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tolvaptan

Brand: Samsca, Jynarque

⚠ BBW Prototype Drug
Drug Class: vasopressin receptor antagonist (vaptans)
Drug Family: diuretic
Subclass: V2 receptor antagonist (aquaretic)
Organ Systems: renalcardiovascular

Mechanism of Action

Selective V2 receptor antagonist preventing aquaporin-2 insertion; causes electrolyte-free water excretion (aquaresis); raises serum sodium without hypovolemia.

V2 vasopressin receptor (renal collecting duct)

Indications

  • hyponatremia (SIADH, hypervolemic hyponatremia in HF/cirrhosis)
  • autosomal dominant polycystic kidney disease (Jynarque — TEMPO 3:4 trial)

Contraindications

  • patients requiring urgent rise in serum sodium
  • anuria
  • volume-depleted hyponatremia
  • concomitant strong CYP3A4 inhibitors
  • liver disease (Jynarque — hepatotoxicity BBW)

Adverse Effects

Common

  • thirst
  • dry mouth
  • polyuria
  • dizziness
  • hyperglycemia

Serious

  • osmotic demyelination syndrome (overly rapid sodium correction)
  • hepatotoxicity (Jynarque — BBW)

Pharmacokinetics (ADME)

Absorption ~40% oral bioavailability
Distribution large Vd
Metabolism extensive hepatic CYP3A4
Excretion fecal
Half-life 12 hours
Onset 2-4 hours
Peak 2-4 hours
Duration 24 hours
Protein Binding 99%
Vd large

Drug Interactions

Drug / Agent Mechanism Severity
strong CYP3A4 inhibitors (ketoconazole, clarithromycin) markedly increases tolvaptan — CONTRAINDICATED major
strong CYP3A4 inducers (rifampin) decreases tolvaptan — may need dose increase major
P-gp inhibitors increase tolvaptan levels moderate

Nursing Considerations

  1. Initiate IN HOSPITAL only (SAMSCA indication) — monitor sodium every 6 hours for first 24 hours
  2. Rate of sodium correction: do NOT exceed 10-12 mEq/L in 24h (osmotic demyelination risk)
  3. Patient must be able to access and drink water freely
  4. Jynarque (ADPKD): LFT monitoring required monthly for 18 months then every 3 months

Clinical Pearls

  • Aquaresis (water loss without electrolytes) vs osmotic diuresis (salt + water): no dyselectrolytemia
  • TEMPO 3:4 trial: tolvaptan (Jynarque) slowed ADPKD progression but hepatotoxicity risk limits use

Safety Profile

Pregnancy avoid
Lactation avoid
Renal Adjustment Required
Hepatic Adjustment Required
TDM Not required
Guideline Update pending

Concordance Terms

Cross-referenced clinical concepts — click any term to see all content where it appears.

Autosomal Dominant Polycystic Kidney Disease (Jynarque — TEMPO 3:4 Trial) Hyponatremia (SIADH, Hypervolemic Hyponatremia In HF/cirrhosis) Vasopressin Receptor Antagonist (vaptans)
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