Short summary

Congenital nephrogenic diabetes insipidus is a rare disease characterized by extreme polyuria (often > 15L / day) and excessive water intake. Currently, no causal treatment exists. An already approved antifungal drug, fluconazole, significantly reduces symptoms in an animal experiment. This study is a national, pharmacological study testing if fluconazole in patients diagnosed with NDI reduce urinary volume, with the perspective to relieve the severe impairment associated with NDI.

Rationale

study objective is to test, if treatment with the antifungal medication fluconazole in patients diagnosed with NDI ameliorates symptoms (diuresis) by an increase in plasma membrane localization of AQP2 in the absence of a functional V2 receptor caused by a mutation in the AVPR2 gene. Recently, the antifungal drug fluconazole was identified as a candidate for AQP2 modulation, based on screening a library of 17,700 molecules in a cell-based assay. Administration of fluconazole increased plasma membrane localization of AQP2 in the absence of AVP and the abundance of AQP2 was improved caused by alterations in the phosphorylation status and ubiquitination and due to inhibition of RhoA. This was observed in cell and mouse studies. Further in vitro experiments confirmed an increased transepithelial water reabsorption in isolated mouse collecting ducts, and subsequent animal experiment with tolvaptan-induced diuresis (V2 antagonist), which represents a model for X-linked NDI, found that fluconazole reduced urinary output. We now want to pursue this observation in NDI patients.

Description of the cohort

Ten patients with nephrogenic diabetes insipidus caused by V2 receptor defects are recruited in Denmark.

Data and biological material

Medical history, symptoms, age, sex, objective findings, radiology, blood- and urine samples

Collaborating researchers and departments

Cardiovascular and renal research, University of Southern Denmark

• Boye L. Jensen