title: Large differences in the biological half-life and volume of distribution of hydrochlorothiazide in normal subjects from eleven studies. Correlation with their last blood sampling times.
abstract: In spite of more than three decades of wide use of hydrochlorothiazide as a diuretic, its mean biological half-life (t1/2) and apparent volume of distribution (Vdarea) in normal subjects were found to vary greatly among 11 studies reported between 1976 and 1986. For example, the mean t1/2 values ranged from 3.2 to 13.1 h and Vdarea values from 1.53 to 4.19 l/kg. Furthermore, a t1/2 of only 2.5 h and a Vdarea of only 0.83 l/kg were cited in a recent textbook. The present analyses show a positive correlation between the length of the last blood sampling time (tlast) employed and the t1/2 or Vdarea. The smaller t1/2 and Vdarea values reported were attributed to the insufficient length of time used in blood sampling for a drug exhibiting polyexponential disposition function. The kinetic and dynamic significance of the findings were briefly described.
authors.affiliation: Division of Biopharmaceutics, Food and Drug Administration, Rockville, Maryland.
authors.forename: T M
authors.initials: TM
authors.lastname: Chen
authors.forename: W L
authors.initials: WL
authors.lastname: Chiou
mesh_terms: D001810:Blood Volume; D001835:Body Weight; D006207:Half-Life; D006801:Humans; D006852:Hydrochlorothiazide / Q000097:blood / Q000493:pharmacokinetics*; D012016:Reference Values
chemical_list: D006852:Hydrochlorothiazide