Vasopressin injection is used for:

• Increasing blood pressure in adults with vasodilatory shock
• As an early adjunct to norepinephrine in patients with septic shock to improve clinical outcomes
• Post-cardiotomy shock
• Septic shock

In the kidneys, vasopressin acts on V2 receptors located on the cells of the collecting ducts. This stimulates the insertion of aquaporin water channels into the cell membranes, enhancing water reabsorption into the bloodstream. As a result, urine output decreases and body water balance is maintained. This mechanism is beneficial in conditions such as diabetes insipidus, where water retention is impaired.

Pharmacokinetics

• Onset of action: 1–2 minutes
• Half-life: 20–30 minutes
• Excretion: Vasopressin is primarily metabolized, and approximately 6% of the dose is excreted unchanged in urine.

Vasopressin injection is a synthetic form of the natural antidiuretic hormone vasopressin. It helps regulate body water balance, controls water reabsorption in the kidneys, and acts as a vasoconstrictor to support blood pressure regulation.

This medication is used in various medical conditions including diabetes insipidus, shock states, and certain bleeding disorders. Vasopressin Injection USP is typically available as a clear, colorless solution for intravenous (IV), intramuscular (IM), or subcutaneous (SC) administration.

0.01 - 0.03 Units/Min.

Dilute the contents of the 20 units/mL single-dose vial 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. Discard any unused diluted solution after 18 hours at room temperature or 24 hours under refrigeration.

Post-cardiotomy shock: 0.03 to 0.1 units/minute. (Recommended starting dose)

Septic shock: 0.01 to 0.07 units/minute. (Recommended starting dose)

Lithium: Lithium may reduce the antidiuretic effect of vasopressin. Close monitoring is required when both drugs are used together.

Corticosteroids: Corticosteroids may alter the effects of vasopressin, particularly on fluid and electrolyte balance.

Other Vasopressors: Concomitant use with other vasopressors may cause an additive increase in blood pressure and requires careful monitoring.

Alcohol: Alcohol may counteract the antidiuretic effect of vasopressin, potentially increasing urine output.

Hypersensitivity: Contraindicated in patients with known hypersensitivity to vasopressin or any component of the formulation.

Chronic Renal Failure: Contraindicated in severe renal disease or conditions where fluid retention is undesirable.

Severe Hypertension: Avoid use in patients with severe hypertension unless urgently needed.

Coronary Artery Disease: Use cautiously, as vasoconstriction may worsen ischemia.

Common Side Effects:

• Headache
• Nausea and vomiting
• Abdominal cramping
• Increased blood pressure
• Water retention and hyponatremia

Serious Side Effects:

• Myocardial ischemia or infarction, especially in patients with existing heart disease
• Severe hyponatremia leading to seizures, water intoxication, or altered mental status
• Arrhythmias caused by electrolyte imbalance
• Gangrene or tissue necrosis at the injection site if extravasation occurs

Pregnancy Category C: Use only if the potential benefit justifies the potential risk to the fetus. Adequate studies in pregnant women are not available. Caution is advised when considering use during pregnancy.

Electrolyte Imbalance: Electrolytes, especially sodium levels, should be monitored closely. Excessive water retention may lead to hyponatremia, seizures, coma, or death.

Vasopressin-Induced Ischemia: Use cautiously in patients with ischemic conditions such as coronary artery disease or peripheral vascular disease.

Extravasation Risk: Intravenous administration should be carefully monitored to prevent leakage into surrounding tissues, which may cause tissue necrosis.

Antidiuretic hormone analog

Store in a refrigerator at 2°C to 8°C. Keep the vial in the outer carton to protect from light.