Noren Mechanism of Action

Pharmacotherapeutics group: Adrenergic and Dopaminergic Agonist. ATC Code: C01CA03 (C: Cardiovascular system).
Pharmacology: Pharmacodynamics: Norepinephrine has a very potent action on alpha receptors and moderate effects on beta-1 receptors. Norepinephrine causes generalized vasoconstriction, except for the coronary vessels which it dilates indirectly by increasing the oxygen consumption. This results in an increase in the force (and in the absence of vagal inhibition) in the rate of myocardial contraction. Peripheral resistance increases and diastolic and systolic pressures are raised.
Pharmacokinetics: Two stereoisomers of Norepinephrine exist, the biologically active L-isomer is the one present in Norepinephrine 1mg/ml concentrate for solution for infusion.
Absorption: Subcutaneous: Poor.
Oral: Norepinephrine is rapidly inactivated in the gastro intestinal tract following oral administration.
After intravenous administration Norepinephrine has a plasmatic half-life of about 1 to 2 minutes.
Distribution: Norepinephrine is rapidly cleared from plasma by a combination of cellular reuptake and metabolism. It does not readily cross the blood-brain barrier.
Biotransformation (Metabolism): Methylation by catechol-o-methyltransferase; Deamination by monoamine oxidase (MAO); Ultimate metabolites from both 4-hydroxy-3-methoxymandelic acid; Intermediate metabolites include normetanephrine and 3,4-dihydroxymandelic acid.
Excretion: Norepinephrine is mainly eliminated as glucuronide or sulphate conjugates of the metabolites in the urine.