Background The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a frequent cause of hyponatraemia consisting of a reduction in plasma sodium concentration values below 135 mEq/L. This condition, reducing the survival of the patient, extends the duration of the hospital stay and therefore increases the cost for a given patient.

Purpose To provide an alternative treatment to the use of tolvaptan, either to enable cost savings and to maintain a good quality of life for patients by raising plasma sodium values, and consequently lowering the cost of hospitalisation.

Material and methods 3 patients were perorally administered urea and sodium chloride (NaCl) capsules to treat SIADH. All were affected by small cell lung cancer and were receiving chemotherapy (carboplatin). We speculated that NaCl and urea should be as effective as tolvaptan.¹ We evaluated the patient’s natraemia four times, and the cost of the pharmacist’s performances for the preparation of 30 g of urea and 2 g of NaCl capsules.

Results The natraemia was normalised after treatment administration, as shown in table 1. With NaCl and urea treatment, effectiveness was achieved, despite carboplatin therapy and the patient’s medical condition which are both well known causes of SIADH.

Treatment with tolvaptan 15 g or 30 g costs 70€ per day, compared with 6.6€ for NaCl 2 g with 30 g of Urea. The patients did not need hospitalisation due to hyponatraemia.

Conclusion These preliminary data may indicate that therapy based on oral administration of urea and NaCl is as effective as tolvaptan in the treatment of SIADH. This new treatment approach being less aggressive and cheaper, may be interesting for further investigations regarding this therapeutic alternative.

References and/or Acknowledgements

1. Soupart A, Coffernils M, Couturier B, et al. Efficacy and tolerance of urea compared with vaptans for long-term treatment of patients with SIADH

References and/or AcknowledgementsNo conflict of interest.