Its use as a bronchodilator in the treatment of asthma has largely been superceded by nebulized albuterol.
Endogenous epinephrine is produced primarily from norepinephrine in the adrenal medulla.
The discovery of epinephrine's pharmacologic effects and synthesis date back to the late 1800s. Epinephrine was approved by the FDA in 1939. Epinephrine administered by metered-dose inhaler is available without a prescription for treatment of asthma, however, in November 1994, the FDA expressed concern regarding OTC status for this dosage form. The effects of epinephrine on smooth muscle are varied and determined by relative receptor density and hormonal effects. When used topically in the eye in patients with open-angle glaucoma, epinephrine lowers intraocular pressure, produces a brief mydriasis, and may improve the coefficient of aqueous outflow.