Norepinephrine (Levophed) is contraindicated in which of the following conditions?
A. Hypovolemic shock.
B. Neurogenic shock.
C. Blood pressures above 80-100 mmHg (systolic).
D. Decreased renal perfusion.
Correct Answer: A. Hypovolemic shock.
Norepinephrine (Levophed) is contraindicated in hypovolemia. Norepinephrine use may be contraindicated to treat hypotension that is likely secondary to cardiogenic mechanisms. Additionally, for hypotension primarily related to hypovolemia, norepinephrine is probably not the best agent. The FDA does state that its use could be a consideration in low volume states, but only as an emergency measure for maintaining coronary or cerebral perfusion pressure while waiting for appropriate volume resuscitation.
Option B: Neurogenic shock is an indication for norepinephrine use. Norepinephrine generally has more predictive pharmacologic properties than other alpha agonists. This predictive quality, in combination with some of its beta-agonism (which improves cardiac function relative to pure alpha agonists), makes norepinephrine a widely used vasoactive agent. It is commonly utilized in intensive care units to treat hypotension secondary to distributive shock.
Option C: Norepinephrine is given to maintain a systolic blood pressure of 80-100 mmHg. Norepinephrine is a sympathomimetic amine derived from tyrosine. It is structurally identical to epinephrine but differs in that it lacks a methyl group on its nitrogen atom. This difference makes it primarily agonistic at alpha1 and beta1 receptors, with little-to-no beta2 or alpha2 activity. At low doses (less than 2 mcg/min), the beta1 effects may be more pronounced and potentially increase cardiac output.
Option D: Decreased renal perfusion is an adverse reaction. The most common adverse effects of norepinephrine relate directly to the activation of alpha1 receptors. That is, excessive vasoconstriction can result in decreased end-organ perfusion, which is primarily caused by infusions of norepinephrine without appropriately treating hypovolemia; this can be detrimental as most patients require infusions of norepinephrine already have poor oxygen delivery or utilization.