Desmopressin Melt Therapy in Patients With Nocturnal Polyuria: a Pharmacokinetic/Dynamic Study

Overview

The objective of this study is to find out what the pharmacokinetic/dynamic (PK/PD) characteristics of desmopressin melt are in nocturia patients (compared to healthy volunteers and children). The main questions the investigators want to answer are: * Are differences related to the pathophysiological factors involved in nocturia? * Are there age/gender/size differences? * Can the investigators identify patients who are likely to develop hyponatraemia? * Can the investigators individualize treatment and reduce risk for hyponatraemia? Day 1: * Patient is being hospitalized in the morning * General anamnesis and clinical examination * Uroflow and residue measurements (3x) * Sober blood sample, to determine plasma concentrations of Na+, Cl-, osmolality and creatinin Day 1-2: \- In the evening at 20h: * start (with empty bladder!) 24h miction-incontinence-residue registration: urine collections every 3 hours (every portion of urine within a period of 3 hours must be collected in the same collection device), with: registration of volumes and measurement urinary concentrations of Na+, Cl-, osmolality and creatinin * Measurement of blood pressure during 24h Day 2-3: * In the evening at 19h (day 2): drink 15mL/kg water * At 20h: take desmopressin melt 120µg + start: * 24h miction-incontinence-residue registration: registration of volumes and measurement urinary concentrations of Na+, Cl-, osmolality and creatinin (U1-U7) * Measurement of blood pressure during 24h * Collection of urine:U1 at 19h, U2 at 20h, together with intake of first desmopressin melt, U3 at 21h = 1h after desmopressin melt intake, U4 at 22h = 2 after desmopressin melt intake,U5 at 23h = 3h after desmopressin melt intake, U6 at 2h (day 3) = 6h after desmopressin melt intake, U7 at 8h = 12h after desmopressin melt intake * Blood samples for blood levels of desmopressin: 1h, 2h, 3h, 6h after desmopressin melt intake, 12h after desmopressin melt intake + plasma concentrations of Na+, Cl-, osmolality and creatinin (safety profile) * At 8h in the morning (day 3): drink 15mL/kg water + collection of urine per hour during 3h with measurement of urinary concentrations of Na+, Cl-, osmolality and creatinin: U8 at 9h, U9 at 10h, U10 at 11h * Patient can go home on day 3, unless he is at high risk for side effects, high-risk patients are hospitalized for 7 days