sizes, to obtain the various sized granules.
GENERAL FORMULAS.—Formula A (Fine powder). "Medicinal agent, in fine powder, fifty grammes (50 Gm.) [1 oz. av., 334 grs.]; saccharated sodium bicarbonate (F. 341), four hundred and seventy-five grammes (475 Gm.) [1 lb. av., 334 grs.]; saccharated tartaric acid (F. 8), four hundred and seventy-five grammes (475 Gm.) (1 lb. av., 330 grs.]. Triturate the ingredients, previously well-dried, until a uniformly mixed powder is obtained.
Formula B (Granular powder).—"Medicinal agent, in fine powder, fifty grammes (50 Gm.) [1 oz. av., 334 grs.]; saccharated sodium bicarbonate (F. 341), four hundred and seventy-five grammes (475 Gm.) [1 lb. av., 330 grs.]; saccharated tartaric acid (F. 8), two hundred and thirty-seven and one-half grammes (237.5 Gm.) [8 ozs. av., 165 grs.]; saccharated citric acid (F. 5), two hundred and thirty-seven and one-half grammes (237.5 Gm.) [8 ozs. av., 165 grs.]. Mix the ingredients in a mortar, transfer them to an evaporating dish, and heat upon a water-bath, kept at 60° to 71° C. (140° to 160° F.), under constant stirring with a wooden spatula, until dry and uniformly granular. The saccharated citric acid, being made from crystallized citric acid containing 1 molecule of water of crystallization, supplies the moisture necessary to cause the powder, when heated, to cake and adhere together. If the somewhat pasty mass is then stirred with the spatula, small granules are readily formed, and these become firm when completely dried. Throughout the process the contact of the powder with metals should be carefully avoided. Effervescent powders should be preserved in well-stoppered, wide-mouthed vials. Note.—To make these effervescent compounds it is not necessary to have the saccharated alkali and saccharated acids in stock. The quantities of sodium bicarbonate, of tartaric acid, of citric acid, and of sugar, required for each formula, are readily ascertained by simple calculation, according to the following rule: Multiply the number of grammes of the saccharate prescribed by the figures indicating the percentage of alkali or acid it contains, and divide the sum of this by 100. The quotient is the quantity of alkali or acid, expressed in grammes, and by deducting this quantity from the total quantity of the saccharate, the quantity of sugar necessary is ascertained. Applying this rule, by way of example, to General Formula B, we have the following result: (1) 475 Gm. of saccharated sodium bicarbonate, containing 75 per cent, require 356.25 Gm. of sodium bicarbonate and 118.75 Gm. of sugar. (2) 237.5 Gm. of saccharated tartaric acid, containing 67.5 per cent, require 160.3 Gm. of tartaric acid and 77.2 Gm. of sugar. (3) 237.5 Gm. of saccharated citric acid, containing 62.5 per cent, require 148.4 Gm. of citric acid and 89.1 Gm. of sugar. And the formula would then be: Medicinal agent, fifty grammes (50 Gm.) [1 oz. av., 334 grs.]; sodium bicarbonate, three hundred and fifty-six and one-fourth grammes (356.25 Gm.) [12 ozs. av., 248 grs.]; tartaric acid, one hundred and sixty and three-tenths grammes (160.3 Gm.) [5 ozs. av., 286 grs.]; citric acid, one hundred and forty-eight and four-tenths grammes (148.4 Gm.) [5 ozs. av., 102 grs.]; sugar, two hundred and eighty-five and five one-hundredths grammes (285.05 Gm.) [10 ozs. av., 24 grs.]; to make one thousand grammes (1000 Gm.) [2 lbs. av., 3 ozs., 120 grs.]"—(Nat. Form.).
The National Formulary directs the preparation of Effervescent Powders as follows:
PULVERES EFFERVESCENTES, Effervescent Powders.—"The effervescent powders for which formulas are given in the Formulary, are most conveniently and efficiently dispensed in the form of fine powders, because in this condition they can be made extemporaneously and with assurance of their freshness and efficiency. The popular demand, however, seems to be for granular effervescent powders, the preparation of which requires certain modifications of the formulas, important only in so far as they enable the dispenser to granulate the powder in a convenient and expeditious manner.
GENERAL OBSERVATIONS AND DIRECTIONS.—"Effervescent powders are composed of the medicinal agent in admixture with an alkaline bicarbonate, an organic acid, and sugar. The proportion of the medicinal agent is dependent upon its dose, that of the alkaline bicarbonate and of the organic acid is dependent upon their molecular relation to each other, while the proportion of sugar is dependent upon the quantity necessary as a sweetening agent and diluent. The ingredients for making the fine pulverulent form of effervescent powders are: The medicinal agent, sodium bicarbonate, tartaric acid, and sugar, and it is necessary that these be well dried before mixing them. To make the granular form of effervescent powders the ingredients need not be dried, unless specially directed, and the ingredients are the same as for the pulverulent form, with the single exception that one-half the molecule of tartaric acid is replaced by one-half a molecule of crystallized citric acid. With the view to simplifying the formulas of effervescent powders, three new preparations have been embodied in this Formulary, viz.: Acidum Citricum Saccharatum (Saccharated Citric Acid), Formula No. 5; Acidum Tartaricum Saccharatum (Saccharated Tartaric Acid), Formula No. 8; Sodii Bicarbonas Saccharatus (Saccharated Sodium Bicarbonate), Formula No. 341. The proportion of sugar in these new saccharates is so adjusted that when either of the acid saccharates is mixed with an equal weight of the alkaline saccharate, the acid and alkali are in molecular relation to each other, and, when dissolved in water, will form the neutral tartrate and citrate of sodium respectively. With these three saccharates in stock, it becomes possible to make effervescent powders quickly with any medicinal agent that may be prescribed, while they simplify the formulas for the effervescent preparations now in the Formulary, their use being exemplified by the following General Formulas:"
Effervescent Powders of the National Formulary.—PULVIS FERRI ET QUININAE CITRATIS EFFERVESCENS (N. F.), Effervescent powder of citrate of iron and quinine, Effervescent citrate of iron and quinine. "Soluble citrate of iron and quinine (U. S. P.), in very fine powder, ten grammes (10 Gm.) [154 grs.]; saccharated sodium bicarbonate (F. 341), four hundred and ninety-five grammes (495 Gm.) [17 ozs. av., 202 grs.]; saccharated tartaric acid (F. 8), four hundred and ninety-five grammes (495 Gm.) [17 ozs. av., 202 grs.]. Mix the ingredients, previously well dried, and triturate them until a uniform powder is obtained. To make Granular Effervescent Citrate of Iron and Quinine, substitute saccharated citric acid (F. 5), not dried, two hundred and forty-seven and one-half grammes (247.5 Gm.) [8 ozs. av., 320 grs.] for an equal weight of the saccharated tartaric acid, and prepare the granulated compound as directed under the general formula (F. 319, B.). Ninety (90) grains (or about a heaped teaspoonful) of this preparation represent about one (1) grain of citrate of iron and quinine"—(Nat. Form.).
PULVIS FERRI PHOSPHATIS EFFERVESCENS (N. F.), Effervescent powder of phosphate of iron, Effervescent phosphate of iron.—"Phosphate of iron (U. S. P.), in very fine powder, twenty-four grammes (24 Gm.) [370 grs.]; saccharated sodium bicarbonate (F. 341), four hundred and eighty-eight grammes (488 Gm.) [17 ozs. av., 93 grs.]; saccharated tartaric acid (F. 8), four hundred and eighty-eight grammes (488 Gm.) [17 ozs. av., 93 grs.]. Mix the ingredients, previously well dried, and triturate them until a uniform powder is obtained. To make Granular Effervescent Phosphate of Iron, substitute saccharated citric acid (F. 6), not dried, two hundred and forty-four grammes (244 Gm.) [8 ozs. av., 266 grs.] for an equal weight of the saccharated tartaric acid, and prepare the granulated compound as directed under the general formula (F. 319, B.). Ninety (90) grains (or about a heaped teaspoonful) of this preparation represent about two (2) grains of phosphate of iron"—(Nat. Form.).
PULVIS POTASSII BROMIDI EFFERVESCENS (N. F.), Effervescent powder of potassium bromide, Effervescent potassium bromide.—"Potassium bromide, in very fine powder, one hundred and ten grammes (110 Gm.) [3 ozs. av., 385 grs.]; saccharated sodium bicarbonate (F. 341), four hundred and forty-five grammes (445 Gm.) [15 ozs. av., 305 grs.]; saccharated tartaric acid (F. 8), four hundred and forty-five grammes (445 Gm.) [15 ozs. av., 305 grs.]. Mix the ingredients, previously well dried, and triturate them until a uniform powder is obtained. To make Granular Effervescent Potassium Bromide, substitute saccharated citric acid (F. 5), not dried, two hundred and twenty-two and one-half grammes (222.5 Gm.) [7 ozs. av., 370 grs.] for an equal weight of the saccharated tartaric acid, and prepare the granulated compound as directed under the general formula (F. 319 B.). Ninety (90) grains (or about a heaped teaspoonful) of this preparation represent about ten (10) grains of potassium bromide"—(Nat. Form.).
PULVIS POTASSII BROMIDI EFFERVESCENS CUM CAFFEINA (N. F.), Effervescent powder of potassium bromide with caffeine, Effervescent potassium bromide with caffeine.—"Potassium bromide, in very fine powder, one hundred and ten grammes (110 Gm.) [3 ozs. av., 385 grs.]; caffeine, in very fine powder, eleven grammes (11 Gm.) [170 grs.]; saccharated sodium bicarbonate (F. 341), four hundred and forty grammes (440 Gm.) [15 ozs. av., 228 grs.]; saccharated tartaric acid (F. 8), four hundred and forty grammes (440 Gm.) [15 ozs. av., 228 grs.]. Mix the ingredients, previously well dried, and triturate them until a uniform powder is obtained. To make Granular Effervescent Potassium Bromide with Caffeine, substitute saccharated citric acid (F. 5), not dried, two hundred and twenty grammes (220 Gm.) [7 ozs. av., 333 grs.] for an equal weight of the saccharated tartaric acid, and prepare the granulated compound as directed under the general formula (F. 319,13.). Ninety (90) grains (or about a heaped teaspoonful) of this preparation represent about ten (10) grains of potassium bromide and one (1) grain of caffeine"—(Nat. Form.). (See also under Aquae Minerales.)
Other Powders.—The following powders are not employed in Eclectic medicine:
PULVIS HYDRARGYRI CHLORIDI MITIS ET JALAPAE (N. F.), Powder of mild chloride of mercury and jalap, Calomel and jalap.—"Mild chloride of mercury, thirty-four grammes (34 Gm.) [1 oz. av., 87 grs.]; jalap, in fine powder, sixty-six grammes (66 Gm.) [2 ozs. av., 143 grs.]. Mix them intimately. Note.—When 'Calomel and Jalap' is prescribed for an adult, without any specification of quantities, it is recommended that about 30 grains be dispensed as a dose"—(Nat. Form.).
PULVIS ANTIMONIALIS (U. S. P.), Antimonial powder, James' powder, Pulvis Jacobi, Pulvis antimonii compositus, James' pulver.—"Antimony oxide, thirty-three grammes (33 Gm.) [1 oz. av., 72 grs.]; precipitated calcium phosphate, sixty-seven grammes (67 Gm.) [2 ozs. av., 159 grs]; to make one hundred grammes (100 Gm.) [3 ozs. av., 231 grs.]. Mix them intimately";(U. S. P.). The foregoing is the official substitute for a nostrum first prepared by Dr. James, of England, who died in 1776. The original secret powder, upon being analyzed, revealed its constituents sufficiently to lead Dr. Pearson, of London, to recommend to the London College the following formula: it is prepared by calcining, in an iron crucible, 1 part of tersulphide of antimony, and 2 parts of horn shavings, stirring constantly until vapors cease to rise. Then rub the residue to powder, put it in a crucible with a perforated cover, and raise it gradually to red heat, which must be maintained for 2 hours. Reduce the product, when cold, to fine powder. It forms a white, gritty, odorless, tasteless powder, partially soluble in boiling water, and which solution gives an orange-yellow precipitate with sulphuretted hydrogen. It possesses the general properties of the antimonials according to the doses in which it is administered, and, like them, is very uncertain in its operation. It was principally used as a sedative and diaphoretic in febrile diseases, in doses of from 1 to 4 grains, in powder or bolus, repeating them every 3 or 4 hours, as required. It is not employed in Eclectic practice.