Tolvaptan (Samsca)

Pharmacology

  • Selective Competitive V2 Vasopressin Receptor Antagonist: aquaretic (water loss)
    • This effect is usually partially offset by patient’s own fluid intake

Indications


Contraindications

  • Anuria
  • Concomitant Use of Strong CYP 3A Inhibitors
  • Hypovolemic Hyponatremia (see Hyponatremia, [[Hyponatremia]])
  • Inability of Patient to Sense or Appropriately Respond to Thirst: includes contraindication to use in mechanically ventilated patient
  • Need to Correct Serum Sodium Rapidly

Dosage/Administration

  • Start (In Hospital): 15 mg PO qday (with no concomitant PO free water restriction, particularly during the first 24 hrs)
  • After At least 24 Hrs, Titrate Up To: 30-60 mg PO qday

Adverse Effects

Gastrointestinal Adverse Effects

  • Constipation (see Constipation, [[Constipation]]): occurs in 7% of patients (vs 2% of placebo-treated patients)
  • Gastrointestinal Hemorrhage (GI Bleed) (see Gastrointestinal Hemorrhage, [[Gastrointestinal Hemorrhage]]): occurs in 9.5% of patients (vs 0.02% of placebo-treated patients): use of tolvaptan should therefore be carefully considered in cirrhotic patients

Neurologic Adverse Effects

  • Asthenia (Weakness) (see Asthenia, [[Asthenia]]): occurs in 9% of patients (vs 4% of placebo-treated patients)
  • Central Pontine Myelinolysis (see Central Pontine Myelinolysis, [[Central Pontine Myelinolysis]]): associated with excessively rapid correction of serum sodium (>12 mEq/L per 24 hrs)

Renal Adverse Effects

  • Hypernatremia (see Hypernatremia, [[Hypernatremia]])
  • Pollakiuria/Polyuria (see Polyuria, [[Polyuria]]): occurs in 11% of patients (vs 3% of placebo-treated patients)
  • Thirst: occurs in 16% of patients (vs 5% of placebo-treated patients)

Other Adverse Effects

  • Hyperglycemia (see Hyperglycemia, [[Hyperglycemia]]): occurs in 6% of patients (vs 1% of placebo-treated patients)

References

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