Epinephrin, or "adrenalin" (C9H13NO3 = 181.76) is an active principle derived from the suprarenal glands of the ox and the sheep.

Pharmacodynamics.

Central Nervous System. - Epinephrin stimulates the terminals of nerve fibers from the thoracicolumbar cord.

Muscular System. - No action.

Respiration. - No action; but relaxes bronchial muscle.

Heart is first accelerated from stimulation of the accelerator terminals; then slowed reflexly from centric vagus action; then quickened as vagus control is inhibited or overcome.

Blood-pressure shows an extraordinary, though transient, rise, due to stimulation of the myoneural junctions of those constrictor fibers supplied from the thoracicolumbar cord.

Eye. - Pupil is dilated through stimulation of the dilator fibers.

Alimentary Tract. - Stimulation of the splanchnic terminations is said to cause peristaltic inhibition and intestinal relaxation, and contraction of the pyloric, ileocolic and anal sphincters; increased movements of the gall-duct.

Secretory glands are slightly stimulated. Increased glycogenolysis. Urine arrested then augmented; local.

Metabolism. - No apparent change.

Temperature. - Not affected.

Absorption does not take place readily from the mucosa. It is absorbed slowly from the subcutaneous tissues, but more readily from the muscular tissues. Its action is very rapid intravenously.

Excretion. - Epinephrin is rendered inert very promptly by some counteracting substance in the blood or vessel walls.

Local Action. - Epinephrin induces a prompt ischaemia through local vasoconstriction.

Symptoms.

Therapeutic Doses.

Cerebral congestion. Acceleration of the heart, followed by strong, full beat. Remarkable, though fleeting, rise of blood-pressure.

Toxic Doses.

Glycosuria.

Diuresis.

Inflammations of liver and kidney.

Prostration.

Collapse of central nervous system.

Respiratory failure.

Pulmonary edema.

Therapeutics.

Epinephrin may be employed to produce local ischaemia, to arrest hemorrhage from mucous surfaces; and, if used intravenously, to combat shock; it is also used in asthma to relax bronchial spasm.

Dosage.

Epinephrin in 1: 1000 solution.

For local application, use full strength.

For hypodermic use, dilute one-half with normal salt solution.

For intravenous use, dilute I to 10 with Locke's solution.

Epinephrin 71

Crimson = stimulation. Violet = depression.