LIQUID FORMS.
MISTURÆ. Mixtures.
These preparations are generally extemporaneous, in which different ingredients are mingled together in the liquid form, or, in which solid substances are diffused through liquid, by the medium of mucilage or syrup: for prescribing mixtures the following general rules may be laid down.
I. Substances which are capable of entering into chemical combination, or of decomposing each other, ought not to be mixed together, unless it be with a view of obtaining the new products as a remedy.
II. Transparency is not a necessary condition,[[302]] and hence insoluble powders may be advantageously introduced into mixtures, if the following precautions be observed.
1. They must be divisible and mechanically miscible in the liquid.
2. They must not possess too great a specific gravity.
3. They must not render the liquid too mucilaginous or thick; thus, f℥j should seldom contain more than ʒss of a vegetable powder, ℈ij of an electuary, and conserve; or grs. xv, or ℈j of an extract.
III. The taste, the smell, and the general aspect of the mixture should be rendered as pleasant as possible; thus milk covers the taste of bark, of the tinctures of guaiacum and valerian, and that of lime water; and a light decoction of the liquorice root disguises a bitter taste more effectually than sugar.
The Physician may also produce occasional changes in the appearance of his mixture, in order to reconcile a delicate taste to its continuance; he never ought however to alter the essential part of plans which he finds advantageous.
A Draught differs merely from a mixture in quantity; it is usually taken at once, and should not exceed f℥iss; it should be always preferred when,
1. The remedy is to be taken in a precise dose.
2. Whenever it is liable to spontaneous decomposition.
3. Whenever the action of the atmosphere occasions change.
In apportioning the dose of mixtures, the following proportions are admissible, although not perfectly accurate. A Table Spoon full (Cochleare Amplum) f℥ss. Dessert Spoon (Cochleare Mediocre) more than fʒij. Tea Spoon (Cochleare Minimum) fʒj. A Wine Glass (Cyathus) although very variable, may be estimated as containing f℥iss. The custom of measuring the dose of a liquid by dropping it from the mouth of a phial is very erroneous;[[303]] it will therefore be proper to dilute an active medicine that is to be so apportioned, with at least a triple quantity of water, that its real dose may not be essentially altered by any slight variation in the quantity.
The temperature at which a liquid medicine should be given may perhaps merit a few observations. In general, the ordinary degree of heat is that which will best answer the intention, but in cases of dyspepsia, the sense of weight and uneasiness, which often follows a dose of medicine, will be prevented by giving it in a tepid state. This remark will apply to the administration of the Decoction of Sarsaparilla; Refrigerants should of course be given as cool as possible; Camomile Infusion, and other vegetable Ptisans, which are designed to promote the operation of an emetic, will be more efficient when warm. In delicate chlorotic females I have sometimes found chalybeate draughts not only more efficacious, but less distressing to the stomach, when exhibited in a tepid state.
ENEMATA. Clysters.[[304]]
“Lavamenta.”
This form of applying a medicine furnishes the practitioner with many valuable resources, although the remedy has not escaped its due share of persecution. Paracelsus bestowed upon it the epithet “turpissimum medicamentum,” and Van Helmont that of “pudendum medicorum subsidium.”
It is calculated to fulfil the following indications, viz.
1. To promote the tardy operation of a Cathartic, or to evacuate the bowels, where, from delicacy of stomach, medicines cannot be retained, or from debility of body they cannot be safely administered.
In the administration of a remedy of this kind, there are two essential circumstances, independent of the strength of its ingredients, which will modify its activity, viz. Impulse and Quantity, by which we obtain the stimulus of distention; warm water without any adjunct may thus be made the means of overcoming those unrelenting obstructions, which had refused obedience to more common measures: Clysters, however, when most forcibly urged, rarely reach beyond the sigmoid flexure of the colon, and yet when the largest quantity of fluid which the bowels will admit is introduced with considerable impulse, the local impression is so powerful that it is at once extended by the medium of sympathy, through the whole of the alimentary canal, and very thorough and copious discharges result.
2. To induce extreme relaxation:
Which is best effected by an infusion of Tobacco. See Tabaci Folia.
3. To produce Astringent and Anodyne, or Carminative effects.
Common starch, with the addition of Tincture of Opium, is the most common and convenient form for this purpose. See also Assafœtida, Terebinthinæ Oleum, and Formulæ 8, 9, 29, 30. In some cases the injection of cold water acts as a powerful astringent, and from its impression upon the rectum, will frequently afford instantaneous relief in the piles.
4. To destroy Ascarides. See Form. 164.
5. To act as an emollient fomentation.
6. To convey nutriment.
In the administration of Clysters, for the fulfilment of any of the last five indications, it is obvious, that the stimulus of distention should be avoided, as being incompatible with our object; the quantity, or bulk of the solution, ought to be also carefully graduated; to prevent, for example, the opiate clyster from being too soon returned, Dr. Cullen has remarked that it seldom should be made of more bulk than that of three or four ounces of liquid, and this also of a very mild kind. In administering a bitter decoction for the cure of Ascarides, the same precaution is necessary, or the gut will suddenly contract and expel the clyster, which always acts with more certainty when allowed to remain for some time. The proportions of fluid vehicle necessary for the different stages of life, under ordinary circumstances, may be stated as follows:—An infant at its birth, or soon after, requires about one fluid ounce; a child between the age of one and five years, from three to four fluid ounces; a youth of ten or fifteen, from six to eight fluid ounces; and an adult may take twelve. With regard to the dose of the active ingredient of a Lavement, it may be estimated as triple of that taken by the mouth.
INJECTIONES.
Under this head may be comprehended the various medicinal preparations which are employed as local applications;—to the urethra for the cure of gonorrhæa, and to the vagina for that of the different discharges to which females are liable.
With respect to the former of these it has been truly observed, that “among the whole class of remedies employed for surgical purposes, there is scarcely one which has occasioned a greater diversity of opinion;” to enter however into an examination of this subject would be entirely foreign to the intention of the present work; it is only necessary to state, that for their preparation the same principles of combination, and the same chemical precautions, apply, as have been already investigated under the head Misturæ. In some cases the practitioner will find it useful to insure the entire solution of his active ingredient; while in others, the presence of a precipitate may enhance the efficacy of the application, as illustrated by Form. 62.
In the preparation of injections for the cure of female discharges, it must be remembered that, if they be of a vegetable nature, their efficacy wholly depends upon the Tannin which they contain, and the prescriber must therefore take care not to invalidate the force of this principle by any incompatible additions.
And it deserves to be remembered, that as Tannin has the power of coagulating animal mucus, and of forming with it an insoluble precipitate, its administration, as an injection, is liable to occasion the evacuation of whitish or ash-coloured flakes, which will come away from time to time, and excite in the patient’s mind, says Mr. Clarke, the apprehension that she is voiding portions of the internal parts of the body, unless her mind be prepared for the occurrence by a previous explanation, and which the judicious practitioner will not neglect to afford. In some cases it will be necessary to correct the irritating effect of the astringent by the addition of a demulcent, as exemplified in Form. 61. In applying this form of remedy an ivory syringe should be always preferred to one of pewter, whenever the solution is likely to be affected by the contact of a metal.
INHALATIONES. Inhalations.
Under this general title may be comprehended two distinct classes of volatilized substances, viz.
Dry Fumes (Suffitus), and Watery Vapours (Halitus).
Before we enter upon the consideration of this particular form of remedy, it may be necessary to state, generally, that it appears to be capable of affording a very expeditious and powerful mode of affecting the body by certain medicines. If the power of a remedy be so greatly modified by circumstances affecting its solubility, as we have already proved, it cannot be a matter of surprise that the still farther diminution of its cohesion should occasion a corresponding influence upon its energies; indeed it would appear that some few substances are entirely inert when applied under any other form, see Hydrargyrum, in the after part of this work. We are, moreover enabled by these means, to bring various bodies into immediate contact with organs, which are inaccessible to such remedies in every other state of aggregation. This observation applies more particularly to the lungs, and the subject has lately occupied the attention of a worthy and skilful physician, whose work[[305]] is well entitled to the serious consideration of the profession.
The practice of causing patients to inhale various volatilized substances appears to have been of very ancient date. It has been already stated in this work (p. 39) that the fumes of Orpiment were directed to be breathed by Galen, and that the practice has been adopted by practitioners of later date.[[306]] Few attempts of this kind however were made, until the time of our countryman Bennet, the author of “Theatrum Tabidorum,” who arranges volatilized substances into the two classes which have been announced at the head of the present section, viz. Suffitus, and Halitus. The numerous trials which have been since made with the different gases must be in the remembrance of every reader, but unfortunately, the injudicious and empirical spirit with which these inquiries have hitherto been conducted, has thrown such discredit upon the subject, that the practitioner who should resume the investigation, must be prepared to hear his understanding, or his integrity, questioned.
Suffitus. Fumes of Burning Substances. The particular forms of pulmonary disease in which Tar fumes appear to be most serviceable, are of the chronic kind; where an inflammatory diathesis prevails, or any tendency to hæmopthysis exists, the practice cannot be said to be free from danger. In treatment of hooping cough the inhalation of tar fumes have been also said to be beneficial. For the mode of applying this remedy, see Pix Liquida.
The practice of smoking the roots of Stramonium, Tobacco, &c. might with propriety be noticed under this head. With the respect to the former of these remedies, much has been said and written, and asthmatic patients have occasionally expressed a belief in its palliative powers; in my own practice however, I have never met with any success that has inspired my confidence. See Stramonii Herba.
Halitus. Aqueous Vapours. In certain catarrhal affections, when accompanied with painful and difficult expectoration, benefit may be occasionally obtained from the inhalation of the steam of hot water, or of vinegar and water, the acid in this case assisting the expectoration, while the whole acts as an emollient and soothing application to the tender and inflamed vessels of the internal surface of the bronchial tubes. The same practice is also highly serviceable in Cynanche Trachealis, and Tonsillaris.
In Pneumonia, after the violence of the arterial excitement has been reduced by depletory measures, the inhalation of the steam of hot water, or decoctions of emollient herbs, will often contribute to the support of an easy expectoration.
It has been already stated under the history of Expectorants (page 106), that in certain dry states of the air, the evaporation of water in an artificially warmed apartment, is frequently attended with considerable relief to the pulmonary patient.
In Dyspnæa, attended with a spasmodic condition of the pulmonary organs, vapours impregnated with sulphuric æther have been recommended for inhalation. Dr. Pearson also states that the efficacy of such an application is materially enhanced by dissolving in it a portion of the extract of Conium. Dr. Bôotcher of Copenhagen, has lately announced the utility of vapours of camphor, in complaints affecting the cavities of the nose, throat, and chest. He states that in the worst case of stoppage of the nose from catarrh, a piece of camphor need only be kept for a few minutes before it, to obtain great relief; the same application has been known to produce good in Cynanche Tonsillaris.
In order to apply such inhalations we may employ the inhaler invented by Dr. Mudge, or if that instrument be not at hand, the spout of a tea pot, or a common basin with an inverted funnel, will be found very convenient substitutes.
REMEDIES OF EXTERNAL APPLICATION.
This class of medicinal agents formerly comprised a much wider range of forms than it at present contains; such as numerous Epithems; Vapours; Aromatic Bags; Medicated Quilts, &c.
The external remedies of the present day may be divided into two orders, viz.
1. Those whose effects are entirely local, as exemplified in the application of certain refrigerating embrocations, stimulating cataplasms, and astringent unguents.
2. Those which excite general effects, or produce an influence upon parts remote from those to which the remedy is more immediately addressed, as illustrated by the operation of mercurial liniments and unguents, or by the general tonic effects of adhesive plaisters.
With respect to the former of these divisions it is unnecessary to multiply our remarks; the objects which they embrace belong more particularly to the department of surgery, and from the investigation of the different modes and forms of external application we shall hereafter derive very ample and instructive illustrations. In considering the objects of the latter division, a very interesting and important question immediately suggests itself for our consideration—How far a medicinal substance, when locally applied to the surface of the body, may be capable of affecting the general system, or some of its more remote parts?—the experienced practitioner will feel no hesitation in admitting numerous proofs of the existence of such agency; and it would seem probable that topical applications may produce general effects by several distinct modes of operation, viz.
1. By exciting an impression on the nervous system.
2. By modifying the cuticular discharge.
3. By being absorbed into the circulation.
In considering the different forms of external applications, it will appear that, for their extemporaneous construction, preparation, and application, the same scientific knowledge, practical skill, and pathological acumen will be required, as we have already stated to be so indispensably requisite to enable the physician to prescribe, and the pharmaceutist to prepare the various remedies intended for internal administration; although in regard to the former, it may be stated generally that the prescriber will more frequently be called upon to exercise that species of knowledge and address which enables the practitioner to impart a convenient and efficient consistency to his remedy; for an external application is far more dependent upon this circumstance for its efficacy, than one intended for internal use.
LOTIONES:
Remedies of a liquid nature, designed for external application.
Under this generic term, which strictly signifies a wash, may be comprehended several species of medicines, calculated for the fulfilment of different indications, as Embrocationes, Collyria, Fomenta, Linimenta, &c. In some instances these applications are entirely local in their effects, as where a morbid action of the skin is changed by a stimulating lotion, as exemplified in the cure of Psora by the decoction of Hellebore, or the relaxed vessels of the tunica conjunctiva of the eye, by an astringent collyrium; in other cases, they operate upon parts not in contact with the remedy, through the medium of sympathetic communication, as where cholic and disorders of the bowels are abated by the application of warm fomentations to the surface of the abdomen, or where paralytic affections are relieved by pumping cold water on the part affected.
Embrocationes. These, as the term[[307]] denotes, are compositions of spirit, decoctions, infusions, or other liquids, applied by sprinkling or rubbing them on an affected part.
Linimenta[[308]] are understood to differ from embrocations in consistence, the former being of an oily, or mucilaginous density, which increases their efficacy by imparting a certain emollient power, in addition to their other virtues. In popular language, however, liniment and embrocation are generally considered synonymous terms. They constitute a valuable class of remedies, and the observations which Dr. Percival has offered on their utility well merit the attention of the medical practitioner. “Volatile and antispasmodic liniments are highly useful remedies, and it is to be lamented that external applications of this kind are not more frequently employed, for there is just reason to apprehend that powerful effects might be expected from them in various diseases.” In chronic affections of the viscera, such applications appear highly serviceable, not only from the friction to which they give origin, but from the influence of that species of sympathy which appears to depend upon the mere proximity and continuity of parts, and which, as Sir Gilbert Blane has observed, is particularly displayed “in the containing on the contained parts, as that of the integuments on the subjacent viscera.”
Collyria[[309]].—Liquid applications to the eyes. The Pharmacopœia Chirurgica contains several different formulæ for lotions of this kind, some of which are simply astringent, while others combine also the virtues of a stimulant.
CATAPLASMATA.[[310]] Poultices, or Pultices.
External applications of a pulpy, and somewhat coherent or tenacious consistence.
They are generally extemporaneous preparations, and are calculated to answer several different indications, viz.
1. As Stimulants, e. g. Cataplasma Sinapis, L. D. which generally inflames the surface to which it is applied so much as to raise blisters; common salt also, muriate of soda, constitutes the active ingredient of a poultice which has lately been brought into considerable repute for the reduction of indolent strumous swellings and enlargements of the glands.[[311]]
2. Antiseptics—Cataplasma Fermenti, L. (see p. 159.) A powerfully antiseptic cataplasm may be also made by stirring finely powdered charcoal into a common linseed meal poultice. A cataplasm of the boiled carrot, beat into a pulp, has been likewise found very effectual in sweetening foul ulcers.
3. Sedatives. The most efficient of these are composed of Conium, Digitalis, or Hyoscyamus, and are eminently serviceable in cancerous and scrophulous sores of a highly irritable and painful nature, to diminish their sensibility and correct the acrid discharges. See Form. 18.
4. Refrigerants. In the formation of a cataplasm for this purpose we must avoid the introduction of substances that are slow conductors of caloric; suppose for example our object is to apply the sub-acetate of lead in this form, it will in such case be judicious to mix the linseed meal, with oatmeal, or crumb of bread; for if the former substance be used singly, it is liable, from its tenacity, to become hard and dry, and in that state to augment the temperature which it was designed to diminish.
5. Emollients.—(The modus operandi of these agents is explained at p. 142.) For which purpose the common farinaceous poultice is the most eligible, made by soaking slices of bread in milk, and simmering them together over a gentle fire until they are reduced to the proper consistence, which ought to be such as to prevent its spreading farther than is designed, and yet not so hard as to occasion any mechanical irritation; the whole is then to be beat smooth with a spoon, and applied as warm as the patient’s feelings will readily admit. Some practitioners have doubted the propriety of milk as an ingredient in this composition, and have preferred water as an excipient, not only because the former is very liable to turn sour, but because it does not possess greater powers as an emollient than water; the observations of the editor of the Pharmacopœia Chirurgica upon this question are judicious, and worthy our notice; “the objection,” he says, “will certainly hold good whenever stale milk is made use of, or if the same poultice be kept too long applied; but if the milk be fresh, and the poultice renewed night and morning, we do not know any thing that occasionally gives such ease and comfort to the patient as this form of cataplasm. If water be substituted for milk, the poultice is seldom of sufficient tenacity; it is true that this inconvenience may be remedied by the addition of a little linseed meal, but in some instances the meal appears to fret and irritate the skin so much, that patients undergo considerable uneasiness from this cause; an objection to which the cataplasm of bread and milk is seldom subject, especially if it be not applied too hot.”
Every substance, whether liquid or solid, may become an ingredient in this species of composition, and although judicious and experienced surgeons have of late very considerably improved the form of their cataplasms, yet the principles of medicinal combination, which it has been the object of the present work to investigate and expound, will suggest many important hints for the farther extension of their utility; and although the direction of them is more frequently left to the nurse than to the medical practitioner, yet in adapting them to each particular occasion some share of chemical address may be necessary; we have already seen that attention must be paid to the selection of ingredients, with respect to their powers of conducting heat, and it is evident that care must be taken not to reduce into pulp, by decoction, substances that contain volatile principles; while in the preparation of active liquids to be subsequently mixed with linseed meal, it is equally evident that we must be directed by the chemical nature of their composition.
EMPLASTRA. L.E.D. Plasters.
These are solid and tenacious compounds, adhesive at the ordinary heat of the human body; they owe their consistence to different causes, viz.
1. To a due admixture of wax or fatty matter, and resin, e. g. Emplast: Ceræ, &c.
They may be said to differ only in consistence from liniments, ointments, and cerates; Deyeux[[312]] accordingly proposes to distinguish them by the appellation of Solid Ointments.
2. To the chemical combination of the semivitreous oxide of lead with oils or fat, e. g. Emplast: Plumbi.
3. To the chemical action of the component parts of the plaster on each other, as Emplast: Ammoniaci, &c.
Plasters are generally kept in rolls, wrapped in paper, and when to be used they are melted and spread on leather; in performing this operation the practitioner ought not to apply a heat above that of boiling water; for if metallic oxides be present, the fatty matter will, at a higher temperature, reduce them, in consequence of the powerful affinity of oil for oxygen at an exalted temperature; and if aromatic substances enter as ingredients they will thus suffer in their strength, besides which the fat itself will undergo a very injurious change by a mismanaged application of heat, and the plaster will be less adhesive.
They are employed as remedies to answer two general indications; mechanically, to afford support to muscular parts and to prevent the access of air; and medicinally, to operate as stimulants, discutients, rubefacients, or anodyne applications. That by affording an artificial support to the various parts of the body, by the application of plasters, we are capable in certain diseases of effecting much benefit, is a truth to be explained upon the principles of physiology, and is daily confirmed by the results of practice; thus by giving support to the muscles of the back, how frequently the stomach is steadied and strengthened? Diseases of the kidneys are in the same way very frequently relieved by tight bandages around the loins; the existence of an intimate connexion between the external and internal parts is strikingly exemplified by the distressing effects which are often experienced in weak habits, such as sickness, giddiness, and other uneasy sensations, from a want of any usual compression, as that of stays, under-waistcoats, &c. The support afforded to persons who have been tapped in Ascites is another instance. I have also lately met with a case in which a morbidly relaxed state of the bowels had harassed the patient for several years, and set at defiance every astringent medicine; upon the application, however, of a tight bandage around the abdomen, the healthy action of the intestines has been completely restored. Sir Gilbert Blane has suggested the trial of mechanical compression of the head in the cure of Hydrocephalus, and several cases, apparently favourable, have been published. Dr. Thackrey of Cambridge has related a very interesting history in support of the practice, and judiciously recommends the substitution of straps of adhesive plaster for the bandages of cloth originally proposed by Sir Gilbert. In reasoning upon this treatment, it will be found strictly conformable with the soundest principles of physiology, and with those views in particular, for the illustration of which I have here directed the reader’s attention to the subject. Where our object is simple support, we should of course select a plaster which is the most adhesive and the least irritating. Many plasters which have gained great celebrity for their curative virtues will be found to owe all their powers to their adhesiveness, such is the Emplastrum Oxidi Ferri Rubri of the Edinburgh Pharmacopœia, for it is impossible that the iron should communicate any tonic effect. The same observation applies to many of those empirical plasters which have at different times acquired so great a share[[313]] of popular applause. In the cure of sore legs[[314]] the importance of adhesive strapping is generally acknowledged, and on such occasions nothing is superior to the Emplastrum Resinæ.
FORMULÆ
IN
ILLUSTRATION OF THE SUBJECT
OF
Medicinal Combination.
“Longum est iter per Præcepta, breve et efficax per Exempla.” Seneca.