title: [Serum concentrations of ranitidine after intravenous administration in geriatric patients under general anesthesia].
abstract: The elimination rate of serum ranitidine was investigated in healthy geriatric patients under general anesthesia. The patients (50-90 y.o., ASA classification 1 and 2) were divided into Group 1 (age greater than or equal to 70, n = 9) and Group 2 (50 less than age less than 65, n = 6). Ranitidine (1 mg.kg-1) was administered intravenously after the induction of anesthesia, and the serum concentration was measured at 60 min and 120 min. The biological half life of serum ranitidine in Group 1 was 98.9 +/- 13.8 (M +/- SD) min, which was not significantly different from that of Group 2. The half life correlated with intraoperative urine volume (r = 0.62), but not with intraoperative bleeding or age. The duration of the above effective ranitidine concentration was calculated as about 4 and half hours after its i.v. injection. This indicates that additional administration is necessary for longer operations.
authors.affiliation: Department of Anesthesiology, Kyoto Prefectural University of Medicine.
authors.forename: K
authors.initials: K
authors.lastname: Hayashi
authors.forename: E
authors.initials: E
authors.lastname: Chihara
authors.forename: T
authors.initials: T
authors.lastname: Hosokawa
authors.forename: Y
authors.initials: Y
authors.lastname: Tanaka
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000768:Anesthesia, General; D006207:Half-Life; D006801:Humans; D007275:Injections, Intravenous; D008875:Middle Aged; D011899:Ranitidine / Q000008:administration & dosage / Q000097:blood*
chemical_list: D011899:Ranitidine