Indications

Tolvaptan is indicated in- Hypervolemic or euvolemic hyponatremia. Autosomal dominant polycystic kidney disease.

Composition

Pharmacology

Tolvaptan is a selective vasopressin V2-receptor antagonist. Tolvaptan affinity for the V2-receptor is 29 times greater than for the V1a-receptor. When taken orally, 15 to 60 mg doses of Tolvaptan antagonize the effect of vasopressin and cause an increase in urine water excretion that results in an increase in free water clearance (aquaresis), a decrease in urine osmolality, and a resulting increase in serum sodium concentrations. Urinary excretion of sodium and potassium and plasma potassium concentrations are not significantly changed.

Dosage & Administration

Hypervolemic or euvolemic hyponatremia : The usual starting dose for Tolvaptan is 15 mg administered once daily without regard to meals. Increase the dose to 30 mg once daily, after at least 24 hours, to a maximum of 60 mg once daily, as needed to achieve the desired level of serum sodium. Do not use for more than 30 days due to the risk of hepatotoxicity. Autosomal dominant polycystic kidney disease (ADPKD) : Initially: 60 mg/day in divided doses (given as 45 mg upon wakening and 15 mg 8 hours later); Titrate per response and tolerability at intervals of at least 7 days between titrations to 90 mg/day in divided doses (given as 60 mg upon wakening and 30 mg 8 hours later) followed by 120 mg/day in divided doses (given as 90 mg upon wakening and 30 mg 8 hours later). Maintain urine osmolality of <300 mOsm/kg if possible; if the maximum dose is not tolerated, administration of a lower dose with the goal of achieving urine osmolality of 250 to 300 mOsm/kg is reasonable.

Contraindications

Hypersensitivity to the active substance or to any of the excipients, anuria, volume depletion, hypovolemic hyponatremia, hypernatremia, Patients who cannot perceive thirst, pregnancy, breast-feeding.

Side Effects

The most common side effects of Tolvaptan are: thirst, dry mouth, weakness, constipation, making large amounts of urine and urinating often & increased blood sugar levels.

Pregnancy & Lactation

There are no or limited amount of data from the use of Tolvaptan in pregnant women. Studies in animals have shown reproductive toxicity. The potential risk for humans is unknown. Tolvaptan is contraindicated during pregnancy. Women of childbearing potential have to use effective contraception during Tolvaptan treatment. It is unknown whether Tolvaptan is excreted in human milk.

Precautions & Warnings

Too rapid correction of serum sodium can cause serious neurologic sequelae.

Therapeutic Class

Selective vasopressin V2-receptor antagonist

Storage Conditions

Store at below 25°C in a dry place, protected from light. Keep out of reach of children.