Renal and hepatic toxicity of the fluorinated ether volatile anesthetics is caused by biotransformation to toxic metabolites. Metabolism also contributes significantly to the elimination pharmacokinetics of some volatile agents. Although innumerable studies have explored anesthetic metabolism in animals, there is little information on human volatile anesthetic metabolism with respect to comparative rates or the identity of the enzymes responsible for defluorination. The first purpose of this investigation was to compare the metabolism of the fluorinated ether anesthetics by human liver microsomes. The second purpose was to test the hypothesis that cytochrome P450 2E1 is the specific P450 isoform responsible for volatile anesthetic defluorination in humans. Microsomes were prepared from human livers. Anesthetic metabolism in microsomal incubations was measured by fluoride production. The strategy for evaluating the role of P450 2E1 in anesthetic defluorination involved three approaches: for a series of 12 human livers, correlation of microsomal defluorination rate with microsomal P450 2E1 content (measured by Western blot analysis), correlation of defluorination rate with microsomal P450 2E1 catalytic activity using marker substrates (para-nitrophenol hydroxylation and chlorzoxazone 6-hydroxylation), and chemical inhibition by P450 isoform-selective inhibitors. The rank order of anesthetic metabolism, assessed by fluoride production at saturating substrate concentrations, was methoxyflurane > sevoflurane > enflurane > isoflurane > desflurane > 0. There was a significant linear correlation of sevoflurane and methoxyflurane defluorination with antigenic P450 2E1 content (r = 0.98 and r = 0.72, respectively), but not with either P450 1A2 or P450 3A3/4. Comparison of anesthetic defluorination with either para-nitrophenol or chlorzoxazone hydroxylation showed a significant correlation for sevoflurane (r = 0.93, r = 0.95) and methoxyflurane (r = 0.78, r = 0.66). Sevoflurane defluorination was also highly correlated with that of enflurane (r = 0.93), which is known to be metabolized by human P450 2E1. Diethyldithiocarbamate, a selective inhibitor of P450 2E1, produced a concentration-dependent inhibition of sevoflurane, methoxyflurane, and isoflurane defluorination. No other isoform-selective inhibitor diminished the defluorination of sevoflurane, whereas methoxyflurane defluorination was inhibited by the selective P450 inhibitors furafylline (P450 1A2), sulfaphenazole (P450 2C9/10), and quinidine (P450 2D6) but to a much lesser extent than by diethyldithiocarbamate. These results demonstrate that cytochrome P450 2E1 is the principal, if not sole human liver microsomal enzyme catalyzing the defluorination of sevoflurane. P450 2E1 is the principal, but not exclusive enzyme responsible for the metabolism of methoxyflurane, which also appears to be catalyzed by P450s 1A2, 2C9/10, and 2D6. The data also suggest that P450 2E1 is responsible for a significant fraction of isoflurane metabolism. Identification of P450 2E1 as the major anesthetic metabolizing enzyme in humans provides a mechanistic understanding of clinical fluorinated ether anesthetic metabolism and toxicity.
来源:Hazardous Substances Data Bank (HSDB)
代谢
异氟醚在人体内经历最小的生物转化。
Isoflurane undergoes minimal biotransformation in man.
Renal and hepatic toxicity of the fluorinated ether volatile anesthetics is caused by biotransformation to toxic metabolites. Metabolism also contributes significantly to the elimination pharmacokinetics of some volatile agents. Although innumerable studies have explored anesthetic metabolism in animals, there is little information on human volatile anesthetic metabolism with respect to comparative rates or the identity of the enzymes responsible for defluorination. The first purpose of this investigation was to compare the metabolism of the fluorinated ether anesthetics by human liver microsomes. The second purpose was to test the hypothesis that cytochrome P450 2E1 is the specific P450 isoform responsible for volatile anesthetic defluorination in humans. Microsomes were prepared from human livers. Anesthetic metabolism in microsomal incubations was measured by fluoride production. The strategy for evaluating the role of P450 2E1 in anesthetic defluorination involved three approaches: for a series of 12 human livers, correlation of microsomal defluorination rate with microsomal P450 2E1 content (measured by Western blot analysis), correlation of defluorination rate with microsomal P450 2E1 catalytic activity using marker substrates (para-nitrophenol hydroxylation and chlorzoxazone 6-hydroxylation), and chemical inhibition by P450 isoform-selective inhibitors. The rank order of anesthetic metabolism, assessed by fluoride production at saturating substrate concentrations, was methoxyflurane > sevoflurane > enflurane > isoflurane > desflurane > 0. There was a significant linear correlation of sevoflurane and methoxyflurane defluorination with antigenic P450 2E1 content (r = 0.98 and r = 0.72, respectively), but not with either P450 1A2 or P450 3A3/4. Comparison of anesthetic defluorination with either para-nitrophenol or chlorzoxazone hydroxylation showed a significant correlation for sevoflurane (r = 0.93, r = 0.95) and methoxyflurane (r = 0.78, r = 0.66). Sevoflurane defluorination was also highly correlated with that of enflurane (r = 0.93), which is known to be metabolized by human P450 2E1. Diethyldithiocarbamate, a selective inhibitor of P450 2E1, produced a concentration-dependent inhibition of sevoflurane, methoxyflurane, and isoflurane defluorination. No other isoform-selective inhibitor diminished the defluorination of sevoflurane, whereas methoxyflurane defluorination was inhibited by the selective P450 inhibitors furafylline (P450 1A2), sulfaphenazole (P450 2C9/10), and quinidine (P450 2D6) but to a much lesser extent than by diethyldithiocarbamate. These results demonstrate that cytochrome P450 2E1 is the principal, if not sole human liver microsomal enzyme catalyzing the defluorination of sevoflurane. P450 2E1 is the principal, but not exclusive enzyme responsible for the metabolism of methoxyflurane, which also appears to be catalyzed by P450s 1A2, 2C9/10, and 2D6. The data also suggest that P450 2E1 is responsible for a significant fraction of isoflurane metabolism. Identification of P450 2E1 as the major anesthetic metabolizing enzyme in humans provides a mechanistic understanding of clinical fluorinated ether anesthetic metabolism and toxicity.
Isoflurane induces a reduction in junctional conductance by decreasing gap junction channel opening times and increasing gap junction channel closing times. Isoflurane also activates calcium dependent ATPase in the sarcoplasmic reticulum by increasing the fluidity of the lipid membrane. Also appears to bind the D subunit of ATP synthase and NADH dehydogenase. Isoflurane also binds to the GABA receptor, the large conductance Ca<sup>2+</sup> activated potassium channel, the glutamate receptor and the glycine receptor.
Prospective, serial blood testing often demonstrates minor transient elevations in serum aminotransferase levels in the 1 to 2 weeks after major surgery and halogenated anesthetic agents. Appearance of ALT levels above 10 times the upper limit of normal, however, is distinctly unusual and points to significant hepatotoxicity. Clinically apparent, severe hepatic injury from isoflurane is very rare, only isolated case reports and small case series having been published. The injury is marked by acute elevations in serum aminotransferase levels (5- to 50-fold) and appearance of jaundice within 2 to 21 days of surgery. There are usually minimal increases in alkaline phosphatase and gammaglutamyl transpeptidase levels. Jaundice is usually preceded by a day or two of fever and may be accompanied by rash and eosinophilia. The acute liver injury may be self-limited and resolve within 4 to 8 weeks, but can be severe and associated with acute liver failure. A strong risk factor is previous exposure to any of the halogenated anesthetics and particularly a history of halothane hepatitis or unexplained fever and rash after anesthesia with one of these agents. The differential diagnosis of acute liver injury after surgery and anesthesia is sometimes difficult, and a clinical picture similar to isoflurane hepatitis can be caused by shock or ischemia, other idiosyncratic forms of drug induced liver injury and acute viral or herpes hepatitis.
来源:LiverTox
毒理性
致癌物分类
对人类无致癌性(未列入国际癌症研究机构IARC清单)。
No indication of carcinogenicity to humans (not listed by IARC).
May lead to cardiac arrhythmias and death (Rarely). In susceptible individuals, Isoflurane anesthesia may trigger a skeletal muscle hypermetabolic state leading to high oxygen demand and the clinical syndrome known as malignant hyperthermia. The syndrome includes nonspecific features such as muscle rigidity, tachycardia, tachypnea, cyanosis, arrhythmias, and unstable blood pressure.(L1471)
◉ Summary of Use during Lactation:There is no published experience with isoflurane during breastfeeding. Because the serum half-life of isoflurane in the mother is short and the drug is not expected to be absorbed by the infant, no waiting period or discarding of milk is required. Breastfeeding can be resumed as soon as the mother has recovered sufficiently from general anesthesia to nurse. When a combination of anesthetic agents is used for a procedure, follow the recommendations for the most problematic medication used during the procedure. In one study, breastfeeding before general anesthesia induction reduced requirements of sevoflurane and propofol compared to those of nursing mothers whose breastfeeding was withheld or nonnursing women. It is possible that requirements for other anesthetic agents would be affected similarly.
◉ Effects in Breastfed Infants:Relevant published information was not found as of the revision date.
◉ Effects on Lactation and Breastmilk:A randomized, but nonblinded, study in women undergoing cesarean section compared epidural anesthesia with bupivacaine to general anesthesia with intravenous thiopental 4 mg/kg and succinylcholine 1.5 mg/kg for induction followed by nitrous oxide and isoflurane. The time to the first breastfeed was significantly shorter (107 vs 228 minutes) with the epidural anesthesia than with general anesthesia. This difference was probably caused by the anesthesia's effects on the infant, because the Apgar and neurologic and adaptive scores were significantly lower in the general anesthesia group of infants.
A randomized study compared the effects of cesarean section using general anesthesia, spinal anesthesia, or epidural anesthesia, to normal vaginal delivery on serum prolactin and oxytocin as well as time to initiation of lactation. General anesthesia was performed using propofol 2 mg/kg and rocuronium 0.6 mg/kg for induction, followed by sevoflurane and rocuronium 0.15 mg/kg as needed. After delivery, patients in all groups received an infusion of oxytocin 30 international units in 1 L of saline, and 0.2 mg of methylergonovine if they were not hypertensive. Fentanyl 1 to 1.5 mcg/kg was administered after delivery to the general anesthesia group. Patients in the general anesthesia group (n = 21) had higher post-procedure prolactin levels and a longer mean time to lactation initiation (25 hours) than in the other groups (10.8 to 11.8 hours). Postpartum oxytocin levels in the nonmedicated vaginal delivery group were higher than in the general and spinal anesthesia groups.
A retrospective study of women in a Turkish hospital who underwent elective cesarean section deliveries compared women who received bupivacaine spinal anesthesia (n = 170) to women who received general anesthesia (n = 78) with propofol for induction, sevoflurane for maintenance and fentanyl after delivery. No differences in breastfeeding rates were seen between the groups at 1 hour and 24 hours postpartum. However, at 6 months postpartum, 67% of women in the general anesthesia group were still breastfeeding compared to 81% in the spinal anesthesia group, which was a statistically significant difference.
来源:Drugs and Lactation Database (LactMed)
吸收、分配和排泄
在麻醉后期间,只有0.17%的异氟醚可以被作为尿液代谢物回收。
In the postanesthesia period, only 0.17% of the isoflurane taken up can be recovered as urinary metabolites.
来源:Hazardous Substances Data Bank (HSDB)
吸收、分配和排泄
目前尚不清楚这种药物是否会被分泌入人乳中。
It is not known whether this drug is excreted in human milk.
Stimulatory effect of anesthetics on dechlorination of carbon tetrachloride in guinea-pig liver microsomes
摘要:
Effects of the anesthetics isoflurane, enflurane, halothane and sevoflurane on the dechlorination of carbon tetrachloride to produce chloroform were investigated using guinea pig liver microsomes. Under anaerobic conditions, chloroform is produced from carbon tetrachloride by the microsomes in the presence of NADPH, and chloroform production from 86 mu M carbon tetrachloride was enhanced to 146%, 133%, 123% and 115% by the addition of isoflurane, enflurane, halothane and sevoflurane, respectively. The half-life of oxidized cytochrome P450 which remained during the reduction by the addition of NADPH was shortened to 51%, 54%, 60% and 80% by isoflurane, enflurane, halothane and sevoflurane, respectively, without alteration of NADPH-cytochrome c reductase activity. These anesthetics hastened the onset of the 445 nm absorption band formation which was shown by microsomes with carbon tetrachloride in the presence of NADPH under anaerobic conditions. These results indicate that the anesthetics isoflurane, enflurane, sevoflurane and halothane stimulate the reduction of cytochrome P450 results in the acceleration of the carbon tetrachloride dechlorination. These results may have implications for other type II drugs that are administered during anesthesia.
The trifluoromethylgroup of certain compoundscontaining one or two trifluoromethylgroups can be converted to the carbomethoxy group by treatment with sodium methoxide followed by aqueous acidic work-up. α-Trifluoromethyl esters can be obtained by selective methanolysis of the 1,1,1,3,3,3-hexafluoroisopropyl group in some cases. The structural requirements for the transformation are delineated, and
A method for preparing a fluorinated vinyl ether compound comprising reacting a fluorinated ether substrate having (i) a hydrogen atom on a carbon atom that is alpha to an etheric oxygen and (ii) a fluorine atom on a carbon atom that is beta to the etheric oxygen, with an organolithium base to provide a reaction product comprising a fluorinated vinyl ether compound.
Diisopropylethylamine mono(hydrogen fluoride) for nucleophilic fluorination of sensitive substrates: synthesis of sevoflurane
作者:Linas V Kudzma、Chialang G Huang、Ralph A Lessor、Leonid A Rozov、Syeda Afrin、Florida Kallashi、Conor McCutcheon、Keith Ramig
DOI:10.1016/s0022-1139(01)00396-7
日期:2001.9
fluoride) (7), is shown to be an effective and selective nucleophilic fluorinating reagent when applied to halogen-exchange reactions of chloromethyl ethers, in particular the conversion of 1,1,1,3,3,3-hexafluoroisopropyl chloromethyl ether (3) to the volatile anesthetic sevoflurane (1,1,1,3,3,3-hexafluoroisopropyl fluoromethyl ether). The amine portion of the reagent does not react with the starting
Production Method for 1,2,2,2-Tetrafluoroethyl Difluoromethyl Ether (Desflurane)
申请人:Central Glass Company, Limited
公开号:US20190345086A1
公开(公告)日:2019-11-14
Fluoral is obtained by gas-phase fluorination of chloral in the presence of a catalyst and then reacted with trimethyl orthoformate, thereby readily forming 1,2,2,2-tetrafluoroethyl methyl ether as an intermediate for production of desflurane. 1,2,2,2-Tetrafluoroethyl difluoromethyl ether (desflurane) is produced with high yield from the thus-formed 1,2,2,2-tetrafluoroethyl methyl ether by chlorination and fluorination. This method enables efficient industrial-scale production of desflurane useful as an inhalation anesthetic