But it should be observed that at least three other explanations of the action of this remedy have been proposed, each of which is possessed of a degree of plausibility.
Some have ascribed its efficacy to the union of a cathartic with a sedative effect, and have even substituted for it a combination of Opium with a drastic purgative. Those who adopt this view of its action aver that Colchicum acts bestwhen it purges freely. But though Purgatives are often of use in gouty disorders, it is generally found that Colchicum operates most favourably when given in too small a dose to produce any purging.
Colchicum stimulates the function of the liver, which is generally deranged in gouty disorders. Mercury, which also promotes the secretion of bile, is in this way useful in Gout. It seems that the formation of this secretion is in some manner essential to the integrity of those blood-processes which are disturbed in arthritic diseases. It might therefore be supposed that Colchicum too acted as a Cholagogue. But it is not clear that it increases the secretion of the bile in any very marked degree.
Thirdly, it is affirmed by some that this medicine is of use in eliminating uric acid from the blood, this product being supposed to accumulate in the system before the paroxysm of Gout. It is said that under the action of Colchicum the natural amount of this substance in the urine is much increased. This would be an important fact if it were certainly proved. But it does not seem to be so; nor is it clearly shown that the observed increase in uric acid is not a symptom of the disorder, rather than of the treatment.
Colchicum is more or less applicable in the gouty forms of Rheumatism, in Lithiasis, and in acid dyspepsia, but it is most efficient in the simple gouty paroxysm.
There are several objections to the indiscriminate use of this remedy. Some have observed that though it cures for a time the gouty attack, it causes the next assault of the disease to recur more quickly than it would otherwise have done. The dose also certainly requires to be considerably increased on each successive occasion. Sometimes this medicine produces a great depression of the spirits. Dr. Todd believes that Colchicum has often a tendency to change the common acute form of Gout into an asthenic form which is lessamenable to treatment. So that, altogether, it is perhaps a good rule to treat the patient without Colchicum as long as it can be done with safety, adopting this medicine only as a last resource, when other remedies have been tried and failed. It ought rarely to be used in Rheumatism. In the asthenic form of Gout, or in old chronic cases, when there are chalk-stones on the knuckles, Quinine, Stimulants, and Purgatives, constitute the best treatment. Alkalies and Mercurials may prove serviceable in acute cases.
But it is certain that in many cases of this painful disorder Colchicum gives immense relief; and it often seems to be the only medicine that is capable of doing so. (Videpp. 194, 247.)
ARSENIC.
Class I. Div. II. Ord. VI.Antiphriodica.
Class I. Div. II. Ord. VII.Anticonvulsiva.
Class I. Div. II. Ord. VIII.Antisquamosa.
This medicine has already been noticed at considerable length in the account of the last three orders of Catalytic medicines. It is again noticed here as one of the most remarkable of those mineral substances that are used to counteract blood-disorders. It appears to be capable of exerting no less than three kinds of action in the blood, which operations result in the counteraction of Periodic disorders, Convulsive diseases, and certain Cutaneous eruptions. That must of necessity be a various and obscure agency, which is gifted with the power of arresting and controlling so great a variety of morbid actions.
It would seem that Ague and its kindred disorders are capable of being combated and cured in two different ways; by Restoratives, such as Quina, which appear to supply the blood with a certain needful material; or by Catalytics, as Arsenious acid, which operate by antagonizing a morbid action,which is either the cause or the result of the blood-disease. I have given my reasons for ranking Quina and Tonics among Restorative medicines. The following are the principal grounds for which Arsenic is included among Catalytics. It is unnatural to the blood, and is at length excreted from the system. It acts as a poison; and is able to work out in the blood a certain process of its own. It has no sudden action on the nervous system, like that which is possessed by Neurotic medicines. And it is able to counteract a number of disorders, as Lepra and Impetigo, which are assumed to depend upon morbid actions in the blood.
Arsenic has been recommended in Syphilis, but it exerts no marked power over that disorder. In ague it possesses this advantage over Quina, that it may be administered with safety during the paroxysm. The ordinary precautions in the administration of the Arsenical solution (Liquor Potassæ Arsenitis) have been already enumerated, viz., that the dose should be small at first, and afterwards gradually increased; that as soon as it produces swelling of the face and eyelids, or irritation of the stomach, it should be discontinued, or the dose reduced; and that it should generally be given on a full stomach, as it is then less likely to irritate. (Videpp. 140, 165, 170, 176, 207, 211, 213.)
AMMONIA.
Class I. Div. I. Ord. III.Alkalia.
Class II. Div. I. Ord. I.Stimulantia Generalia.
Class IV. Ord. II.Expectorantia.
Class IV. Ord. V.Diaphoretica.
This medicine may be taken as the type of simple General Stimulants. It tends to excite the nervous forces generally. The remedies of this group are not very potent in their action, Ammonia being perhaps as powerful as any of them. Alcohol, an Inebriant Narcotic, produces at first a greater stimulanteffect, but its action is followed up by a depression of the nervous forces, and an affection of the powers of the mind. This influence over the intellectual functions is confined to the Narcotic division of nerve-medicines, and is not possessed by Ammonia.
Ammonia is capable of acting chemically as an alkali in the system, and may be used in the various cases in which alkalies are wont to be employed; but it is inferior to Potash in such disorders, because its affinities are far less powerful than those of that alkali. It is also caustic and irritant when applied externally in any form.
Administered internally in solution, it has a power of quickening the action of the heart, and exciting the circulation generally. It is therefore particularly useful in the common case of fainting, or threatened syncope. This stimulant power is possessed only by the free alkali and its carbonates. And as the secretion of the stomach is acid, Dr. Pereira supposes that the free or carbonated Ammonia becomes neutralized before absorption; that it is therefore unable to act in the blood except as a salt, and can only operate as a Stimulant while in contact with the coat of the stomach. Its influence must then be conducted by the nerves from the surface of the stomach to the heart. But though the nerves are the natural channels of various motor and sensory impressions, it is to assume an unprecedented thing to suppose that a medicinal action can be transmitted by their means to a distant part. For this and for other reasons it seems to me to be most likely that the solution of Ammonia is absorbed too fast in the stomach to be neutralized by the gastric juice. Or even if it were neutralized before absorption, it would probably be again set free on entrance into the blood, in which there is a slight excess of alkaline matter. Thus Ammonia would exist in the blood in a free state, except in those morbid conditions in which there is a general excess of acid in the system. I suppose the same to be the case with Potash, when it is given in any quantity. The great diffusibility of the free Ammonia would be an additional reason for its rapid absorption. When the gas is inhaled, as in the use of smelling-salts, and applied thus to the nasal and pulmonary mucous membranes, it must pass through to the blood in a free state, for these surfaces do not secrete an acid. And yet its effects in this case are the same as when it is taken into the stomach, which further renders it probable that in the latter instance it is absorbed free.
When there is an excess of acid in the system, Ammonia may be used as a Restorative. It diminishes the acid reaction of the secretions by combining with the acid to form a salt.
In ordinary conditions (i.e.when not required in the system) it has to be excreted from the blood. Both Ammonia and its salts act as Expectorants and Diaphoretics, being excreted on the mucous surface of the lungs, and on the skin. Free Ammonia is a better Expectorant than any of its neutral salts. The secretion of sweat contains an acid. The Ammonia which passes out on the skin combines with this acid. But on the pulmonary surface it is probably excreted free. For it is found that the careful inhalation of Ammoniacal gas has the same effect in augmenting the mucous secretion as the internal use of Ammonia. Ammonia is volatile, and soluble in air; and tends for that reason to pass off freely from those secreting surfaces which are immediately in contact with the atmosphere. (P. 278.)
It is supposed by some that diffusible Stimulants act simply on the ganglionic system of nerves, being able through them to excite the functions of the heart, vessels, and glands. But Ammonia is used with advantage in some cases in which the whole nervous system is implicated in the disorder. It has been employed in cases of Typhus, of simple febrile exhaustion, of Hysteria, Epilepsy. In such affections the brain is at least involved, if not often the chief seat of the disorder.
Spasms and convulsions are due to a general derangement of the nervous forces, and particularly of the brain, in which these centre and originate. Stimulants, by exalting the natural functions, counteract and control this derangement. It is thus that Ammonia and volatile oils are of use in convulsive disorders; but they are seldom of any permanent efficacy, as in most cases of Hysteria and Epilepsy there is at the bottom a blood-disease, of which the spasmodic fits are only the symptom and outbreak. (Videp. 176.) So also is there a limit to the efficiency of Stimulants in such cases as Typhus fever; there is a certain point of exhaustion beyond which they are of no avail. For I have attempted to show that though Stimulants are competent to exalt nervous force, they are unable to supply vital force. A degree of nervous force is necessary to the continuance of life; but when the powers of life themselves are ebbing away, it is impossible then to prolong any further the thread of existence by the exhibition of stimulant medicines.
The action of Ammonia is directly the reverse of that of Prussic acid, which is a General Sedative, producing Convulsions and Syncope. Ammonia is thus used in cases of poisoning by that liquid. (Videpp. 126, 227, 278, 283, 301.).
STRYCHNIA.
Class II. Div. I. Ord. II.Stimulantia Specifica.
Strychnia is the chief alkaloid and active principle of Nux Vomica. This medicine is comparatively simple in its action. It has no claim to the title of Sedative, which is sometimes applied to it. It does not affect the nerves generally. It has no direct action on the brain, but stimulates chiefly the function of the spinal cord, and its system of nerves. Of these nerves it affects the motor considerably more than the sensorybranches. Along with the spinal cord, it doubtless also acts upon that part of the brain which is immediately associated with the spinal system of nerves. But the function of reflex motion, which is thought to reside in the spinal cord, is particularly stimulated.
Strychnia is thus an exciter of muscular contraction and of motion; exalting sensation in a less degree. It has also apparently some action on part of the ganglionic system of nerves, by which it is enabled to promote the function of the stomach, and becomes temporarily a tonic when given in relaxed conditions of that organ. But it does not excite the action of the heart.
In cases of poisoning by Nux Vomica, the brain and the heart are unaffected. Tetanic and general convulsions are produced; and the immediate cause of death is a spasm of the muscles of respiration.
Strychnia causes a contraction of the muscles by stimulating the motor centres, and originating in them an impulse which is propagated along the motor nerves. So that when these centres are diseased, or the continuity of their fibres destroyed, it is unable to exert its power. It is used as a medicine in cases of Paralysis. But when the lesion of the nervous centre is of recent occurrence, or when it has been of so serious or extensive a nature as to admit of no repair in the course of time, the remedy will be ineffectual. It is only successful in cases where the injury to the nervous centre has healed up, and where the limb continues paralyzed merely because the motor nerves have lost the power to transmit the necessary impulse, from having been so long unaccustomed to the discharge of this office.
As it is able to act on the nerve itself, it is sometimes thought best to apply it to the affected part on a raw surface produced by a blister. The advantage of this plan is most obvious in the case of Lead-palsy, where the cause of theparalysis is local, residing in the nerve, and not in the centre. But in this case also it is necessary that the nerve-centre be sound. Dr. Neligan recommends Strychnia in Lead-colic, in which disorder constipation and distention of the bowel are produced by a paralysis of a portion of the large intestine.
Strychnia has been used with benefit by Dr. Golding Bird in cases of Phosphaturia connected with a functional derangement of the spinal cord. (Videp. 232.)
ALCOHOL
Class II. Div. II. Ord. I.Narcotica Inebriantia.
Class IV. Ord. V.Diaphoretica.
Class IV. Ord. VI.Diuretica.
We have already considered in order the peculiarities in action that distinguish Narcotics alike from Stimulant and Sedative medicines; how they tend first to exalt the nervous forces, and then to depress them, and have further a particular action on the intellectual part of the brain. We have observed that these remedies may be divided into three minor groups, which differ considerably, if only regarded in their action on the nervous forces generally. For that Inebriants approach very nearly to Stimulants, and Deliriants to Sedatives, while Soporifics occupy an intermediate place. We have seen also that though, during the stage of stimulation, these three orders tend all more or less to excite the powers of the mind, they differ characteristically in their secondary or depressing effect upon the same. That, with respect to our present purpose, the intellectual functions may be divided into three parts: the mind itself; volition and sensation, by which it is united to the body; and the special senses, by means of which it is connected with external things. And that the secondary or depressing action of Inebriants is such as toimpairthese three in a tolerably equal degree; that of Soporificsextinguishesfor a time sensation, volition,and the five senses, while it may leave the mind unaffected; but that of Deliriantsexcitesandderangesall the intellectual functions.
If these things are borne in mind, the physiological action of Alcohol will be tolerably understood when it is said to be an Inebriant Narcotic. But it must be observed that when given in small quantities its stimulant effect may be the chief action manifested, its secondary sedative effect may hardly take place, and the production of Inebriation, or drunkenness, may be altogether avoided. So much is this the case that Alcohol is by some regarded as a Stimulant. But the same thing is remarked of Opium, though in a less degree. And the effects of a large dose of Alcohol are sufficiently obvious to indicate its place amongst Narcotics. For the state of Inebriation may even pass on into coma, and death.
In small quantities, for the purpose of producing exhilaration, and of overcoming various depressing causes which are of daily occurrence, alcoholic liquors of various kinds, Beer, Wine, and Spirits, are habitually employed by a large portion of mankind. On the broad and important question of their use and abuse as articles of diet this is not the opportunity to enter.
In the form of Brandy (which is more agreeable to the palate,) Alcohol is applicable as a medicine in low Fevers, in asthenic Erysipelas, in Typhoid forms of Pneumonia, and in Collapse or Syncope produced by surgical injuries or other causes. It restores the action of the heart, and enables the system to bear up against the disorder. The stimulant action may be maintained, and the secondary sedative effect prevented, by a continual repetition of the dose. Thus when once the employment of this stimulant has been determined upon, it should be steadily and unremittingly persevered in until decided symptoms of improvement have shown themselves in the patient.
The tendency of the practice of the present day is towards a freer use of Stimulants, and a more sparing employment of blood-letting and antiphlogistic agents, than was some time ago prescribed. And this is probably an advance in the right direction; for in morbid actions there is altogether very little that is really sthenic; and it is, as a general rule, a wiser thing to support the system against the wearing action of a disorder, than to add to the heap of its various troubles another depressing cause.
But Alcohol is a potent agent for evil as well as for good. When large quantities are taken continually for a considerable length of time, it is capable of producing a chronic injury of the brain and mind. By impairing the function of the former, it brings on the shaking paralysis of Delirium tremens. By an action on the mind, it causes the strange hallucinations and the habitual despondency which characterize that disorder. Habitual drinking may likewise cause a chronic inflammation of the liver, called Cirrhosis, which is succeeded by Dropsy. Alcohol is absorbed by the stomach; and, on passing through the Portal vein to the liver, may there produce this condition of the organ by the continual irritation which it excites.
When taken in considerable quantity Alcohol passes out of the system by the skin and kidneys, and thus acts as a Diaphoretic and Diuretic.
But Liebig states that when taken in small quantities it does not pass off in the secretions, but is consumed or burnt in the system into Carbonic Acid and water. He has found that persons who are accustomed to take Beer in moderation require less bread in their food. (Animal Chemistry, Part I., p. 96.) And as it contains more Hydrogen than starchy food, and by the combustion of this Hydrogen the animal heat is partly maintained, Vierordt has shown that during the use of alcoholic liquors the amount of Carbonic Acid exhaled by the lungs is diminished. Thus Alcohol may be regarded as one of the calorifacient articles of food. (Videpp. 234, 237, 241, 255.)
CHLOROFORM.
Class II. Div. II. Ord. I.Narcotica Inebriantia.
Class IV. Ord. V.Diaphoretica.
Class IV. Ord. VI.Diuretica.
Chloroform, or Terchloride of Formyle, is a volatile liquid which is analogous to Ether and Alcohol both in nature and medicinal action, but very different in chemical construction.
Ether = C4H5, O.Alcohol = C4H5, O+HO.Chloroform = C2H, Cl3.
Ether = C4H5, O.Alcohol = C4H5, O+HO.Chloroform = C2H, Cl3.
A solution of Chloroform in spirit, sold under the namesTerchloride of CarbonandChloric ether, is in very general use, and is employed in very much the same cases as Nitric ether, being in the first place stimulant, and subsequently anodyne, soporific, and diaphoretic.
Chloroform is physiologically an Inebriant. But it is for certain peculiar actions that are coincident with, or immediately follow, this production of inebriation, that it has been so widely and so successfully employed in medicine since its recent discovery. Its two important operations are its anæsthetic effect on sensory nerves, and its paralyzing influence on muscle.
With regard first to the general selection of anæsthetic or anodyne remedies, it is to be observed that there are four distinct kinds of Pain, which differ very much in the treatment required. (1.) Firstly, there isinflammatorypain, caused by an active disease. It is aggravated by pressure; and it has a local cause. For this Opium is the best Neurotic remedy, but it should not be used without an attempt being previously or at the same time made to subdue the active inflammation. (2.)Irritativepain is different. It depends merely on nervous irritation. It also has a local origin; but it is relieved, instead of being aggravated, by a pressure or friction. Such is the pain produced by lead-colic, or by the passage of a gallstone or renal calculus. The pain of Neuralgia is generally of the irritative kind. So is that of Gastrodynia. So also the pain artificially inflicted by the knife in surgical operations. For irritative pain on the surface Aconite is most efficacious. Belladonna comes next to it. In Gastrodynia Hydrocyanic Acid is to be preferred. But to counteract the pain of a surgical operation we require a medicine which shall be capable of producing a powerful effect on the whole system at once. Such medicines are Ether and Chloroform. It is found most convenient to bring the patient under their influence by causing him to inhale the vapour into his lungs. Being absorbed by the pulmonary mucous surface, and passing directly into the circulation, the medicine thus takes effect rapidly. There is no time for the volatile liquid to be excreted from the blood, so that the ulterior effect of the anæsthetic cannot be escaped. The third and most important advantage of this mode of administering Chloroform is that by it we are enabled to regulate with exactness the degree of its action, which is a dangerous one, and to stop it when it has gone far enough. When introduced by inhalation into the general circulation, Chloroform acts upon the brain and sensory nerves throughout the body, so as completely to extinguish their natural sensibility. It is thus an agent of immense value where we wish to save the patient from an extreme and agonizing degree of irritative pain, whether to be caused by the edge of a cutting instrument, or by the throes of parturition. But it also acts as an anæsthetic when applied locally, as to a painful ulcer, or a hollow tooth-stump. (3.) The third kind of pain isreflexin its origin; as the pain in the knee in Hip-joint disease. We should do no good if we troubled ourselves to combat the local symptom in such a case; we should ratherdirect our attention to that condition which is the distant cause of the pain. (4.) A fourth kind of pain may be calledeccentric. Like the last, it does not originate in the painful part. It has its origin in the brain or nervous centres. Of such a kind are the various pains of Hysteria. Local anæsthetics are here worse than useless. The brain disorder must, if possible, be remedied.
Chloroform is better adapted for inhalation than Ether, because it is considerably less irritating. It is, on the whole, very safe, when proper care is taken. And yet it cannot be denied that sudden deathshaveoccurred from the use of Chloroform, which could not have been avoided by any known precautions. Such an admission tells little against the remedy; for supposing the proportion of deaths from inhalation to be about 1 in 10,000, it must be confessed that it is better that one out of that number should die of the Chloroform than that 100 should die of fright. Out of 9000 cases of its inhalation at St. Bartholomew's Hospital it is reported that not one died of the anæsthetic.
The stages of the action of Chloroform when inhaled may be briefly stated as follows:1st stage: some alteration in the feelings of the patient;2d stage: inebriation; the mind and volition are impaired; consciousness remains;3d stage: unconsciousness; anæsthesia.[48]The loss of sensibility may even occur in the second stage, the patient remaining conscious. The inhalation should not be prolonged beyond the occurrence of the third stage. The pulse is still full. There may be muscular movements, or even cries. In the next stage there is stertorous breathing; the eyelids no longer contract when touched with the finger; the pulse is felt to falter. This is dangerous. To this succeed stoppage of the heart and respiration;—death.
There are four rules which it is safe to follow in the administration of Chloroform; not to go on when there is stertorous breathing; not to administer it when there exists any serious disease of the heart or lungs; not to undertake under its influence an extensive operation on the mouth or jaws; and so to arrange the process as that the vapour shall be freely diluted with air. If the third rule be neglected, the blood may flow into the windpipe and cause suffocation, for the patient is deprived of the power of swallowing. The dilution with air is necessary, not only to moderate the action of the remedy, but that the necessary vital function of respiration may not be interfered with. It is also well known that it is convenient to administer Chloroform on an empty stomach, or it will be likely to produce vomiting.
Though Chloroform rarely fails to annihilate pain, and thus greatly to diminish the terror of the patient, it will not prevent him from sometimes dying of the shock of a serious operation. An extensive injury to the body will suffice to produce a prejudicial effect upon the heart and nervous system, which is independent of the feeling of pain, and may occur without moral suffering.
Chloroform is employed by some to relieve the pain of parturition. It is not found to interrupt the action of the uterus.
But, with this exception, it is a general muscular relaxer and paralyzer, and may thus be inhaled before an attempt to reduce an old dislocation, or to restore a hernia of long standing. It is more efficient in such cases than either Opium or Tartar Emetic, and produces less distress than the latter. For the same operation it is sometimes employed in spasmodic disorders. It has even been known to arrest the paroxysm of that most incurable of all disorders, Tetanus. I have known it to do great service both in Epilepsy and in Hysteria, when ordered to be inhaled regularly twice a day. It has been highly recommended by some who have tried it in Delirium tremens. (Videp. 237.)
OPIUM.
Class II. Div. II. Ord. II.Narcotica Somnifera.
Class IV. Ord. V.Diaphoretica.
Opium is the chief member of the second division of Narcotics, which consist of medicines that, in their action on the heart, are about intermediate between Stimulants and Sedatives, and in their secondary action, on the intellectual functions produce in them, the condition of sleep (p. 239.) Opium produces at first some stimulation, and exhilaration of the mind, with a full pulse, and general febrile excitement. This soon subsides, and is succeeded by drowsiness and sleep. Large doses cause slowness of the pulse, slow and difficult breathing, and coma. If a small dose of Opium be continually repeated, the stimulant action may be maintained for a time, and the Narcotic effect prevented. But whenever it is taken habitually, the dose will require to be gradually increased, or the desired effect will not be produced, for the system is induced by degrees to tolerate the remedy in larger and larger quantities. Given in moderate doses, it powerfully relieves pain, and controls nervous irritability. Though it always tends to produce sleep, its anodyne effect may take place without its soporific action.
It is useful in the painful inflammations of the serous and mucous membranes. But it tends to cause congestion of the brain. It should thus be generally avoided in brain-disorders; and, on account of its primary stimulant action, it should only be very cautiously used, or altogether avoided in cases of high fever, where there is a hot dry skin, or a full and hard pulse. The system may sometimes be prepared for it by antiphlogistic treatment; or Tartar Emetic or Ipecacuanha may be conjoined with the dose of Opium. Ipecacuanha and Opium are combined in Dover's powder.
Opium is a Diaphoretic; but it diminishes all the othersecretions, and most especially that of the bowels. In the treatment of fevers and inflammations it is often combined with Calomel, for the purpose of preventing the latter from passing out by the bowels, and of allaying at the same time the nervous excitement and pain.
Whether any precise connexion may exist between these various actions of Opium, is a difficult thing to determine. It is certain that there are other Narcotics and Sedatives which are able to relieve pain, but which neither cause constipation, nor produce cerebral congestion. Purgative medicines, which open the bowels and diminish cerebral congestion, are so far opposed to Opium. Those effete matters which it is the function of the bowels to excrete from the blood, and whose excretion is promoted by purgative medicines, have an action on the brain which in some degree resembles that of Opium. Constipation produces drowsiness, and torpor of the mental faculties. And it is worthy of remark that Opium does not seem to produce quite its proper effect when combined with a medicine which causes purging. Thus it is barely possible that the action of Opium in causing congestion of the brain may be in part referrible to the influence of those excrementitious matters which it hinders from passing out through the intestinal glands (p. 291.) But nothing conclusive is known on the subject.
How, we may ask in the next place, does Opium produce constipation? It has none of the characters of a general Astringent, and yet there is no Astringent like it in its action on the bowels. An attempt has been made to explain it on mechanical grounds. Poisseuille some time ago asserted that a solution of Morphia prevented the process of endosmosis through a dead animal membrane. Matteucci and others account for the operation of Opium on this principle, supposing that by exerting this action on the living mucous membrane, it is able to prevent the transudation of fluids from theblood into the cavity of the bowel. But this view seems even at first sight unsatisfactory. If such a force is really exerted, and the passage of fluids through a membrane prevented by the action of Opium, must it not apply to the stomach as well as to the bowel? Why is Morphia absorbed at all? It should stop the digestive process altogether. And why is the secretion of the skin increased by Opium, while that of the bowels is suppressed? (VideMatteucci'sLectures, p. 74.)
But there is reason to suppose that a serious error of observation has been made by those who first asserted that a solution of Morphia tended to arrest the process of endosmosis. Dr. Cogswell has lately made some careful experiments on the subject, and he finds that a solution of Muriate of Morphia passes readily through the bladder of an endosmometer to serum or a heavy saline solution. And when experiments are made on two other liquids of different density, the addition of Morphia to one or other of them is found to effect no alteration in the direction or rapidity of the current.
Opium is a general paralyzer to muscular fibre, both of the voluntary and involuntary kind, but particularly of the latter. And the only reasonable attempt that can be made to explain the action of Opium in producing constipation, is by a reference to this its paralyzing influence on the coat of the bowel, taken in conjunction with the torpid condition of the general system, and suspension of the animal functions, produced by the secondary action of this Narcotic on the nervous forces.
A considerable dose of Opium produces contraction of the pupil of the eye. A larger dose causes coma. The Deliriant Narcotics,i. e.Hyoscyamus, Belladonna, and Stramonium, dilate the pupil, and in large doses cause delirium. Their action is thus readily distinguished in cases of poisoning.
Opium is the best internal remedy in all cases of pain and nervous irritation, except where contraindicated by great febrile excitement, by stomach irritation, or by cerebral congestion. It acts powerfully on children, and should be administered to them very cautiously, or not at all. It is given to lessen the secretion in some cases of diarrhœa. It is generally unadvisable to give it when there is constipation or hepatic congestion. In wakefulness, mania, and delirium, when unattended with congestion of the brain or fever, it is highly serviceable. In spasmodic disorders, convulsions, and cough, it is more or less applicable.
That the active principles of Opium are absorbed, and pass into the blood, has been proved by their detection in the urine. (P. 223.) It does not act on the system before time has been allowed for this absorption. If taken by a mother during suckling, it may act upon the infant by passing into the secretion of milk. It acts upon the nervous system, and probably on the muscles also (see note, p. 224,) through the medium of the blood.
As a Diaphoretic in fevers and inflammations, Opium is to be preferred in cases where the skin is already moist and cool, where the pulse is soft, and the tongue not coated. But where there is febrile excitement, Antimony, or Ipecacuanha, is rather indicated. Opium may act on the glands of the skin as a true Eliminative; or it may possibly operate in the same indirect way as a nauseant dose of Tartar Emetic, relaxing the ducts of the sudorific glands by its paralyzing influence on their muscular fibre.
The chemical construction of Opium is a matter of considerable interest. Morphia, the chief active principle, is an alkaloid which is almost identical with Opium in its narcotic actions but slightly more sedative. Unencumbered by inert matters, it presents us with an anodyne in a more concentrated form. But the combination of the Morphia with other principles in the crude Opium is worthy of remark. Both Morphia and Opium are liable occasionally to produce nausea, headache, loss of appetite, and depression of the spirits. Thereare various ways in which we may try to obviate these unpleasant symptoms. To prevent nausea, we may combine the dose with an aromatic. Dr. Copland has successfully combined Morphia with an aromatic spirit, in cases where alone it was apt to bring on hypochondriasis. And to prevent the loss of appetite in Delirium tremens, Dr. Todd recommends to combine Morphia or Opium with Quinine or some other Tonic. But it is very curious that in the construction of Opium an attempt is made by nature at the very things that we so much desire in practice. For the drug contains, in addition to Morphia, an aromatic volatile oil, and a neutral principle, wrongly called Narcotine, which has been proved by some experiments made in India to be a simple Tonic, like Quinine. So that if we could only separate from the other parts of the drug the Morphia, volatile oil, and Tonic principle, we should obtain an admirable combination made ready to our hand. But Opium contains also other matters which are mere incumbrances, but which are more or less taken up by the various liquid menstrua that we employ; as, an irritant resin; other neutral principles, as narceine, Meconine, and Papaverine,—and Meconic acid,—all of which are probably inert; and, what is worst of all, a small quantity of an alkaloid called Thebaia, said by Magendie to have an action identical with that of Strychnia.
Though Morphia constitutes only about twelve per cent. of the best Opium, the dose of it required is at least one fourth of that of the latter. It seems therefore that Opium must contain some other narcotic principle. Codeia is a Narcotic, of less power than Morphia, and though it is contained in Opium, it is scarcely in sufficient quantity to explain the strength of the drug. It is likely that Opium contains more than one volatile oil, and that the odorous principle to which its peculiar smell is owing is itself narcotic in its action. A parallel case to this is verified in the instance of bitteralmonds, which not only yield Hydrocyanic acid, the most powerful Sedative known, but contain a large quantity of a volatile oil, which remarkably resembles the acid in its poisonous action. (Videpp. 238, 268.)
HYDROCYANIC ACID.
Class II. Div. III.Ord. I.Sedantia Generalia.
Hydrocyanic or prussic acid (C2N, H,) a very volatile liquid, soluble in water, is one of those mysterious vegetable compounds which, containing no chemical element that is not also contained in animal structure, are yet gifted with a wonderful power over the vital forces. One drop of the pure acid is sufficient to cause death. But the officinal acid is an aqueous solution, containing only 2 per cent. of the other.
It is a powerful Sedative to the nerves generally. Its action is direct, and is not preceded by any primary stimulation. Diminishing sensibility, it is therefore used as an anodyne. Controlling muscular action, it is employed as an anti-spasmodic. But it appears especially to influence the reflex nervous actions. It is therefore of especial use in the paroxysmal coughs of Hooping-cough and of Phthisis, which have a reflex origin in the irritation of the mucous membrane. It acts on nerves as well as on nerve-centres. Thus it is particularly useful in neuralgic forms of Gastrodynia; and it seems to allay the pain in the stomach by diffusing itself directly it reaches it, so passing through the mucous membrane at all points, and coming in contact every where with the irritated sensory nerves. It is sometimes useful in cases of vomiting, or pyrosis.
If applied to the surface of the skin, it numbs the superficial nerves; but on account of its rapid volatility, and the dangerous results that would follow the inhalation of its vapour, it is not appropriate as an external anaesthetic.
A poisonous dose produces first convulsions of the whole frame, then syncope, and death. Strychnia produces convulsions, but they are not caused in the same way as those of Hydrocyanic acid. For the two medicines are obviously opposed in their action, Strychnia being an exalter of sensation and of reflex action, and Hydrocyanic acid a depresser of the same. The convulsion caused by Strychnia is tonic; that by Hydrocyanic acid, asthenic. The one, being a special Stimulant, causes convulsions by an excitement of the spinal cord; the other, being a Sedative, does it by deranging the function of that centre. (Videpp. 245, 243.)
ACONITE.
Class II. Div. III. Ord. I.Sedantia Generalia.
This medicine, like the last, is a powerful General Sedative, and a dangerous poison. It depresses the influence of the brain, and paralyzes all the nervous functions. It tends at length to kill by producing syncope.
It acts especially on the superficial sensory nerves, and tends to extinguish feeling and pain. It is the best external anæsthetic with which we are acquainted. It is thus eminently useful in the treatment of that most painful of all disorders, Tic douloureux, or irritative Neuralgia of the face. When Quinine and all internal remedies have failed, the tincture of Aconite, or an ointment containing the alkaloid, will in most cases, if applied to the part, effectually relieve the pain. It is applicable in local irritative pain at any part of the surface, as in Sciatica, Lumbago, or a Scirrhus of the breast that has not opened. But, like the other local anæsthetics, it is of little service in cases of inflammatory pain, for this, when local, depends upon an active cause, and would be liable to be increased by the rubbing required in the application of the Aconite. When the remedy takes effect, some heat is first experienced at the part; there is then tingling; and lastly, complete numbness, and a sensation of cold, which endure for some time. No visible change is effected.
Aconite subdues the action of the heart. Dr. Fleming has therefore recommended small doses internally in cases of acute rheumatism. But considerable care is required in the internal employment of the drug, on account not only of its dangerous properties, but of the great variety in strength which exists among the preparations that are usually employed. The difficulty experienced in the preparation of the alkaloid Aconitina, which is the active principle of the plant, and the very high price at which that substance is usually sold, have prevented it from being so extensively employed in practice as its medicinal properties would appear to deserve for it. On account of its cleanliness as an outward application, and the certainty and uniformity of its sedative and anæsthetic actions, the pure alkaloid is far preferable as a medicine to Aconite itself, and is adapted for all the cases in which the latter has been employed.
Having some time ago been successful in an attempt to discover a mode of preparing Aconitina,[49]I have made some experiments with it on various small animals, for the purpose of ascertaining its power, and the symptoms of its action. It is a very active poison. Proceeding upwards in the animal scale, I find that 1/300th of a grain, in solution in water, suffices to kill a mouse. 1/100th kills a small bird after a few minutes; 1/50th almost instantaneously. 1/20th of a grain has killed a cat. 1/10th invariably proves fatal to the unfortunate feline in the course of twenty minutes or half an hour.
Calculating as well as I can from these data, I consider that 1/10th of a grain of this alkaloid would be sufficient to cause the death of an adult man. During the action of the poison on cats the following succession of symptoms is generally observed. They will illustrate in most of its phases the action of a Sedative medicine.
1. An increased flow of the salivary secretion. (Videp. 282.)
2. Vomiting.
3. Delirium, with hallucinations. Impairment of volition; apparent loss of sensation.
4. Convulsions; paralysis.
5. Breathing difficult and gasping,—gradually ceasing.
6. Death; pupils of the eye are seen to be dilated.
Aconitina has thus a powerful action on the brain, and on the nerves generally. The flow of saliva seems partly to arise from a paralysis of the fauces. The animal makes ineffectual attempts to swallow, and breathes spasmodically. By a small dose the anæsthesia would probably be produced, without the other effects. On examination of the body after death the lungs are found to be healthy, but shrunken and bloodless; the trachea contains much frothy mucus, which may possibly have flowed into it on account of the palsy of the glottis; the cavities of the heart are full; the mucous membrane of the stomach pale. It seems then that the immediate cause of death is paralytic syncope,—a loss of power in the heart. As the mucous coat of the stomach evinces no trace of congestion, it is probable that the vomiting is not caused by irritation, but by a sedative or deranging action on the function of the Vagus nerve. (Videpp. 242, 245.)
DIGITALIS.
Class II. Div. III. Ord. II.Sedantia Specifica.
Class IV. Ord. VI.Diuretica.
This important medicine has already been prominently noticed as one of the agents that exert a special sedative and deranging power over the functions of the Vagus nerve. It will only be necessary now to sum up shortly the details of its action.
It does not depress nervous force generally. It has noaction on the brain, except as connected with the Vagus nerve. Neither does it affect the spinal cord, or the nerves of sensation or motion. Its most obvious action in small doses is to depress the force of the heart. It sometimes quickens the pulse, but always weakens it, and reduces its rate in the end. It therefore supplies us with a ready means of weakening the heart, whenever we desire to do this. In cases of hypertrophy, where the heart is too strong,—or in aortic aneurism, or active hemorrhage, where a forcible beat would be dangerous,—Digitalis may be used for this purpose. But it is especially useful in dropsies; for by its action on the heart, it diminishes congestion of the venous system, and by thus removing the pressure from the veins, it favours the absorption of the fluids effused. It should, however, be avoided in cases where there is very serious cardiac obstruction, or where the heart is habitually weak, and there is a natural liability to syncope. For the tendency of the medicine is to cause death by producing syncope.
Certain precautions are necessary in its administration. The patient should be generally confined to the recumbent posture; for if, while under the influence of Digitalis, he should suddenly rise, and the heart, already weakened, have further to contend with the force of gravity in the propulsion of the blood upwards, it may actually stop. The dose also should be cautiously regulated, and, if it do not operate at once, it must not be increased, or too soon repeated; for this medicine is apt sometimes to accumulate in the blood, and though several doses may perhaps be given without effect, they are afterwards liable at any time to be suddenly discharged upon the nervous system, and may then produce by their united action a dangerous result.
A considerable dose of Digitalis, as of Tartar Emetic, deranges the control of the Vagus nerve over the function of the stomach, and may in this way produce nausea and vomiting. There is no reason for supposing that it irritates the coat of the stomach. (Videp. 93.)
The active principle of Digitalis is secreted from the system in the urine, and probably acts as a true Eliminative Diuretic. But it tends more powerfully to promote diuresis in another indirect way. Any thing which diminishes the pressure on the vascular system, as Digitalis, by weakening the force of the heart, tends thereby to promote absorption, and to increase the secretion of urine.
So that the employment of Digitalis in Dropsy is attended with a twofold advantage; by its cardiac action, it prevents a renewal of the dropsical effusion; by its diuretic power, it causes a quantity of fluid to be drained out of the system through the kidneys. That it may do this the more effectually, it is generally considered advisable to combine it with other diuretics. (Videpp. 251, 304, 308.)
TANNIC ACID.
Class III. Ord. II.ASTRINGENTIA VEGETABILIA.
This is the chief astringent principle of vegetables. It is very soluble in water, crystallizable, and has a strong astringent taste. It is not possessed of those marked properties that are vulgarly attributed to acids; but its solution reddens litmus-paper, and it combines with bases to form salts.
When received into the stomach, it is absorbed, and passes in the circulation to distant parts. Its action consists in a power of causing the contraction of muscular fibre when in contact with it; and this power appears to depend mainly upon a chemical property that it possesses of coagulating albumen and analogous compounds. Capillary vessels, and the small ducts of glands, contain in their walls certain fibres of unstriped muscle; and Tannic Acid, by causing this muscle to contract, is able to diminish the caliber of these tubes, andthus to moderate or arrest the flow of blood in the vessel, or to lessen the amount of the excretion of the gland. Thus, in all cases of hæmorrhage from the small vessels, or of inordinate secretion from any glandular organ, Tannic acid is appropriate. It is the best and safest of all Astringents for internal use, excepting only Gallic acid.
I have already stated as worthy of remark the fact that Gallic acid is of little or no use as an Astringent when applied to external parts. Given internally, it is very efficacious. From this alone it would seem that there must be something in the blood which enables it to take effect. Reasons have also been alleged for supposing that Tannic acid is not a simple substance. When it is taken into the system, Gallic acid is secreted in the urine; and it appears that Tannic must actually consist of Gallic acid combined with certain other elements, or with some other definite substance; and that the astringent property which is so valuable is confined to the compound body thus produced. Gallic acid alone has not the power of precipitating albumen.
What then is this other substance? It must be something which is contained in or formed in the blood, which added to Gallic, will be capable of forming Tannic acid; and which, when united to it, will enable Gallic acid to precipitate Albumen. These various requirements are fulfilled by the group of elements that constitutes grape-sugar (C12H12O12.) This compound is continually forming in the blood during the blood-processes that are connected with respiration. It has been observed that a solution of gum (C12H11O11,) added to one of Gallic acid, will enable the latter to coagulate Albumen. And the elements of Tannic acid may be constructed out of those of Gallic acid and grape-sugar.