II. Indications

III. Physiology: ADH Related Water Regulation Mechanisms

  1. See Sodium and Water Homeostasis
  2. Antidiuretic Hormone (ADH or Arginine Vasopressin) overall effect is to increase renal water reaborption
  3. ADH is a polypeptide released from the posterior pituitary
    1. Released in response to Sodium osmoreceptors in the hypothothalamus detecting hypertonicity
    2. Hypertonicity also stimulates thirst Sensation
  4. Response to increased plasma osmolality (and increased plasma Sodium concentration, Hypernatremia)
    1. Increased ADH secretion
    2. Water retention by the Kidneys
    3. Decreased plasma Sodium concentration (and decreased plasma osmolality)
  5. Response to decreased plasma osmolality (and decreased plasma Sodium concentration, Hyponatremia)
    1. Decreased ADH secretion
    2. Free water diuresis
    3. Increased plasma Sodium concentration (and increased plasma osmolality)
  6. Direct Sympathetic System effects to increase Blood Pressure
    1. See Blood Pressure Physiology
    2. Antidiuretic Hormone (Vasopressin) strongly increases Vasoconstriction and Peripheral Vascular Resistance
  7. Abnormal Antidiuretic Hormone
    1. Syndrome Inappropriate ADH Secretion (SIADH)
      1. Inappropriate ADH release, resulting in water retention despite normal Sodium and water status
      2. Results in Isovolemic Hypoosmolar Hyponatremia
    2. Diabetes Insipidus
      1. Excessive constant water diuresis due lack of pituitary ADH release or lack of renal response
      2. Nephrogenic Diabetes Insipidus
      3. Central Diabetes Insipidus

IV. Mechanism: Vasopressin

  1. Receptor Activity
    1. Exclusively at Vasopressin receptors (some on vasculature)
  2. Effects
    1. Increases Systemic Vascular Resistance while still maintaining CNS and cardiac Blood Flow
    2. Effective, even in severe acidosis

V. Dosing: Adults

  1. Diabetes Insipidus
    1. Vasopressin 5-10 units IM or SQ twice daily to four times daily as needed
  2. Septic Shock
    1. Vasopressin Infusion: 0.01 to 0.04 units/min (up to 0.1 units/min have been used)
  3. Cardiac Arrest (old ACLS guidelines)
    1. Vasopressin 40 units IV once (second dose may be given after 3 minutes if if first ineffective)
    2. Per older guidelines, Vasopressin 40 units IV once was given instead of Epinephrine 1 mg every 3-5 min
  4. Bleeding Esophageal Varices
    1. Vasopressin 0.2 to 0.4 units/min (up to max of 0.8 units/min - very high dose)

VI. Adverse Effects

  1. Higher doses may be associated with Myocardial Ischemia
  2. Hyponatremia (and Water Intoxication)
  3. Tissue necrosis on extravasation
  4. Gastrointestinal distress (Abdominal cramping, Nausea, Vomiting, Flatulence)
  5. Headache
  6. Sweating

VIII. References

  1. (2020) Tarascon Pharmacopeia, accessed 12/28/2020

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