Simple and sensitive determination of free and total morphine in human liver and kidney using gas chromatography-mass spectrometry

Optimization and analytical behavior of a morphine electrochemical sensor in environmental and biological samples based on graphite rod electrode using graphene/Co3O4 nanocomposite

In this research, a new sensor based on graphene/Co₃O₄ (Gr/Co₃O₄) nanocomposite was employed for electrochemically determination of morphine (MOR). The modifier was synthesized with a simple hydrothermal technique and well characterized using X-ray difraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) tools. The modified graphite rod electrode (GRE) was revealed a high electrochemical catalytic activity for the MOR oxidation and employed for the electroanalysis of trace MOR concentration by means of differential pulse voltammetry (DPV) technique. At the optimum experimental factors, the resulting sensor offered a good response for MOR in the concentration range of 0.5-100.0 μM with a detection limit of 80 nM. In addition, the modified electrode demonstrated an acceptable selectivity, stability and reproducibility. This assay was also provided a valid platform for the detection of MOR in environmental and biological samples with acceptable recoveries and RSD in the range of 97.2-102.8% and 1.7-3.4%, respectively. Taking to the simplicity, low cost and short analysis time, this approach is suggested for clinical, environmental and forensic testing of MOR.

Naked-Eye Detection of Morphine by Au@Ag Nanoparticles-Based Colorimetric Chemosensors

In this study, we report a novel and facile colorimetric assay based on silver citrate-coated Au@Ag nanoparticles (Au@AgNPs) as a chemosensor for the naked-eye detection of morphine (MOR). The developed optical sensing approach relied on the aggregation of Au@Ag NPs upon exposure to morphine, which led to an evident color variation from light-yellow to brown. Au@Ag NPs have been prepared by two different protocols, using high- and low-power ultrasonic irradiation. The sonochemical method was essential for the sensing properties of the resulting nanoparticles. This facile sensing method has several advantages including excellent stability, selectivity, prompt detection, and cost-effectiveness.

Postmortem Liver and Kidney Tissue Concentrations of Heroin Biomarkers and Their Metabolites in Heroin-Related Fatalities*†

A method was developed and validated for analyzing 6-monoacetylmorphine, morphine, 6-acetylcodeine, and codeine in routine postmortem liver and kidney specimens using liquid chromatography-tandem mass spectrometry. Samples were prepared with a Stomacher instrument followed by solid-phase extraction. All calibration curves [0.5-1000 ng/g] were linear with coefficients of determination greater than 0.99 and limits of quantification of 1.0 ng/g. Within-run precision ranged between 2.0% and 8.0%, between-run precision ranged between 1.0% and 9.0%, and accuracy ranged between -5.0% and +3.0%. Matrix effects ranged from -18% to +9%. After matrix effects were excluded, analytical recoveries ranged from 76% to 94%. The distributions of 6-monoacetylmorphine, morphine, 6-acetylcodeine, and codeine were investigated in 31 postmortem cases in which heroin was the primary cause of death. In the current study, the median free morphine ratios were calculated for liver to blood and kidney to blood, which were 2.2 and 4.0, respectively. The current report highlights the importance of testing multiple specimens, including liver and kidney, in heroin-related deaths, especially if no blood samples are available. Furthermore, this work presents new information regarding the distribution of heroin metabolites in liver and kidney.

Quantification of morphine and its major metabolites M3G and M6G in antemortem and postmortem samples

Morphine is one of the most effective agents for the control of significant pain, primarily metabolized to morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G). While M6G is a potent opioid agonist, M3G has no opioid action and seems to have a role in side-effects caused by morphine. In this study, a reversed-phase high-performance liquid chromatographic method with diode-array and electrochemical detection was developed for the simultaneous determination of morphine, M3G and M6G in antemortem and postmortem samples (plasma, whole blood, urine, liver, kidney and brain). Morphine, glucuronides and internal standard were extracted by double solid-phase extraction and the separation was carried out with a Waters Spherisorb® ODS2 reversed-phase column and potassium phosphate buffer (pH = 2.2)–acetonitrile containing sodium dodecyl sulfate as the mobile phase. The method proved to be specific with good linearity for all analytes in a calibration range from 1 to 600 ng/mL and proved to be accurate and have adequate precision and recovery. Limits of detection in the studied matrices were 0.4–4.5 ng/mL for morphine, 2.7–6.1 ng/mL for M3G and 0.8–4.4 ng/mL for M6G. The proposed method can be successfully applied to quantify morphine and its metabolites in several biological samples, covering the major routes of distribution, metabolism and elimination of morphine.

Spectrofluorimetric and spectrophotometric analysis of two analgesic drugs in pharmaceutical formulations and biological fluids

Simple, reliable, sensitive, and accurate spectrofluorimetric and spectrophotometric methods were proposed for the determination of two selected analgesic drugs, namely tramadol and morphine, in pharmaceuticals and biological fluids. The proposed methods were based on the oxidation of the studied drugs by Cerium (Ce)IV in an acidic medium. The spectrofluorimetric method is based on measuring the relative fluorescence intensity of Ce(III) arising from Ce(IV) at 350 nm with an excitation wavelength at 250 nm. The spectrophotometric method involves on addition of a known excess of Ce(IV) to the studied drugs in an acid medium, followed by the determination of residual Ce(IV) by reacting with a fixed amount of methyl orange and measuring the absorbance at 510 nm. Different variables affecting the reaction conditions, such as the concentrations of Ce(IV), type and concentration of the acid medium, reaction time, temperature, and the diluting solvents, were carefully studied and optimized.

First demonstration that brain CYP2D-mediated opiate metabolic activation alters analgesia in vivo

The response to centrally acting drugs is highly variable between individuals and does not always correlate with plasma drug levels. Drug-metabolizing CYP enzymes in the brain may contribute to this variability by affecting local drug and metabolite concentrations. CYP2D metabolizes codeine to the active morphine metabolite. We investigated the effect of inhibiting brain, and not liver, CYP2D activity on codeine-induced analgesia. Rats received intracerebroventricular injections of CYP2D inhibitors (20 μg propranolol or 40 μg propafenone) or vehicle controls. Compared to vehicle-pretreated rats, inhibitor-pretreated rats had: (a) lower analgesia in the tail-flick test (p<0.05) and lower areas under the analgesia-time curve (p<0.02) within the first hour after 30 mg/kg subcutaneous codeine, (b) lower morphine concentrations and morphine to codeine ratios in the brain (p<0.02 and p<0.05, respectively), but not in plasma (p>0.6 and p>0.7, respectively), tested at 30 min after 30 mg/kg subcutaneous codeine, and (c) lower morphine formation from codeine ex vivo by brain membranes (p<0.04), but not by liver microsomes (p>0.9). Analgesia trended toward a correlation with brain morphine concentrations (p=0.07) and correlated with brain morphine to codeine ratios (p<0.005), but not with plasma morphine concentrations (p>0.8) or plasma morphine to codeine ratios (p>0.8). Our findings suggest that brain CYP2D affects brain morphine levels after peripheral codeine administration, and may thereby alter codeine's therapeutic efficacy, side-effect profile and abuse liability. Brain CYPs are highly variable due to genetics, environmental factors and age, and may therefore contribute to interindividual variation in the response to centrally acting drugs.

Sample preparation and separation techniques for bioanalysis of morphine and related substances

In present time the use or misuse of morphine and its derivatives are monitored by assaying the presence of the drug and its metabolites in biofluids. In the present review, focus is placed on the sample preparation and on the separation techniques used in the current best practices of bioanalysis of morphine and its major metabolites. However, as methods for testing the misuse of heroin, a morphine derivative, often involve bioanalytical methods that cover a number of other illicit drug substances, such methods are also included in the review. Furthermore, the review also includes bioanalysis in a broader perspective as analysis of plant materials, cell cultures and environmental samples. The review is not intended to cover all publications that include bioanalysis of morphine but is more to be considered a view into the current best practices of bioanalysis of morphine, its metabolites and other related substances.

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.