Background Tolvaptan is an orally active vasopressin V2-receptor antagonist used to treat hyponatremia associated with congestive failure, cirrhosis, and the syndrome of inappropriate antidiuretic hormone (SIADH). Hyponatremia (< 135 mmol/l) is a predictor of death among patients with chronic heart failure and cirrhosis. Current therapy for acute and chronic hyponatremia is often ineffective and poor tolerated.

Purpose Our aim is to analyse the use of the drug, benefit and adverse effects, checking if the prescription complies with the guidelines and accuracy of the dosage.

Materials and methods The study was conducted between March-August 2.011. Patients with a tolvaptan prescription were reviewed: analysis, diagnose and admission's reason, treatment duration, evolution and possible side-effects.

Results 14 patients (57% male) received tolvaptan in the study period. Average age was 69.28 (55-88) years. Location of patients among the clinical units was, 28% Cardiology department, 21.4% Geriatric department, 14.3% Hepathology and other units (Internal Medicine, Oncology and Critical Care Unit). Main diagnoses were 28.6% hyponatremia, 28.5% heart failure. Treatment duration was 13.6 (3-51) days and starting dose was 15 mg/24 h, only in 2 patients dose was increased to 30 mg. Another patient began with 30 mg/24 h and dose was increased to 60 mg/24h. Average pretreatment parameters: serum sodium concentration SSC: 125.1 (113-129) mg/dl, creatinine: 1.41 mg/dl (0.41-3.07), glucose: 125.14 mg/dl (113-139) and potassium 4.55 mg/dl (3.2-5.6). Average post-treatment parameters: SSC: 135.3 (129-143), creatinine: 1.36 mg/dl (0.54-3.20), glucose: 135.3 mg/dl (129-143) and potassium 4.21 mg/dl (3.2-5.2). No adverse events due to treatment were registered. Exitus: a critical patient, a terminal cancer patient and 2 85-year-old patients. Mean cost of the treatment: 1.214 €/patient (260-4431) €.

Conclusions Tolvaptan is used in our patients to treat hyponatremia (not secondary to SIADH) and optimises sodium serum levels. The treatment diminished successfully the admission time and improved the clinical situation without adverse events.