The Action of Medicines in the System

cerning the subject of which I have to treat; because by so doing I may to some extent indicate what points are to be regarded as determin

scertained by observing the manner in which they have arranged and classified them,

We are now to make inquiry as to the action of classes and groups. So that, in examining classifications as a key to the opinions

be regarded. We may ask,-1. What is the ultimate effect of its action on the system

ion of a medicine, of the direction of the action of

e call another an alterative, because the manifestations of vital action are somewhat different after its use from what they were before. The last question

nd according to this their predominant idea, I will take the liberty of grouping them into three schools for the sake of convenience; considering, first, some theories and therapeutical

me time or in some way act on the nervous system. The same term means a very different thing when found in a classification based on the mode of operation of medicines, for then it signifies a medicine acting on the nerves in a certain way which is defined, and it conveys to us an amount of information respecting that medicine and its applicability which we had not otherwise acquired. A classification of this third kind, though difficult of construction, would naturally be of great practical and scientific utility. The precise mode in which groups of medicines operate has first to be discovered and laid down, together with the results of that operation; and it has then to be proved that each remedy included in a class operates in the exact way predicated of that class. None which do not do so

mate Effect of Medicines, and C

ode of operation or behaviour of a medicine after passage into the system; nor do they ask whether this action is especially dir

. Dr. Murray indeed confounds these two effects, and adopts an idea on this subject which was originated by Mr. Brown.

Yo

mical

tics

tal A

orting

rie

sing a

and tra

ts, Astrigents, Alt

mane

ni

ing action

mari

eants, Sedative

onda

urie

nsible

cif

and the word insensible, applied to the third class, is a confession of absolute ignorance. It does not attach to a medicine any distinctive character to say that we know nothing of its operation. Pursuing the subdivision further, we find that the distinctions are not well maintained. Tonics support strength as well as cause action; and it can hardly be said that the action of an Alterative, such as mercury, is partial and transitory. It seems u

t an erroneous one. There is no such universal distinction. A medicine which at one time raises or excites the vital forces, may at another time depress them; it may do one thing with a sick man, the other thing with a healthy man; it may have the one effect when taken for a short time in moderation, the other effect when taken for a long time or in excess. In fine, the result of the operat

nes, we may proceed to divide them into groups in a natural way. Food and liquids are of use in the nutrition of the tissues, and will form the first class. A second set of substances act so as to expel from the body certain humours and secretions. Another

Du

men

ia, Dem

cua

ina, Expectorantia

ulan

irritant

ia perm

ia tran

imen

antia, N

em

, Alk

imulants are divided into those which are transitory in action, and those whose effect is permanent, as Tonics. Dr. Duncan is concerned only with the ultimate effect, and enters into no theory respecting the action of To

e blood the agency of certain morbid poisons? In an arrangement founded on ultimate effect, they should be grouped in a class as Alteratives, as medicines which result in altering for the better the condition of the system. Both Dr. Duncan and Dr. Murray seem to have thought that no medicines could act in the fluids but such as have a well known chemical effect upon them. It cannot be that medicines should be able to affect t

ement of this kind should be constructed, I shall quote as another specimen the

Mu

l Stim

fus

rco

spasm

man

on

rine

Stim

nts, I

cal A

ical A

t is, that they both produce a primary stimulation followed by a secondary depression; only that, in the case of Narcotics (under which head all Sedatives are included) the stimulation is very brief, and rapidly passes away, to be followed by a great depression. Now, even if this were true, the most prominent action would be the depressing effect, and it is on the most prominent action that denominations such as these are usually based. But it is well urged by Dr. Thomson that in the case of true sedatives there is no stimulant action whatever; and it is manifestly unreasonable to suppose that the depressing effect follows as a consequence on the primary stimulation, when th

al Tendency of Medicines, and C

make an impression on a certain organ or set of organs, to select those medicines which especially influence it or them. There is no doubt whatever of the existence of these local tendencies. There is no doubt that some medicines, such as Iodine, Bromine, Mercury, and Iron, tend especially to affect the blood and the blood-making organs, as the liver and spleen, rather than to act on the nervous or glandular systems. That some tend particularly towards the nerves, and prefer individually different parts of the nervous syst

ems to be, that we may quickly learn from it the general action or effect of a medicine; so that, if it is stated to have many different tendencies, and is ranged under no one particular head, we can gain from this no very distinct practical information respecting it. In an arrangement of the kind that we have last examined, the most important result is the chief point considered. Thus it is rendered useful. And in one of the third kind, where the mode of operation is the gr

dicines seem to have no relation to those that act on the glands, though connected with them as Stimulants by Dr. Murray. They are thus separated. Tonics are also separated from Stimulants, and included with those which act on the muscular and sanguiferous systems. This seems to me to be a correct view of their action. I do not consider that they act prim

lassification of Eberle, which seems to have been the prot

rle's C

on the intestinal ca

cting on the m

e uterin

e nervou

circulat

organs of

respirat

Stimulants are classed as acting on the circulating system. They no doubt act on the nerves, and then through them on the vessels; but so also do Narcotics, from which they are separated. If in class E are only included medicines acting on the organic nerves of the

to be thrown into the shade, but should rather be placed before all its other operations, as being of more importance than any of them. Dr. Pereira arranges in six classes those medicines which are given internally, having previously made three classes of external or topical a

eira's

IV. H?

pan?

?mat

V. Pne

VI. Ne

ebro-s

nglio

VII. C

III. Ec

IX. Ge

f Lead, Silver, Copper, etc. In the selection of the above name attention is paid to the abstract physiological effect of these medicines, rather than to their therapeutical applications. The impoverishing of the blood may be the ultimate action of such a medicine as Potash or Mercury, but not exactly the primary operation for which it is used in medicine. It is produced by the remedy when taken in excess, and not when given in small doses. Neurotics, or medicines which act on the nerves, are divided into those wh

to object, are, first, the multiplicity of classes, and secondly, t

s, among Neurotics. The same with C?liacs; for Cathartics, found among Eccritics, are the most important medicines acting on the intestines. Genetics contain medicines which control the uterine and sexual systems, which may all be reckoned among Neu

th Dr. Pereira, who ranks them among Neurotics. Emetics are classed by him among Eccritics; but it seems to me that their action is either external, and of an irritant nature, or when from the blood, that it is exerted upon the nerves of the stomach. The stomach is not, like most glandular organs, a simple emunctory, and it is affected by medicines in a different way. Whereas gland-medicines increase secretion, the chief action of Emetics is to cause an evacuation of the contents of the stomach by contraction of itself and of other muscles. All substances w

is any mention made of the primary action or modus operandi of medici

e of Operation of Medicines, and

such theories as these that I am more immediately concerned in this Essay. Such writers have dived into a deeper subject than those who have directed attention to the general effects or tendencies of medicines rather than to the means by which such results are att

the modus operandi of therapeutic age

hanical p

emical p

al or vital

is a tendency in the human mind to explain every thing; and it was only natural for men who knew little of chemistry or of ph

in 1689, gave it as his opinion, that the shapes of the minute particle

igure of any of the wheels, we should be able to tell beforehand that rhubarb will purge, hemlock kill, and opium make a man sleep." This idea did not originate with the great metaphysician. The first rudiments are to be found in the doctri

he fluids often depended on their being too viscid, and that this condition might be improved by agents which should attenuate this viscidity. Dr. Archibald Pitcairn, a Scotchman, the immediate predecessor and contemporary of Boerhaave, was elected to the Chair of Physic in Leyden in 1691, and was also an able exponent of the mathematical theories. But he applied to physiology those ideas which were employed by the other to throw light upon physic; if that may be called light which was at least an improvement on the ignorance which preceded it.[8] He explained the digestive

ble, when shaken about in the vessels, to break up and to annihilate those crude acrid humours which were the causes of disease; and that Arsenic acted as an irritant by

s ponderous particles may break the weak lamell?.[10] He was the Court Physician in the reign of George II. He accounted for the poisonous

in subtle vapours which emanated from them, and affected the vital spirits. This was a very misty notion. He stated that he

, that the operation of some medicinal agents, particularly those which act on the nerves, may depend in some way on the shapes of the atoms of these substances, as related to those of the tissues which they influence. At least, there is no other possible explanation of the power of such substances. We know that the nerves are very much under the influence of mechanical impressions, upon which depend the phenomena of two at least out of the five senses, those of hearing and touch, as probably also of the other three, if we understood them better. We know also that if we accept the Atomic theory, by which so many chemical phenomena are cleared up and explained, we must admit a certain defi

e stomach and intestines. Poissenille and Matteucci have attempted to prove that the action of saline liquids in causing purging, and that of a solution of morphia in preventing the sa

e to explain the general action o

grees of each of these properties. In the Pharmacop?ia Londinensis of 1702, translated by Dr. Salmon, it is stated of every herb that it possesses in a certain degree one or more of these qualities. It is amusing to find Dr. Salmon in great doubt as to w

ed to prepare a medicine that should render life perennial. A most impracticable formula for the preparation of this Elixir Vit? was given, among others, by Carolus Musitanus. Basil Valentine, who flourished in the fifteenth century, did good service by adding to the Materia Medica the preparations of Antimony, as well as the Mineral Acids. In the sixteenth lived Paracelsus and Von Helmont, the latest and most enthusiastic of the medical

of fermentations in the blood which took place in the neighbourhood of the glandular organs. (Vide Eliminatives.) In some of their ideas there was much that was reasonable; but it must be confessed that they were rather imaginative than argumentative, and, knowing really but little of the principles of that science on which their system was ostensibly based, they were ill-q

t to be wondered at that most of them have faded away before the advance of science, and particularly before that wonderful de

planation of the action of these remedies is generally adopted by writers at the present day. It is known that they have powe

fect the condition of the blood; but that acids tend to dissolve and destroy the corpuscles, wherefore he terms them H?matolytica

of medicines in general. This is an error to which those who have devoted th

m to me to be untenable,-for what reasons I shall have to show when I consider these remedies. Liebig has hazarded several other explanations of a similar kind, of which the following is an example:-"The frightful effects of Sulphuretted Hydrogen and Hydrocyanic Acid are explained by the well-known action of these compounds on those of Iron, when Alkalies are present, and free Alkali is never absent in the blood." (Organic Chemistry, p. 274.) Now in the first place it is not proved that the complete abstraction of iron from the blood would occasion sudden death, though doubtless it is a necessary constituent of that fluid. Further, Prussic Acid acts on

considerations, it is impossible to account for the influence of all alike in this way. For at least the

s concern actions which could only take place in the living body. They may be termed general principles, because the grounds on which they are based are neit

But when others have adopted a single inflexible hypothesis to account for the action of all alike, this is found, as might be supposed, to be of a very untenable character. I will now consider very briefly several such ideas; first

rees of s

unter-st

oppo

imilar

elimin

terative

ious coun

al agents were stimulants, only that some acted so powerfully as to produce "indirect debility." These latter were to be used in sthenic, the others in asthenic disorders. But it is to be urged against this idea, that many sedatives produce no appreciable degree of "primary stimulation;"

dicines on this plan. The two classes of medicines are termed "Hypersthenics," and "Hyposthenics,"-i. e. Stimulants, and Contra-stimulants, or Sedatives. These were to be used respectively in asthenic and in sthenic disorders. But this ide

ary condition the disorder is to be neutralized. This was the maxim of Hippocrates-τα εναντια των εναντιων εστιν ιηματα-"contraries are the remedies of contraries." (De Flatibus, par. iii.) On this principle we give purgatives in constipation, opium in diarrh?a, sedatives to relieve pain, sudorifics to combat

n such remedies are known, their employment would certainly be singularly objectionable. Who would administer Strychnia in tetanus, Opium in congestion of the brain, or irritants in Gastrodynia? The arguments alleged in support of the theory are of the most fallacious kind. For example, it is said that diaphoretics cured the sweating-sickness, and purgatives are given with advantage in diarrh?a, on the "Hom?opathic" pr

ina, and also a condition resembling hydrophobia, and thus cures both of these disorders. Of these three propositions it is almost needless to say that all are equally erroneous. Further, an experimental trial of this principle was made by Andra

expectant" treatment of diseases, he thought it better to rely on the "vis medicatrix natur?," than to make rash or violent attempts at a cure. He maintained that what we call a disease was in fact "no more than a vigorous effort of nature to throw off the morbific matter, and thus recover the patient."[14] He proposed, therefore, that our efforts should be directed to assist nature to procure the evacuation of a poison, promoting its elimination by acting on the various secretions-as by purgatives, diaphoretics and such medicines. For he had noticed that in fevers and febrile disorders the crisis or turning-point was generally accompanied or preceded by an increase in one or more of these secretions, and he regarded this as an indication of the treatment to be pursued in all such cases. "That," said he, "appears to be the bes

, when thus needed, of evacuant medicines; but at the same time we must allow that there are many other advantageous modes of treatment,-that we may s

lsive action, by producing a distinct effect which diverted the attention of the system from the disease. His followers have

their own. The term Revulsive is especially applied to medicines which produce a powerful local effect, and are supposed so to occupy the attention of the system

s medicines into Biolytics, tending to dissolve life and structure; Anabiotics, which tend to stimulate the same; and Agonistics, tending to produce a "defensive" process, and acting by revulsion.

s Classi

ica. (Dep

ca. (Mercury,

tica. (Acid

ytica. (S

tica. (Ex

iotica. (A

ca. (Diffusibl

ica. (Opium,

tica. (Re

istica. (Pur

onistica.

ica. (Emetics,

e is too much generalization, and, what is more important, that many medicines may cure diseases without necessarily causing either excitation or depression or acting distinctly by revulsion. The only principles of action admitted here are these three, the same which are adopted by the disciples of Broussais. To suppose that medicines acting on the glands are only of use as revulsives, tha

many and too great to be thus easily accounted for, and we do not know enough about many of them to be able to define their operation so exactly. A

d the threefold action supposed by Broussais, were further advances in the right direction. But these views were all too confined. Correct as far as

y of his knowledge, each of these writers was tempted to apply the view which was applicable to a certain set to all remedies alike. On

e, different diseases. This counteraction is distinct from contrary action; it may be direct or indirect; and it allows of any action in a medicine, tending to restore health, except an effect similar to the disease. Such a view was adopted by Dr. Cullen, the well known Nosologist, who lectured at Edinburgh towards the close of the last century. He discarded all special and confined vi

lish writers on this subject, appears, like many othe

that disorders, generally temporary, which depend on nervous derangement, are to be benefited by remedies which affect the nerves; and in the same way that a laxity of

e vital in its nature-that it must be such as could only be exerted in the living body. Even then we are unable to fix upon any single rule or formula which shall be capable of accounting for the act

ntroduces my