Increase of thiopental concentration in tissues of the rat due to an anesthesia with halothane.
In rats anesthetized with halothane (CAS 151-67-7) (1.5 vol%) and rats without any further treatment (control) the early distribution phase of thiopental (CAS 76-75-5) (i.v. 30 mg/kg) was studied. In serum and 8 tissues thiopental concentration (T) was determined using ultraviolet detection at 305 nm after extraction and TLC. In rats anesthetized with halothane, T in serum was significantly higher during the 30 min following the thiopental injection (at least +27% and maximally +51%) as compared to the control (same dose), and several pharmacokinetic parameters (e.g. central volume of distribution) were found to be changed thereby; furthermore, at 3, 10 and 30 min T was significantly increased in liver, brain, heart, lung and spleen; in kidney and skeletal muscle a rise of T was also seen, however, it occurred later (after 10 and 30 min). T in fat tissue increased time-dependently; a T-difference in adipose tissue between both groups was not observed. Thiopental was "trapped" during the early distribution phase to a considerable extent in the vessel-rich tissues of rats simultaneously anesthetized with halothane; this pharmacokinetic interaction might be explained hemodynamically: in many tissues regional blood flow is reduced by halothane; thereby a delayed "washout" of thiopental from the vessel-rich tissues could take place and redistribution would be delayed; additional factors as e.g. an increased binding of thiopental at tissue proteins could also play a role. An unusually high T was found at least temporarily in myocardial tissue due to this interaction between the two anesthetics.
Büch
U
U
Clinic of Anesthesiology and Intensive Care Medicine, University of the Saarland, Homburg, Fed. Rep. of Germany.
Altmayer
P
P
Isenberg
J C
JC
Büch
H P
HP
D000758:Anesthesia; D000818:Animals; D002855:Chromatography, Thin Layer; D004347:Drug Interactions; D005045:Etomidate; D005260:Female; D006221:Halothane / Q000494:pharmacology*; D009609:Nitrous Oxide; D051381:Rats; D011919:Rats, Inbred Strains; D013056:Spectrophotometry, Ultraviolet; D013874:Thiopental / Q000493:pharmacokinetics*; D014018:Tissue Distribution; D014673:Vecuronium Bromide
D014673:Vecuronium Bromide; D013874:Thiopental; D009609:Nitrous Oxide; D006221:Halothane; D005045:Etomidate