| Class | Vasopressin receptor agonist |
|---|---|
| Chemistry |
Benzazepine |
| Routes of administration |
Oral only |
| Absorption |
Oral bioavailability 56% |
| Solubility |
pKa 13.4; practically insoluble in water |
| Distribution |
VOD=3L/kg; 99% protein-bound |
| Metabolism |
99% metabolised in the liver, mainly by CYP3A |
| Elimination |
Half life is 12 hours |
| Time course of action |
Duration of effect is about 24 hrs |
| Target receptor |
Binds to V2 vasopressin receptors, inhibiting the insertion of aquaporins |
| Mechanism of action |
By decreasing the insertion of aquaporins into the apical membrane of collecting duct cells, prevents the reabsorption of water. This distal site of action means this class of drugs is free from electrolyte-depleting side effects (i.e. only water is excreted) |
| Clinical effects |
Hypernatremia, hyperkalemia, diuresis, LFT derangement |
| Literature reference |
Tvaptan brochure |
| CICM details of understanding | Not specifically listed in the CICM syllabus |
| Mentioned around Deranged Physiology | |
| Related SAQs |