Tolvaptan is an ADH antagonist.  We will have few indications, but in the rare true SIADH patient, this drug will have some value.  I do not know the cost.

I see many hyponatremia patients, and few of them have persistent SIADH.  I am glad to have this option for those rare patients.

The NEJM had a couple of important articles about tolvaptan a couple of years ago.