title: Pharmacokinetics, pharmacodynamics and safety of tolvaptan, a novel, oral, selective nonpeptide AVP V2-receptor antagonist: results of single- and multiple-dose studies in healthy Japanese male volunteers.
abstract: OBJECTIVE
  Single- and multiple-dose studies were conducted to assess the pharmacokinetics, pharmacodynamics and safety of tolvaptan in healthy Japanese subjects.
  
  
  METHODS
  All studies were single-center, randomized, placebo-controlled, single-blind or double-blind. In an ascending single-dose study, subjects were given a single oral dose of 15-120 mg tolvaptan or placebo. In multiple-dose studies, subjects were given 30, 60, 90 or 120 mg tolvaptan or placebo once daily for 7 days.
  
  
  RESULTS
  After a single dose of 15-120 mg tolvaptan, the maximum plasma concentration (C(max)) and the area under the plasma concentration-time curve from zero to time t (AUC(t)) increased dose-dependently, and increases in AUC(t) were dose-proportional. Increases in 24-hour cumulative urine volume were dose- and AUC(24hr)-dependent. Urine excretion rates reached a maximum within 2-4 h after dosing. The maximal urine excretion rates increased dose-dependently, and appeared to reach a plateau at doses ≥ 60 mg. A decrease in urine osmolality and an increase in free water clearance indicated an aquaretic effect of tolvaptan. Serum sodium concentrations were increased by tolvaptan and were higher than that with placebo, even 24 h after dosing, while serum potassium concentrations were unchanged. No tolvaptan accumulation was found after multiple dosing for 7 days. Although 24-hour cumulative urine volume following multiple dosing slightly decreased, a sustained diuretic effect was observed throughout the dosing period. The most common adverse event was mild thirst.
  
  
  CONCLUSIONS
  Single and multiple oral doses of tolvaptan exhibited dose-dependent aquaretic effects. Tolvaptan was well tolerated at all doses tested.
authors: Department of Clinical Research and Development, Otsuka Pharmaceutical Co., Ltd, 3-2-27 Otedori, Chuo-ku, Osaka, 540-0021, Japan. kims@otsuka.jp
authors: Seong Ryul
authors: SR
authors: Kim
authors: Tomoko
authors: T
authors: Hasunuma
authors: Osamu
authors: O
authors: Sato
authors: Tadashi
authors: T
authors: Okada
authors: Mitsuhiro
authors: M
authors: Kondo
authors: Junichi
authors: J
authors: Azuma
mesh_terms: D000328:Adult; D065092:Antidiuretic Hormone Receptor Antagonists; D019540:Area Under Curve; D001127:Arginine Vasopressin / Q000097:blood; D044466:Asian People; D001552:Benzazepines / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology / Q000652:urine; D018592:Cross-Over Studies; D004232:Diuretics / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology / Q000652:urine; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D018565:Food-Drug Interactions; D006801:Humans; D008297:Male; D011188:Potassium / Q000097:blood; D012964:Sodium / Q000097:blood; D000077602:Tolvaptan; D055815:Young Adult
chemical_list: D065092:Antidiuretic Hormone Receptor Antagonists; D001552:Benzazepines; D004232:Diuretics; D001127:Arginine Vasopressin; D000077602:Tolvaptan; D012964:Sodium; D011188:Potassium