External

They have none.

Internal

Alimentary canal. - Solutions of any of the first three bromides, frequently painted on the throat, diminish its sensibility. Medicinal doses have no other effect on the alimentary canal. All bromides are quickly converted into sodium bromide in the stomach and intestines, and they are readily absorbed.

Nervous System

Bromides are powerful depressants to the nervous system; the action of the potassium salt being most marked. Thus, if an animal be given large doses of any of them, irritation of the cortical motor areas, which before easily excited movements, fails to do so. Experiments also show that the reflex excitability of the cord is considerably diminished, and that the activity of the sensory mechanism is also impaired, for large doses of bromides given to frogs cause cutaneous anaesthesia. In man, at least, not only the cortical motor area, but the brain as a whole is depressed, therefore these drugs are powerful hypnotics. It is probable that in addition to the brain and spinal cord the peripheral nerves are depressed, so that bromides are well worthy to be called powerful nervous depressants. The activity of the muscles is also diminished, not only by the action of the drugs on the nervous system, but by their direct action on them. It has been definitely shown by Wright that excessive doses of potassium bromide cause in man and rabbits degeneration of the cortical cells, and that this degeneration begins at the periphery of the dendrons.

Circulation

Here also bromides are depressant; large doses exert a direct paralyzing influence on the heart, lessening the force and the frequency of the beat and producing stoppage in diastole; the potassium having the greatest effect, the sodium salt has less influence; the ammonium salt slightly stimulating the heart. They are said to cause vaso-motor spasm; but the evidence of this is very unsatisfactory. Toxic doses produce a fall of temperature; this is probably in some way secondary to the depression of the circulation.

Respiration is slightly depressed by bromides.

Metabolism

The amount of carbon dioxide exhaled is greatly decreased by taking large doses of bromides. The amount of urine is increased particularly after the use of the lithium salt; the coloring matters, the sulphur, and the nitrogen in it are increased; but the phosphorus is decreased.

Sexual Organs

If bromides are taken for a long time a failure of sexual vigor is produced, and ultimately there is a great lessening of the sexual appetite. Bromides are therefore anaphro-disiacs.

Elimination

Bromides are rapidly eliminated by the kidneys, skin, saliva, intestinal mucous membrane, bronchial mucous membrane, and milk.

Bromism

If bromides are taken for too long a period, a Teries of symptoms of poisoning, to which the above name has been given, may appear. The hydrobromic acid {see p. 258), although containing a larger proportion of bromine, rarely gives rise to bromism. The earliest of them is a rash, consisting of red papules, chiefly on the face and back, exactly resembling some forms of acne. This is probably the result of the excretion of bromide by the skin. The next symptoms are a general lowering of the cutaneous sensibility and also of that of the pharynx, then there is diminution of sexual power, the patient becomes low-spirited, easily fatigued, unfit for work, and his intellect is dulled, and in bad cases this passes on to dementia, melancholia, and other disorders. There may be a little conjunctivitis, and some increased secretion from the bronchi. A coated tongue and disordered digestion are constant symptoms.

Potassium bromide owes its action largely to the bromine in it, but probably also, to a less extent, to the potassium. In man, at least, the higher functions of the brain are depressed before the lower, and these again before the spinal. Thus the depression takes place in regular order from above downwards, in the reverse order of the physiological development of the functions, and this is commonly the case with many drugs (see Law of Dissolution, p. 104).

Those who take bromides habitually find themselves unable to sleep without them, and their intellect becomes obscured. These bad effects are intensified by the fact that gradually larger doses are required to produce sleep, and thus the unfortunate sufferer becomes more and more a slave to the drug. Also occasionally maniacal excitement, mental confusion and even delirium are observed after continued use of moderate doses, particularly of the potassium salt.

Therapeutics of the Bromides

External. - None

Internal

Alimentary canal. - Formerly the back of the throat was painted with a solution of a bromide before a laryngeal examination, but now cocaine is employed for this purpose.

Nervous System

Because of their depressing effect bromides are largely used for many nervous diseases. They are the most valuable drugs we have for the treatment of epilepsy, acting no doubt by diminishing the excitability of the cerebral cortex. They rarely cure, but often greatly diminish the number of fits. Rubidium and ammonium bromide appears to be the best bromide for some cases of epilepsy (dose, 30 gr. 2. gm. ). It is impossible to say in any given case whether bromides will do good, therefore they should be tried in all; petit ma/is more difficult to influence than grand mal. The next most common use of bromides is as hypnotics. They are most useful when there is no organic cause to explain the insomnia, and therefore they are not employed when pain keeps the patient awake, but are given with great benefit in the insomnia of overwork, worry, or that connected with the climacteric period. The sleep induced is quiet and refreshing, without dreams, and therefore these drugs are of great value in nightmare, and in the night-screaming of children, which may be regarded as allied to it. Also because of their depressant effect on the nervous system they are given in migraine, and often they are the only drugs which do any good for the intense headache of this disease. Large doses, often a drachm 4. gm. at a time, are given in delirium tremens especially in combination with chloral hydrate, and sometimes the patient seems quieter for this treatment. Not only the insomnia, but the other nervous symptoms that are common at the climacteric period may be relieved by bromides. For their depressing power on centres below the cortex they are used, and with good results, in laryngismus stridulus, and have been given in whooping-cough; but the benefit is not marked. Some cases of tetanus have recovered after enormous doses of bromides. Here their value is, no doubt, due to their power of diminishing the reflex function of the spinal cord. Bromides have been given as antidotes for strychnine poisoning. Sometimes they succeed in cases of hysteria and neuralgia, and some varieties of functional disease of the heart are much improved by them.

Sexual Functions

Because of its depressant effect potassium bromide is given for spermatorrhoea and nymphomania.