The bromides in common use for narcotic effect are those of potassium, sodium, and ammonium, and to a small extent those of lithium, strontium, and calcium. All have a strongly salty, bitterish taste, all are very soluble in water, and all except potassium bromide are moderately soluble in alcohol. The dose depends on the desired result. For nervousness and restlessness it is 10 to 30 grains (0.7-2 gm.) two to four times a day; as a hypnotic, 20 to 60 grains (1.3-4 gm.); for epilepsy, 20 to 60 grains (1.3-4 gm.) three times a day. L. Pierce Clark reports the use of 400 grains (27 gm.) a day for five days in epilepsy. Diluted hydrobromic acid (10 per cent.) is sometimes used as a bromide in dose of 1 dram (4 c.c.). In equivalent sedative dose it has no' advantage over the alkaline bromides, and is strongly acid.

Pharmacology

Local

Bromides have no effect upon the unbroken skin; but on mucous membranes and raw tissues they have a salt action, and are irritant unless well diluted. This irritation is followed by slight anesthesia. Before the use of cocaine their solutions were painted on the throat as mild anesthetics to favor laryngeal examination. From irritation of the stomach they sometimes cause nausea and vomiting.

Absorption is fairly rapid from stomach and intestines.

Nervous System

On the whole central nervous system except the medulla there is a moderate but lasting general depression which can be maintained day after day for long periods, with little, if any, effect upon the vital medullary centers.

Cerebrum

The mind is less alert, the special senses are less keen, the sense of pain is diminished, and there is indifference or lack of attention to what is going on. Large doses produce drowsiness, and if the dose is given at bedtime, favor the onset and maintenance of sleep; but even enormous doses (400 grains a day) will not force sleep in the daytime, when the patient is up and about. As a hypnotic, the drug acts rather to permit sleep, as when the patient is anxious, worried, or nervous, than to force it by marked depression of the cerebrum. Ulrich claims that large doses will banish melancholia and the depression of neurasthenia.

From repeated very large doses, as sometimes used in epilepsy, the patient passes into a condition of mental and physical sluggishness, with defective memory, stupidity, general apathy, and inferior mental power.

The motor areas of the cortex are depressed, for in a dog under bromides it is impossible to produce a convulsion by their stimulation. In man, too, voluntary motion is sluggish, and the cerebral convulsions of epilepsy may be absolutely prevented. These cerebral effects are directly opposed by caffeine.

Spinal Cord

If a toxic dose of strychnine is given to a bromidized dog, a reflex response to a stimulus may be obtained, but the extensive convulsive response which would result from the strychnine alone does not occur. The effect of bromide is the opposite to that of strychnine, the passage of impulses from afferent fibers to motor areas being retarded. There is some evidence that it acts on the same part of the cord as strychnine, i. e., the primary sensory synapses. It is, therefore, irrational to administer bromides and strychnine together. The depression of the reflexes makes a general depression of muscular tone throughout the body, and loss or depression of the sexual reflex, but not usually the bladder reflex.

Circulation

Under ordinary conditions there is no essential effect from therapeutic doses upon the heart, the arteries, or the nervous mechanisms of control. But in the cardiac neuroses, palpitation, tachycardia, etc., and when the heart is overacting, as from general nervousness, the effect of a bromide may be to steady and quiet the beat by its general sedative effect upon the patient. By enormous doses the muscles of the heart and arteries and the vasoconstrictor center are depressed and arterial pressure falls. In large amounts the potassium ion is distinctly depressing to the heart muscle; hence potassium bromide in the large doses tends to be more depressing than the other salts. Greene and Kruse found by perfusion experiments that in physiologic balanced solutions bromides are relatively non-toxic to heart muscle. For example, a bromide Ringer's solution sustained a frog's heart for twenty-eight hours. But if bromides are used without reference to isotonicity the base (K, Na, Ca, etc.) becomes important.

Fig. 41.

Fig. 41. - Bromide eruption (Schamberg).

Fig. 42.

Fig. 42. - Pustulobullous eruption, resembling small-pox, from the ingestion of bromides (Schamberg).

Pharmacology 66Fig. 43.

Fig. 43. - Fungating potassium bromide eruption (A. F. Biichler).

Fig. 44. - Pustular and crustaceous bromide eruption (W. S. Gottheil in Archives of Diagnosis).

Respiratory

Therapeutic doses have no effect except to diminish the coughing reflex and lessen the tone of the respiratory muscles. Enormous doses somewhat depress the center.

Sexual Organs

Both sexual desire and sexual power are diminished through cerebral and spinal depression, and these effects are made use of in therapeutics.

Elimination

Bromides are excreted chiefly in the urine, but somewhat also in the sweat, in mucous secretions, and in milk. Large doses given to a nursing mother may affect the infant. The excretion begins very quickly, traces being found in the urine and saliva in a few minutes after ingestion. But a part of the bromide enters the body fluids and protoplasm and replaces some of the normal sodium chloride, and this portion is but slowly excreted, so that bromide may be found in the urine weeks after its administration has been stopped. The excretion of bromides is hastened by large doses of sodium chloride; so in extreme bromide administration, as in some epileptic cases, the amount of chlorides is reduced, the bromide being taken with the food in the place of table salt (sodium chloride). Where much bromide is given continually, hydrobromic acid is said to replace some of the hydrochloric acid of the gastric juice.