Excretion of trifluoroacetic acid as a metabolite of halothane in digestive juices.

The excretion of trifluoroacetic acid (TFAA) in bile, saliva and gastric juice of two groups of guinea pigs with bile fistulae was measured by ion-chromatography during inhalation of halothane (0.25% and 1.0%) for two hours and after inhalation of halothane. In another two groups without bile fistulae, excretion of TFAA was measured in saliva and gastric juice during and after inhalation of same concentrations of halothane.The excretion of TFAA increased with time and showed the highest concentrations in the saliva. The highest excretion rate and cumulative amounts of excreted TFAA were observed in bile. The cumulative amounts of TFAA excreted into the bile, saliva and gastric juice was 4.85 +/- 1.87 micro mol, 0.89 +/- 0.62 micro mol, 0.11 +/- 0.06 micro mol, respectively, after inhalation of 0.25% halothane and 5.36+/- 2.29 micro mol, 1.50 +/- 0.59 micro mol, 0.25 +/- 0.19 micro mol, respectively, after inhalation of 1.0% halothane. The excretion of TFAA in bile and saliva was saturated after inhalation of the higher concentration of halothane. The excretion of TFAA into the gastric juice was higher with 1.0% concentration of halothane and in animals without bile fistulae. We concluded that TFAA a metabolite of halothane is excreted not only in bile but also in saliva and gastric juice. Biotransformation of halothane in salivary glands seems very likely. A small amount of TFAA excreted in bile enters the enterohepatic circulation. The excretion of TFAA in digestive juice seems to be controlled by a rate-limiting mechanism.