However, it should be said that there are substantial questions that remain to be answered about the use of this drug. The large trial published in the NEJM last year showed that tolvaptan reduced the rate of growth in kidney size while also leading to a slowdown in the rate of GFR decline. However, these are surrogate endpoints and we have been burned by surrogate endpoints in nephrology before (see Bardoxolone). Also, the majority of patients had good renal function at baseline. Not all patients with PCKD will develop ESRD and there is no indication at this time who should be treated with this drug and for how long. It should also be said that there was a high rate adverse events in the treatment group (primarily related to thirst and polyuria) and 23% of participants discontinued the drug. It is extremely expensive and it is important that there are clear guidelines for its use. As mentioned in this post, copeptin levels may be useful in determining who will respond to tolvaptan.
That said, it is always interesting and revealing to know the patient’s point of view on this difficult issues.
I have used Tolvaptan in context of palliation on a patient with worsening lung cancer who wanted to be at home surrounded by family and wanted to be as cognitively well as she could be. She lived 3 months on it and then succumbed to her primary disease. She needed pre approval to use this. The insurance company agreed as this came way cheaper than several nights in the ICU. This is the only indication I would use Tolvaptan for. also, I dis follow a CMP weekly till she passed.
I volunteered for every US study when Tolvaptan was being studied as a drug for SIADH (Syndrome of Inappropriate Anti-Diuretic Hormone). I was laughed at by researchers. Apparently, they wanted volunteers who were so cognitively impaired, it didn't matter if Tolvaptan corrected sodium levels so quickly it fried their brains. This drug was never studied on people whose cognitive functioning was fine nor on people who do okay on Demeclocycline or just with fluid restriction. Despite FDA so-called "approval", I wouldn't take this drug. Like so many other drugs that have been approved with flawed research, I don't trust it. Having been rejected by every SIADH study because I was too "normal" sounding, well, you draw your own conclusion.