Tolvaptan phosphate

Tolvaptan

Chemical structure of Tolvaptan

Tolvaptan is a vasopressin receptor antagonist used primarily in the treatment of hyponatremia and autosomal dominant polycystic kidney disease (ADPKD). It is a selective V2 receptor antagonist that works by increasing the excretion of free water, thereby correcting the imbalance of water and sodium in the body.

Mechanism of Action

Tolvaptan acts by selectively binding to the V2 receptors in the kidneys, which are responsible for the antidiuretic effects of vasopressin. By blocking these receptors, Tolvaptan prevents the action of vasopressin, leading to an increase in the excretion of free water without the loss of electrolytes. This results in an increase in serum sodium concentration, making it effective in treating hyponatremia.

Clinical Uses

Tolvaptan is primarily used in the management of:

• Hyponatremia: Particularly in cases associated with the syndrome of inappropriate antidiuretic hormone secretion (SIADH).
• Autosomal dominant polycystic kidney disease (ADPKD): Tolvaptan slows the progression of kidney cyst development and renal insufficiency in patients with ADPKD.

Side Effects

Common side effects of Tolvaptan include:

• Increased thirst
• Dry mouth
• Polyuria
• Fatigue

Serious side effects may include:

• Liver injury
• Hypernatremia

Contraindications

Tolvaptan is contraindicated in patients with:

• Anuria
• Hypovolemic hyponatremia
• Urgent need to raise serum sodium acutely
• Inability to sense or respond to thirst

Pharmacokinetics

Tolvaptan is well absorbed after oral administration, with a bioavailability of approximately 56%. It is extensively metabolized in the liver, primarily by the cytochrome P450 enzyme CYP3A4. The elimination half-life of Tolvaptan is about 3 to 4 hours.

Related Pages

• Vasopressin receptor antagonist
• Hyponatremia
• Autosomal dominant polycystic kidney disease
• Kidney