The blood-pressure-raising principle of the suprarenal gland, also produced synthetically, is official in the French, Italian and Belgian Pharmacopeias as adrenalin and in the German Pharmacopeia and the supplement to the Netherlands Pharmacopeia as suprarenin. In N. N. R. the following synonyms are enumerated: adnephrin, adrenalin, supra capsulin, suprarenalin and lsuprarenin synthetic.

Properties : Chemically epinephrin is described as 1, 2-di-hydroxy-42-methylamino-ethyl-41-ol benzene, C6H3(CHOH.CH2NH-CH2), a substance with feeble basic properties, occurring in the suprarenal gland of the sheep or other animal. As commercially obtained it is a finely crystalline white or yellowish powder, odorless and slightly bitter. The free base is practically insoluble in water and is usually dispensed in the form of an aqueous solution, 1 :1,000, of one of its salts. Epinephrin is oxidized readily and is thus destroyed in dilute alkaline solution.

Action and Uses: Epinephrin excites the action of the sympathetic nerves in such a way as to produce a variety of effects according to the function of the part supplied by the nerve. It produces a sudden rise of blood-pressure by contraction of the arterioles. The pulse is slowed by an action on the vagi. The heart is stimulated directly, but the resistance offered by the contraction of the blood-vessels is such that at times the heart is unable to overcome it and suffers passive dilatation. The rise of blood-pressure which results from the action of this drug is very transient, lasting, as a rule, not more than five minutes. When given by the mouth it produces no evident effect on the circulation, but it is readily absorbed from the mucous membranes of the nose, mouth, urethra, vagina and rectum, producing local contraction of the blood-vessels. Very large doses are tolerated when given hypodermically on account of the slow absorption due to the constriction of the blood-vessels of the part into which it is injected. It acts promptly after intravenous injection, but it appears to be rapidly eliminated or destroyed or its action is neutralized by antagonistic influences on the sympathetic ganglia. Epinephrin dilates the pupil, and this dilatation was employed at one time as a measure of the amount of epinephrin present in the blood, serum or other liquid. It inhibits the peristaltic movements of the intestine and increases the secretion of saliva and other glands which receive their nerve-supply from the sympathetic. Epinephrin may produce hyperglycemia and glycosuria, and its continued use may cause a degeneration of the internal coats of the arteries.

The chief therapeutic use of epinephrin is to constrict the peripheral blood-vessels by local application. In this way it may be used to diminish hyperemia of the conjunctiva, to reduce swelling of the turbinated bodies and to arrest hemorrhage from the mucosa of the upper respiratory tract. It is successful only in capillary or small arterial bleeding, as it cannot stop a large vessel hemorrhage. It is used to prevent hemorrhage in operations on the eye, nose, ear, etc.

For the arrest of hemorrhage it must be applied directly to the bleeding vessels or congested area. If the blood washes it away the application may fail because it has not time to act. It may be swallowed to check hemorrhage from the stomach, but the chances of success are small because a quantity of liquid is usually present in the stomach which dilutes the remedy so that it is useless. It should never be given for internal, concealed hemorrhage, because it is never desirable to raise blood-pressure in internal hemorrhage.

Epinephrin is employed in conjunction with local anesthetics, especially cocain, to limit the absorption of the anesthetic and secure a more efficient local action. It has been used in asthma both by applying a spray to the nose or throat, or by the absorption of a tablet, powder or solution from the tongue, and also by hypodermic injection.

Dosage: Epinephrin or one of its salts is employed in solutions of a strength of from 1 : 10,000 to 1 : 1,000. For internal administration the dose of a 1 : 1,000 solution is from 5 to 10 drops. When an oily vehicle is to be used the base itself is prescribed, but when aqueous solutions are wanted one of the salts should be employed.