The presence of an inhibitor of ethylmorphine N-demethylase in old ethylmorphine.
Explore the source record for details and available documents.
Animals↗
SEARCH · Search PubMed
Results for “Ethylmorphine”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Synthesis of ethylmorphine-6-glucuronide: a metabolite of ethylmorphine in man.
Explore the source record for details and available documents.
Ethylmorphine↗
Kinetic studies on the control of ethylmorphine N-demethylase. The role of ethylmorphine activation of reduced nicotinamide adenine dinucleotide phosphate-cytochrome P-450 reductase.
Explore the source record for details and available documents.
Animals↗
Biotransformation and pharmacokinetics of ethylmorphine after a single oral dose.
1. The pharmacokinetics of ethylmorphine after administration of a single dose of the cough mixture Cosylan were investigated in 10 healthy subjects. 2. The median urinary recovery of ethylmorphine and measured metabolites was 77% over 48 h. The median tmax of unchanged ethylmorphine was 45 min, and the terminal elimination t1/2 was 2 h. Ethylmorphine-6-glucuronide was found to be the major metabolite. 3. Two subjects had significantly lower urinary recovery (0.48 h) of morphine and morphine-glucuronides than the remainder. Furthermore, these two had urinary metabolic ratios (MRO) and partial metabolic clearances (CLmO) for O-deethylation of ethylmorphine tentatively classifying them phenotypically as poor metabolisers of the debrisoquine/sparteine type. 4. Genotyping for cytochrome P450 (CYP) 2D6 alleles revealed five homozygote (wt/wt) and five heterozygote subjects. Two subjects phenotypically classified as poor metabolisers were genotypically CYP2D6A/wt and CYP2D6D/wt, respectively. 5. Serum and urine samples taken more than 8 and 24 h after administration of ethyl-morphine respectively, contained morphine and morphine-glucuronides, but no ethylmorphine, ethylmorphine-6-glucuronide or (serum only) norethylmorphine. Norethylmorphine could be detected after hydrolysis of urine samples in all subjects. The urinary recovery of the active metabolites morphine and morphine-6-glucuronide after administration of ethylmorphine varied by a factor of 9 between individuals. 6. The wide variation in recovery of morphine and morphine-glucuronides after oral administration of ethylmorphine could not be explained simply by a difference in CYP2D6 genotype. Constitutional variation in other enzymatic pathways involved in ethylmorphine metabolism is probably crucial. Ratios of morphine to parent drug cannot be used to distinguish the source of morphine after administration of ethylmorphine. Norethylmorphine should be included in urine assays for opiates in forensic toxicology, and no firm conclusions about the source of morphine are possible based on serum samples obtained more than 24 h after drug administration.
Adult↗
Ethylmorphine metabolism in isolated rat hepatocytes.
The metabolism of ethylmorphine has been studied in suspensions of isolated rat hepatocytes. Early during incubation, the two major metabolic intermediates detected were morphine and norethylmorphine following N- and O-dealkylation of ethylmorphine, respectively. During subsequent incubation the concentration of the second metabolic intermediate, normorphine increased, before the concentration peaked at approximately 20 microM (100 microM ethylmorphine). Both morphine and normorphine were glucuronidated to form morphine-3-glucuronide and normorphine-3-glucuronide, respectively, which appeared to be the major metabolic end products. The percentage of ethylmorphine metabolized to morphine-3-glucuronide was found to be dependent on the initial concentration of ethylmorphine. With increasing initial ethylmorphine concentration the relative formation of morphine-3-glucuronide was reduced (29 +/- 10% at 5 microM, 18 +/- 5% at 20 microM, and 15 +/- 4% at 100 microM mean +/- S.D., n = 10). The concentrations of ethylmorphine and its metabolites were found to be higher in liver cells than in medium. Thus the ratios between the intra-/extra-cellular concentrations of ethylmorphine increased somewhat from an initial value of 4 during the period for which ethylmorphine could be detected intracellularly. The drug metabolites all exhibited ratios above 10 for the initial 100 min. of incubation. With time these ratios showed a decline, but even for prolonged incubation the ratios were 5 or higher for the end products. Thus considerable drug concentration gradients existed across the cell membrane of isolated rat hepatocytes.
Animals↗
Effects of ethanol on ethylmorphine metabolism in isolated rat hepatocytes: characterization by means of a multicompartmental model.
Hepatic cytochrome P-450 enzymes mediate at least two important biotransformation pathways of codeine and ethylmorphine starting with either N-demethylation or O-dealkylation, producing polar metabolites which are then subsequently glucuronidated. The present study was designed to characterise the acute effects of ethanol on the metabolism of ethylmorphine and to compare it with the effects on codeine in suspensions of freshly isolated rat hepatocytes. Isolated rat hepatocytes from male Wistar rats were prepared by a collagenase perfusion method. Ethylmorphine, codeine and their metabolites were quantified by HPLC with UV detection. The total ethylmorphine elimination rate was reduced by 12% at 5mM and 38% at 100 mM ethanol. The corresponding percentages for codeine were 16 and 43%. In the presence of ethanol the concentrations of several intermediate and end products of ethylmorphine and codeine changed markedly from the control situation. The experimental data were applied to a mathematical compartmental linear model to estimate the influence of ethanol on the separate reaction rates in the two main metabolic pathways. The ratios between reaction rate constants in the ethylmorphine experiments at 100 and 0 mM ethanol were 0.65 for ethylmorphine-->norethylmorphine, 0.63 for norethylmorphine-->normorphine, 0.56 for ethylmorphine-->morphine, 0.49 for morphine-->normorphine, 0.31 for normorphine-->normorphine-3-glucuronide and 0.49 for morphine-->morphine-3-glucuronide. Almost similar effects of ethanol on codeine metabolism were found. In additional experiments, norethylmorphine or norcodeine (50 microM) was incubated with 5 mM to 100 mM of ethanol and the metabolism of both norethylmorphine and norcodeine was found to be inhibited by ethanol in a concentration-dependent manner. The glucuronidation of morphine and normorphine added in separate experiments was also inhibited by ethanol, from 22 to 36% for morphine-3-glucuronide and 30 to 60% for normorphine-3-glucuronide, respectively, in the presence of 5 mM to 100 mM of ethanol. It was concluded that all steps in the metabolism of ethylmorphine (and codeine) leading to the end products morphine-3-glucuronide and normorphine-3-glucuronide were inhibited by ethanol, and that the glucuronidation process were the ones most affected by ethanol.
Animals↗
Fatal poisonings where ethylmorphine from antitussive medications contributed to death.
The hypothesis that antitussives containing ethylmorphine are abused by alcoholics and drug addicts and that this may lead to fatal poisonings where ethylmorphine causes or contributes to death was investigated. For this purpose 14 cases were analysed where a blood ethylmorphine concentration above the therapeutic level of >/= 0.3 microg/g was found in autopsy blood samples. Alcohol was found in 8 of the 14 cases and alcoholism or drug addiction was noted on 8 of the 14 death certificates. Other drugs, mostly benzodiazepines, were found in all 14 cases. The cause of death was fatal poisoning in 8 of the 14 cases and although there were no mono-intoxications, the cause of death was specified as fatal ethylmorphine poisoning in 2 cases. Among the unspecified medicinal drug poisonings there were five cases with very high blood levels of ethylmorphine, indicating that this drug played an important contribution to the cause of death. The results indicate that deaths due to ethylmorphine in antitussive medicines may occur among drug addicts and alcoholics taking it in overdose. Physicians should therefore be restrictive in prescribing cough mixtures containing ethylmorphine to these categories of patients. Prescription of large amounts of the drug should be avoided.
Adult↗
Characterization of sheep liver and lung microsomal ethylmorphine N-demethylase.
Ethylmorphine N-demethylase activity of the sheep liver and lung microsomes was reconstituted in the presence of solubilized microsomal cytochrome P-450, NADPH-cytochrome c reductase and synthetic lipid, phosphatidylcholine dilauroyl. The Km of the lung microsomal ethylmorphine N-demethylase was calculated to be 4.84 mM ethylmorphine from its Lineweaver-Burk graph and lung enzyme was inhibited by its substrate, ethylmorphine, when its concn was 25 mM and above, reaching to 67% inhibition at 50 mM concn. The Lineweaver-Burk and Eadie-Hofstee plots of the liver enzyme were found to be curvilinear. From these graphs, two different Km values were calculated for the liver enzyme as 4.17 mM and 0.40 mM ethylmorphine. Ethylmorphine N-demethylase activities of both liver and lung microsomes were inhibited by NiCl2, CdCl2 and ZnSO4. Ethylalcohol inhibited N-demethylation of ethylmorphine in lung and liver microsomes. Acetone (5%) slightly enhanced the N-demethylase activity of the liver enzyme, whereas 5% acetone completely inhibited the lung enzyme. Phenylmethylsulfonyl fluoride at 0.10 mM and 0.25 mM concn had no effect on liver enzyme activity, while at these concns, it inhibited the activity of the lung enzyme by about 35%.
Acetone↗
Urinary excretion of codeine, ethylmorphine, and their metabolites: relation to the CYP2D6 activity.
The formation of morphine from codeine and ethylmorphine is mainly mediated by the polymorphic enzyme CYP2D6. The objective of this study was to investigate whether CYP2D6 poor metabolizers (PM) and CYP2D6 extensive metabolizers (EM) would respond differently during testing for opiate drugs of abuse in urine after intake of these drugs. Five PM and five EM of dextromethorphan were administered single oral doses of codeine (25 mg) and ethylmorphine (25 mg), and the urinary excretion of parent compounds and selected metabolites was observed for 72 hours. Analysis was performed with GC-MS after hydrolysis of the glucuronide conjugates. Selected urine samples were screened for the presence of opiates by the Abbott ADx immunoassay method. The results from one PM and one EM were excluded because of technical analytical problems. EM excreted significantly more morphine than PM after intake of both codeine (6.5% vs. 1.1% of the dose; p < 0.05) and ethylmorphine (11.0% vs. 3.0% of the dose; p < 0.05). Screening results were positive significantly longer for EM than for PM after codeine intake (mean, 33 hours vs. 17 hours; p < 0.05), and the same trend, albeit nonsignificantly, was noted for ethylmorphine (mean, 33 hours vs. 24 hours). Regardless of CYP2D6 phenotype, significantly more morphine was formed after intake of ethylmorphine than after intake of codeine (7.0% vs. 3.8% of the dose; p < 0.05). There were high correlations between dextromethorphan metabolic ratios and the ratios of codeine to morphine, ethylmorphine to morphine, norcodeine to normorphine, and norethylmorphine to normorphine (r = 0.80 to 0.92; p = 0.030 to 0.001). Although this study should be interpreted with caution because of the few subjects included and the single-dose design, it demonstrates that the CYP2D6 phenotype clearly affects the results when testing for opiates in urine after intake of codeine and ethylmorphine.
Adult↗
The effect of NADH and low oxygen pressure on the hepatic microsomal ethylmorphine N-demethylase activity of the male rat.
Plots of reciprocal initial rate of formaldehyde formation as a function of reciprocal ethylmorphine concentration provide parallel lines for oxygen concentrations ranging from 5.41 to 211 microM, and the apparent Km values for ethylmorphine at these extremes are 167 and 417 microM, respectively. Similarly, the apparent Km for O2 decreases from 7.69 microM at 2 mM ethylmorphine to 3.64 microM at 0.2 mM ethylmorphine. Reciprocal plots of 1/Km app and 1/Vm for ethylmorphine against 1/[O2] give Km values for O2 of 9.35 microM and 9.09 microM, respectively. Similar plots give Km values for ethylmorphine of 0.28 mM and 0.36 mM. Similarly, NADH causes an uncompetitive stimulation. These data suggest that hepatic microsomal ethylmorphine N-demethylase follows parallel plot sequential kinetics. These results, along with studies of other workers, suggest that cytochrome P-450 forms an active complex with O2 which is stable for at least many milliseconds.
Animals↗
Studies on the N-demethylation and O-de-ethylation of ethylmorphine[6-3H] by male rat hepatic microsomes.
A sensitive and convenient radioassay for the in vitro determination of ethylmorphine N-demethylase and O-de-ethylase activity has been developed. Ethylmorphine[6-3H] was prepared by reduction of the corresponding morphinone in nearly quantitative yield. After incubation with hepatic microsomes from male rats, the reaction was terminated by the addition of 5 ml of acetone. The sample was saturated with potassium acetate and extracted twice with acetone giving complete extraction of the radiolabeled ethylmorphine and its metabolites. After the combined organic phases were evaporated, the samples were dissolved in methanol and applied to a Silica Gel GF plate with subsequent development in ethyl acetate-methanol-concentrated NH4OH. The amount of radioactivity detected for the morphine and norethylmorphine bands at zero time was approximately 0.05% of the original amount of labeled ethylmorphine added to the incubation media. Similarly, the Km values were 52 and 250 microns for the O- and N-dealkylation respectively, while the Vmax values were 5.0 and 1.8 nmol/mg of protein per min. Finally, with this assay we have observed constant specific activity for both the N- and O-dealkylation of ethylmorphine[6-3H] with as little as 10 micrograms of microsomal protein per ml of incubation media.
Animals↗
Sex- and strain-dependent hepatic microsomal ethylmorphine N-demethylation in mice: the roles of type I binding and NADPH-cytochrome P-450 reductase.
The roles of type I binding and NADPH-cytochrome P-450 reductase in ethylmorphine demethylation were investigated in two strains of mice, using sex differences in these activities as a tool. In the CPB-SE strain, females metabolize ethylmorphine faster than males. Sex differences in cytochrome P-450 content and endogenous NADPH-cytochrome P-450 reductase activity were too small to account for this. On the other hand, the differences in the magnitudes of type I spectra and ethylmorphine-induced enhancement of cytochrome P-450 reduction were considerable larger than those in the rates of demethylation. All parameters, except endogenous cytochrome P-450 reduction, were modified in a similar way by testosterone pretreatment: in females they were depressed to the male level, whereas in males they remained unchanged. Castration had no effect in females and enhanced the activities in males. The CPB-V strain exhibited little or no sex differences in ethylmorphine demethylation, cytochrome P-450 content and endogenous cytochrome P-450 reduction. Testosterone pretreatment had little or no influence on these activities. Type I binding and reductase stimulation, however, showed sex differences, comparable to those observed in the CPB-SE strain, which were also abolished by testosterone. A relationship between reductase stimulation and type I binding was observed, which was, apparently, independent of sex or strain. It is concluded that androgen primarily influences the amount of cytochrome P-450-substrate complex formed, but that the reduction of this complex is not rate-limiting in the demethylation of ethylmorphine.
Animals↗
Evidence for a role of cytochrome P450 2D6 and 3A4 in ethylmorphine metabolism.
Ethylmorphine is metabolised by N-demethylation (to norethylmorphine) and by O-deethylation (to morphine). The O-deethylation reaction was previously shown in vivo to co-segregate with the O-demethylation of dextromethorphan indicating that ethylmorphine is a substrate of polymorphic cytochrome P450(CYP)2D6. To study further the features of ethylmorphine metabolism we investigated its N-demethylation and O-deethylation in human liver microsomes from eight extensive (EM) and one poor metaboliser (PM) of dextromethorphan. Whereas N-demethylation varied only two-fold there was a 4.3-fold variation in the O-deethylation of ethylmorphine, the lowest rate being observed in the PM. Quinidine, at a concentration of 1 microM, inhibited O-deethylation in microsomes from an EM, but was unable to do so in microsomes from the PM. The immunoidentified CYP2D6 and CYP3A4 correlated with the rates of O-deethylation (r = 0.972) and N-demethylation (r = 0.969), respectively. We conclude that the O-deethylation of ethylmorphine is catalysed by the CYP2D6 in human liver microsomes consistent with previous findings in healthy volunteers.
Adult↗
The effect of antidepressants on ethylmorphine and imipramine N-demethylation in rat liver microsomes.
The effects of single and multiple doses of desipramine, amitriptyline or citalopram on the rat liver microsomal cytochrome P-450 level and on the rate of ethylmorphine and imipramine demethylation in-vitro have been investigated. Desipramine, amitriptyline or citalopram when given to rats as a single dose, did not affect the level of cytochrome P-450 in the liver microsomes, however, there was a tendency towards acceleration of imipramine, and particularly ethylmorphine, demethylation. Prolonged administration of desipramine and citalopram, but not amitriptyline, elevated the microsomal level of cytochrome P-450 and accelerated the rate of ethylmorphine demethylation. All the drugs investigated, when given chronically, inhibited the rate of imipramine demethylation. Since demethylation of ethylmorphine and imipramine in a CO atmosphere was inhibited by ca 90% for the former and only by 58% for the latter, it can be assumed that prolonged administration of the drugs investigated has two different effects on the oxygenase systems in rat liver microsomes: on the one hand they stimulate the cytochrome P450 oxygenase system involved in ethylmorphine demethylation and, on the other, they inhibit the other microsomal oxygenase system involved in demethylation of imipramine.
Animals↗
Comparison of human fetal hepatic and adrenal cytochrome P450 activities with some major gestational steroids and ethylmorphine as substrates.
The immunoidentified human fetal liver and adrenal microsomal contents of cytochromes P450IIIA and P450XVIIA1 were compared to the metabolism of steroids and ethylmorphine. In fetal liver microsomes, 16 alpha-hydroxylation of dehydroepiandrosterone (DHA) was catalyzed at a high rate in almost all investigated specimens and accompanied by a high ethylmorphine N-demethylase activity. Progesterone 16 alpha- and 17 alpha-hydroxylation was found only in the livers with the highest DHA 16 alpha-hydroxylation activities, while 21-hydroxylation of progesterone was catalyzed only occasionally in these samples. In fetal adrenal microsomes, 21-hydroxylation of progesterone to 11-desoxycorticosterone (DOC) and 11-desoxycortisol (DOCOL) was catalyzed. In contrast to fetal liver, the adrenals also catalyzed the 17 alpha-hydroxylation of pregnenolone and the formation of DHA from 17 alpha-OH-pregnenolone. 16 alpha-hydroxylation of DHA and ethylmorphine N-demethylation were modest in the adrenals. P450IIIA/HLp was immunoidentified in all investigated liver specimens except two (18/20) in which no ethylmorphine N-demethylation or 16 alpha-hydroxylation of DHA was found. P450XVIIA1 bands were observed in 8/20 blots of liver specimens, but there was no correlation between the density of these bands and the 17 alpha-hydroxylation of progesterone. All 11 fetal adrenal samples catalyzed DHA 16 alpha-hydroxylation, although only 8 were positive for P450IIIA/HLp. All investigated adrenals were positive in regard of the P450XVIIA1 band, except one (8/9) with a low 17 alpha-hydroxylation of progesterone. All adrenal specimens catalyzed 21-hydroxylation of progesterone and contained P450C21 bands in immunoblots and all samples catalyzed the formation of DOC and DOCOL from progesterone. Our findings in the fetal livers show a correlation between the DHA 16 alpha-hydroxylation and immunoidentified P450IIIA/HLp bands. In adrenals, there was a correlation between the immunoidentified P450XVIIA1 bands and the 17 alpha-hydroxylation of progesterone.
Adrenal Glands↗
Effects of polyamines on ethylmorphine N-demethylation in rat liver microsomes.
The time course linearity of ethylmorphine N-demethylation was improved by the addition of polyamines to the reaction mixture. The most remarkable effect on the time course linearity of ethylmorphine N-demethylation was observed when spermine was used. The apparent stimulatory effect of spermine was decreased remarkably by the simultaneous addition of EDTA to inhibit lipid peroxidation. Similar results were observed when an additional lipid peroxidation inhibitor such as Co2+, Mn2+ or 2,2'-bipyridine was used in place of EDTA. Hydrogen peroxide-dependent ethylmorphine N-demethylation activity in rat liver microsomes was not influenced by the addition of spermine. In addition, neither lipid peroxides formation nor the stimulatory effects of polyamines on ethylmorphine N-demethylation was observed in the reconstituted monooxygenase system. These results suggest that the inhibitory effects of polyamines on lipid peroxidation might be responsible for the stimulatory effects on drug oxidations.
Animals↗
Sex differences in the kinetic constants of ethylmorphine demethylation and type I binding to hepatic microsomal cytochrome P-450 in mice. The influence of castration and testosterone.
1. In the CPB-SE mouse strain sex differences were observed in the Km and Vmax of ethylmorphine demethylation and in the deltaAmax of its type I binding to cytochrome P-450. In the CPB-V strain a small sex difference in the Vmax of the demethylation was found, whereas Ks and deltaAmax of type I binding differed considerably. 2. Testosterone pre-treatment of female CPB-SE mice abolished all sex differences, as did castration of males, except in Vmax, which was partially decreased. In the CPB-V strain testosterone pre-treatment of females abolished sex differences in type I binding, but had no effect on ethylmorphine demethylation. 3. Km values exceeded the corresponding Ks in all cases and sex differences in deltaAmax far exceeded those in Vmax. It is concluded that the Km is determined not only by the Ks of type I binding and the reduction rate of the type I complex between ethylmorphine and cytochrome P-450. The larger sex differences in deltaAmax as compared with Vmax may be attributable to type I binding of ethylmorphine to cytochrome P-450 subspecies not involved in its demethylation.
Animals↗
The influence of NADH on the ethylmorphine-N-demethylation in liver microsomes from control and phenobarbital-treated rats or different ages.
The ethylmorphine-N-demethylation by liver microsomes from control and phenobarbital-treated rats of different ages was investigated by means of adding NADPH in combination with NADH to the incubation medium. The rate of ethylmorphine-N-demethylation in the presence of NADPH without NADH is greater in adult than in young rats and greater in induced that in control rats. The higher the activity of ethylmorphine metabolism with NADPH alone the more it is abolsutely enhanced by NADH. The relative increase in ethylmorphine metabolism caused by NADH is equal in all groups of animals. It is concluded that there are no differences in the introduction of the second electron from NADH to the oxygenated cytochrome P-450 but there are differences in the concentration of cytochrome-substrate complex and, consequently, in the oxygenated cytochrome-substrate complex. The enhancing effect of NADH is higher at lower NADPH concentrations. In the presence of NADH, the NADPH concentrations necessary to obtain a msximum metabolic rate are lower than without NADH.
Animals↗