(Purpose) To conduct a prospective study on the efficacy and safety of desmopressin for nocturnal polyuria. (Materials and methods) We selected 51 Japanese men, aged ≥50 years, with complaints of nocturia and a nocturnal polyuria index of ≥0.33. We administered 25 or 50 μg desmopressin (Minirinmelt Orally Disintegrating Tablet®), once daily at bedtime. We evaluated the nighttime urinary frequency and urine volume, nocturnal polyuria index, time to the first urination after falling asleep, and International Prostate Symptom Score (IPSS) at baseline and at 4, 8, and 12 weeks after administration. In addition, they underwent clinical examinations and blood tests at 1, 4, and 12 weeks to evaluate the safety of the drug. (Results) We observed a decrease in the nighttime urinary frequency and urine volume, and nocturnal polyuria index, increased prolonged time to the first urination after falling asleep, and improved IPSS at and after 4 weeks, compared to baseline data. Furthermore, the drug remained effective even at 12 weeks for all parameters. We observed adverse events in 31.3% of the patients. The incidence of hyponatraemia was particularly high in 15.7% of the patients. Those with a lower serum sodium level and lesser body weight at baseline were more likely to develop hyponatraemia. (Conclusion) Desmopressin was identified as a potential drug for the treatment of nocturnal polyuria. However, hyponatraemia, an important adverse event, resulted in treatment discontinuation in several patients. A sodium level lower than the normal level and low body weight at baseline were the risk factors for hyponatraemia.
Keywords: desmopressin; nocturia; nocturnal polyuria.