Tonics are medicines which produce a permanent exaltation of the energies of the general system, without materially increasing the vital manifestations in any particular organ. They give tone to the muscular system without increasing the temperature of the body or rapidity of the circulation, producing no immediate and marked excitement like stimulants. Their influence is manifested by a very slow and permanent exaltation of organic action, evinced by an increased force of the circulation, and increased muscular power. The heart contracts with more force, but its contractions are not increased in frequency; the pulse acquires fullness and firmness, and loses that soft, flaccid and atonic character which is a manifestation of debility. The protracted use of tonics may produce an increased temperature of the body and an acceleration of the pulse; but these are but secondary effects arising from increased nutrition.
From what has been said of the influence which they exert, it will readily be seen that they are particularly adapted to atonic states of the system. Their primary sanative impressions are doubtless made upon the nervous system, while the manifestation of these impressions is seen in the increased tone of the muscular system, in the improved state of the secretions, in the augmented force and fullness of the pulse, and in the increased rapidity and perfection of digestion. The increased energy which they impart to the nervous system, the impetus which they give to the circulation and the improvement in the digestive functions, together with the increased secretion and absorption which they effect, are among the many evidences of their sanative powers.
Very peculiar, and apparently very dissimilar effects upon the secretory organs and tissues follow from the use of tonics, under different pathological conditions of these organs and tissues. When the secretions become abnormal and superabundant, from an atonic state of the secretory organs, this class of agents have the power to restrain and control them. Thus, if the cutaneous exhalation becomes superabundant from debility, as is the case in the advanced stages of phthisis, typhus and typhoid fever, etc., tonics often promptly restore the tone of the system and arrest it. Also, in phthisis and other diseases of the respiratory apparatus, when the secretion from the lungs becomes excessive from debility; and when this discharge would tend to increase that debility, tonics, combined with astringeuts, are of much value in arresting the secretion. The same remarks apply to diabetes, chronic diarrhea, leucorrhea, menorrhagia, passive hemorrhages and passive dropsies; in all of which cases, tonics will be found important auxiliary agents in restraining the morbid discharges. When, on the contrary, the secretions are lessened or arrested from torpor or atony of the organs, or from a languid or enfeebled state of the circulation, or of the general system, tonics are by no means an unimportant class of agents in aiding in the reestablishment of them. If the kidneys, skin, uterus or lungs, fail to furnish their due secretion, from a torpid state of the organ, or from an enfeebled state of the general system, tonics are of much importance in restoring them; in such cases they exert a diuretic, diaphoretic, emmenagogue and expectorant influence.
Tonics are mostly derived from the vegetable kingdom, and are remarkable for their bitterness; though from the similarity of their action, we include in this class the mineral acids and the chalybeate preparations.
The chalybeates do not, like the bitter tonics, act topically upon the stomach and alimentary canal, imparting new vigor to the parts with which they come in contact. They act on the restorative principle entirely; being absorbed, they supply a material to the blood, improving its quality, and in this way exert a tonic influence upon the entire system. Iron is found to be an important ingredient in the red globules of the blood; and when these globules are deficient, as they are in anemia, the administration of iron will use a regeneration of these, and a restoration of the system to health.
Action of Tonics.—Tonics act in two ways upon the system, producing their restorative effects.
1st. By their topical influence they give increased nervous and muscular energy to the stomach and bowels, and stimulate the mucous membrane to normal action; they thus improve digestion, increasing the appetite, and improving the quantity and quality of the chyle. If digestion is imperfect, the chyle must be unhealthy and scanty, and as the chyle supplies the material for the formation of the blood, which in turn supplies the system with the material to replenish the waste of tissue, and for the growth of the body, it is evident that normal digestion must be carried on, if the system maintains its healthy functions. Tonics, then, by their influence over the alimentary canal, prove indirectly restorative, by increasing the appetite, increasing digestion, chymification and chylification, and furnishing a healthy pabulum, both in quantity and quality, for the formation of the blood.
2d. All of this class of agents are readily soluble in the fluids of the body, and hence are absorbed into the circulation, and act from it upon every part of the system. We have already seen that they exert a tonic and strengthening influence when topically applied to the stomach; and we may notice a similar influence, from their application to indolent ulcers, wounds, etc., when applied so that we can notice their effects. If this is the case then, that they impart strength and tone when brought into contact with the tissues, as it undoubtedly is, we have a solution of their effects after absorption. The circulation conveys them to every part of the system, they are brought in contact with every fiber and every cell; and if they act in the circulation as they do when topically applied, they give new energy and tone to every part.
They likewise act as restoratives in many cases, adding to the blood some material that was deficient in it. In this way both the vegetable bitters, iron, acide, and alkalies act as tonics. For a further description of the action of these remedies see general therapeutics.
Tonics not only produce their specific impressions when taken internally, but also when applied to the surface of the body, from which they may be absorbed. Their external application is of much importance in all cases where there is extreme debility, and when the stomach is weak and irritable, and will not tolerate the use of medicine. In all cases of extreme debility, they may be used as a bath, or by enema, when they will exert their ordinary invigorating influence upon the system. In the "night-sweats" of debilitating diseases, they are often of much advantage, strengthening the skin and checking the morbid secretion.
Their topical application deserves a passing notice. They are frequently applied to old atonic and indolent ulcers, and also to gangrenous parts, as topical tonics, with much advantage. We thus cleanse the gangrenous or ulcerated parts thoroughly and frequently with a strong decoction of the tonic, and also apply it in the form of a poultice mixed with slippery-elm.
Tonics are administered with much advantage in dyspepsia. When the stomach is debilitated, its coats do not act with the necessary energy upon the alimentary mass, and the gastric secretions are either scanty, or do not possess their proper solvent powers, and chymification will therefore be imperfect, and the train of dyspeptic symptoms follow. These results are counteracted by the use of tonics, in the manner already referred to.
In all cases of asthenia they are indicated, unless it be connected with some local inflammatory affection that would be aggravated by their use. They become important agents in the advanced stages of most of the acute diseases, after fever has subsided, and when high inflammatory action no longer exists; in such cases they enable the system to throw off the disease, and render convalescence much shorter. In adynamic fevers, as typhus gravior, typhoid, scarlatina maligna, gangrenous erysipelas, or in any case where there is a tendency to gangrene or putrescency, they are agents of the first importance. In smallpox, where the vital powers are much prostrated, in carbuncle, scorbutis, scrofula, and other similar affections, their employment constitutes an important part of the treatment. They are also indicated in passive dropsies and hemorrhages.
Debility of a single organ or of the entire system, predisposes to the morbid influences of surrounding causes of disease, as the infection of certain contagious diseases, changes of temperature causing the retention of a customary secretion, the morbid effects of miasmata, etc. Tonics aid the enfeebled energies of the system in warding off these extraneous causes of disease. Malarious influences occasionally produce almost every variety and type of fever, particularly the intermittent, beside many anomalous diseases which have a more or less periodic character. Hence we have headache,—especially hemicrania,—neuralgia, toothache, rheumatism, deafness, dyspnea, convulsions, etc., assuming a periodic form. It has been proved beyond cavil, by medical reports from the malarious coast of Africa, that tonics administered as prophylactics, are a certain preventative against this influence.
In diseases marked by a periodic character the most powerful tonics are administered. Some of them are supposed to possess antiperiodic in addition to their tonic properties, and are therefore called antiperiodics. The cinchona and its alkaloid principles are examples of this kind. The question then arises, do tonics arrest these periodical diseases by virtue of their tonic properties alone, or are they possessed offebrifuge or antiperiodic powers in addition to these. The latter view appears the most probable, for we find that those agents which act as antiperiodics possess but feeble tonic properties, in diseases in which this periodic element is lacking; that is, they do not increase the appetite, improve digestion, etc., in cases of common debility. These agents may likewise be administered in any stage of the fever, and if the stomach is not in an irritable condition, they will lessen instead of increasing the pyrexia. Why certain agents of this class exert this peculiar antiperiodic property we are unable to explain, any more than we are why some causes produce periodic fever; the fact, however, is evident that some of then possess a power over this form of disease that is not possessed by others of the class.
As probably the best explanation of the action of the antiperiodic tonics we will introduce two quotations. Liebig in considering this subject, says:—"This action is commonly said to be dynamic—that is, it accelerates, or retards, or alters in some way the phenomena of motion in animal life. If we reflect that this action is exerted by substances which are material, tangible and ponderable; that they disappear in the organism; that a double dose acts more powerfully than a single one; that, after a time, a fresh dose must be given if we wish to produce the action a second time; all these considerations viewed chemically, permit only one form of explanation; the supposition, namely, that these compounds, by means of their elements, take a share in the formation of new, or the transformation of existing brain and nervous matter." Dr. Wood says in relation to this subject: "I know of no better explanation of the antiperiodic property, than that which supposes it to depend upon the powerful influence exercised by the remedy upon the nervous centers, through which probably the paroxysms are produced. Every consideration in connection with the peculiarities of regular intermittent diseases, leads to the conclusion, that the paroxysms are produced by an influence acting through the cerebral centers, without which the result would not take place. Now, if these cerebral centers can be preoccupied by a strong impression from some other source, they may be rendered insensible to the morbid influence, and the paroxysm, therefore, is set aside."
In addition to this influence upon the nervous system, antiperiodics undoubtedly exert a specific and decided influence upon the blood. This they may do in two ways:—First, by counteracting the chemical changes going on in that fluid,—preventing the septic action of the morbid material (which we suppose to be the cause of the fever) upon the blood. They also give increased vitality to the circulating fluids, (see antiseptics). Second, by causing an increased elimination, they remove the cause of the disease. We have long since arrived at the conclusion, that quinia, which may be taken as the type of the antiperiodic agents, owes its virtues in part, in periodic diseases, to its action on the excretory organs. When successfully administered it invariably causes relaxation and increased secretion from the skin, and this secretion gives evidence by its sensible qualities of an increased elimination of solids. It likewise increases the action of the kidneys, and consequently elimination by this channel. To sum up then, we may say, that antiperiodics act upon the nervous centers, increasing innervation, and changing the character of nervous action; that they act as tonics, increasing the vital force of the system; that they act as antiseptics, counteracting the septic tendency in the blood; and that finally they act as diminutives, removing morbid material from the system.
In conclusion we may say in reference to this clase of agents, that their use is indicated whenever the system is depressed below its normal level. They act directly in support of the vital force, and not as is the case with stimulants to produce merely nervous excitation; they therefore assist nature in the removal of disease. "Tonics," says Headland, "are among the most useful of all medicines. And it is certainly not the least of their recommendations, that we can seldom or never do harm by their use. They are remedies, but not poisons. Many a man has been killed by opium, many a constitution ruined by mercury, but it has never been known that quinine has done the one or the other."
The American Eclectic Materia Medica and Therapeutics, 1898, was written by John M. Scudder, M.D.