Epinephrine, together with norepinephrine, is secreted principally by the medulla of the adrenal gland . Heightened secretion caused by fear or anger results in increased heart rate and the hydrolysis of glycogen to glucose. This reaction, often called the "fight or flight" response, prepares the body for strenuous activity. The hormone was first extracted in 1901 from the adrenal glands of animals and it was synthesized in 1904. Epinephrine is used medicinally as a stimulant in cardiac arrest, as a vasoconstrictor in shock, and as a bronchodilator and antispasmodic in bronchial asthma.

Formation of Epinephrine
Phenylalanine > Tyrosine > L-Dopa > Dopamine > Norepinephrine > Epinephrine.

Catecholamines (norepinephrine, dopamine, epinephrine) act in the brain as chemical neurotransmitters and represent integrative component of many anatomical and functional interrelationships, which play important role in the maintenance of the basic physiological processes and homeostasis of living organism.

Epinephrine Tablet?
March 2006 - It may be possible to administer epinephrine in a tablet -- placed under the tongue -- for the emergency treatment of anaphylaxis. Dr. Keith J. Simons from the University of Manitoba in Winnipeg and colleagues tested this approach in rabbits, which were given a new, rapidly disintegrating tablet containing epinephrine placed under the tongue. The oral treatment resulted in blood levels of epinephrine similar to those achieved with 0.3 mg epinephrine administered intramuscularly in the thigh -- the currently recommended emergency treatment for anaphylaxis. Tablets containing increasing doses of epinephrine were retained under the tongue for 5 minutes and the EpiPen was injected in the thigh. Blood was collected before dosing and at various times afterwards up to 180 minutes. The maximum blood concentrations and time to maximum blood concentrations were similar when epinephrine was given under the tongue or by EpiPen injection. The epinephrine tablets will be tested in humans.