Tolvaptan phosphate

Tolvaptan phosphate is a pharmaceutical drug used primarily in the treatment of hyponatremia (low blood sodium levels) associated with congestive heart failure, cirrhosis, and the syndrome of inappropriate antidiuretic hormone (SIADH). It is a selective vasopressin receptor 2 antagonist that increases the excretion of water without affecting the excretion of electrolytes.

Mechanism of Action

Tolvaptan phosphate works by blocking the action of vasopressin, a hormone that regulates the balance of water and sodium in the body. By inhibiting the vasopressin receptor 2, tolvaptan phosphate increases the excretion of water in the urine, thereby increasing the concentration of sodium in the blood.

Clinical Use

Tolvaptan phosphate is used in the management of hyponatremia in patients with congestive heart failure, cirrhosis, and SIADH. It is also used in the treatment of autosomal dominant polycystic kidney disease (ADPKD), a genetic disorder characterized by the growth of numerous cysts in the kidneys.

Side Effects

Common side effects of tolvaptan phosphate include thirst, dry mouth, and increased urination. Serious side effects may include liver damage, low blood sodium levels, and dehydration.

Contraindications

Tolvaptan phosphate is contraindicated in patients with hypersensitivity to the drug or any of its components. It is also contraindicated in patients with anuria (inability to urinate), hypovolemic hyponatremia, and in patients who cannot sense or respond to thirst.

Drug Interactions

Tolvaptan phosphate may interact with other drugs such as CYP3A4 inhibitors, which can increase the concentration of tolvaptan in the blood and potentially increase the risk of side effects.

Dosage and Administration

The dosage of tolvaptan phosphate is individualized based on the patient's condition and response to treatment. It is usually taken orally once daily.