Overview
11 DESCRIPTION Norepinephrine (sometimes referred to as l-arterenol/Levarterenol or l-norepinephrine) is a sympathomimetic amine which differs from epinephrine by the absence of a methyl group on the nitrogen atom. Norepinephrine bitartrate, USP is (-)-α-(aminomethyl)-3,4-dihydroxybenzyl alcohol tartrate (1:1) (salt), monohydrate (molecular weight 337.
Mechanism of Action
12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Norepinephrine is a peripheral vasoconstrictor (alpha-adrenergic action) and an inotropic stimulator of the heart and dilator of coronary arteries (beta-adrenergic action). 12.2 Pharmacodynamics The primary pharmacodynamic effects of norepinephrine are cardiac stimulation and vasoconstriction. Cardiac output is generally unaffected, although it can be decreased, and total peripheral resistance is also elevated. The elevation in resistance and pressure result in reflex vagal activity, which slows the heart rate and increases stroke volume. The elevation in vascular tone or resistance reduces blood flow to the major abdominal organs as well as to skeletal muscle.
Indications
- 1 INDICATIONS AND USAGE Norepinephrine bitartrate injection is indicated to raise blood pressure in adult patients with severe, acute hypotension. Norepinephrine bitartrate injection is a catecholamine indicated for restoration of blood pressure in adult patients with acute hypotensive states. ( 1 )
Common Doses
- 0.25 mL
- 0.375 mL
- 8 mcg
- 12 mcg
Dosage
2 DOSAGE AND ADMINISTRATION Initial dose of 0.25 mL to 0.375 mL (from 8 mcg to 12 mcg of base) per minute, adjust the rate of flow to establish and maintain a low to normal blood pressure (usually 80 mm Hg to 100 mm Hg systolic) sufficient to maintain the circulation of vital organs. ( 2.2 ) The average maintenance dose ranges from 0.0625 mL to 0.125 mL per minute (from 2 mcg to 4 mcg of base). ( 2.2 ) 2.1 Important Dosage and Administration Instructions Correct Hypovolemia Address hypovolemia before initiation of norepinephrine bitartrate injection therapy.
Contraindications
- 4 CONTRAINDICATIONS None. None. ( 4 )
Side Effects
- 6 ADVERSE REACTIONS The following adverse reactions are described in greater detail in other sections: Tissue Ischemia [see Warnings and Precautions (5.1) ] Hypotension [see Warnings and Precautions (5.2) ] Cardiac Arrhythmias [see Warnings and Precautions (5.3) ] The most common adverse reactions are hypertension and bradycardia. The following adverse reactions can occur: Nervous system disorders: Anxiety, headache Respiratory disorders: Respiratory difficulty, pulmonary edema Most common adverse reactions are ischemic injury, bradycardia, anxiety, transient headache, respiratory difficulty,...
Interactions
- 7 DRUG INTERACTIONS Monoamine oxidase inhibitors (MAOI) or antidepressants of the triptyline or imipramine types may result in hypertension. ( 7.1 ) Cyclopropane and halothane anesthetics increase cardiac autonomic irritability. ( 7.4 ) 7.1 MAO-Inhibiting Drugs Co-administration of norepinephrine bitartrate with monoamine oxidase (MAO) inhibitors or other drugs with MAO-inhibiting properties (e.g., linezolid) can cause severe, prolonged hypertension.