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Flashcards in Aquaretics Deck (8):
1

Site of axn?

The collecting ducts

2

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]

3

Which drugs are considered vaptans?

Conivaptan & Tolvaptan

4

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+]

5

Clinical applications of conivaptan?

- Trx of euvolemic and hypervolemic hyponatremia in pts who are hospitalized, symptomatic, and not responsive to fluid restriction

- ADPKD

- Monitor neuro status & plasma sodium closely --> too rapid serum sodium correction (>12 mEq/L/day) can lead to seizures, osmotic demyelination, coma, or death

6

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

7

Toxicities of conivaptan?

- Orthostatic hypotension, fatigue, thirst, polyuria, bedwetting

8

Tolvaptan?

- Selective V2 R antagonist administered PO; initiate and reinitiate tolvaptan in pts only in hospital where plasma sodium can be closely monitored; must use for less than 30 days for hyponatremia, longer use --> potentially fatal hepatotoxicity

- Used to slow progression of adults polycystic kidney dz (must monitor liver)

- Effx ↑ to peak at ~ 4 hrs, effx last 4-8 hrs