Pharmacological properties : תכונות פרמקולוגיות

Pharmacodynamic Properties

5.1 Pharmacodynamic properties
Pharmacotherapeutic group: Adrenergic and dopaminergic drugs, ATC code: C01CA04.
Dopamine acts as an agonist on specific dopamine receptors and on alpha and beta adrenergic receptors.
It decreases peripheral resistance and causes mesenteric and renal vasodilation.
It increases renal blood flow, glomerular filtration and urinary flow.
As regards the heart, dopamine causes an increased inotropism.
It differs from noradrenaline in the action on the region of the kidneys and from isoproterenol, as it does not increase the heart rate.
The knowledge about cardiovascular activities of dopamine involving the activation of alpha and beta adrenergic receptors, as well as dopaminergic receptors, allows to better modulate the amine infusion, which, depending on the dose, can give effects of vasoconstriction or vasodilation, cardiac stimulation, inhibition of the increase in heart rate, diuresis, natriuresis and inhibition of aldosterone circulation.

Pharmacokinetic Properties

5.2 Pharmacokinetic properties
The effect of dopamine administered intravenously occurs within 5 minutes.
Its half-life is about 2 minutes.
The drug is widely distributed in the body, but it does not significantly cross the brain blood barrier.
Dopamine is metabolized in the liver, kidney and plasma by MAO (monoamine oxidase) in 3,4- dihydroxyphenylacetic acid (DOPAC) and by COMT (catechol O methyltransferase) in homovanillic acid (HVA); in small amounts it is hydroxylated in adrenergic nerve endings, thus producing norepinephrine.
The drug is rapidly excreted in the urine (approximately 80% in 24 hours), mainly in the form of HVA, DOPAC and glucuronide conjugates.