Nursing Pharmacology  Autonomic Pharmacology Adrenergic Drugs 

Norepinephrine (Levophed)

• Norepinephrine is the primary neurotransmitter released by postganglionic neurons of the autonomic sympathetic system.

  • Norepinephrine (Levophed) is a potent activator of α and ß₁ adrenergic receptors.

• Blood Pressure Effects

  • Norepinephrine is a potent vasopressor

    • Systolic and diastolic pressure increase

      • Pulse pressure widens

    • Norepinephrine (Levophed) increases blood pressure by:

      1. vasoconstriction α₁ receptor effects

         • Precapillary resistance vessels of the skin, kidney, and mucosa

         • Veins

    •  Elevation of systolic pressure following norepinephrine is likely to activate the baroreceptor system resulting in a reflex-mediated decrease in heart rate.

Adaptation of Table 10-2 from: Hoffman, B.B and Lefkowitz, R.J, Catecholamines, Sympathomimetic Drugs, and Adrenergic Receptor Antagonists, In, Goodman and Gillman's The Pharmacologial Basis of Therapeutics,(Hardman, J.G, Limbird, L.E, Molinoff, P.B., Ruddon, R.W, and Gilman, A.G.,eds) The McGraw-Hill Companies, Inc.,1996, pp.199-242

 

                Norepinephrine Effects on Vascular Tone of Arterioles  (Sympathetic Nervous System Effects)          

Coronary	α1,2; β2	constriction; dilatation
Skin/Mucosa	α1,2	constriction
Skeletal Muscle	α; β2	constriction; dilatation
Cerebral	α1	slight constriction
Pulmonary	α1 , β2	constriction; dilatation
Abdominal viscera	α1, β2	constriction; dilatation
Salivary glands	α1,2	constriction
Renal	α1,2;β1,2	constriction; dilatation

Based on Table 6-1: Lefkowitz, R.J, Hoffman, B.B and Taylor, P. Neurotransmission: The Autonomic and Somatic Motor Nervous Systems, In, Goodman and Gillman's The Pharmacologial Basis of Therapeutics,( Hardman, J.G, Limbird, L.E, Molinoff, P.B., Ruddon, R.W, and Gilman, A.G.,eds) The McGraw-Hill Companies, Inc.,1996, pp.110-111.

Vascular Effects

• Norepinephrine significantly increases total peripheral resistance, often inducing reflex cardiac slowing.

• Norepinephrine (Levophed) causes vasoconstriction in most vascular beds.

• Blood flow is reduced to the kidney, liver and skeletal muscle.

• Glomerular filtration rates are usually maintained.

• Norepinephrine may increase coronary blood flow (secondary to increased blood pressure and reflex activity)

• Norepinephrine (Levophed) may induce variant (Prinzmetal's) angina.

  •  

    "Microvascular Angina and Coronary Artery Spasm"

    "Professor Juan Carlos Kaski, Head of the Cardiovascular Sciences Research Centre, St. George's University of London, UD discusses Microvascular Angina for this Expert Opinion interview." CVSRCVideos https://www.youtube.com/watch?v=3TmUvQJ0hr4 .

     

• Pressor effects of norepinephrine (Levophed) are blocked by α-receptor blockers.

• ECG changes following norepinephrine (Levophed) are variable, depending on the extent of reflex vagal effects.

increase, decrease

0.1-0.4 ug/kg/min IV infusion

Adaptation of Table 10-2 from: Hoffman, B.B and Lefkowitz, R.J, Catecholamines, Sympathomimetic Drugs, and Adrenergic Receptor Antagonists, In, Goodman and Gillman's The Pharmacologial Basis of Therapeutics, Hardman, J.G, Limbird, L.E, Molinoff, P.B., Ruddon, R.W, and Gilman, A.G.,eds) The McGraw-Hill Companies, Inc.,1996, pp.199-242

• Therapeutic use: Norepinephrine

  • Norepinephrine may be used in some circumstances in treatment of shock

Hoffman, B.B and Lefkowitz, R.J, Catecholamines, Sympathomimetic Drugs, and Adrenergic Receptor Antagonists, In, Goodman and Gillman's The Pharmacologial Basis of Therapeutics, (Hardman, J.G, Limbird, L.E, Molinoff, P.B., Ruddon, R.W, and Gilman, A.G.,eds) TheMcGraw-Hill Companies, Inc.,1996, pp.204-213.