Norepirin Mechanism of Action

Pharmacology: Pharmacodynamics: Norepinephrine functions as a peripheral vasoconstrictor (alpha-adrenergic action) and as an inotropic stimulator of the heart and dilator of coronary arteries (beta-adrenergic action).
Norepirin Injection belongs to a group of medicines called sympathomimetic and vasoconstriction.
Pharmacokinetics: Absorption: Norepinephrine is ineffective orally, and subcutaneous absorption is poor. As a result, it is recommended that norepinephrine be administered only via the intravenous route. Following IV administration, the onset of activity is rapid, with a short duration of action of only 1-2 minutes after the infusion is discontinued.
Distribution: Norepinephrine localizes mainly in sympathetic nervous tissue. The drug crosses the placenta but not the blood-brain barrier.
Elimination: The pharmacologic actions of norepinephrine are terminated primarily by uptake and metabolism in sympathetic nerve endings. The drug is metabolized in the liver and other tissues by a combination of reactions involving the enzymes catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO). The major metabolites are normetanephrine and 3-methoxy-4-hydroxy mandelic acid (vanillylmandelic acid, VMA), both of which are inactive. Other inactive metabolites include 3-methoxy-4-hydroxyphenylglycol,3,4-dihydroxymandelic acid, and 3,4-dihydroxyphenylglycol. Norepinephrine metabolites are excreted in urine primarily as the sulfate conjugates and, to a lesser extent, as the glucuronide conjugates. Only small quantities of norepinephrine are excreted unchanged.