Therapeutic Classification: electrolyte modifiers
Pharmacologic Classification: vasopressin antagonists
Absorption: 40% absorbed following oral administration.
Distribution: Well distributed to tissues.
Protein Binding: >99%.
Metabolism/Excretion: Extensively metabolized in the liver via the CYP3A4 isoenzyme; 59% excreted in the feces (19% as unchanged drug), with 40% excreted in the urine (<1% as unchanged drug).
Half-Life: 12 hr.
- Samsca and Jynarque should not be used interchangeably
Hyponatremia (Samsca)
- PO (Adults ): 15 mg once daily initially; may ↑ at intervals of ≥1 day to 30 mg once daily, up to a maximum of 60 mg once daily. Do not use for longer than 30 days.
Autosomal Dominant Polycystic Kidney Disease (Jynarque and Jinarc)
- PO (Adults ): 60 mg/day initially (taken as 45 mg upon wakening and then 15 mg 8 hr later); may be ↑ after at least 1 wk to 90 mg/day (taken as 60 mg upon wakening and then 30 mg 8 hr later); may then be ↑ after at least 1 wk to 120 mg/day (taken as 90 mg upon wakening and then 30 mg 8 hr later); Concurrent use of moderate CYP3A inhibitors: 30 mg/day initially (taken as 15 mg upon wakening and then 15 mg 8 hr later); may be ↑ after at least 1 wk to 45 mg/day (taken as 30 mg upon wakening and then 15 mg 8 hr later); may then be ↑ after at least 1 wk to 60 mg/day (taken as 45 mg upon wakening and then 15 mg 8 hr later).
