Detection of cocaine and its polar transformation products and metabolites in human urine

Optimization and validation of simultaneous analyses of ecgonine, cocaine, and seven metabolites in human urine by gas chromatography-mass spectrometry using a one-step solid-phase extraction

The presence of ecgonine in urine has been proposed as an appropriate marker of cocaine use. Only a few methods have been published for their determination along with cocaine and the rest of its metabolites. Due to their high polarity and consequent solubility in water, these have low recoveries, which is why it is necessary to increase the sensitivity, by the formation of hydrochloric salts or multiderivatization of the analytes or by performing two solid-phase extractions (SPEs), considerably increasing the time and cost of the analysis. This work describes a fast and fully validated procedure for the simultaneous detection and quantification of ecgonine, ecgonine-methyl-ester, benzoylecgonine, nor-benzoylecgonine, m-hydroxybenzoylecgonine, cocaethylene, cocaine, norcocaine, and norcocaethylene in human urine (500 μL) using one SPE and simple derivatization. Separation and quantification were achieved by gas chromatography-electron ionization-mass spectrometry (GC-EI-MS) in selected-ion monitoring mode. Quantification was performed by the addition of deuterated analogs as internal standards. Calibration curves were linear in the adopted ranges, with determination coefficients higher than 0.99. The lower limits of quantification ranged from 2.5 to 10 ng/mL. The intra- and inter-day precision, calculated in terms of relative standard deviation, were 1.2%-14.9% and 1.8%-17.9%, respectively. The accuracy, in terms of relative error, was within a ± 16.4% interval. Extraction efficiency ranged from 84% to 103%. Compared with existing methods, the procedure described herein is fast, since only one SPE is required, and cost-effective. In addition, this method provides a high recovery for ecgonine, resulting in a better alternative to the previously published methods.

Comparison of Cocaine/Crack Biomarkers Concentrations in Oral Fluid, Urine and Plasma Simultaneously Collected From Drug Users

The use of oral fluid (OF) as an alternative specimen for drug analysis has become very popular in forensic toxicology. Many clinical studies have evaluated the correlations between concentrations of cocaine and its metabolites in OF and other matrices, but results have shown high variability. In addition, there are no data available regarding the correlations between biomarkers of crack-cocaine use in different matrices. This study evaluated the relationship between concentrations of cocaine/crack-cocaine biomarkers in OF, urine and plasma samples collected from cocaine users. All samples were analyzed for the presence of cocaine (COC), benzoylecgonine (BZE) and anhydroecgonine (AEC) by a validated liquid chromatography-mass spectrometry method. Median COC, BZE and AEC concentrations ranged from 4.20 to 33.26 ng/mL, from 13.03 to 3,615.86 ng/mL and from 7.40 to 1,892.5 ng/mL across matrices, respectively. The relationship between drug concentrations in OF versus plasma (OF/P) and OF versus urine (OF/U) was evaluated by their coefficients of determination (R2). Least-squares regression analyses demonstrated significant correlations between OF/P and OF/U for cocaine and BE (P < 0.05), with R2 = 0.17, 0.07 for cocaine and R2 = 0.73, 0.45 for BE, respectively. The correlation coefficients (r) found for BZE, COC and AEC in OF/P and OF/U were 0.85 and 0.67 (P < 0.05); 0.41 and 0.26 (P < 0.05); and 0.30 and -0.37 (P > 0.05), respectively. Many factors contribute to the variability of drug correlation ratios in studies involving random samples, including uncertainty about the time of last administration and dosage. Overall, we found significant R2 values for COC and BZE in OF/P and OF/U, but not for AEC. Despite the good correlations found in some cases, especially for BZE, the large variation in drug concentrations seen in this work suggests that OF concentrations should not be used to estimate concentrations of COC, BZE or AEC in plasma and/or urine.

The persistence of illicit drug smoke residues and their recovery from common household surfaces

Third-hand smoke is the residue remaining on surfaces during smoking events. It is composed of particles and vapours that form upon heating. The phrase 'third-hand smoke' is primarily used to describe nicotine and other chemicals from cigarettes, but any residues formed from the smoking of various substances could be classified similarly. There has been an increasing body of research on third-hand smoke from cigarettes in the last decade, but little has been done in regards to understanding the persistence of particles and vapours from illicit drugs. In this work, small samples of cocaine and methamphetamine were volatilized to produce an illicit drug smoke that was collected onto various surface materials and left exposed to ambient conditions over 672 h (four weeks). Chemical analyses by electrospray ionization-mass spectrometry of residues on silicon, plastic, laminate, and artificial leather surfaces indicated a rapid decrease in recovery of the parent molecule, with varied formation of decomposition products over the first 168 h of exposure. Measurable amounts of the parent molecule were still present after 672 h, exhibiting a strong persistence of these drugs on various household materials. This is important in a forensic science context, as third-hand smoke residues could provide a viable source of trace evidence previously not utilized. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

The use of mixed-mode ion-exchange solid phase extraction to characterize pharmaceutical drug degradation

Solid phase extraction (SPE) has been utilized extensively in the pharmaceutical industry for the isolation of pharmaceuticals from interfering biological matrices and the purification and concentration of impurities and degradation products present in analytical samples. The work described herein involves the novel use of mixed-mode ion-exchange solid phase extraction to characterize degradation products of several pharmaceutical drugs, thereby giving important clues to their structure and sites of reactivity. Several examples of the use of mixed-mode ion-exchange solid phase extraction to illustrate the utility of this technique are presented.

Application of a Pyroprobe to Simulate Smoking and Metabolic Degradation of Abused Drugs Through Analytical Pyrolysis

Smoking of illicit drugs can produce unique metabolic biomarkers. Smoking conditions can be partially modeled via pyrolysis, a process that decomposes a chemical compound by extreme heat. Pyrolytic decomposition was found to be useful as a limited metabolic mimic in that analytical pyrolysis can be used to generate some of the same compounds produced by metabolic degradation. This project focused on the pyrolysis of cocaine and methamphetamine using a pyroprobe coupled with a GC/MS and more generally, potential applications of pyrolysis to forensic toxicology. Common diluents including lidocaine, caffeine, and benzocaine were pyrolyzed in mixtures with cocaine and methamphetamine. Correlations between pyrolytic and metabolic degradations revealed that this method has the capability to produce some of the reported metabolites such as norcocaine and cocaethylene for cocaine, and amphetamine for methamphetamine. The results demonstrate that analytical pyrolysis has the potential to identify some metabolic products and to supplement in vivo and enzymatic studies.

Analysis of opiates, cocaine and metabolites in urine by high-performance liquid chromatography with diode array detection (HPLC-DAD)

An analytical method is proposed for the simultaneous determination of morphine, codeine, 6-acetyl-morphine (MAM), cocaine, benzoylecgonine (BEG), cocaethylene, methadone and 2-ethylen-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in urine using high performance liquid chromatography coupled to a diode array detector (HPLC-DAD). The selection of working wavelengths is based on the highest chromatographic response for each component: 233 nm for cocaine, BEG and cocaethylene; 285 nm for morphine, codeine and MAM; and 292 nm for methadone and EDDP. The mobile phase, which is a mixture of acetonitrile and 0.02 M phosphate buffer at pH 6.53, was eluted in gradient mode through an XTerra RP-8 column (250 mm x 4.6 mm i.d., 5 microm particle size). After applying a solid-phase extraction procedure with Bond Elut Certify cartridges, the recoveries obtained were between 60% (EDDP) and 97% (cocaethylene). A good linearity of the method in the 0.1-10 microg mL(-1) range of urinary concentrations was obtained because the coefficient of correlation exceeded 0.99 for each drug. The precision and accuracy were quite good, with values of <7% and within the range +/- 6%, respectively. Finally, the proposed method was applied to 23 urine samples from fatal intoxications related to methadone, heroin and[sol ]or cocaine.

In vitro stability of cocaine in whole blood and plasma including ecgonine as a target analyte

The in vitro stability of cocaine (COC) was monitored in fresh whole blood and plasma stabilized with potassium fluoride (0.25%) for as long as 15 days. The samples were stored at 4 degreesC, 20 degreesC and 40 degreesC. Additionally, fresh plasma samples containing either benzoylecgonine (BZE), ecgonine methyl ester (EME) or ecgonine (ECG) were stored at 4 degreesC and 20 degreesC. Data were established using subsequent solid-phase extraction procedures and high-performance liquid chromatography coupled to atmospheric pressure ionization mass spectrometry for isolation and quantitation of COC, BZE, EME, and ECG. COC, BZE, and EME concentrations decreased with increasing storage temperature and time after an apparent first-order reaction kinetic. Only ECG appeared to be stable at storage temperatures as high as 20 degreesC for the entire observation period. At 40 degreesC, the amount of ECG produced from hydrolysis of COC still totalled 80% of the initial COC concentration. Hydrolysis of COC to EME occurred more rapidly in plasma than in blood. The dynamic degradation profiles obtained were dependent on the storage temperature. The conversion of COC to BZE, EME, and ECG appeared to be stoichiometric at all time intervals at storage temperatures of 4 degreesC and 20 degreesC. The presence of any hydrolysis product of COC in blood or plasma constitutes confirmatory evidence of COC incorporation, and determination of ECG seems most promising even in samples stored under unfavorable conditions.

Stability of Methylecgonidine and Ecgonidine in Sheep Plasma in Vitro

Background: Crack smokers are exposed to a pyrolysis product, methylecgonidine (MEG), which can be used as an analytical marker for crack smoking. Ecgonidine (EC), a hydrolytic product of MEG, has been identified in urine of crack smokers. MEG undergoes conversion to EC, complicating analysis and perhaps explaining a lack of forensic blood specimens containing MEG.

Methods: We developed gas chromatography–mass spectrometry (GC-MS) assays for MEG and EC. Plasma was collected from sheep blood containing 0, 0.06, or 0.24 mol/L (0%, 0.25%, or 1%) NaF. MEG was added to these plasmas, and they were incubated at −80, 1, 21, or 37 °C to determine whether there were temporal, temperature, or storage effects on MEG stability over 48 h.

Results: Decreased temperature and increased NaF concentrations limited MEG degradation and EC formation. MEG stored in plasma at −80 °C was stable up to 1 month, even in the absence of NaF.

Conclusions: MEG is stable in sheep plasma collected in commercially available, evacuated blood-collection tubes containing NaF and stored at −80 °C. In vitro formation of EC can be minimized with appropriate sample handling, and its in vivo formation may provide a better marker of crack smoking than its parent pyrolysis product.

Cocaine causes increased type I interferon secretion by both L929 cells and murine macrophages

Cocaine has been demonstrated to have a number of different effects on immune cell functions. We have reported alterations of cellular functions by macrophages (Mphi) exposed to cocaine in vitro, including the inhibition of mouse hepatitis virus replication. Here, we present evidence that cocaine stimulates the secretion of an antiviral product that is neutralized by anti-interferon (anti-IFN). A dose-dependent increase in the secretion of IFN by both Mphi and L929 cells incubated with cocaine, with a concomitant decrease in virus replication, is also reported. The increase in IFN secretion was most pronounced when cells were cultured in the presence of the IFN inducer poly(I.C). The effect of cocaine on IFN production was found to be primarily at the transcript level in both Mphi and L929 cells. These findings further support our previous research demonstrating an antiviral activity of cocaine in vitro. The relevance of this activity to viral infections in general remains to be determined.

Inhibition of influenza virus replication by cocaine

Cocaine has been shown to have a number of diverse effects on the immune system. The current investigators have previously demonstrated an inhibitory effect of cocaine on murine hepatitis virus replication in peritoneal macrophages in vitro. The present study was undertaken to examine the effects of cocaine on influenza virus replication and to further characterize that effect in an animal model. Cocaine was capable of inducing a dose-dependent reduction in influenza PR-8 replication using MDCK cells in vitro. Concentrations of 100 microg/ml caused a 50% reduction of virus. To further characterize the effect in vivo, C57Bl/6 mice infected with influenza PR-8 by intranasal instillation were given daily ip injections of 10 mg/kg cocaine just prior to and for 4 days after exposure to influenza. Lungs from mice exposed to cocaine had viral titers that were reduced approximately 50% compared to controls as demonstrated by hemagglutination titers. Additional studies suggest that this reduction appears to be caused by an increase of cocaine-induced interferon.

A validated stable isotope dilution liquid chromatography tandem mass spectrometry assay for the trace analysis of cocaine and its major metabolites in plasma

A validated method has been developed for the simultaneous quantitation of cocaine and its major metabolites (ecgonine methyl ester, benzoylecgonine, and norcocaine) in rat plasma. The method is based upon the use of stable isotope dilution liquid chromatography/atmospheric pressure chemical ionization/tandem mass spectrometry. Previously reported methods do not have the sensitivity and specificity that can be attained with this method. Plasma samples required no cleanup apart from protein precipitation, and no derivatization was required. Selected reaction monitoring was performed on the transitions of m/z 200 to m/z 182 (ecgonine methyl ester), m/z 290 to m/z 168 (benzoylecgonine), m/z 304 to m/z 182 (cocaine), and m/z 290 to m/z 168 (norcocaine). The standard curves were linear over the range from 2 ng/mL (benzoylecgonine, cocaine, and norcocaine) or 5 ng/mL (ecgonine methyl ester) to 1000 ng/mL in rat plasma. The lower limit of quantitation (LLQ) for benzoylecgonine, cocaine, and norcocaine was 2 ng/mL, and for ecgonine methyl ester, the LLQ was 5 ng/mL for plasma. This simple, rapid, reliable, and sensitive method of quantitation had excellent accuracy and precision for the four analytes. The method was sensitive enough to permit a detailed study of the pharmacokinetics of cocaine and its metabolites after administration of a bolus intravenous dose to rats.

Rapid liquid-liquid extraction of cocaine from urine for gas chromatographic-mass spectrometric analysis

A novel, simple and economic liquid-liquid extraction method for isolating cocaine from urine was developed utilizing gas chromatography-mass spectrometry (GC-MS) for analysis and quantification. The use of a single nonpolar organic solvent allowed only nonpolar analytes to be extracted from the biological fluid, and consequently, no derivatization step was necessary before GC-MS analysis. Large numbers of specimens (>60) can be extracted in approximately 3 h with this procedure. The method is highly precise (C.V. <7%), accurate (>98%), sensitive (limit of detection of 5 ng/ml) and has a mean recovery of 48.8%.