A highly sensitive assay for the simultaneous determination of morphine, morphine-3-glucuronide, and morphine-6-glucuronide in human plasma by high-performance liquid chromatography with electrochemical and fluorescence detection

Controlled-release oxycodone compared with controlled-release morphine in the treatment of cancer pain: A randomized, double-blind, parallel-group study

Controlled-release oral formulations of oxycodone and morphine are both suitable analgesics for moderate to severe pain. They were compared in cancer-pain patients randomized to double-blind treatment with controlled-release oxycodone (n = 48) or controlled-release morphine (n = 52) every 12 h for up to 12 days. Stable analgesia was achieved by 83% of controlled-release oxycodone and 81% of controlled-release morphine patients in 2 days (median). Following titration to stable analgesia, pain intensity (0=none to 3=severe) decreased from baseline within each group (p </= 0.005), from 1.9 (0.1) to 1.3 (0.1), mean (SE), with controlled-release oxycodone, and from 1.6 (0.1) to 1.0 (0.1) with controlled-release morphine (no significant between-group differences). Typical opioid adverse experiences were reported in both groups. Hallucinations were reported only with controlled-release morphine (n = 2). Visual analog scores (VAS) for 'itchy' and 'scratchin' were lower with controlled-release oxycodone (p </= 0.044), as was peak-to-trough fluctuation in steady-state plasma concentration (p = 0.004). The correlation between plasma concentration and dose was stronger (p = 0.026) for oxycodone (0.7) than morphine (0.3). The relationship between pain intensity (VAS) and plasma concentration was more positive for oxycodone (p = 0.046). There was a positive relationship between morphine-6-glucuronide concentrations and urea nitrogen and creatinine levels (p = 0.001). Controlled-release oxycodone was as effective as controlled-release morphine in relieving chronic cancer-related pain, and as easily titrated to the individual's need for pain control. While adverse experiences were similar, controlled-release oxycodone was associated with less itching and no hallucinations. Controlled-release oxycodone provides a rational alternative to controlled-release morphine for the management of moderate to severe cancer-related pain.

Determining plasma morphine levels using GC-MS after solid phase extraction to monitor drug levels in the postoperative period

OBJECTIVE

To implement a selective and sensitive analytical method to quantify morphine in small volumes of plasma by gas-liquid chromatography-mass spectrometry (GC-MS), aimed at post-operatively monitoring the drug.

METHOD

A gas-liquid chromatographic method with mass detection has been developed to determine morphine concentration in plasma after solid phase extraction. Morphine-d3 was used as an internal standard. Only 0.5 mL of plasma is required for the drug solid-phase extraction in the Bond Elut-Certify, followed by the quantification of morphine derivative by GC-MS using a linear temperature program, a capillary fused silica column, and helium as the carrier and make-up gas. The method was applied to determine morphine content in plasma samples of four patients during the postoperative period of cardiac surgery. Patient-controlled analgesia with morphine was performed by a venous catheter, and a series of venous blood samples were collected. After the oro-After the orotracheal extubation, morphine plasma levels were monitored for up to 36 hours.

RESULTS

The run time was 16 minutes because morphine and the internal standard were eluted after 8.8 minutes. The GC-MS method had 0.5 -1000 ng/mL linearity range (r(2)=0.9995), 0.1 ng/mL limit of detection, intraday and interday precision equivalent to 1.9% and 6.8%, and 0.1% and 0.8% systematic error (intraday and interday, respectively). The analytical method showed optimal absolute (98%) and relative (100.7%) recoveries. Morphine dose requirements and plasma levels are discussed.

CONCLUSION

The analytical gas-liquid chromatography-mass spectrometry method is selective and adequate for morphine measurements in plasma for applications in clinical studies.

Morphine and its metabolites: Analytical methodologies for its determination

The present article reviews the methods of determination published for morphine and its metabolites covering the period from 1980 until at the first part of 2006. The overview includes the most relevant analytical determinations classified in the following two types: (1) non-chromatographic methods and (2) chromatographic methods.

Development and validation of a radioreceptor assay for the determination of morphine and its active metabolites in serum

This article describes the development and validation of a radioreceptor assay for the determination of morphine and morphine-6-beta-glucuronide (M6G) in serum. The assay is based on competitive inhibition of the mu-opioid-selective radiolabeled ligand [3H]-DAMGO by opioid ligands (e.g. M6G) for binding to the striatal opioid receptor. The assay has been validated according to the Washington Conference Report on Analytical Method Validation. The radioreceptor assay can be performed in serum without prior pre-treatment of the sample. Direct addition of the sample results in no significant loss in maximal binding sites, and therefore, no loss in sensitivity. The assay proves to be selective for a multitude of opioid agonists and antagonists (e.g. morphine IC50 = 4.1 nM and M6G IC50 = 12.8 nM). Moreover, morphine-3-glucuronide (M3G) displays a low affinity (IC50 = 1100 nM) for the mu-opioid receptor and according to the literature demonstrates no analgesic activity. This makes discrimination, in relation to the analgesic effect, of the two metabolites of morphine possible. The assay is fast (assay time <4h, analysis 5 min/sample), easy and the sensitivity (limit of detection (LOD) = 1.6 nM M6G-equivalents) is such that very potent agonists, like morphine and M6G, can be measured at the desired serum levels. The assay is accurate (<18%), but precision is limited if measured over several days (>35%). The assay is most accurate and precise if measured over a range from 3.5 to 40 nM M6G-equivalents. Based on the limited inter-assay precision, we propose to use this receptor assay mainly as a screening tool for neonates treated with morphine.

Determination of morphine, morphine-3-glucuronide and morphine-6-glucuronide in monkey and dog plasma by high-performance liquid chromatography–electrospray ionization tandem mass spectrometry

A specific and simultaneous assay of morphine, morphine-3-glucuronide (M-3-G) and morphine-6-glucuronide (M-6-G) in monkey and dog plasma has been developed. These methods are based on rapid isolation using solid phase extraction cartridge, and high-performance liquid chromatography (HPLC)-electrospray ionization (ESI)-tandem mass spectrometric (MSMS) detection. Analytes were separated on a semi-micro ODS column in acetonitrile-formic (or acetic) acid mixed solution. The selected reaction monitoring for assay in monkey and dog plasma, as precursor-->product ion combinations of m/z 286-->286 for morphine, m/z 462-->286 for glucuronides and m/z 312-->312 for internal standard (IS, nalorphine) were used. The linearity of morphine, M-3-G and M-6-G was confirmed in the concentration range of 0.5-50, 25-2500, 2.5-250 ng/ml in monkey plasma, 0.5-100, 25-5000, 2.5-500 ng/ml in dog plasma, respectively. The precision of this assay method, expressed as CV, was less than 15% over the entire concentration range with adequate assay accuracy. Therefore, the HPLC-ESI-MSMS method is useful for the determination of morphine, M-3-G and M-6-G with sufficient sensitivity and specificity in pharmacokinetic studies.

Simultaneous determination of in total 17 opium alkaloids and opioids in blood and urine by fast liquid chromatography-diode-array detection-fluorescence detection, after solid-phase extraction

A fast liquid chromatographic method with tandem diode array-fluorescence detection for the simultaneous determination of in total 17 opium alkaloids and opioids is presented. Blank blood and urine samples (1 ml) were spiked with different concentrations of a standard mixture, as well as with the internal standard, butorphanol (2000 ng/ml). After solid-phase extraction, based on weak cation exchange (Bond Elut CBA SPE columns), the extracts were examined by HPLC-DAD-FL. By using a "high-speed" phenyl column (53 x 7.0 mm I.D., particle size 3 microm) eluted with a gradient system (A: water-methanol (90:10, v/v), B: methanol, both containing 25 mM triethylammoniumformate (pH(A) = 4.5)) all compounds could be baseline separated within 12 min. The method was validated and its applicability was demonstrated by the analysis of real-time forensic cases.

Comparison of phenyl-type columns in the development of a fast liquid chromatographic system for eighteen opiates commonly found in forensic toxicology

We report a precise and reliable method for the detection of 18 of the most commonly found opiates on the Belgian legal and illicit market, by ion-exchange, reversed-phase high-performance liquid chromatography, using a conventional phenyl-type analytical column (150x4.6 mm I.D., particle size 5 microm) and diode-array detection. We also describe a performance (efficiency and sensitivity) comparison of this column to a recently developed "high-speed" column (53x7.0 mm I.D., particle size 3 microm) packed with the same stationary phase, and used under slightly adjusted flow and gradient conditions. The final method, using the "high-speed" column, showed a significant reduction (55%) in analysis time without loss of resolution and sensitivity.

The role of liquid chromatography-mass spectrometry in the determination of heroin and related opioids in biological fluids

The opioid most commonly sold in the illicit market is heroin. This substance, classified as an analgesic narcotic drug, has an extremely short half-life, and it is rapidly metabolized to 6-monoacetyl-morphine and further to morphine. Morphine is principally metabolized by conjugation to morphine-3 and morphine-6 glucuronides. Morphine itself is a potent analgesic that is frequently used in the pharmacological intervention of cancer pain. The toxicological and clinical evaluation of heroin and morphine have stimulated pharmacokinetic studies in human and animal models. Although a number of methods exist to determine opiates and their metabolites, liquid chromatography (LC) appears to be the technique that can separate without any pretreatment the lipophilic and the hydrophilic analytes of the complete metabolic profile of heroin and/or morphine. Moreover, mass spectrometry (MS) used as a detector for liquid chromatography is unique, because it offers universality and selectivity. Furthermore, efforts have been made to develop LC/MS interfaces that could overcome the previous problem of poor sensitivity. For this reason, in recent years LC combined with MS has been applied to the analysis of opiates--parent drugs and metabolites--in biological fluids. This article reviews the existing literature on the determination, using liquid chromatography coupled to mass spectrometry, of opiate metabolites found in different biological matrices after the administration of the parent compounds.

Determination of drugs of abuse in blood

The detection and quantitation of drugs of abuse in blood is of growing interest in forensic and clinical toxicology. With the development of highly sensitive chromatographic methods, such as high-performance liquid chromatography (HPLC) with sensitive detectors and gas chromatography-mass spectrometry (GC-MS), more and more substances can be determined in blood. This review includes methods for the determination of the most commonly occurring illicit drugs and their metabolites, which are important for the assessment of drug abuse: Methamphetamine, amphetamine, 3,4-methylenedioxymethamphetamine (MDMA), N-ethyl-3,4-methylenedioxyamphetamine (MDEA), 3,4-methylenedioxy-amphetamine (MDA), cannabinoids (delta-9-tetrahydrocannabinol, 11-hydroxy-delta-9-tetrahydrocannabinol, 11-nor-9-carboxy-delta-9-tetrahydrocannabinol), cocaine, benzoylecgonine, ecgonine methyl ester, cocaethylene and the opiates (heroin, 6-monoacetylmorphine, morphine, codeine and dihydrocodeine). A number of drugs/drug metabolites that are structurally close to these substances are included in the tables. Basic information about the biosample assayed, work-up, GC column or LC column and mobile phase, detection mode, reference data and validation data of each procedure is summarized in the tables. Examples of typical applications are presented.

Improved one-step solid-phase extraction method for morphine, morphine-3-glucuronide, and morphine-6-glucuronide from plasma and quantitation using high-performance liquid chromatography with electrochemical detection

This communication describes an improved one-step solid-phase extraction method for the recovery of morphine (M), morphine-3-glucuronide (M3G), and morphine-6-glucuronide (M6G) from human plasma with reduced coextraction of endogenous plasma constituents, compared to that of the authors' previously reported method. The magnitude of the peak caused by endogenous plasma components in the chromatogram that eluted immediately before the retention time of M3G has been reduced (approximately 80%) significantly (p < 0.01) while achieving high extraction efficiencies for the compounds of interest, viz morphine, M6G, and M3G (93.8 +/- 2.5, 91.7 +/- 1.7, and 93.1 +/- 2.2%, respectively). Furthermore, when the improved solid-phase extraction method was used, the extraction cartridge-derived late-eluting peak (retention time 90 to 100 minutes) reported in our previous method, was no longer present in the plasma extracts. Therefore the combined effect of reducing the recovery of the endogenous components of plasma that chromatographed just before the retention time of M3G and the removal of the late-eluting, extraction cartridge-derived peak has resulted in a decrease in the chromatographic run-time to 20 minutes, thereby increasing the sample throughput by up to 100%.

High-performance liquid chromatography-mass spectrometry-mass spectrometry analysis of morphine and morphine metabolites and its application to a pharmacokinetic study in male Sprague-Dawley rats

A high-performance liquid chromatography tandem mass spectrometry-mass spectrometry (LC-MS-MS) assay was developed for the analyses of morphine, morphine glucuronides and normorphine in plasma samples from rats. The analytes were extracted by using C2 solid-phase extraction cartridges. The extraction recoveries were 100% for morphine, 84% for morphine-3-glucuronide, 64% for morphine-6-glucuronide and 88% for normorphine. Both intra- and inter-assay variabilities were below 11%. Using a plasma sample size of 100 microliters, the limits of detection were 13 nmol l-1 (3.8 ng ml-1) for morphine, 12 nmol l-1 (5.5 ng ml-1) for morphine-3-glucuronide, 26 nmol l-1 (12 ng ml-1) for morphine-6-glucuronide and 18 nmol l-1 (5.0 ng ml-1) for normorphine, at a signal-to-noise ratio of 3. The present assay was applied to a pharmacokinetic study in rats after intraperitoneal administration of morphine.

Determination of morphine and its 3- and 6-glucuronides, codeine, codeine-glucuronide and 6-monoacetylmorphine in body fluids by liquid chromatography atmospheric pressure chemical ionization mass spectrometry

A selective assay of morphine-3-glucuronide (M3G), morphine-6-glucuronide (M6G), morphine, codeine, codeine-6-glucuronide (C6G) and 6-monoacetylmorphine (6-MAM) based on liquid chromatography atmospheric pressure chemical ionization mass spectrometry (LC-APCI-MS) is described. The drugs were extracted from serum, autopsy blood, urine, cerebrospinal fluid or vitreous humor using C18 solid-phase extraction cartridges and subjected to LC-APCI-MS analysis. The separation was performed on an ODS column in acetonitrile-50 mM ammonium formate buffer, pH 3.0 (5:95), using a flow-rate gradient from 0.6 to 1.1 ml/min (total analysis time was 17 min). The quantitative analysis was done using deuterated analogues of each compound. Selected-ion monitoring detection was applied: m/z 286 (for morphine, M3G-aglycone and M6G-aglycone), 289 (for morphine-d3, M3G-d3-aglycone and M6G-d3-aglycone), 300 (for codeine and C6G-aglycone), 303 (for C6G-d3-aglycone), 306 (for codeine-d6), 328 (for 6-MAM), 334 (for 6-MAM-d6), 462 (for M3G and M6G), 465 (for M3G-d3 and M6G-d3), 476 (for C6G) and 479 (for C6G-d3). The limits of quantitation were: 1 microg/l for morphine, 2 microg/l for 6-MAM, 5 microg/l for M3G, M6G and codeine and 200 microg/I for C6G. The recovery ranged from 85 to 98% for each analyte. The method appeared very selective and may be used for the routine determination of opiates in body fluids of heroin abusers and patients treated with opiates.