Comparative toxicities of enflurane, fluroxene and nitrous oxide at subanaesthetic concentrations in laboratory animals.

We compared the toxicities of subanesthetic concentrations of fluroxene, enflurane and nitrous oxide in mice, rats and guinea pigs which were in an active growth phase. Fluroxene produced a greater mortality and decrement in weight gain than enflurane and nitrous oxide despite administration of far lower concentrations. Enflurane, 0.1 MAC, resulted in a detrimental effect on weight and early mortality in mice but not in rats or guinea pigs. Nitrous oxide, 0.1 MAC, resulted in only a minor effect on weight gain in guinea pigs and an increased incidence of focal inflammatory liver changes in mice. No consistent injury to any organs other than liver or kidney were found.