Vasopressin
Vasopressin (antidiuretic hormone, ADH) is a posterior-pituitary peptide that promotes water reabsorption in the kidney and vasoconstriction. Medically it is used for diabetes insipidus, vasodilatory shock, and GI variceal bleeding. It is the parent hormone of the more selective analogue desmopressin.
01 Overview
Vasopressin is a nonapeptide secreted by the posterior pituitary. Acting on V2 receptors it inserts aquaporin water channels in the renal collecting duct to concentrate urine; acting on V1 receptors it constricts vascular smooth muscle, raising blood pressure.
Synthetic vasopressin (argipressin) is given IV or IM in critical care as a vasopressor in septic and other vasodilatory shock, and to control bleeding from esophageal varices. Its short half-life and dual receptor actions require careful titration.
02 Mechanism
Agonism at renal V2 receptors drives aquaporin-mediated water reabsorption (antidiuresis); agonism at vascular V1a receptors causes vasoconstriction.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Vasodilatory shock | 0.01–0.04 units | IV | 0.01-0.04 units/min continuous IV infusion |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Vasoconstriction / raised blood pressureRestores vascular tone in vasodilatory shock, sparing catecholamines. | Clinical | ||
| AntidiuresisConcentrates urine, correcting polyuria in central diabetes insipidus. | Clinical |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Peripheral and mesenteric ischemiaIntense vasoconstriction can compromise perfusion of digits, skin, or gut, especially at higher doses. | Severe | Uncommon | Clinical | |
| Hyponatremia / water intoxicationExcess water retention can lower serum sodium. | Moderate | Common with antidiuretic use | Clinical |