What are the clinical uses and dosing recommendations for vasopressin?

Clinical Uses and Dosing Recommendations for Vasopressin

Vasopressin is primarily indicated to increase blood pressure in adults with vasodilatory shock who remain hypotensive despite fluids and catecholamines, with specific dosing recommendations for septic shock (0.01-0.07 units/minute) and post-cardiotomy shock (0.03-0.1 units/minute). 1

Primary Clinical Uses

• Vasopressin is FDA-approved for the management of vasodilatory shock in adults who remain hypotensive despite adequate fluid resuscitation and first-line catecholamine vasopressors 1
• It serves as a second-line vasopressor after norepinephrine in septic shock, not as a first-line agent 2
• Vasopressin can be used for acute variceal hemorrhage in cirrhosis at doses of 0.2-0.4 units/minute, which can be increased to a maximum of 0.8 units/minute 3

Dosing Recommendations by Indication

Septic Shock

• Standard dose: 0.01-0.07 units/minute when added to norepinephrine 2, 1
• Typical starting dose: 0.03 units/minute 4
• Doses higher than 0.03-0.04 units/minute should be reserved for salvage therapy when other vasopressors have failed to achieve target MAP 4, 2
• Vasopressin should not be used as the single initial vasopressor for septic shock 2

Post-Cardiotomy Shock

• Recommended dose range: 0.03-0.1 units/minute 1
• Can be added to norepinephrine to either raise mean arterial pressure or decrease norepinephrine dosage 2

Administration Guidelines

• Dilute 20 units/mL multiple dose vial contents with normal saline (0.9% sodium chloride) or 5% dextrose in water (D5W) to either 0.1 units/mL or 1 unit/mL for intravenous administration 1
• Discard unused diluted solution after 18 hours at room temperature or 24 hours under refrigeration 1
• Administration requires central venous access, and arterial catheter placement is recommended for continuous blood pressure monitoring 2
• Target mean arterial pressure (MAP) is typically 65 mmHg in septic shock 2, 3

Mechanism of Action and Physiological Effects

• Vasopressin mediates vasoconstriction via V1-receptor activation on vascular smooth muscle 5
• It also has antidiuretic effects via V2-receptor activation in the renal collecting duct system 5
• At low plasma concentrations, vasopressin can mediate vasodilation in coronary, cerebral, and pulmonary arterial circulations 5
• Septic shock causes first a transient early increase in blood vasopressin concentrations that later decrease to very low levels, creating a state of "relative vasopressin deficiency" 5, 6

Potential Benefits

• Increases systemic vascular resistance and arterial blood pressure 7
• Reduces the dosage requirements of adrenergic agents 7, 8
• May enhance urine production due to increased glomerular filtration rate 7
• May decrease pulmonary vascular resistance 5

Adverse Effects and Precautions

• Can worsen cardiac function, potentially reducing cardiac output and heart rate 1, 7
• May cause tachyarrhythmias and bradycardia 1
• Risk of tissue ischemia (coronary, mesenteric, skin, digital) 1, 9
• Can cause hyponatremia and reversible diabetes insipidus 1
• Contraindicated in patients with known allergy or hypersensitivity to 8-L-arginine vasopressin or chlorobutanol 1

Drug Interactions

• Pressor effects of catecholamines and vasopressin are expected to be additive 1
• Indomethacin may prolong effects of vasopressin 1
• Co-administration of ganglionic blockers or drugs causing SIADH may increase the pressor response 1
• Co-administration of drugs causing diabetes insipidus may decrease the pressor response 1

Clinical Pearls

• Limiting the dosage to 0.03 units/minute or less may minimize the development of adverse effects 7
• Vasopressin should be considered if response to one or two adrenergic agents is inadequate 7
• Careful monitoring is essential in patients with cardiac dysfunction due to potential reduction in cardiac output 7
• Safety and effectiveness have not been established in pediatric patients 1