At higher doses, however, vasoconstriction and elevation of both peripheral vascular resistance and blood pressure can occur. The metabolic effects of epinephrine relate primarily to the regulatory processes that control glucose concentration in the plasma. Serum potassium concentrations fluctuate after administration of epinephrine. Initially, hyperkalemia occurs secondary to release of potassium ions from hepatocytes. Hypokalemia quickly follows as potassium ions are taken up by the skeletal muscle.
Subcutaneous administration is favored over intramuscular.
The onset of action after IM administration is variable, and the duration of action is 1-4 hours. Absorption of an IM dose may be increased both quantitatively and qualitatively by massaging the area of injection, which increases local blood flow. After inhalation of a normal dose, the drug is only slightly absorbed systemically, and its effects are limited primarily to the respiratory tract. The onset of action of various effects of an intraocular dose range from minutes to 1 hour, and the duration of these actions are from less than 1 hour to 24 hours. Epinephrine is distributed throughout the body.