Stimulants are medicines which produce a temporary increase of one or more of the vital functions. A much more comprehensive signification is often given to this word; thus, the true stimulant, the astringent and tonic, are distinguished as general stimulante, while emetics, cathartics, diaphoretics, diuretics, emmenagogues, sialagogues, errhines, parturients, etc., are termed local stimulants. In this sense every medicine is a stimulant, not excepting, according to many authors, even "sedatives."
But it is not in this wide and indefinite sense that the word can with propriety be used in the classification of remedial agents. The term stimulant or excitant is here applied to those medicines which produce a temporary increase of the action of the heart and arteries, and in the supply of nervous energy, without any sensible increase in the evacuations or secretions.
The first effects of narcotics are those of stimulation, yet we do not consider them as true stimulants. Many agents, however, which we have classed as stimulants, after exerting their stimulant effect, are followed by nervous depression or sedation; as the alcoholic liquors, etc.
It must be admitted that many of the different classes of remedial agents glide by an indefinable gradation into each other, and partake of the properties common to other classes. It will also be recollected that numerous articles of the materia medica are possessed of a variety of different properties,—thus we often have an agent possessed of stimulant, diaphoretic, diuretic, expectorant and purgative properties. From these remarks it must be apparent to all that our present classification is erroneous, or at least not based upon an unobjectionable foundation. "We shall, however, pursue the beaten track, acknowledging at the same time our inability to confine particular medicines to the respective classes under which they may be technically ranked.
Action of Stimulants.—Stimulants belong to the class of neurotic medicines; that is, they act upon the nerves, and as we have already seen, the action of such remedies is transient. The question has been much discussed, whether stimulants really exalt nervous force (increase its quantity), or whether they merely call it forth (expend that which already exists). We are led to believe that stimulants really increase the amount of nervous force; for if they did not, we would always have as a result of their use a depression corresponding with the primary excitation—which is not the case. Again, we may maintain a certain degree of stimulation for an indefinite period by continuing the use of the remedy, which we could not do, if they merely expended nervous force without causing a reproduction of it.
We must, however, carefully distinguish between nervous and vital force; for nervous force may exist in excess, when the vital force or that power which preserves life, is depressed. "Nervous force," says Headland, "may be very much increased, as in high inflammatory fever, without a corresponding increase of the vital. The advantage of a stimulant is regulated by this rule.—When there is a failure in vital energy, no stimulant will serve to prolong life, for it can not communicate fresh vital power. But there may be no such failure of vital energy, and yet a sudden or accidental deficiency of nervous force may serve to peril the continuance of health, or even the tenure of life. For a certain degree of this nervous force is necessary both for life and health. When it is diminished, all the functions must suffer: when it fails entirely, the circulation must stop and death ensues. It is in these cases that a stimulant medicine is appropriate. It does not do good by communicating vital energy, but by remedying the want of nervous action, by which want the manifestation of the vital energy is subdued. This must always be borne in mind when the applicability of stimulants is under consideration."
The first effect of a stimulant is that of a topical excitant. When taken into the stomach, they stimulate the mucous membrane to increased secretion, and the macular fibers to greater activity; the food is more readily and rapidly digested, and chylosis facilitated. This local stimulating influence is transmitted to every portion of the body by sympathy, and the whole system participates in the excitation.
All stimulating agents are soluble in the fluids of the body, and are hence absorbed into the circulation, and by it brought into contact with the entire nervous system. These agents, as we have already noticed, prove stimulant to any nerve with which they are brought into contact; thus we have the topical stimulation of the stomach, the topical stimulation when applied to the skin, etc. We thus see that they act directly on nerve-matter, whenever brought in contact with it; and through the circulation they are brought into direct contact with the entire nervous matter of the body. As the result of this, the contractions of the heart are increased in force and frequency, the pulse becomes more energetic and frequent, respiration is accelerated, animal heat augmented, the countenance is enlivened, the intellectual and physical powers increased, and the cutaneous and renal secretions exhibit increased activity. They produce a temporary exhilaration of mind, revive and elevate the spirits—in a word, the phenomena of health are active when the system is under their influence, unless overpowered by disease. In some cases the excitation, when carried too far, or too long continued, may result in febrile or inflammatory action. The super-excitation which follows their too free use, often results in prostration, though this is not always proportioned to the intensity of the previous excitement.
As has been already remarked, many stimulants exert an especial influence over particular secretions, or over particular organs. Thus the carbonate of ammonia is diaphoretic as well as stimulant; the cantharides and juniper diuretic; while the turpentine, gum-resins, copaiba, benzoic acid, etc, though stimulants, exert an especial influence upon the mucous membranes, diminishing excessive secretion—and especially is this the case with the genito-nrinary mucous membrane.
Those agents, generally denominated tetanics, or muscular stimulants, as the strychnia and brucia, are peculiar agents, whose excitant influence appears to be exerted upon the motor column of the spinal cord, the motor parts of the brain, and the motor nerves. Thus, in large doses, they cause spasmodic and powerful contractions of the muscles of the body, and they may even produce death in this way, by rendering respiration impossible. In order that these agents should produce their specific effect, two things are necessary: first, that the muscles to be acted upon should be in a normal condition; and second, that the nerves passing from the nervous centers to them must be sound, so as to afford a medium for the passage of the increased nervous current. It is proved that they act upon the nerves, and not upon the muscles, by the fact, that when the nerves are injured, so that they can not convey an impression, these agents have no etfect upon the muscles, though every other condition is present.
As has been before stated, the moderate use of stimulants renders digestion more rapid and more perfect, the circulation is more vigorous, and its centripetal or congestive tendency is superseded by the centrifugal, and all the secretions are facilitated. But if they are too freely used, if the dose is large and too often repeated, or administered with any great degree of persistence, their sanative powers are lost, and they become engines of disease. If too freely employed, irritation, or even inflammation may supervene in the organ with which they come in direct contacts—or in a neighboring one, and symptomatic fever may result; under which many of the functions instead of being promoted by the stimulant, will be retarded. This is the case with the secretions and excretions generally—they are always deranged during febrile excitement.
Another result follows from exalted organic action, whether it depends upon artificial stimulation, or is the result of disease; that is, the exalted action is always followed by depression to a greater or less extent. This is the case with either mental or physical excitement, prostration being always the result of it, when carried to an extreme. Prostration is always the more marked the greater the stimulation. To a certain point stimulation may be carried without subsequent prostration; but passing beyond this point, we may say that it is proportioned to the amount of stimulation.
If one organ is over-excited in any way, some other organ is apt to become equally depressed, or to take on a state of inactivity, atony or debility. We frequently meet with cases of extreme debility of an organ, or of the general system, when the debility is apparent, but not real, some other organ being over-excited, thereby causing the apparent prostration. This is often a nice point to determine in the progress of disease, and one upon which the most expert diagnostician will sometimes err. When the prostration is but apparent, and depends upon some local and deep-seated congestion or inflammation, which is oppressive to the vital powers, a course of depletive medication, instead of increasing the debility, will often increase the strength, by removing the congestion or cause of oppression, and apparent debility: whereas, if the debility had been real, the same mode of medication would have destroyed the patient.
The morbid condition, atony or debility of one organ induced by over-excitement of another, arise from the withdrawal of the due nervous impressibility and diminished vascular stimulus from the atonic organ, by its concentration upon the one undergoing the undue and artificial stimulation. There are numerous cases in which excitants are of great importance, yet the extent of excitation indicated in disease, is a matter of interest to the physician as well as to the patient; for it must be confessed, the general tendency of the too free and protracted use of this class of agents is to impair the vital energies of the general system, when general stimulants are used, or of particular organs, when special ones are used, and finally, to wear out the natural sensibility and excitability of the organ, or even the whole system.
It may be asserted, we think, as an axiom, which can not be controverted, that super-excitation in a single organ, or in the whole system, whether it is dependent upon excrementitious matter retained in the system, and acting as a source of irritation, or is the result of incessant heating or stimulating medication, is always compensated for by a corresponding loss of action in some other organ or organs, or even in the entire system, and ultimately, with a diminution of the activity, or even the entire loss of the functions of the organ upon which this super-excitation or undue stimulation has been made.
From the foregoing remarks, it must appear evident that the long-continued use of stimulants of a hot and very exciting character, must be attended with great injury. There are some classes of physicians (Bashing the Thomsonians. -Henriette) who make the stomach the great theater of therapeutic action—the organ which is made to receive the major part of all their impressions, and the one upon which the nervous and vascular action is concentrated by the unbalancing weight of their whole mode of medication. This organ is first distended and relaxed by enormous quantities of hot fluid, strongly charged with capsicum, or the "composition powder," which renders it the great central organ of sympathies, a center of fluxion,—one upon which the vital energies are concentrated, while other organs are deprived of their ordinary vital afflux by the abstraction or destruction of the equilibrium just referred to. These pungent, acrid, heating medicines acting upon this relaxed and now morbidly sensitive organ, and followed up for from six to twelve hours, and repeated daily for weeks, and even months, sometimes until "three hundred courses" of the kind are gone through with, can not fail to debilitate the stomach and wear out its natural sensibilities, and produce those of an abnormal character, together with an irritation and thickening of the mucous coat, and a permanent chronic phlogosis. In this way the normal sensibility of the stomach is blunted, and often destroyed; while other organs lack innervation from the undue concentration which has there taken place. Chronic gastritis and dyspepsia are two very common forms of disease which result from the repeated and long-continued use of these pungent acrid excitants. The skin is another tissue upon which they act so frequently, and with such vehemence, that they often destroy its normal functions and produce a state of innervation, or loss of vital energy, incompatible with a state of health in other organs or parts of the system.
We do not deny that these measures are capable of exerting a very powerful influence over many morbid and diseased states of the system; on the contrary, we know that this is the case. We also admit that, through these influences, the functions of many other organs are frequently restored or improved; but we object to this course of medication, because the great burden of removing disease is imposed upon one or two organs. Instead of dividing the influences, and throwing the burden alternately upon different organs and emunctories, one or two are made to perform the eliminating functions which should fall upon all.
Another class of physicians pursue a very different mode of medication, and one that unbalances the normal conditions of particular organs, as well as the general system, and proves far more detrimental to the unfortunate victims upon whom its blighting influences are exerted, than the once popular "course" just alluded to.
It has been the practice with these physicians to administer mercury in all diseases to which man is heir (Bashing the Regulars. -Henriette), for the purpose of stimulating the liver to increased secretion, and through the diseased condition of this viscus, thus produced, remove the disease. Nothing could be more absurd than such practice; for in the normal condition of the system, this secretion is not formed for elimination, but to answer a further purpose in the economy. Though mercury, at this day, is almost entirely discarded by the better informed, yet it is still made the great therapeutic lever by a large class of routine practitioners; while that important gland, the liver, is made the fulcrum upon which their principal curative means are used. With this weapon of destruction they enter the arena of life and death, too often to insure victory to the latter, or to render the constitution a wreck, and the survivor the subject of the physician's care through life. If called to treat a disease, either acute or chronic, symptomatic or idiopathic, neuropathic or asthmatic, febrile or inflammatory, anemia or plethora, dropsy or excessive excretion, such a physician fancies the liver is torpid, and is suffering from some functional derangement or organic lesion. Indeed it matters not what the case may be, that organ is the one which must take on itself the great burden of throwing off the disease. Should it not speedily succeed in doing so, the salivary glands and gums must next receive especial attention. The gums must be "touched," and the glands abnormally stimulated, in order to subvert the original diseased condition, by setting up a new and abnormal action in the system, counteracting the original one by substituting its own. To act upon the liver, remove its torpor, increase and regulate its secretions, restrain them if excessive, render them healthy if unhealthy, etc., etc., appears to constitute in the minds of mercurialists the great therapeutic indications to be fulfilled.
As has been before stated, by stimulating one organ, and making it the point of undue excitation, either general or local irritation may supervene, fever may follow, other organs be rendered torpid or debilitated, and this undue stimulation not unfrequently wears out or greatly impairs the liver, if it does not destroy life itself. The continued excitement of this organ by such treatment is one of the most prolific sources of chronic hepatitis, torpor or derangement of that organ, that can be named; indeed, we may safely say that this one agent, so often used, and so entirely depended upon to remove all hepatic derangements, causes more of the identical diseases which it is so often given to remove, than the sum total of all other agencies. The use of mercury to fulfill the indications referred to, is doubtless one of the greatest fallacies of the dominant practice of the nineteenth century, and one which in a future day, and that by no means a distant one, will be viewed as one of the most marvelous and visionary practices that ever obtained countenance from the great mass of the medical profession. Happily even now the more candid professors and practitioners confess that the liver is an organ "more sinned against than sinning."
It is scarcely necessary to refer to the effects of alcohol as a stimulant, as they are known to all. It is an agent capable of doing a great amount of good when judiciously taken, "in disease"; but if too freely and too frequently used, and its use persisted in for any considerable length of time, it is capable of doing a more than equal amount of injury. The excitement which it causes in the system is followed by a corresponding loss of action. It produces enervation, stony or debility of some organs, while others are unduly excited; which excitation is succeeded by irritation, chronic inflammation, ulceration, and a thickening of the mucous membrane of the stomach; and finally by an entire loss of its natural sensibilities and functions. Visceral obstructions, dropsies, torpor of the glandular system, phrenitis, apoplexy, etc., are but so many pathological states of the system induced by undue and improper stimulation. All modes of stimulation, if carried beyond a certain point, result in a morbid over-excitement of the organ acted upon, and finally eventuate in the entire loss of its normal sensibility.
In atonic states of the stomach, when the mucous and muscular coats have lost their tone, when the food taken produces oppression, when there is flatulence, acid eructations, and the general evidences of dyspepsia, excitants become valuable. If the disease is transient, and arises from previous over-excitement which has produced a temporary exhaustion, ether, alcohol, wine, the essential oils, capsicum, aromatics, etc., may palliate, or even give entire relief. In the flatulent colic of children, aromatic excitants sometimes give prompt and speedy relief. If, however, these symptoms are protracted, we may rest assured that it is not a mere temporary loss of nervous energy, but a more permanent disease, in which agents more permanent in their influence upon the system, are demanded. In such cases, excitants combined with tonics comprise our most efficient curative means; gentle stimulation arouses the torpid gastric sensibilities to the influence of tonics, which impart permanent tone to the organ, and often restore it to its normal state.
In violent spasm of the stomach or bowels, dependent upon the translation of gouty irritation to these parts, unattended with inflammation, the most diffusible stimulants, either alone or combined with narcotics, are of great importance; external excitants or revellents to the epigastric region are also useful. These combined influences diminish the erythism of the nerves implicated, and frequently give relief.
In constipation, not attended with inflammation, excitants combined with cathartics often prove valuable auxiliaries, by stimulating the muscular coat, and thus quickening the peristaltic action of the bowels, facilitating the action of the cathartic. They are also valuable as correctors of cathartic medicines, as they prevent griping. The use of excitants in cases of nausea and vomiting, arising from pregnancy, hardly fails to palliate, and not unfrequently entirely removes these unpleasant symptoms.
Stimulants are important in the advanced stages of febrile and inflammatory disease, when a high grade of excitement no longer exists; even when the prostration is not great, if the arterial excitement is not very vigorous, the moderate use of stimulants will often hasten the progress of convalescence. In fevers of an adynamic type, when the prostration is great and the vital powers are apparently nearly exhausted or rapidly sinking, the pulse feeble and thread-like, a cold, clammy sweat, etc., active, diffusible stimulants of the most powerful kind become an indispensable part of the medication—their external employment is also demanded. In typhus and typhoid fevers, where the system is prostrated by the vitiated character of the circulating fluids, and a tendency to putrescence, great advantage is derived from the use of stimulants, either alone or in combination with tonics.
In passive dropsies, as auxiliaries to diuretics, they often exert a salutary influence. By their stimulating and exciting powers they impart new vigor to the atonic vessels, and thus counteract exudation.
The same remarks apply to their use in passive hemorrhages, indicating great prostration of the vital powers, and in petechia arising from the passive transudation of the diseased and dissolved blood, through the relaxed parietes of the atonic vessels. These hemorrhages are of frequent occurrence in adynamic fevers, typhus, typhoid, and other malignant and putrid fevers, scorbutis, etc.; in which cases the local revellent influence of an active excitant, as the capsicum, together with the increased vital energy which it imparts to the atonic vessels, recommend them to our use.
In general debility, torpor or languor of the system, when the circulation is sluggish, in the atony of old persons, and enfeebled and enervated states of the system which occasionally occur in both the old and the young, or which arise as secondary results of other diseases, excitants, alone or conjoined with tonics, are the therapeutic agents upon which our main reliance must be placed.
Paralysis is a disease of the nervous system, in which stimulants, both as internal and external agents, may be used with a prospect of advantage. When, however, the paralytic affection arises from a lesion of the cerebro-spinal axis, congestion or inflammation of those parts, this class of agents are contraindicated.
A gentle excitant in hysteria, may sometimes be used with much advantage; a combination with antispasmodics increuses their value. In other nervous affections, palpitation of the heart, headache, delirium tremens, and in all cases where there is either a permanent or transient depression of the vital powers, the diffusible stimulants, as camphor, wine, ammonia, etc., may be used as palliatives, or in some cases as curative agents.
Aromatics are spoken of by some authors as a distinct class of excitants or stimulants, but a distinction of this character is wholly uncalled for. They may be defined to be stimulants possessing a very fragrant or agreeable odor, and which when masticated or taken into the mouth, impart a sensation of warmth and pungency to the taste. Many of these aromatic stimulants are also tonic and astringent.
These medicines are also termed carminatives, and are employed very frequently to remove flatus from the stomach and bowels; but this effect depends wholly upon their local excitant influence upon the mucous membrane of the stomach and bowels, and the transmission of that impression to the contiguous muscular coat, from the action of which the expulsion or diffusion of the flatus takes place, and relief follows.
If flatus accumulates in the alimentary canal, the muscular fiber becomes paralyzed from over-distension, the bowels losing their wonted energy and contractile power, are incapable of expelling or diffusing it through the tube; hence the pain in flatulent colic. In this case an aromatic stimulant imparts tone and increased energy to the stomach and bowels, which enables them to contract upon it, and expel it through the cardia or pylorus, if in the stomach; if in the bowels, it causes a diffusion or an expulsion downward.
Conditions Contra-indicating their Use.
Stimulants are contraindicated in cases of gastro-intestinal irritation or inflammation. In such cases their administration is attended with increased phlogosis.
In febrile and inflammatory affections, excitants are improper during the early stages, and it is only in the advanced stages of these diseases, after the arterial excitement has been moderated, and rapid prostration is manifestly unavoidable, that they are proper. Even in these cases, if there is pain in the epigastric region, if it is tender to pressure, if the distress is increased by the use of warm drinks, and the edges and apex of the tongue are red and dry, stimulants are highly improper.
In hypertrophy of the heart, in palpitation of the heart, if it depends upon an organic disease of that organ, stimulants are inadmissible.
They are also contraindicated in phrenitis, apoplexy and congestion of the brain. Under circumstances of this character, their employment would be highly prejudicial to the patient.
In neuralgia, chorea, tetanus, epilepsy, etc., excitants are occasionally used with profit; but as a general rule they are unimportant, and in many cases very prejudicial. In these cases tonics are more permanent in their influence upon the system, and take the precedence over stimulants, especially if coupled with antispasmodics.
The American Eclectic Materia Medica and Therapeutics, 1898, was written by John M. Scudder, M.D.