Vasopressin

Vasopressin injection is used for:

• Vasopressin injection is indicated to increase blood pressure in adults with vasodilatory shock.
• Vasopressin as an early adjunct to norepinephrine for patients with septic shock could be beneficial to patient outcomes.
• Post-cardiotomy shock
• Septic shock.

In the kidneys, vasopressin acts on the V2 receptors located on the cells of the collecting ducts. This binding stimulates the insertion of aquaporin water channels into the membranes of these cells, which enhances water reabsorption back into the bloodstream. This reduces urine output and helps maintain body water balance. This mechanism is beneficial in conditions such as diabetes insipidus, where water retention is impaired.

Pharmacokinetics:

• On set of action :1-2 min
• Half-life 20 to 30 minutes.
• Excretion Vasopressin is predominantly metabolized and only about 6% of the dose is excreted unchanged into urine.

Vasopressin injection is a synthetic form of the natural antidiuretic hormone vasopressin. It is primarily involved in regulating the body’s water balance, controlling water reabsorption in the kidneys, and also acting as a vasoconstrictor to help regulate blood pressure. The medication is used in various medical situations, 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) injection.

0.01 - 0.03 Units/Min.

Dilute 20 units/mL single-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. Discard unused diluted solution after 18 hours at room temperature or 24 hours under refrigeration.

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

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

Lithium: Lithium may decrease the antidiuretic effect of vasopressin, requiring close monitoring if both are used concurrently.

Corticosteroids: Corticosteroids may alter vasopressin's effects, especially regarding fluid and electrolyte balance.

Other Vasopressors: Combining vasopressin with other vasopressors may result in an additive increase in blood pressure, requiring careful monitoring.

Alcohol: Alcohol can counteract the antidiuretic effect of vasopressin, potentially leading to increased urine output.

Hypersensitivity: Known hypersensitivity to vasopressin or any of its components.

Chronic Renal Failure: In cases of severe renal disease or where fluid retention is contraindicated.

Severe Hypertension: Vasopressin should be avoided in patients with significant hypertension unless there is an urgent need.

Coronary Artery Disease: Caution in patients with coronary artery disease, as vasoconstriction can worsen ischemia.

Common Side Effects:

• Headache
• Nausea, vomiting
• Abdominal cramping
• Increased blood pressure
• Water retention and hyponatremia (low sodium levels)

Serious Side Effects:

• Myocardial ischemia or infarction: Due to vasoconstriction, especially in patients with pre-existing heart disease.
• Severe hyponatremia: Can lead to water intoxication, seizures, and altered mental status.
• Arrhythmias: Increased risk of arrhythmias due to fluid shifts and electrolyte imbalances.
• Gangrene: If extravasation occurs during infusion, tissue necrosis may develop at the injection site.

Pregnancy (Category C): Use only if the benefits justify the risks. There are no adequate studies in pregnant women. Vasopressin should only be used during pregnancy if the potential benefit justifies the potential risk to the fetus. Caution is advised when considering its use in pregnant patients.

Electrolyte Imbalance: Close monitoring of electrolytes is required, particularly for sodium levels. Excessive water retention can lead to hyponatremia, which can cause seizures, coma, or even death.

Vasopressin-Induced Ischemia: Because of its vasoconstrictor properties, vasopressin should be used cautiously in patients with ischemic conditions (e.g., coronary artery disease, peripheral vascular disease).

Extravasation Risk: When administered intravenously, extravasation (leakage of the drug into surrounding tissues) should be avoided, as it can lead to necrosis and other serious tissue damage.

Antidiuretic hormone analog

Store in a refrigerator (2-8°C). Keep the vial in the outer carton in order to protect from light.