From these activities the blood-pressure will decidedly fall under the action of nitrites.

If cardiac pain is due to high pressure, or to coronary disease, it may be relieved by the relaxing dilating effect of a nitrite on the general circulation, and an anginal pain will often be immediately relieved by inhalation of amyl nitrite. Nitrites have no action in the body except that caused locally by a change in circulation, therefore the action on the brain is due to the circulatory changes. Nitrites are oxidized into nitrates, and are thus excreted in the urine.

Over-action. The symptoms of over-action are headache, full-headedness, dizziness, and perhaps syncope. On account of amyl nitrite so readily causing such a condition, it is rarely used except for emergencies.

Severe poisoning can hardly occur clinically from a nitrite. The most serious symptoms that can occur from too large a dose of a nitrite is heart weakness, cyanosis, and coldness of the extremities. The treatment would be to give quick-acting vasoconstricting drugs, such as the active principle of the posterior lobe of the pituitary gland, epinephrine, strychnine, atropine and caffeine.

Uses.-The emergencies in which a quick-acting nitrite is needed are angina pectoris and epilepsy. A patient who has anginal attacks should always carry soluble nitroglycerin tablets in his pocket, each 1100 of a grain, to dissolve quickly in his mouth whenever he has an attack. If one tablet is not sufficient, in ten minutes he should take another one, and this may again be repeated, the only limit being the throbbing in the head, especially in the forehead, and a full-headed feeling. If deemed best, he may also carry ampules of nitrite of amyl. The quicker action of the nitrite of amyl when an ampule is crushed in the handkerchief and inhaled is generally reserved for an aura of an epileptic attack. An epileptic who has an aura long enough for him to crush such an ampule and inhale it may prevent the fit.

The only other emergency use of a nitrite is in asthma, although the emergency is not so urgent. Such a patient may also dissolve nitroglycerin tablets in his mouth and get quick

relaxing results. He should be instructed to dissolve a 100 grain tablet under his tongue, and repeat it every half hour until he obtains relief.

When it is decided to lower blood-pressure with nitroglycerin the choice is generally nitroglycerin or erythrol tetranitrate tablets. The frequency of the dose depends upon the effect on the individual, but generally four times in twenty-four hours is sufficient, a tablet after each meal and on going to bed. For this vaso-dilating effect the tablet should not be dissolved in the mouth, but should always be taken with plenty of water, and preferably when something is in the stomach. In other words, rapid action is not desired, and the disagreeable pressure feelings in the head need not be caused.

Symptoms of high pressure such as dizziness, a feeling of tension in the head, occipital headache, and cardiac ache, and possibly cold hands and feet, may be relieved many times by a small dose of nitroglycerin, as 1400 to 500 grain, when a larger dose, as 1200 grain may cause headache; but the dose depends on the individual. It is rarely necessary, however, to give more than 100 of a grain, although that dose may be needed every three or four hours.

As stated under the subject of alcohol, in high fever, when apparently alcohol is indicated, nitroglycerin may act as well to dilate the peripheral blood-vessels and promote perspiration.

In spasmodic conditions such as occur in dysmenorrhea, at times vaso-dilatation from nitroglycerin may cause relief.

In insomnia from high pressure a dose of nitroglycerin taken with a cup of malted milk at bedtime will often promote sleep. In attacks of asthma nitroglycerin will generally cause immediate relief. If the blood-pressure is low, however, and there is venous congestion and cardiac weakness, epinephrine on the tongue will often act more satisfactorily.

CLASS V

DRUGS USED FOR ACTION ON THE CENTRAL NERVOUS SYSTEM

This class includes drugs which have a very slight effect on the brain and spinal cord and drugs that have a profound effect

on the central nervous system, as anesthetics. Their action can only well be discussed in their separate sub-classes.

DRUGS USED TO STIMULATE THE BRAIN AND SPINAL CORD

The once called "antispasmodics" are drugs that seem to modify hyper-excitability and prevent various pseudo-spasmodic conditions and relax pain. These drugs are not narcotics, but cause improvement by stimulating the higher brain centers of control, actually as by camphor perhaps, or suggestively as by the disagreeable odor of the long used asafetida and valerian. These last named drugs may aid nervous control in hysteria by the psychic effect of the smell, or if in alcoholic preparations, may cause sufficient alcoholic cerebral effect to quiet the patient. Spirit of lavender has been much lauded for hysteria, but it is the alcohol only that is effective.

These drugs, namely, asafetida, valerian and lavender, at times so valuable in hysteria, are often less effective than is socalled "Christian Science."

Camphor is really a cerebral stimulant and dilates the peripheral blood-vessels, and may change the view-point of the hysteric. However, before hysteria is diagnosed as an entity in a given case, all other more tangible conditions must be excluded. There is generally a cause for these disturbed impulses, often an endocrine gland dysfunction. The thyroid gland is the one most generally in trouble, and frequently the ovarian function is abnormal.

Thyroid gland extracts are cerebral stimulants, especially in conditions that need such stimulation. The value of caffeine and atropine as circulatory stimulants has been discussed. They are also cerebral stimulants, the caffeine especially stimulating brain activity, and atropine especially stimulating the medullary centers and in large doses causing cerebral excitement. Strychnine is not only a medullary stimulant, but is especially a spinal motor stimulant. The discussion of the use of these drugs, caffeine, atropine, and strychnine as nervous stimulants would take us into the discussion of the treatment of shock, coma, and paralysis. Suffice it to say under this caption that none of these drugs should be used in nervous

irritability or in sleeplessness, and that coffee and tea are often the cause of insomnia.

Belladonna.-Belladonna is official both as the leaves and the root, but as all activities of belladonna are those of atropine, as far as its therapeutic use is concerned, there is no need for the preparations of this drug for internal use; we do not need the extract, the tincture, or the fluidextract of belladonna. The official belladonna plaster which represents 20 per cent. of the drug, and the official ointment of belladonna which represents 10 per cent. of the drug are useful preparations for external use. The official liniment of belladonna is superfluous, as the absorption of atropine could not be limited and poisoning might be caused.

The only use for belladonna externally is as a sedative to relieve pain and irritation. In susceptible individuals, even the belladonna plaster may cause poisoning, and the belladonna ointment should, also, not be used in a large amount at any one time.

Hyoscyamus.-There seems to be no good reason why this drug should be used as such or in its three official preparations. The tincture of hyoscyamus has been long used as a sedative, more especially in irritable conditions of the bladder, and in pelvic disturbances. There is no proof that there is an activity of this drug other than that of atropine. Its atropine-like alkaloid is termed hyoscyamine, but this alkaloid, unlike atropine, when used alone is likely to cause secondary depression. The other alkaloid of hyoscyamus, scopolamine (hyoscine) besides having a primary atropine action has a sedative action on the central nervous system; this alkaloid is used only as a hypnotic.

Hyoscyamine is official as Hyoscyamine Hydrobromidum, but as this drug is likely to cause unexpected depression, there seems to be no justification for its use.

Scopolamine Hydrobromidum (hyoscine hydrobromide) is very soluble in water, and is used principally hypodermatically in intense cerebral excitement, in acute delirium, and in the sleeplessness of insanity. When given hypodermatically, or in a tablet to be dissolved in the mouth, it generally quickly causes sleep. However, when there is an idiosyncrasy to

atropines, it may cause considerable cerebral excitement. Consequently, before giving a full dose of this drug, it should be ascertained that the patient is not susceptible to atropine. After a sleep from scopolamine there is likely to be considerable circulatory depression. Consequently, it is not wise to give scopolamine as a hypnotic and then allow the patient to be up and about the next morning.

Scopolamine has also been used in spinal irritability, and in paralysis agitans. The dose for these purposes is smaller, not sufficient to produce sleep, and it should be administered two or three times a day. In such patients a tolerance has sometimes been developed, and larger doses may be needed.

Although scopolamine may cause atropine stimulation, it should never be considered that it is anything but a depressant, and when serious poisoning occurs, depression must be combated.

The average dose is 0.0003 Gm. (1200 grain). It is often necessary, however, to give double this dose, 100 of a grain. Stramonium is official as the leaves. The action of this drug is only that of atropine, and therefore there is no good excuse for its four official preparations. The action and poisoning of stramonium is that of an atropine.

The only use for stramonium is in the form of the leaves, to be made into cigarettes or pastilles, or to be burned as a powder, for inhalation in asthma. Generally the leaves are combined with nitrate of potassium (saltpetre) which causes the drug to burn rapidly, and also gives some relaxation from the nitrite formed when the fumes are inhaled. The action of stramonium when inhaled is that of a sedative from the action of the atropine on the nerves of the mucous membrane of the air passages. Although inhaling this fume of atropine may give local sedative action to irritated nerve terminals in the region that is spasmodically contracted, still atropine sulphate given hypodermatically or dissolved in the mouth may cause the same satisfactory effect.

Atropine.-Administration.-This drug is best used in the form of the official sulphate, which occurs as a white powder, very soluble in water. The dose varies from 0.0003 to 0.0006