Flashcards in Aquaretics Deck (8):
Site of axn?
The collecting ducts
MOA for Vaptans?
- Block ADH from binding to its receptor on the interstitial side --> ↓ H2O reabsorption in the CD through aquaporin channels
- Affinity for receptor subtypes V1A and V2
- ↓ plasma volume & ↑ plasma osmolality, primarily d/t to an ↑ in plasma [sodium]
Which drugs are considered vaptans?
Conivaptan & Tolvaptan
Effects of conivaptan?
- Promotes the excretion of free water without the loss of serum electrolytes
- leads to net fluid loss --> ↑ urine output, ↓ Uosm, ↑ Posm, restoration of nml plasma [Na+]
Clinical applications of conivaptan?
- Trx of euvolemic and hypervolemic hyponatremia in pts who are hospitalized, symptomatic, and not responsive to fluid restriction
- Monitor neuro status & plasma sodium closely --> too rapid serum sodium correction (>12 mEq/L/day) can lead to seizures, osmotic demyelination, coma, or death
Pks of conivaptan?
- Administered IV
- Substrate of CYP3A4, concern w/ inducers and inhibitors
- water loss can concentrate other electrolytes or drugs to toxic range
- t1/2: eliminated primarily in feces as metabolites; 5.3-8.1 hrs
Toxicities of conivaptan?
- Orthostatic hypotension, fatigue, thirst, polyuria, bedwetting