Vasopressin lowers the amount of urine and bleeding by constricting (narrowing) the blood vessels which, in turn, prevents the loss of water from the body.
Uses of Vasopressin
Prevention/control of polydipsia, polyuria, and dehydration in pts with neurogenic diabetes insipidus or differential diagnosis of diabetes insipidus.
Vasoconstriction: To increase blood pressure in adults with vasodilatory shock who remain hypotensive despite fluids and catecholamines.
PHARMACOTHERAPEUTIC: Posterior pituitary hormone.
CLINICAL: Vasopressor, antidiuretic.
OFF-LABEL: Adjunct in treatment of acute massive GI haemorrhage or oesophagal varices.
Precautions of Vasopressin
Contraindications: Hypersensitivity to vasopressin. Cautions: Seizure disorder, migraine, asthma, vascular disease, renal/cardiac disease, goiter (with cardiac complications), arteriosclerosis, nephritis, elderly pts.
Action of Vasopressin
Increases reabsorption of water by renal tubules. Directly stimulates smooth muscle in GI tract.
Therapeutic Effect: Causes peristalsis, and vasoconstriction. Decreases urine output.
Pharmacokinetics
| Route | Onset | Peak | Duration |
| IV | N/A | N/A | 0.5–1 hr |
| IM, SQ | 1–2 hrs | N/A | 2–8 has |
Distributed throughout the extracellular fluid. Metabolized in liver, kidney. Primarily excreted in urine. Half-life: 10–20 min.
Lifespan consideration pregnancy/Lactation: Caution in giving to breastfeeding women.
Children/Elderly: Caution due to risk of water intoxication/hyponatremia.
InteractionsDRUG: Alcohol, demeclocycline, lithium, norepinephrine may decrease antidiuretic effect. CarBAMazepine, chlorproPAMIDE, clofibrate may increase antidiuretic effect. HERBAL: None significant. FOOD: None known.
LAB VALUES: None significant.
Availability (Rx) of Vasopressin
Injection Solution: 20 units/mL.
Administration/handling of Vasopressin
IV
Reconstitution
• Dilute with D5W or 0.9% NaCl to concentration of 0.1–1 unit/mL (usual concentration: 100 units/500 mL D5W).
Rate of Administration
• Give as IV infusion.
Storage
• Store at room temperature.
IM, SQ
• Give with 1–2 glasses of water to reduincompatibilities
IV incompatibilities of Vasopressin
Furosemide (Lasix), phenytoin (DilantdShock
Indications/routes/dosage of Vasopressin
Diabetes Insipidus
NOTE: May be administered intranasally by nasal spray or on cotton pledgets; dosage is individualized.
IM, SQ: ADULTS, ELDERLY: 5–10 units 2–4 times/day. CHILDREN: 2.5–10 units, 2–4 times/day.
Vasodilatory Shock
IV Infusion: ADULTS, ELDERLY: Initially, 0.01 units/min. Titrate by 0.005 units/min at 10–15-min intervals. Maximum: 0.07 units/min.
Dosage in Renal/Hepatic Impairment: No dose adjustment.
Side effects
Frequent: Pain at injection site (with vasopressin tannate). Occasional: Abdominal cramps, nausea, vomiting, diarrhoea, dizziness, diaphoresis, pale skin, circumoral pallor, tremors, headache, eructation, flatulence. Rare: Chest pain, confusion, allergic reaction (rash, urticaria, pruritus, wheezing, difficulty breathing, facial/peripheral oedema), sterile abscess (with vasopressin tannate).
Adverse effects/toxic reactions
Anaphylaxis, MI, water intoxication have occurred. Elderly, very young are at higher risk for water intoxication.
Nursing considerations
Baseline assessment
Establish baselines for weight, B/P, pulse, serum electrolytes, Hgb, Hct, urine specific gravity.
Intervention/evaluation
Monitor I&O closely, restrict intake as necessary to prevent water intoxication. Weigh daily if indicated. Check B/P, pulse frequently. Monitor serum electrolytes, Hgb, Hct, urine specific gravity. Evaluate injection site for erythema, pain, abscess. Report side effects to physician for dose reduction. Be alert for early signs of water intoxication (drowsiness, listlessness, headache, seizures). Observe for evidence of GI bleeding. Withhold medication, report immediately any chest pain, allergic symptoms.
Patient/family teaching
• Promptly report headache, chest pain, shortness of breath, other symptoms.
• Stress importance of I&O.
• Avoid alcohol.
• Report confusion, seizure activity.