Vasopressin (Vasostrict®)

ED / ICU / Transport

• Septic shock on escalating norepinephrine: the second pressor, added on top of norepinephrine. Not the first-line agent.
• Vasodilatory shock despite fluids and catecholamines: the use the FDA label covers, in adults.
• Post-cardiotomy vasoplegia: vasodilatory shock after cardiac surgery. The FDA label calls it post-cardiotomy shock.
• Pediatric septic shock on high-dose catecholamines: SSC 2026 children suggests two options, adding vasopressin or titrating catecholamines further. PICU specialist use, off-label (see Pediatric Shock).
• In-hospital cardiac arrest (IHCA): not recommended. AHA 2025 Part 9 rates vasopressin, alone or with epinephrine, Class 3: No Benefit (B-R). Steroids during arrest sit at Class 2b, C-LD: uncertain benefit. The VAM-IHCA trial (512 in-hospital arrests) lifted ROSC with vasopressin plus methylprednisolone (42% vs 33%). It did not move 30-day survival (9.7% vs 12%) or favorable neurologic outcome (7.6% vs 7.6%). Mention only. No trial dosing on this page.

Available Forms

• Concentrate vials (must be diluted): 20 units/mL in a 1 mL single-dose vial (no preservative), and 200 units/10 mL (20 units/mL) multiple-dose vial with 0.5% chlorobutanol
• Premixed in 5% dextrose, ready to use (single-dose vials): 20 units/100 mL (0.2 units/mL), 40 units/100 mL (0.4 units/mL), 60 units/100 mL (0.6 units/mL) and 50 units/50 mL (1 unit/mL)
• Label dilutions: 0.1 units/mL (2.5 mL in 500 mL) or 1 unit/mL (5 mL in 100 mL, fluid restriction) in 0.9% NaCl or D5W

Adult Dosing

Dosing weight: adult shock dosing is a fixed units/min rate. There is no weight math.

Pediatric Dosing

Continuous Infusion

Preparation & Administration

• Dilution: dilute vials in 0.9% NaCl or D5W. Premixed vials need no further dilution. Discard diluted solution after 18 hr at room temperature or 24 hr refrigerated.
• Pump requirement: run it as a continuous infusion on a smart pump: units/min for adults, units/kg/min for children. Never push it for shock. The label route is IV only.
• Line: a dedicated line or lumen. SSC 2026 suggests starting vasopressors peripherally rather than waiting on central access. Move to a central line as support escalates, per local protocol.
• Weaning: catecholamines come off first. Once target BP has held for 8 hr without catecholamines, taper vasopressin by 0.005 units/min every hour as tolerated (label).

Contraindications

• Known allergy or hypersensitivity to 8-L-arginine vasopressin.
• Chlorobutanol allergy: the 10 mL multiple-dose vial is the one that carries it. Use a preservative-free single-dose vial or premix.

Precautions

• Impaired cardiac function: vasopressin can lower cardiac index. Right heart failure has been reported (label). Use the lowest effective dose and reassess output in cardiogenic, mixed or right ventricular failure.
• Ischemia-prone patients (peripheral vascular disease, coronary disease, mesenteric risk): the more you give, the more coronary, mesenteric, skin and digital ischemia you see.
• Hyponatremia or free-water excess: the V₂ antidiuretic effect holds on to water.
• Stopping the infusion: diabetes insipidus can follow discontinuation, and it is reversible.

Hold / Reassess If

• Mottled or dusky digits, ischemic skin lesions, abdominal pain or rising lactate: drop to the lowest effective dose, reassess volume and output, and get vascular or surgical review early.
• New bradycardia, falling cardiac output or ischemic ECG changes: ask whether you still need vasopressin.
• Na⁺ falling: look at free-water intake and whether vasopressin is still needed.
• MAP above goal: catecholamines come off first. Taper vasopressin only after 8 hr off catecholamines.
• Polyuria with rising Na⁺ after stopping: think diabetes insipidus. Restart vasopressin or give desmopressin.

Common

• Decreased cardiac output and bradycardia
• Tachyarrhythmias, including atrial fibrillation
• Hyponatremia
• Ischemia: coronary, mesenteric, skin and digital

Also reported (label, frequency unknown): acute renal insufficiency, increased bilirubin, intractable bleeding with hemorrhagic shock, decreased platelets and right heart failure.

Serious / Life-Threatening

Overdose & Toxicity Management

• Signs: peripheral, mesenteric and coronary vasoconstriction, plus hyponatremia. Less often you see ventricular tachyarrhythmias including torsades de pointes, rhabdomyolysis and gastrointestinal symptoms.
• Immediate: stop or reduce the infusion. The direct effects fade within minutes, because the half-life is 10 min or less.
• Antidote: none. Supportive care means correcting Na⁺, treating arrhythmias per ACLS (magnesium for torsades) and monitoring CK for rhabdomyolysis.

Clinically Significant Interactions

IV Compatibility

• Diluents: 0.9% NaCl or D5W. Commercial premixes come in 5% dextrose.
• Dedicated line or lumen: keep boluses, flushes and intermittent drugs off the vasopressor line.
• Check against your institutional compatibility resource.

• Pediatrics: safety and effectiveness are not established (FDA label). SSC 2026 children suggests adding vasopressin or titrating catecholamines further when they are already high dose (conditional, low certainty). There is no agreed threshold. See the Pediatric Dosing table.
• Neonates: the label has no data. Only the neonatal intensivist and pharmacy dose it.
• Pregnancy: there are no human or animal data on fetal risk. Clearance rises through the second and third trimesters, about 4-fold in the third and up to 5-fold at term. Higher doses may be needed. Vasopressin can cause tonic uterine contractions. Do not withhold it from a mother in refractory shock.
• Lactation: there are no data on whether it reaches human milk or what it does to the infant.
• Older Adults: start at the low end of the dosing range (label). For septic shock at age 65 or older, SSC 2026 suggests an initial MAP range of 60–65 mmHg.
• Renal Impairment: no specific adjustment is established. Only about 6% leaves the body unchanged in urine.
• Hepatic Impairment: no specific adjustment is established. Titrate to effect.
• Obesity / Dosing Weight: adult dosing is fixed in units/min, with no weight math. Children are dosed in units/kg/min. See the Pediatric Dosing table (specialist use only).

• Scope: RN and critical-care transport (CCT). Usually it is a running interfacility infusion with norepinephrine. It varies by state and agency protocol.
• Storage & Stability: keep unopened vials refrigerated at 2–8°C (36–46°F). Do not freeze them. Unopened vials may be held at 20–25°C (68–77°F) for up to 12 months. When you move one to room temperature, write the new expiry on it and use the earlier date. Opened 10 mL multiple-dose vial: refrigerate it and discard 30 days after first puncture. Diluted solution lasts 18 hr at room temperature.
• Carried Concentration: check the concentration against the pump library: 0.1, 0.2, 0.4, 0.6 or 1 unit/mL. The same 0.03 units/min runs at 18, 9, 4.5, 3 or 1.8 mL/hr, depending on which concentration is hung.
• Infusions in Transport: give it a dedicated pump channel, and carry enough volume for the trip plus delays. The pressor effect fades within 20 min of any interruption.
• Handoff Essentials: dose in units/min (never units/hr), concentration, start time, norepinephrine dose when vasopressin was added, MAP goal, Na⁺ and urine output, digit and skin checks.

Mechanism of Action

• V₁ (V1a) receptors on vascular smooth muscle: Gq and phospholipase C, which cause vasoconstriction. That raises systemic vascular resistance and MAP without touching adrenergic receptors.
• V₂ receptors in the renal collecting duct: adenylyl cyclase, then water reabsorption. The result is antidiuresis, and with it a risk of hyponatremia.
• V1b receptors in the anterior pituitary → ACTH release.
• Septic shock: endogenous levels rise early, then drop back into the normal range within 24–48 hr. That is the relative deficiency. Low replacement doses raise MAP.

Pharmacokinetics

• Half-life: 10 min or less (apparent).
• Metabolism: serine protease, carboxypeptidase and disulfide oxidoreductase; clearance 9–25 mL/min/kg at 0.01–0.1 units/min.
• Active metabolites: none described.
• Elimination: about 6% unchanged in urine.
• Protein binding / Vd: not protein bound; volume of distribution 140 mL/kg.

Generic Name

Vasopressin injection, USP (8-L-arginine vasopressin, AVP; antidiuretic hormone)

Brand Names

Vasostrict (US); generic vasopressin vials

Pharmacologic Class

Vasopressin receptor agonist (V₁, V₂); endogenous peptide hormone

Therapeutic Class

Vasopressor (non-catecholamine)

Controlled Substance

Not controlled

ISMP High-Alert

Yes: ISMP high-alert medication (vasopressin, IV or intraosseous)

Look-Alike / Sound-Alike

ISMP confused-name pair: vasopressin / desmopressin (DDAVP). Desmopressin is a V₂-selective analog with no useful pressor effect

Error-Prone Abbreviations to Avoid

"U" for units (misread as 0 or 4); write "units"