USMLE

ADH Antagonists (Conivaptan, Tolvaptan)

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Summary

The Vaptans include the drugs tolvaptan and conivaptan, and these drugs work by blocking V2 receptors as vasopressin or ADH antagonists.  By suppressing V2 receptor signaling, these drugs decrease water reabsorption in the kidney and inhibit vasoconstriction in blood vessels. They are mainly used for treating SIADH, and are associated with minor side effects such as increased thirst and nausea.

Key Points

  • Tolvaptan and Conivaptan
    • Mechanism of Action
      • V2 Receptor Antagonists
        • Blocks ADH/Vasopressin signaling at V2 receptors in the kidney
        • Reduces apical expression of aquaporins at principal cells of collecting duct, causing less reabsorption of water from urine
    • Clinical Use
      • SIADH
        • SIADH causes the body to retain too much water, leading to hyponatremia
    • Adverse Effects
      • Increased thirst; dry mouth
      • Nausea/vomiting