Vasopressin

ADH, Anti-diuretic Hormone

Mechanism :

This is a synthetic hormone having anti-diuretic properties. It causes water retention in the body. It also causes vasoconstriction and clot formation.

Indication :

• Central Diabetes Insipidus
• Bleeding esophageal varices

Contraindications :

Hypersensitivity; Vascular disease especially coronary artery disease; chronic nephritis (until reasonable blood-nitrogen concentration attained).

Dosing :

Diabetes Insipidus:

2.5-10 units IM/SC/intranasally every 8-12 hourly doses. Max: 60 units/day.

Continuous IV infusion: 0.005 unit/kg/hour initially, then double the dose every 30 minutes to reach desired effect; Maximum dose: 0.01 unit/kg/hour. Titrate dose on basis of serum sodium, serum osmolality, fluid balance, and urine output.

Gastrointestinal bleeding (Off label use):

0.3 units/kg IV; (Maximum dose = 20 units). Start with 0.002-0.005 unit/kg/min IV initially; may be increased to 0.01 unit/kg/min IV as and when required. If bleeding has been controlled for 12-24 hours, taper off over 24-36 hours.

Adverse Effect :

Pallor, nausea, hypersensitivity reactions, coronary vasoconstriction.

Interaction :

Carbamazepine, Chlorpropamide, Clofibrate, Urea, Fludrocortisone and Tricyclic Antidepressants: May potentiate the antidiuretic action of vasopressin.

Demeclocycline, Noradrenaline, Lithium, Heparin and Alcohol: May decrease antidiuretic action of vasopressin.
Ganglionic Blockers: May increase sensitivity to the pressor effect of vasopressin.

Dolasetron: Increased risk of QT prolongation with dolasetron.

Hepatic Dose :