Mutagenic effects of inhalational anesthetics.
Explore the source record for details and available documents.
Abnormalities, Drug-Induced↗
Biomedical subjects
J M Baden
Publications and source records attributed to J M Baden.
Mutagenic activity of vinyl compounds and derived epoxides.
Many vinyl compounds, such as vinyl chloride and some inhalational anesthetics, are known to be mutagens. In the present study, 10 vinyl compounds or derived epoxides, widely used in industry, were assayed in the Salmonella typhimurium/mammalian microsome system. 3 strains of histidine-dependent S. typhimurium, TA1535, TA98 and TA100 were used. Of the 10 compounds, 4 were mutagens. They were 9-vinylanthracene, vinylcarbazole, 3-vinyl-7-oxabicyclo[4.1.0]heptane and 3-epoxyethyl-7-oxabicyclo[4.1.0]-heptane. The study confirmed the overall genotoxicity of vinyl compounds and epoxides and the need to carefully screen them for mutagenic/carcinogenic effects.
Mutagenicity Tests↗
Oxygen mutagenicity.
Explore the source record for details and available documents.
Dose-Response Relationship, Drug↗
Enflurane has no effect on haemopoiesis in mice.
Male and female Swiss/ICR mice were exposed to 0.3% enflurane in air, 4 h per day, 5 days per week for 52 weeks. A control group was exposed to air alone. After 52 weeks, all animals were sacrificed and peripheral blood and bone marrow samples were examined for alterations in haemopoiesis. In general, there was no difference between treated and control groups.
Animals↗
Lack of mutagens in urines of operating room personnel.
Mutagenic activity of urines obtained from operating room personnel was assayed in the Ames Salmonella/mammalian microsome system using three strains of histidine-dependent S. typhimurium, TA1535, TA1538, and TA100. Two procedures were employed. In the first, 100- and 200-microliter aliquots of urine obtained from 28 subjects working in either scavenged or unscavenged operating rooms were tested. In the second, urine samples obtained from 13 physicians before and after starting an anesthesia residency, as well as 250-fold concentrates of these samples, were assayed. There was no statistically significant difference in urinary mutagenic activities between individuals working in scavenged and those working in unscavenged operating rooms. Furthermore, urines of anesthesiologists collected before and after beginning training had similar mutagenic activities. Only heavy smokers had mutagenic urine. It was concluded that the majority of operating room workers do not excrete mutagens in the urine.
Air Pollutants↗
Metabolic and toxicologic studies with enflurane in Swiss/ICR mice.
Swiss/ICR mice were tested to determine whether the volatile ether anesthetic, enflurane, causes induction of anesthetic defluorination and organ toxicity. Mice were exposed in utero and postnatally to 0.01, 0.1 and 1.0 volumes percent enflurane vapor. Body weight was measured at frequent intervals throughout the experiment. Animals were sacrificed at 73 days of age and liver microsomal cytochrome P-450 content and the rate of defluorination of enflurane, isoflurane, methoxyflurane ans sevoflurane were determined. In addition, the liver, kidney and testis were weighed and examined histologically for drug induced damage. The maximum tolerated dose of enflurane delivered over a twelve week period was determined to be 0.5 volumes percent for four hours a day, five days a week. Even at this high dose there was no evidence in either sex of liver, kidney or testicular damage. Following enflurane exposure, neither the liver microsomal cytochrome P-450 content nor the rate of anesthetic defluorination was increased. The rate of in vitro inorganic fluoride production per unit time was greatest for methoxyflurane, and approximately equal for enflurane, isoflurane and sevoflurane. Since there was no evidence of enzyme induction or specific organ toxicity, it was concluded that enflurane is a comparatively nontoxic volatile anesthetic under conditions of this study.
Animals↗
Mutagenicity of inhalation anaesthetics: trichloroethylene, divinyl ether, nitrous oxide and cyclopropane.
The mutagenic potential of trichloroethylene, divinyl ether, nitrous oxide and cyclopropane was assessed in vitro by microbial assay employing two histidine-dependent strains of Salmonella typhimurium, TA1535 and TA100. Anaesthetic agents in various concentrations were incubated with bacteria in the presence or absence of an enzyme system prepared from enzyme-induced rat liver. Nitrous oxide and cyclopropane were not mutagenic, whereas divinyl ether gave a strongly positive response. Results for trichloroethylene were equivocal. These and previous studies with the salmonella system, together with mutagenicity studies using different test systems, indicate that modern inhalation anaesthetic agents are unlikely to be mutagenic.
Anesthesia, Inhalation↗
Carcinogenicity of halothane in Swiss/ICR mice.
A simplified in-vivo bioassay system was used to test the carcinogenic potential of halothane in Swiss/ICR mice. Halothane was tested only at its maximum tolerated dose, and histologic examination was performed only on tumor masses and other grossly abnormal tissues found at necropsy. Two groups, each of 15 timed pregnant mice, were exposed to either halothane, 500 ppm (0.05 per cent), or compressed air for two hours on days 10--19 of pregnancy. Five days after birth the offspring were similarly exposed, three times weekly, for 78 weeks. After a ten-week, no-treatment, observation period, all remaining mice were examined by necropsy. Mice dying or killed in extremis before final sacrifice at 88 weeks of age also underwent complete gross necropsy unless extensive cannibalism or autolysis precluded examination. The incidences of malignant tumors, hepatomas or modular hyperplasias, and benign tumors in halothane-treated mice were 7, 6, and 20 per cent, respectively; there were similar incidences of these lesions in control animals. It is concluded that under the conditions of this experiment, lifetime administration of halothane at its maximum tolerated dose is not associated with an increased incidence of neoplasia in Swiss/ICR mice.
Adenoma↗
Mutagenicity studies with volatile metabolites of halothane.
The mutagenicities of two volatile metabolites of halothane, 2-chloro-1,1,1-trifluoroethane (CF3CH2Cl) and 2-chloro-1,1-difluoro-ethylene (CF2CHCl), and a presumed halothane metabolite, 2-bromo-2-chloro-1,1-difluoroethylene (CF2CBrCl), were investigated in the bacterial assay system developed by Ames and co-workers. Both gas-phase and liquid culture tests were made. In addition, mutagenicity of CF2CBrCl was studied in a modified Ames test system using rapidly growing cells in enriched liquid medium. The purity of tested compounds was verified by combined gas chromatography and mass spectrometry. In the standard Ames test, CF3CH2Cl and CF2CBrCl were not mutagenic, and CF2CHCl was only weakly mutagenic. CF2CBrCl was detectable as weakly mutagenic, however, in the modified Ames test using rapidly growing cells. Although these results are reassuring, the effects of long-term exposure to halogenated anesthetics are still not fully known.
Biological Assay↗
Fetal morphology in mice exposed to halothane.
The teratogenic potential of subanesthetic and anesthetic exposure to halothane was studied in Swiss/ICR mice. Two treatment regimens were employed: daily exposure of males and females for nine weeks prior to conception and on days 1 through 17 of pregnancy; and exposure of females only on days 6 through 15 of pregnancy. Mice were exposed to subanesthetic concentrations of halothane for 0.025, 0.1, 0.4, and 1.2 MAC hours/day; anesthetic exposure was 4.0 MAC hours/day. Fetal morphologic development was normal at the two lowest exposures. Exposures of 0.4 MAC hours/day and more were associated with decreased fetal ossification. At the 1.2 MAC hour/day exposure, renal pelvic masturation was retarded and the incidence of skeletal variants was increased. The incidences of major malformations and minor anomalies were not increased following exposure to subanesthetic concentrations of halothane. Anesthetic exposure to 4.0 MAC hours/day was lethal to both dams and embryos, and resulted in major developmental malformations in surviving fetuses. These effects were probably due to altered maternal physiologic status. It is concluded that exposure of mice to subanesthetic concentrations of halothane does not result in important morphologic abnormalities in their offspring.
Abnormalities, Drug-Induced↗
Fluroxene mutagenicity.
The commercially available volatile anesthetic fluroxene (2,2,2-trifluoroethyl vinyl ether) which contains the stabilizer N-phenyl-1-napthylamine, was tested for mutagenicity using four strains of S. typhimurium, TA1535, TA1537, TA98 and TA100, and one strain of E. coli, WP2. In addition, purified fluroxene; N-phenyl-1-napthylamine; trifluoroethanol, a major metabolite of fluoroxene; and urine from rats anesthetized with fluroxene were tested. Several procedures were utilized including exposure of bacteria to vapor in desiccators and in liquid suspension. Results indicate that fluroxene, but not its stabilizer, was mutagenic to strains TA1535, TA100 and WP2 only in liquid suspension and only in the presence of a rat-liver enzyme system. Trifluoroethanol and urine from fluroxene-treated rat were not mutagenic to any strain of bacteria. These findings indicate that fluroxene is a promutagen which requires preincubation before it is recognized. Further experiments were performed with enzymes prepared from mouse, hamster and human liver. Fluroxene was mutagenic only in the presence of enzymes prepared from Aroclor 1254 pretreated rodents. Since fluroxene was not mutagenic in the presence of enzymes prepared from three human livers, the significance of these findings to man are unclear.
Animals↗
Fertility, reproduction and postnatal survival in mice chronically exposed to halothane.
Reproductive studies were performed in Swiss/ICR mice chronically exposed to subanesthetic and anesthetic concentrations of halothane. Male and female mice were treated five or seven days a week for nine weeks prior to mating; exposure of females was continued daily throughout pregnancy. Halothane exposures were 0.025, 0.1, 0.4, 1.2, and 4.0 MAC hours per day. No adverse effect on reproduction was observed at the lowest two exposure levels studied. Exposures to 0.4 MAC hour per day or more were associated with decreased maternal weight gain, fetal fetal length and weight, and early postnatal weight gain. Pregnancy rate, implantation rate, and number of live fetuses per litter were significantly decreased at 1.2 MAC hours per day. The percentage of resorption or fetuses dead in utero was not increased, and postnatal survival of offspring was unaltered. Subsequent matings between untreated females and males exposed to halothane, 1.2 MAC hours per day for 17 weeks, resulted in normal reproductive performance; this suggests that the adverse reproductive changes observed when both males and females were exposed represented a primary effect on females. The least exposure at which effects were seen is approximately 40 times greater than the level of human occupational exposure is unscavenged operating rooms.
Anesthesia, Inhalation↗
Mutagenicity of halogenated ether anesthetics.
An in vitro microbial assay system employing two histidine-dependent strains of Salmonella typhimurium, TA1535 and TA100, was used to test the mutagenicities of enflurane, methoxyflurane, isoflurane and fluroxene. Enflurane, isoflurane and fluroxene in concentrations ranging from 0.01 to 30 per cent and methoxyflurane in concentrations ranging from 0.01 to 7 per cent were incubated with bacteria in the presence or absence of homogenates of liver prepared from rats pretreated with the enzyme inducer, Aroclor 1254. Enflurane, methoxyflurane, isoflurane, and urines from patients anesthetized with these agents were not mutagenic. Fluroxene, however, was highly mutagenic, and therefore poses a possible hazard for operating room personnel and patients.
Anesthesia, Inhalation↗
Mutagenicity of volatile anesthetics: halothane.
The mutagenicity of halothane was tested in an in-vitro microbial assay system employing two histidine-dependent mutants of Salmonella typhimurium, TA98 and TA100, Halothane in concentrations ranging from 0.1 to 30 per cent was incubated with bacteria in the presence or absence of a metabolic activation system prepared from either rat liver treated with Aroclor 1254 or human liver. Trifluoroacetic acid, a major metabolite of halothane, and urine from patients anesthetized with halothane also were tested. Halothane, trifluoroacetic acid, and patients' urines were not mutagenic.
Aminobiphenyl Compounds↗
Mutagenicity of fluroxene.
Explore the source record for details and available documents.
Carcinogens↗
Anticholinergic actions of steroid muscle relaxants.
The chronotropic effects of two new steroid muscle relaxants have been investigated. Each was compared individually with pancuronium bromide, using acetylcholine as an agonist on the isolated perfused rabbit heart. One of the drugs. Organon 6368, was very similar to pancuronium in its degree of antagonism to the bradycardia produced by acetylcholine and may therefore be a useful drug clinically. Dacuronium, on the other hand, would appear to have marked chronotropic effects at dose levels needed for adequate neuromuscular blockade and thus may be less useful.
Acetylcholine↗
Effects of subchronic intermittent exposure to isoflurane in Swiss Webster mice.
Swiss Webster mice were treated to determine if subchronic intermittent exposure to the inhalation anesthetic isoflurane causes organ toxicity or enhances its own metabolism or that of other anesthetics. One-hundred twenty, four-week-old male and female mice were exposed to compressed air or to 0.02%, 0.1% or 0.5% of isoflurane for four hours per day, five days per week for nine weeks. Body weights among the groups were the same prior to exposure. Overall, there were no significant differences in body weights among exposure groups (ANOVA with day as a repeated measure: females - F = 2.12, P = 0.1085; males - F = 1.80, P = 0.1583). There was, however, a significant interaction of group and days; differences were isolated to the start of exposure (weeks 1 through 3 for females; week 2 for males). At all times, differences remained within 10% of the control body weights. Organ weights (liver, spleen, kidney, testis and uterus), hematocrits, and SGOT levels were similar among exposure groups. Histologic evaluation of organs revealed no anesthetic-related organ toxicity. The concentration of hepatic cytochromes, b5 and P-450, per mg of microsomal protein were similar among exposure groups and between sexes. The rates of hepatic microsomal metabolism (defluorination) of three volatile halogenated ether anesthetics (methoxyflurane, enflurane, and isoflurane) were not different among groups following nine weeks of exposure. Isoflurane exposures of 0.5% or less for four hours per day for five days per week would appear to be the maximum tolerated concentration for any chronic study. Since there was no evidence of organ toxicity or of enhanced or inhibited hepatic microsomal enzyme activity, isoflurane seems to be relatively non-toxic inhalation anesthetic under the conditions of this study.
Animals↗
Effects of subchronic intermittent exposure to nitrous oxide in Swiss Webster mice.
Swiss Webster mice were treated to determine whether the inhalational anesthetic, nitrous oxide (N2O), causes organ toxicity and enhances anesthetic defluorination. Two-hundred and sixteen young adult male and female mice were exposed to room air or to 5,000 (.5%), 50,000 (5%) or 500,000 (50%) N2O for four hours per day, five days per week for periods up to fourteen weeks. Body weight was measured twice weekly throughout the experiment. Liver, kidney, spleen and testis were weighed and examined histologically along with brain, stomach, seminal vesicle, and ovary for evidence of drug induced damage. Blood smears were examined microscopically and complete blood count, differential white cell count, and reticulocyte and platelet counts were performed. In addition, liver microsomal cytochrome P-450 content and the rates of defluorination of enflurane and methoxyflurane were determined. The maximum tolerated concentration of N2O was approximately 5000,000 ppm. Even at this high dose, there was no evidence of organ damage. Following N2O exposure, neither the hepatic microsomal cytochrome P-450 content nor the rates of anesthetic defluorination were increased; the rate of in vitro inorganic fluoride production was greater for methoxyflurane than for enflurane. Since there was no evidence of specific organ toxicity or of enzyme induction or inhibition, it was concluded that N2O is a comparatively nontoxic inhalational anesthetic under the conditions of this study.
Anesthetics↗