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Pain Feb 1994Recent studies have suggested that morphine-3-glucuronide (M3G) may antagonize the analgesic effects of morphine and morphine-6-glucuronide (M6G). To investigate this...
Concentrations of morphine, morphine-6-glucuronide and morphine-3-glucuronide in serum and cerebrospinal fluid following morphine administration to patients with morphine-resistant pain.
Recent studies have suggested that morphine-3-glucuronide (M3G) may antagonize the analgesic effects of morphine and morphine-6-glucuronide (M6G). To investigate this hypothesis, steady-state concentrations of morphine, M6G and M3G in serum and cerebrospinal fluid (CSF) were measured in 11 patients receiving chronic morphine therapy (9 orally and 2 subcutaneously) for treatment of cancer-related pain. All patients appeared to have morphine-resistant pain and had elected to proceed to intrathecal bupivacaine or percutaneous cordotomy. Morphine, M6G and M3G concentrations were measured by high-performance liquid chromatography. The concentrations (median and range) for morphine, M6G and M3G in serum were 193 (14-1086) nmol/l, 847 (210-4113) nmol/l and 4553 (1324-24035) nmol/l, respectively, while in CSF concentrations of morphine, M6G and M3G were 200 (21-1461) nmol/l, 115 (30-427) nmol/l and 719 (249-3252) nmol/l, respectively. Median molar ratios of M6G/morphine and M3G/morphine in serum were 3.79 and 22.1, respectively, while in CSF the same ratios were 0.42 and 2.39, respectively. Median molar ratios of M3G/M6G in serum and CSF were 5.84 and 6.61, respectively. The median molar ratios for CSF/serum distribution of morphine, M6G and M3G were 1.23, 0.12 and 0.14, respectively. Thus, despite their relatively poor ability to penetrate into the CSF, the high serum concentrations of M6G and M3G resulted in substantial concentrations of these metabolites in the CSF. Nevertheless, M3G/M6G ratios in our morphine-resistant patients were similar to published values in patients with well-controlled pain, suggesting that the hypothesis that M3G plays a major role in morphine-resistance is not correct.
Topics: Adult; Aged; Chromatography, High Pressure Liquid; Drug Resistance; Female; Humans; Male; Middle Aged; Morphine; Morphine Derivatives; Neoplasms; Pain
PubMed: 8008404
DOI: 10.1016/0304-3959(94)90088-4 -
British Journal of Pharmacology Sep 2003(1) We investigated the distribution of morphine and morphine-6beta-glucuronide (M6G) in the brain and spinal cord after intracerebroventricular (i.c.v.) injection of...
(1) We investigated the distribution of morphine and morphine-6beta-glucuronide (M6G) in the brain and spinal cord after intracerebroventricular (i.c.v.) injection of each drug in rats. (2) The cerebrospinal fluid (CSF) concentration of M6G was 5-37 times greater than that of morphine 10, 60 and 120 min after the i.c.v. injection. The apparent elimination clearance of M6G from the CSF was 10 times lower than that of morphine. (3) The intrathecal CSF concentration of M6G measured by the microdialysis method was 29-79 times greater than that of morphine, and M6G was rapidly distributed into the intrathecal space after the i.c.v. injection. (4) M6G was detected in the cerebrum, brainstem, cerebellum and spinal cord at concentrations 2-21 times higher than morphine after the i.c.v. injection of each drug. The distribution volume of M6G in rat brain slices was three times lower than that of morphine, and close to the extracellular fluid space in the brain regions corresponding to the vicinity of the opioid receptors. (5) These brain distribution characteristics of M6G, namely, low clearance from the central nervous system, localization in the extracellular fluid and rapid distribution into the intrathecal space, may contribute to the potent analgesic effect of M6G after i.c.v. injection.
Topics: Animals; Brain; Injections, Intraventricular; Male; Morphine; Morphine Derivatives; Rats; Rats, Sprague-Dawley; Spinal Cord
PubMed: 12967951
DOI: 10.1038/sj.bjp.0705418 -
Journal of Chromatography. B,... Feb 2015The determination of morphine and its isobaric metabolites morphine-3-beta-d-glucuronide (M3G) and morphine-6-beta-d-glucuronide (M6G) is useful for therapeutic drug...
The determination of morphine and its isobaric metabolites morphine-3-beta-d-glucuronide (M3G) and morphine-6-beta-d-glucuronide (M6G) is useful for therapeutic drug monitoring and forensic identification of drug use. In particular, capillary electrophoresis with mass spectrometry (CE-MS) represents an attractive tool for opioid analysis. Whereas volatile background electrolytes in CE often improve electrospray ionization for coupled MS detection, such electrolytes may reduce CE separation efficiency and resolution. To better understand the effects of background electrolyte (BGE) composition on separation efficiency and detection sensitivity, this work compares and contrasts method development for both volatile (ammonium formate and acetate) and nonvolatile (ammonium phosphate and borate) buffers. Peak efficiencies and migration times for morphine and morphine metabolites were optimal with a 25mM ammonium borate buffer (pH=9.5) although greater sensitivities were achieved in the ammonium formate buffer. Optimized CE methods allowed for the resolution of the isobaric morphine metabolites prior to high mass accuracy, electrospray ionization quadrupole time-of-flight (ESI-QTOF) MS detection applicable to the analysis of urine samples in under seven minutes. Urine sample preparation required only a 10-fold dilution with BGE prior to analysis. Limits of detection (LOD) in normal human urine were found to be 1.0μg/mL for morphine and 2.5μg/mL for each of M3G and M6G by CE-ESI-QTOF-MS. These LODs were comparable to those for CE-UV analysis of opioid standards in buffer, whereas CE-ESI-QTOF-MS analysis of opioid standards in buffer yielded LODs an order of magnitude lower. Patient urine samples (N=12) were analyzed by this new CE-ESI-QTOF-MS method and no significant difference in total morphine content relative to prior liquid chromatography-mass spectrometry (LC-MS) results was found as per a paired-t test at the 99% confidence level. Whereas the LC-MS method applied to these samples determined only total morphine content, this new CE-ESI-QTOF-MS method allowed for species differentiation in addition to total morphine determination. By this method, it was found that M3G and M6G metabolites were present in a 5:1 concentration ratio, on average, in patient samples. Therefore, the CE-ESI-QTOF-MS method not only allows for total morphine concentration determination comparable to established LC-MS methods, but also allows for differentiation between morphine and its trace glucuronides, yielding additional biochemical information about drug metabolism.
Topics: Electrophoresis, Capillary; Humans; Mass Spectrometry; Morphine; Morphine Derivatives
PubMed: 25589256
DOI: 10.1016/j.jchromb.2014.11.035 -
Regional Anesthesia 1997It has been suggested that the potency of epidural morphine might be explained by spinal metabolism to the active and potent metabolite morphine-6-glucuronide (M6G). The... (Clinical Trial)
Clinical Trial
BACKGROUND AND OBJECTIVES
It has been suggested that the potency of epidural morphine might be explained by spinal metabolism to the active and potent metabolite morphine-6-glucuronide (M6G). The main objective of this study was to describe the early pharmacokinetics of epidurally administered, morphine with special attention to the appearance of the glucuronated metabolites in cerebrospinal fluid (CSF).
METHODS
Morphine was administered epidurally to eight patients scheduled for major abdominal surgery. The concentrations of morphine and its 6-glucuronide and 3-glucuronide metabolites were monitored in blood and CSF at 10, 30, 60, and 120 minutes and 10 and 24 hours. Postoperative pain was estimated on a visual analog scale, and analgesia requirements (administered by a patient-controlled technique) were recorded.
RESULTS
Only traces of the metabolites were found in CSF and in only two patients throughout the 24 hours. Both metabolites appeared rapidly (within 30 minutes) in plasma in all patients and were found in plasma throughout the study period. Morphine concentration peaked in CSF within 30 minutes at a very high level; in plasma, it peaked at 10 minutes. No correlation was seen between initial or later concentrations of morphine in CSF and postoperative pain or morphine requirements.
CONCLUSIONS
No evidence of spinal metabolism of morphine could be found. Rapid distribution of morphine to CSF and plasma occurred after epidural administration. No value of initial CSF morphine concentrations for prediction of analgesic requirements could be demonstrated.
Topics: Abdomen; Adult; Aged; Analgesia, Epidural; Analgesics, Opioid; Female; Humans; Injections, Epidural; Male; Middle Aged; Morphine; Morphine Derivatives
PubMed: 9089854
DOI: 10.1016/s1098-7339(06)80031-3 -
Biochemical and Biophysical Research... Apr 2020UDP-Glucuronosyltransferase (UGT, Ugt) is a major drug metabolizing enzyme family involved in the glucuronidation and subsequent elimination of drugs and small...
Hetero-oligomer formation of mouse UDP-glucuronosyltransferase (UGT) 2b1 and 1a1 results in the gain of glucuronidation activity towards morphine, an activity which is absent in homo-oligomers of either UGT.
UDP-Glucuronosyltransferase (UGT, Ugt) is a major drug metabolizing enzyme family involved in the glucuronidation and subsequent elimination of drugs and small lipophilic molecules. UGT forms homo- and hetero-oligomers that enhance or suppress UGT activity. In our previous study, we characterized mouse Ugt1a1 and all the Ugt isoform belonging to the Ugt2b subfamily and revealed that mouse Ugt2b1 and Ugt1a1 cannot metabolize morphine. Mouse Ugt2b1 had been believed to function similarly to rat UGT2B1, which plays a major role in morphine glucuronidation in rat liver. Thus, in this study, we hypothesized that hetero-oligomerization with another Ugt isoform may affect Ugt2b1 catalytic ability. We co-expressed Ugt1a1 and Ugt2b1 in a baculovirus-insect cell system, and confirmed hetero-oligomer formation by co-immunoprecipitation. As reported previously, microsomes singly expressing Ugt1a1 or Ugt2b1 were inactive towards the glucuronidation of morphine. Interestingly, in contrast, morphine-3-glucuronide, a major metabolite of morphine was formed, when Ugt2b1 and Ugt1a1 were co-expressed. This effect of hetero-oligomerization of Ugt1a1 and Ugt2b1 was also observed for 17β-estradiol glucuronidation. This is the first report demonstrating that UGT acquires a novel catalytic ability by forming oligomers. Protein-protein interaction of Ugts may contribute to robust detoxification of xenobiotics by altering the substrate diversity of the enzymes.
Topics: Animals; Biocatalysis; Glucuronosyltransferase; Mice; Microsomes, Liver; Morphine; Morphine Derivatives; Protein Multimerization
PubMed: 32093886
DOI: 10.1016/j.bbrc.2020.02.075 -
British Journal of Clinical Pharmacology Nov 1992Plasma morphine concentrations were measured in five cancer patients receiving long-term epidural morphine administration. Peak concentrations were observed within 1 h...
Plasma morphine concentrations were measured in five cancer patients receiving long-term epidural morphine administration. Peak concentrations were observed within 1 h of dosage and concentrations then declined biexponentially. Plasma morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) concentrations were measured in two patients and plasma M3G concentrations were observed to be much higher than plasma M6G and morphine concentrations. Peak plasma M6G concentrations occurred within 1.0 h of dosing and plasma M6G concentrations then remained higher than plasma morphine concentrations.
Topics: Analgesia, Epidural; Chromatography, High Pressure Liquid; Humans; Male; Morphine; Morphine Derivatives; Neoplasms; Pain, Intractable; Spectrometry, Fluorescence
PubMed: 1467139
DOI: 10.1111/j.1365-2125.1992.tb05651.x -
Clinical Pharmacology and Therapeutics Dec 2000Morphine-6-glucuronide (M6G) is an active metabolite of morphine with potent analgesic activity. Morphine-3-glucuronide (M3G), the most prevalent metabolite, has minimal... (Clinical Trial)
Clinical Trial Comparative Study Randomized Controlled Trial
BACKGROUND
Morphine-6-glucuronide (M6G) is an active metabolite of morphine with potent analgesic activity. Morphine-3-glucuronide (M3G), the most prevalent metabolite, has minimal affinity for opioid receptors. It has been suggested from animal model data and by examination of metabolite ratios in humans that M3G may functionally antagonize the respiratory depressant and analgesic actions of morphine and M6G.
METHODS
We performed a double-blind placebo-controlled trial with 10 healthy volunteers. The trial had 6 arms: (1) placebo, (2) 10 mg/70 kg of morphine, (3) 3.3 mg/70 kg of M6G, (4) 30.6 mg/70 kg of M3G, (5) 30.6 mg/70 kg of M3G with 10 mg/70 kg of morphine, and (6) 30.6 mg/70 kg of M3G with 3.3 mg/70 kg of M6G; all were give by slow intravenous bolus. Analgesia was assessed with the use of the submaximal ischemic pain model. The effects were quantified on numerical and visual analogue scales. Respiratory parameters and response to steady state 5% carbon dioxide challenge were assessed with spirometry, mass spectroscopy, and earlobe blood gas analysis.
RESULTS
Morphine and M6G produced significant pain relief compared with placebo (morphine, P < .0001; M6G, P = .033). Pain relief after M6G was less than after morphine (P = .009) and M3G was no better than placebo (P = .26). Pain relief with morphine and M6G were not significantly altered by M3G (P = .59 and P = .28, respectively). Significant and similar dysphoria and sedation occurred with both morphine (P < .002) and M6G (P < .016) but were absent with both M3G and placebo. Respiratory parameters suggested that M6G produced less respiratory depression than morphine. Both morphine and M6G caused a significant reduction in respiratory drive compared with placebo (morphine, P = .002; M6G, P = .013); this effect was not reversed by M3G (P = .35 and P = .83, respectively).
CONCLUSIONS
M3G appears to be devoid of significant activity; in these circumstances and at these doses, it does not antagonize either the analgesic or respiratory depressant effects of M6G or morphine.
Topics: Adult; Analgesics, Opioid; Conscious Sedation; Cross-Over Studies; Double-Blind Method; Drug Interactions; Female; Humans; Male; Morphine; Morphine Derivatives; Pain; Pain Measurement; Placebos; Pulmonary Ventilation
PubMed: 11180027
DOI: 10.1067/mcp.2000.111934 -
Journal of Analytical Toxicology 1998The distribution of morphine, morphine-3-glucuronide (M3G), and morphine-6-glucuronide (M6G) in whole blood, plasma, and packed erythrocytes was studied. Parameters...
The distribution of morphine, morphine-3-glucuronide (M3G), and morphine-6-glucuronide (M6G) in whole blood, plasma, and packed erythrocytes was studied. Parameters investigated were the hematocrit values (10, 42, 44, and 71%) and the water content of the samples. The blood-to-plasma ratio of morphine concentrations was unaffected by variations in hematocrit and water content, whereas the corresponding ratios for M3G and M6G were strongly influenced. Ratios were 0.53 to 0.65 and 0.52 to 0.62 in specimens with average hematocrit values (42 and 44%, respectively), and the ratios were 0.81 or 0.89 (hematocrit 10%) and 0.27 or 0.28 (hematocrit 71%) in blood samples with different hematocrit values. In contrast to the morphine conjugates, morphine was highly bound to or partitioned into red blood cells (beta e = 55.9). Although the present data are limited, they already demonstrate that conclusions drawn from pharmacokinetic studies and transferred to parent drug to metabolite ratios resulting from forensic blood samples may be biased by the particular biological matrix under investigation.
Topics: Centrifugation; Erythrocytes; Hematocrit; Humans; Morphine; Morphine Derivatives
PubMed: 9681326
DOI: 10.1093/jat/22.4.261 -
The Journal of Pharmacology and... Jan 1994Morphine-6-beta-D-glucuronide (M6G) is a metabolite of morphine with opioid activity in adults. No data are available, however, on the developmental pharmacology of M6G...
Morphine-6-beta-D-glucuronide (M6G) is a metabolite of morphine with opioid activity in adults. No data are available, however, on the developmental pharmacology of M6G including investigation of the respiratory effects of M6G in the neonate. A randomized, placebo-controlled study comparing the time-action, dose-response and potency of the respiratory effects of M6G to morphine was done using a nonanesthetized neonatal guinea pig model and a noninvasive computerized plethysmograph technique. Respiration was measured while the neonate breathed room air followed by 5% CO2 in air. M6G (0.5-5.0 mg/kg) and morphine (1.5-15 mg/kg) administered subcutaneously decreased ventilation in 3-, 7- and 14-day-old neonatal guinea pigs given a 5% CO2 challenge. During CO2 inhalation, time-to-peak action for M6G occurred 21 min later than for morphine. At maximal ventilatory depression on day 3, a dose of 1.5 mg/kg morphine or M6G decreased minute ventilation while breathing 5% CO2 by 30% compared to placebo. Ventilation also decreased as a function of age in both placebo and drug-treated animals. The percent respiratory depression relative to placebo remained constant for a given dose of morphine as the neonate aged, but not for M6G, which increased in potency. M6G was equipotent to morphine on day 3 after birth, but was 8-fold more potent by day 7. This increase in potency persisted through day 14. The increased potency of M6G that accompanies aging may be caused by either a change in M6G disposition or a change in opioid receptors during development of the neonatal guinea pig.
Topics: Animals; Animals, Newborn; Body Weight; Female; Guinea Pigs; Male; Morphine; Morphine Derivatives; Naloxone; Random Allocation; Respiration; Sex Ratio; Time Factors
PubMed: 8301546
DOI: No ID Found -
Drug Metabolism and Disposition: the... 1986The pharmacokinetic disposition of morphine was studied in sham-operated dogs, dogs with hepatic devascularization, and dogs with bile duct and ureter ligation after iv...
The pharmacokinetic disposition of morphine was studied in sham-operated dogs, dogs with hepatic devascularization, and dogs with bile duct and ureter ligation after iv administration of 1 mg/kg of morphine. In sham-operated dogs, morphine is rapidly distributed and eliminated, with a terminal half-life of 65 +/- 30 min. Morphine glucuronide appeared in plasma within 5 min and rose rapidly to levels an order of magnitude higher than morphine levels, before both declined in parallel. In hepatic devascularized dogs, there was a marked delay in morphine elimination due to a 47% reduction in clearance. The appearance of morphine glucuronide in plasma was not delayed, but the AUC of morphine glucuronide was reduced by 56% compared to control for the first 180 min. In bile duct- and ureter-ligated dogs, elimination of morphine was increased and morphine glucuronide elimination from plasma was decreased, suggesting that glucuronide normally excreted in bile is hydrolyzed back to the parent compound and reabsorbed in sham-operated control animals. In conclusion, morphine was glucuronidated by both hepatic and extrahepatic glucuronyltransferases to an approximately equal extent in the dog.
Topics: Animals; Dogs; Female; Kinetics; Liver; Male; Metabolic Clearance Rate; Models, Biological; Morphine; Morphine Derivatives
PubMed: 2877817
DOI: No ID Found