What is the maximum dose of vasopressin (antidiuretic hormone) per hour?

Maximum Dose of Vasopressin Per Hour

The maximum dose of vasopressin is 0.8 units/minute (48 units/hour) when used for variceal hemorrhage, but for vasodilatory shock states (septic shock, post-cardiotomy shock), the maximum recommended dose is 0.04 units/minute (2.4 units/hour), with limited safety data above 0.1 units/minute for post-cardiotomy shock and 0.07 units/minute for septic shock. 1, 2

Context-Specific Maximum Dosing

Variceal Hemorrhage (Highest Maximum Dose)

• Maximum dose: 0.8 units/minute (48 units/hour) 1
• Starting dose: 0.2-0.4 units/minute, titrated upward as needed 1
• Critical limitation: Can only be used continuously at the highest effective dose for a maximum of 24 hours to minimize serious side effects including cardiac ischemia, arrhythmias, hypertension, and bowel ischemia 1
• Must always be accompanied by IV nitroglycerin (starting 40 µg/minute, maximum 400 µg/minute) to mitigate vasoconstrictive complications 1

Vasodilatory Shock (Septic Shock, Post-Cardiotomy Shock)

• FDA-approved maximum: 0.1 units/minute for post-cardiotomy shock and 0.07 units/minute for septic shock 2
• Practical upper limit: 0.04 units/minute (2.4 units/hour) - doses above this threshold significantly increase risk of cardiac arrest and tissue ischemia 3, 4, 5
• Starting dose for post-cardiotomy shock: 0.03 units/minute 2
• Starting dose for septic shock: 0.01 units/minute 2
• Titrate up by 0.005 units/minute at 10-15 minute intervals until target blood pressure achieved 2

Critical Safety Considerations

Dose-Dependent Toxicity

• Above 0.04 units/minute, vasopressin may lead to cardiac arrest 3
• Side effects increase substantially with higher doses, including ischemic skin lesions, intestinal ischemia, cardiac ischemia, and arrhythmias 1, 3, 4
• Vasopressin causes gastrointestinal hypoperfusion even at therapeutic doses 4

Duration Limitations

• For variceal hemorrhage: Maximum continuous use of 24 hours at highest doses 1
• For vasodilatory shock: Can be used for longer durations (days) but only at low doses (≤0.04 units/minute) 6, 4, 5

Clinical Pitfalls to Avoid

Never Use as Sole Vasopressor

• Vasopressin must never be used as the only vasopressor agent in shock states 7
• Should be combined with norepinephrine, with vasopressin used to reduce catecholamine requirements 6, 7, 4

Avoid Dose Titration as Primary Strategy

• Unlike other vasopressors, vasopressin should be used at a fixed low dose (typically 0.04 units/minute or less) rather than titrated upward 7, 4
• Adjust norepinephrine dose to achieve blood pressure targets, not vasopressin 7

Context Matters

• The 0.8 units/minute maximum for variceal bleeding is NOT applicable to shock states - this higher dose is only appropriate for acute variceal hemorrhage with concurrent nitroglycerin and limited to 24 hours 1
• In cirrhosis patients with hepatorenal syndrome, use even more conservative dosing with gradual titration 8

Practical Dosing Algorithm

For Septic/Vasodilatory Shock:

1. Start at 0.01-0.03 units/minute 2, 6
2. Titrate by 0.005 units/minute every 10-15 minutes 2
3. Stop escalation at 0.04 units/minute - if inadequate response, add or increase other vasopressors rather than exceeding this threshold 3, 4, 5
4. Taper by 0.005 units/minute every hour once stable for 8 hours 2

For Variceal Hemorrhage:

1. Start at 0.2-0.4 units/minute with concurrent IV nitroglycerin 1
2. Titrate up to maximum 0.8 units/minute if needed 1
3. Discontinue after 24 hours regardless of response 1
4. Consider terlipressin as safer alternative with fewer side effects 1