Vasopressin

ADH Analog·Cardiovascular - Vasopressors & ICU

Refractory septic shock, vasoplegic shock post-cardiac surgery, diabetes insipidus

VASOPRESSORPitressinAmpoules (20 units/1 mL)S4TGA

Max Dose

0.04 units/min

Half-life

10-20 mins

Ischaemia

SPLANCHNIC RISK

Sepsis

2ND LINE

Rapid Summary

Overview

Synthetic Antidiuretic Hormone (ADH). Potent, non-catecholamine vasopressor. Works completely independently of adrenergic receptors, making it brilliant for refractory, acidotic septic shock.

Maximum Dose

Max 0.04 units/min (Higher doses cause catastrophic bowel/digit ischemia).

Clinical Focus

Given at a flat, non-titrated rate (usually 0.04 units/min) as an 'add-on' to Noradrenaline to spare massive catecholamine doses.

Bottom Line

Vasopressin is a second-line vasopressor for septic shock and cardiac arrest (non-shockable rhythms), but causes peripheral ischaemia including digital gangrene and must be infused through central access.

Formulation & Access

Brand Names

Pitressin

Parenteral

Ampoules (20 units/1 mL). MUST be heavily diluted in Normal Saline/D5W.

Prescribing & PBS

Hospital ICU/OT supply only.

Indications & Use

Primary

TGA

Refractory septic shock, vasoplegic shock post-cardiac surgery, diabetes insipidus.

Clinical Place

Second-line vasopressor added when Noradrenaline doses are climbing dangerously high, or when profound acidosis renders Noradrenaline useless.

Quick reference

Class & Role

ADH Analog — Synthetic Antidiuretic Hormone (ADH).

Route / Formulation

Ampoules (20 units/1 mL). MUST be heavily diluted in Normal Saline/D5W. (Pitressin)

Usual Dose & Max

IV Infusion 0.01 to 0.04 units/minute (Flat rate, rarely titrated). Run via Central Line. Max 0.04 units/min (Higher doses cause catastrophic bowel/digit ischemia).

Key Indication Doses

Vasodilatory / Septic Shock: IV Infusion 0.01 to 0.04 units/minute (Flat rate, rarely titrated). Run via Central Line. Post-Cardiotomy Vasoplegia: IV Infusion 0.01 to 0.06 units/minute.

Best Uses

Avoid / Cautions

Uncorrected hypovolemia. Extreme caution in severe coronary artery disease (can cause myocardial infarction). Pregnancy Category B3.

Key Risks

Cardiovascular: Severe splanchnic (gut) ischaemia, digital necrosis (fingers/toes falling off), coronary vasospasm, reflex bradycardia. Metabolic: Hyponatremia (due to massive free water retention via V2 receptors), water intoxication.

Key Interactions

Additive profound vasoconstriction with Noradrenaline (though intentionally used together for synergy).

Monitoring

Intra-arterial BP line. Assess fingers, toes, and bowel function strictly for signs of ischemic necrosis. Monitor U&E (sodium) and ABGs (Lactate tracking for gut ischemia).

Clinical Pearl

When a patient is in severe septic shock, their blood becomes highly acidic. Acidosis physically warps the alpha-1 receptors, causing Noradrenaline to bounce off and fail. Vasopressin uses the V1 receptor, which is immune to acidosis, instantly restoring blood pressure.

Access

Pitressin

Brand: Pitressin

Vasopressin

ADH Analog·Cardiovascular - Vasopressors & ICU

Refractory septic shock, vasoplegic shock post-cardiac surgery, diabetes insipidus

VASOPRESSORPitressinAmpoules (20 units/1 mL)S4TGA

Max Dose

0.04 units/min

Half-life

10-20 mins

Ischaemia

SPLANCHNIC RISK

Sepsis

2ND LINE

Rapid Summary

Overview

Synthetic Antidiuretic Hormone (ADH). Potent, non-catecholamine vasopressor. Works completely independently of adrenergic receptors, making it brilliant for refractory, acidotic septic shock.

Maximum Dose

Max 0.04 units/min (Higher doses cause catastrophic bowel/digit ischemia).

Clinical Focus

Given at a flat, non-titrated rate (usually 0.04 units/min) as an 'add-on' to Noradrenaline to spare massive catecholamine doses.

Bottom Line

Formulation & Access

Brand Names

Pitressin

Parenteral

Ampoules (20 units/1 mL). MUST be heavily diluted in Normal Saline/D5W.

Prescribing & PBS

Hospital ICU/OT supply only.

Indications & Use

Primary

TGA

Refractory septic shock, vasoplegic shock post-cardiac surgery, diabetes insipidus.

Clinical Place

Second-line vasopressor added when Noradrenaline doses are climbing dangerously high, or when profound acidosis renders Noradrenaline useless.

Quick reference

Class & Role

ADH Analog — Synthetic Antidiuretic Hormone (ADH).

Route / Formulation

Ampoules (20 units/1 mL). MUST be heavily diluted in Normal Saline/D5W. (Pitressin)

Usual Dose & Max

IV Infusion 0.01 to 0.04 units/minute (Flat rate, rarely titrated). Run via Central Line. Max 0.04 units/min (Higher doses cause catastrophic bowel/digit ischemia).

Key Indication Doses

Vasodilatory / Septic Shock: IV Infusion 0.01 to 0.04 units/minute (Flat rate, rarely titrated). Run via Central Line. Post-Cardiotomy Vasoplegia: IV Infusion 0.01 to 0.06 units/minute.

Best Uses

Avoid / Cautions

Uncorrected hypovolemia. Extreme caution in severe coronary artery disease (can cause myocardial infarction). Pregnancy Category B3.

Key Risks

Key Interactions

Additive profound vasoconstriction with Noradrenaline (though intentionally used together for synergy).

Monitoring

Intra-arterial BP line. Assess fingers, toes, and bowel function strictly for signs of ischemic necrosis. Monitor U&E (sodium) and ABGs (Lactate tracking for gut ischemia).

Clinical Pearl

Access

Pitressin

Brand: Pitressin