✔️Their binding to V1 receptors causes vasopressor effects.
✔️Activation of V2 receptors in the collecting tubule increases water absorption
✔️In the acute intensive care unit setting, aqueous vasopressin may be preferred due to its short duration of effect (2–8 hours) compared with that of desmopressin (6–18 hours) as DI may be a transient clinical situation.
✔️Vasopressin can be given subcutaneously in doses of 4–10 units every 6 hours as needed for urine output exceeding 200 mL.
✔️Alternatively, a continuous infusion can be used, as the half-life of vasopressin given IV is only 20 minutes. A dose of 0.008 – 0.04 units/kg/hour is usually effective
✔️If serum osmolality falls too low, the infusion can be stopped until osmolality is restored to the normal range.
✔️DDAVP is a synthetic form of vasopressin that has less potent (2000- to 3000-fold) vasopressor effects than vasopressin.
✔️It has a much longer duration of effect and is the preferred therapy for permanent or slowly resolving DI.
✔️It is available as intranasal, oral, or IV forms.
✔️The intranasal preparation of DDAVP delivers a 10 ug dose per spray, and doses of 10-30 g per day are usually effective.
✔️The IV form (4 ug/mL) is given IV, intramuscularly (IM), or subcutaneously in doses of 0.5–2 ug every 8–12 hours as needed.
✔️Oral tablets (0.1–0.2 mg) in doses of 0.1–1.2 mg/day can also be given to obtain adequate diuresis.
✔️Cardiovascular effects such as acute myocardial ischemia, arrhythmias, and hypertension have been reported.
✔️Peripheral vasoconstriction may cause cutaneous gangrene.
✔️Thrombosis is a very rare complication of vasopressin and DDAVP, which occurs as a result of increasing levels of factor VIII and von Willebrand factor.
Reference: Considerations in Fluids and Electrolytes After Traumatic Brain Injury; Denise H. Rhoney and Dennis Parker, Jr Nutr Clin Pract 2006 21: 462
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