Background Tolvaptan is indicated to treat syndrome of inappropriate antidiuretic hormone secretion (SIADH).

Purpose To describe and assess the use of tolvaptan in a tertiary hospital.

Materials and methods An observational and retrospective study was conducted on patients treated with tolvaptan. Data was collected from the review of medical histories, lab tests and dispensing records. These data included age, sex, diagnosis, cause of prescription, clinical department that prescribed it and sodium blood concentration at start of the treatment.

Results The study was conducted with 4 patients. The average age was 70 years and all the patients were men. Depending on the condition, the clinical department that wrote the prescription was cardiology in three of the cases and digestive in the other one. The background pathology was heart failure in three cases and liver carcinoma in the fourth. The cause of prescription was that all the patients had serious oedema, anasarca and no response to diuretics. Only three of the subjects had hyponatraemia at the beginning of the treatment and none of them had syndrome of inappropriate antidiuretic hormone secretion (SIADH). Two subjects started the treatment with an initial dosage of 15 mg/day and the other two started directly with 30 mg/day. The maintenance dosage was 30 mg/day for all of them. The cost-day average per patient was 88.32 €. The average length of treatment was 55.75 days, SD 39.89. The reason for stopping the treatment was death for the first three patients and the fourth is still on treatment.

Conclusions In our hospital, tolvaptan was not used for the approved indication in any of the patients and for all them it was processed as compassionate use. The authors do not have enough data to evaluate the efficacy of this treatment in these patients. The high cost of the treatment and the limited experience in its use require strict control in its administration.