Levophed SF Mechanism of Action

Pharmacotherapeutic group: Adrenergic and dopaminergic agents. ATC code: C01CA03.
Pharmacology: Pharmacodynamics: Noradrenaline exists as 2 enantiomers where the L-form is the active isomer and the D-form is the inactive isomer (see Shelf-Life under Storage).
The vascular effects in the doses normally used clinically result from the simultaneous stimulation of alpha- and beta-adrenergic receptors in the heart and vascular system. Except in the heart, its action is predominantly on the alpha receptors. 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.
The increase in blood pressure may cause a reflex decrease in heart rate. Vasoconstriction may result in decreased blood flow in kidneys, liver, skin and smooth muscles. Local vasoconstriction may cause hemostasis and/or necrosis.
The effect on blood pressure disappears 1-2 minutes after stopping the infusion.
Pharmacokinetics: Up to 16% of an intravenous dose is excreted unchanged in the urine with methylated and deaminated metabolites in free and conjugated forms.
Toxicology: Preclinical Safety Data: Most of the adverse effects attributable to sympathomimetics result from excessive stimulation of the sympathetic nervous system via the different adrenergic receptors.
Noradrenaline may impair placental perfusion and induce fetal bradycardia. It may also exert a contractile effect on the uterus and lead to fetal asphyxia in late pregnancy.