Norlapex Mechanism of Action

Pharmacology: Pharmacodynamics: Norlapex functions as a peripheral vasoconstrictor (alpha-adrenergic action) and as an inotropic stimulator of the heart and dilator of coronary arteries (beta-adrenergic action).
Pharmacokinetics: Absorption: The drug is poorly absorbed after subcutaneous injection. It is rapidly inactivated in the gastro-intestinal tract following oral administration. After intravenous administration the drug has a short duration of action and a plasmatic half-life of about 1 to 2 minutes.
Distribution: The drug crosses placenta but not the blood-brain barrier. It is rapidly cleared from plasma by a combination of cellular reuptake and metabolism.
Metabolism: 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-methoxyl-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.
Elimination: It is mainly eliminated as glucuronide or sulphate conjugates of the metabolites in the urine. Only small quantities of norepinephrine are excreted unchanged.