title: Halothane and enflurane metabolite elimination during anaesthesia in man.
abstract: Ten patients received 0.75% halothane and 12 received 1.5% enflurane for 1 h in a 50:50 nitrous oxide/oxygen mixture. Plasma and end-tidal concentrations were measured by gas-liquid chromatography (GLC) using the head-space method. Fluoride ion assay was performed with a specific electrode by HPLC, trifluoroacetate and oxalate ion levels were determined after extraction, by GLC. Comparison of the evolution of the non-metabolized forms showed that enflurane was more rapidly eliminated: by the third hour after starting, enflurane plasma concentrations were 3.6 micrograms ml-1 compared with 6.3 micrograms ml-1 for halothane. Fluoride plasma levels were nearly constant in the halothane group, but a significant increase up to 14.9 microM was observed in the enflurane group. The ratio of 10:1 in peak urinary concentrations was linked to the molecular structure and the metabolic pathways.
mesh_terms: D000328:Adult; D000769:Anesthesia, Inhalation; D002849:Chromatography, Gas; D002851:Chromatography, High Pressure Liquid; D004737:Enflurane / Q000097:blood / Q000378:metabolism*; D005459:Fluorides / Q000097:blood / Q000652:urine; D006221:Halothane / Q000097:blood / Q000378:metabolism*; D006801:Humans; D008875:Middle Aged; D010070:Oxalates / Q000097:blood / Q000652:urine; D013997:Time Factors; D014269:Trifluoroacetic Acid / Q000097:blood
chemical_list: D010070:Oxalates; D004737:Enflurane; D014269:Trifluoroacetic Acid; D005459:Fluorides; D006221:Halothane