Name: Norepinephrine
Class: Catecholamine
Mech.: Stim. a and b1, but not b2. Approx equal affinity as EPI at b1, less at a. Causes in systolic & diastolic pressure. CO unchanged or ¯ due to reflexive bradycardia. TPR. Marked vasoconstriction but coronary flow due to myocardial contractility.
Absorption: No oral. Usu slow IV. Poor subcut.
Dist.:
Metab.: Catab. by COMT and MAO, esp. in liver and kidneys. Glucuronidation and sulfconjugation.
Excretion, t½: Short duration (1-2 min)
Toxicity/S.E.s: Less severe than EPI. Anxiety, resp. difficulty, slow forceful heart beat, transient headache. Risk of cardiac arrhythmia ® contraind. w/halogenated hydrocarbon anesthetics. ¯ blood to vital organs. Necrosis at infusion site if extravasated. Contraind. for pregnant women, halog. hydroc. anesthetics, tricyclics.
Utility: Limited value. 1° for shock, certain acute hypotensive states (e.g., hypotension persisting after correction of blood volume deficit). Adjunct in treatment of cardiac arrest w/profound hypertension.