How Do Vasopressin Antagonists Work?

Vasopressin antagonists or vasopressin receptor antagonists (VRA) are a new group of nonpeptide drugs used to treat hyponatremia (low sodium levels in the blood) which is the most common electrolyte abnormality observed in hospitalized patients. These drugs work by binding to vasopressin receptors and inhibit the action of vasopressin. The pituitary gland releases vasopressin, an antidiuretic hormone that constricts blood vessels and increases the reabsorption of water by the kidneys.

Tolvaptan is the first oral VRA, also known as aquaretics. Tolvaptan works by selectively inhibiting vasopressin V2-receptors in the kidneys and cause an increase in urine water excretion. This increases electrolyte-free water excretion (aquaresis) and decreases urine osmolality and corrects hyponatremia by increasing serum sodium concentration. Tolvaptan also slows down the growth of cysts in polycystic kidney disease.

Vasopressin antagonists are used to treat:

• Hyponatremia
• Polycystic kidney disease

Side effects of vasopressin antagonists may include:

• Nausea 
• Diarrhea 
• Dizziness
• Fatigue
• Weakness
• Palpitations
• Abdominal distention
• Anorexia (eating disorder)
• Hyperglycemia (high blood sugar levels)
• Fever
• Dry mouth
• Dry skin
• Increased urine frequency 
• Anaphylaxis (life-threatening allergic reactions)

The information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Generic and brand names of vasopressin antagonists include:

• Jynarque
• Samsca
• Tolvaptan