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

Inferences and Legal Considerations Following a Blood Collection Tube Recall

In mid-2019, medical, forensic and legal communities were notified that a certain shipment of evacuated blood sampling tubes were recalled by the manufacturer. This recall order described that the preservative sodium fluoride (100 mg) and anticoagulant potassium oxalate (20 mg) were missing from a small batch of 10-mL evacuated tubes. This gave cause for concern for possible implications in criminal justice (e.g., in drink-driving offenses) when blood-alcohol concentrations are interpreted. In reality, the lack of an anticoagulant would have been immediately obvious during sample preparation, owing to the formation of a large clot in the tube when received. Certain impairing drugs (e.g., cocaine and 6-acetylmorphine) are unstable in blood and tend to degrade without an enzyme inhibitor, such as sodium fluoride, present. In reviewing available literature related to current practices and the stability of ethanol in stored blood samples, there does not appear to be a clear consensus regarding the amount of sodium fluoride preservative necessary, if any at all, when blood is taken from living subjects under sterile conditions for typical forensic ethanol analysis.

Systematic Studies on Temperature-Dependent in Vitro Stability During Storage and Smoking of the Synthetic Cannabinoid 5F-MDMB-P7AICA

Metabolism studies have shown that the synthetic cannabinoid (SC) 5F-MDMB-P7AICA is predominantly degraded by ester hydrolysis to 5F-MDMB-P7AICA dimethyl butanoic acid. To investigate the stability of 5F-MDMB-P7AICA during storage for a certain period of time or smoking, in vitro stability tests were performed. Blood and serum samples were collected repeatedly during a toxicokinetic study using a pig model and were retested after a 5 and 12 months storage at different temperatures (-20 °C, 4 °C, or room temperature, RT). Analysis was performed using fully validated liquid chromatography tandem mass spectrometry methods following liquid-liquid extraction and protein precipitation. One set of samples was analyzed immediately following the experiment (WS). In the WS samples, 5F-MDMB-P7AICA and 5F-MDMB-P7AICA dimethyl butanoic acid were present in every sample collected throughout the whole experiment. Analysis of the blood and serum samples stored for 5 and 12 months at -20 °C and 4 °C revealed relatively stable concentrations of the parent substance and the dimethyl butanoic acid metabolite. Regarding the samples stored at RT, concentrations of 5F-MDMB-P7AICA decreased, whilst concentrations of the hydrolysis product increased. This change could particularly be observed in samples with a high initial concentration of the analytes. A further screening of the samples stored at RT revealed no other degradation products. In conclusion, the SC 5F-MDMB-P7AICA could be detected even after 12 months of storage at RT and therefore seems to be more stable than its isomer, 5F-ADB. Regarding the smoke condensate, beside the parent compound only trace amounts of dimethyl butanoic acid were found.

Stability of Cocaine Compounds in Biological Fluids During Post-Analytical Sample Storage

The objective of this study is to evaluate in vitro stability of cocaine compounds, cocaine (COC), benzoylecgonine (BE), ecgonine methyl ester (EME) and benzoylecgonine ethyl ester (EBE), in blood and urine, during post-analysis custody. Stability was evaluated by measuring percent recovery. Parameters evaluated were time of custody (1 year), storage temperature (-20°C and 4°C), influence of preservative (only for blood samples) and pH (only for urine samples). The impact of the temperature is very important in blood samples. At -20°C all compounds demonstrated to be stable, with recoveries higher than 80% after 1 year. In contrast, degradation was observed in the concentration for all four compounds when the samples were maintained at 4°C. In these same conditions, the influence of the preservative was also noticeable and a higher stability was found in samples preserved with NaF. COC and EBE had similar profiles, and both compounds disappeared after 30 days in samples without NaF and after 150 days in samples with NaF added. EME disappeared after 185 days and after 215 days in samples without and with preservative, respectively. BE recoveries, after 365 days of storage, were 68.5% (in samples with NaF) and 3.7% (in samples without NaF). In urine samples, the four compounds were stable in all the studied conditions except when samples were at pH 8 and stored at 4°C where the compounds disappeared (COC and EBE after 75 days of storage and EME after 15 days). The exception was BE, with a recovery of 23% after 1 year of storage. Of the temperatures evaluated, -20°C seems to be optimal for storage to maintain the stability of cocaine and metabolites in biological samples. This can be further enhanced by maintaining a pH of 4 in urine samples and adding a NaF preservative to blood.

Evaluation of Dräger DrugTest 5000 in a Naturalistic Setting

Reliable field testing devices for psychoactive drugs would be useful tools for the police for detecting drug-impaired drivers. The Norwegian Mobile Police Service (NMPS) started using Dräger DrugTest 5000 (DDT5000) in 2015 as an on-site screening instrument for drugs in samples of oral fluid. The aim of this study was to compare the results of field testing of DDT5000 with drug findings in blood and oral fluid samples taken from drivers suspected for driving under the influence of drugs (DUID). In total, 369 drivers were included in this field testing; blood samples were obtained from all of them, while oral fluid samples were collected with the Intercept device from 301 of them. The median time from field testing with DDT5000 and collection of blood and oral fluid samples was 50 min. The proportions of false positive results with DDT5000 compared to findings in blood samples above the Norwegian legal per se limits were for cannabis 14.5%, amphetamine 23.2%, methamphetamine 38.4%, cocaine 87.1%, opiates 65.9% and benzodiazepines 36.4%. The proportions of false negatives were for cannabis 13.4%, amphetamine 4.9%, methamphetamine 6.1%, cocaine 0.0%, opiates 0.0% and benzodiazepines 18.8%. Among drivers who had drug concentrations above the legal limits in blood, the proportion who tested positive using DDT5000 was 82.9% for THC, 90.8% for amphetamine, 75.7% for methamphetamine, 100.0% for cocaine, 100.0% for opiates and 37.2% for benzodiazepines. In cases with false-positive DDT5000 results compared to blood, traces of drugs were most often found in oral fluid. The DDT5000 did not absolutely correctly identify DUID offenders due to fairly large proportions of false-positive or false-negative results compared to drug concentrations in blood. The police reported that DDT5000 was still a valuable tool in identifying possible DUID offenders, resulting in more than doubling the number of apprehended DUID offenders.

Bioavailability and Pharmacokinetics of Oral Cocaine in Humans

The pharmacokinetic profile of oral cocaine has not been fully characterized and prospective data on oral bioavailability are limited. A within-subject study was performed to characterize the bioavailability and pharmacokinetics of oral cocaine. Fourteen healthy inpatient participants (six males) with current histories of cocaine use were administered two oral doses (100 and 200 mg) and one intravenous (IV) dose (40 mg) of cocaine during three separate dosing sessions. Plasma samples were collected for up to 24 h after dosing and analyzed for cocaine and metabolites by gas chromatography-mass spectrometry. Pharmacokinetic parameters were calculated by non-compartmental analysis, and a two-factor model was used to assess for dose and sex differences. The mean ± SEM oral cocaine bioavailability was 0.32 ± 0.04 after 100 and 0.45 ± 0.06 after 200 mg oral cocaine. Volume of distribution (Vd) and clearance (CL) were both greatest after 100 mg oral (Vd = 4.2 L/kg; CL = 116.2 mL/[min kg]) compared to 200 mg oral (Vd = 2.9 L/kg; CL = 87.5 mL/[min kg]) and 40 mg IV (Vd = 1.3 L/kg; CL = 32.7 mL/[min kg]). Oral cocaine area-under-thecurve (AUC) and peak concentration increased in a dose-related manner. AUC metabolite-to-parent ratios of benzoylecgonine and ecgonine methyl ester were significantly higher after oral compared to IV administration and highest after the lower oral dose. In addition, minor metabolites were detected in higher concentrations after oral compared to IV cocaine. Oral cocaine produced a pharmacokinetic profile different from IV cocaine, which appears as a rightward and downward shift in the concentration-time profile. Cocaine bioavailability values were similar to previous estimates. Oral cocaine also produced a unique metabolic profile, with greater concentrations of major and minor metabolites.

Cocaine and metabolite concentrations in DBS and venous blood after controlled intravenous cocaine administration

BACKGROUND

DBS are an increasingly common clinical matrix.

METHODS & RESULTS

Sensitive and specific methods for DBS and venous blood cocaine and metabolite detection by LC-HRMS and 2D GC-MS, respectively, were validated to examine correlation between concentrations following controlled intravenous cocaine administration. Linear ranges from 1 to 200 µg/l were achieved, with acceptable bias and imprecision. Authentic matched specimens' (392 DBS, 97 venous blood) cocaine and benzoylecgonine concentrations were qualitatively similar, but DBS had much greater variability (21.4-105.9 %CV) and were lower than in blood.

CONCLUSION

DBS offer advantages for monitoring cocaine intake; however, differences between capillary and venous blood and DBS concentration variability must be addressed.

Pharmacodynamic effects and relationships to plasma and oral fluid pharmacokinetics after intravenous cocaine administration

BACKGROUND

No controlled cocaine administration data describe cocaine and metabolite disposition in oral fluid (OF) collected with commercially-available collection devices, OF-plasma ratios, and pharmacodynamic relationships with plasma and OF cocaine and metabolite concentrations.

METHODS

Eleven healthy, cocaine-using adults received 25mg intravenous cocaine. Physiological and subjective effects (visual analogue scales), and plasma were collected one hour prior, and up to 21h post-dose. OF was collected with the Quantisal™ device up to 69h post-dose. Cocaine, benzoylecgonine (BE) and ecgonine methyl ester were quantified in plasma by liquid chromatography-tandem mass spectrometry; cocaine and BE were quantified in OF by two dimensional-gas chromatography-mass spectrometry.

RESULTS

Increases in heart rate, blood pressure and positive subjective effects occurred within the first 15min, persisting up to 1h ("Rush"), with clockwise hysteresis observed for plasma and OF concentrations and some subjective measures. Peak subjective effects ("Rush," "Good drug effect" and "Bad drug effect") occurred prior to peak OF cocaine concentration, whereas observed peak plasma concentrations and subjective measures occurred simultaneously, most likely due to significantly earlier plasma Tmax compared to OF Tmax.Tlast was generally longer in OF (12.5h cocaine; 33.0h BE) than plasma (9.5h cocaine; >21h BE, cutoffs 1μg/L); 8 and 10μg/L OF cocaine confirmatory cutoffs yielded detection times similar to cocaine's impairing effects, suggesting usefulness for DUID testing.

CONCLUSIONS

OF offers advantages as an alternative matrix to blood and plasma for identifying cocaine intake, defining pharmacokinetic parameters at different confirmation cutoffs, and aiding different drug testing programs to best achieve their monitoring goals.

The use of mass spectrometry to analyze dried blood spots

Dried blood spots (DBS) typically consist in the deposition of small volumes of capillary blood onto dedicated paper cards. Comparatively to whole blood or plasma samples, their benefits rely in the fact that sample collection is easier and that logistic aspects related to sample storage and shipment can be relatively limited, respectively, without the need of a refrigerator or dry ice. Originally, this approach has been developed in the sixties to support the analysis of phenylalanine for the detection of phenylketonuria in newborns using bacterial inhibition test. In the nineties tandem mass spectrometry was established as the detection technique for phenylalanine and tyrosine. DBS became rapidly recognized for their clinical value: they were widely implemented in pediatric settings with mass spectrometric detection, and were closely associated to the debut of newborn screening (NBS) programs, as a part of public health policies. Since then, sample collection on paper cards has been explored with various analytical techniques in other areas more or less successfully regarding large-scale applications. Moreover, in the last 5 years a regain of interest for DBS was observed and originated from the bioanalytical community to support drug development (e.g., PK studies) or therapeutic drug monitoring mainly. Those recent applications were essentially driven by improved sensitivity of triple quadrupole mass spectrometers. This review presents an overall view of all instrumental and methodological developments for DBS analysis with mass spectrometric detection, with and without separation techniques. A general introduction to DBS will describe their advantages and historical aspects of their emergence. A second section will focus on blood collection, with a strong emphasis on specific parameters that can impact quantitative analysis, including chromatographic effects, hematocrit effects, blood effects, and analyte stability. A third part of the review is dedicated to sample preparation and will consider off-line and on-line extractions; in particular, instrumental designs that have been developed so far for DBS extraction will be detailed. Flow injection analysis and applications will be discussed in section IV. The application of surface analysis mass spectrometry (DESI, paper spray, DART, APTDCI, MALDI, LDTD-APCI, and ICP) to DBS is described in section V, while applications based on separation techniques (e.g., liquid or gas chromatography) are presented in section VI. To conclude this review, the current status of DBS analysis is summarized, and future perspectives are provided.

Validation of a fast UPLC–MS/MS method for quantitative analysis of opioids, cocaine, amphetamines (and their derivatives) in human whole blood

Background: Conventional methods for analysis of drugs of abuse require multiple assays which can be both expensive and time-consuming. This work describes a novel, rapid, simple and sensitive method for the quantification of 14 illicit drugs and their metabolites in whole blood. Results/methodology: This method employed a rapid liquid–liquid sample extraction of whole blood followed by UPLC–MS/MS analysis. Calibration curves were validated for analysis of appropriate concentrations. Inter- and intra-assay variations were <14.8%. Deviation of accuracy was <14.9% from target concentration for each quality control level. Conclusion: This work described the development and the full validation of a precise, sensitive and accurate assay. After validation, this new assay was successfully applied to routine toxicological analysis.

Stability of heroin, 6-monoacetylmorphine, and morphine in biological samples and validation of an LC-MS assay for delayed analyses of pharmacokinetic samples in rats

Degradation of heroin to 6-monoacetylmorphine (6-MAM) and then morphine happens rapidly in vivo and in vitro. The rates of heroin and 6-MAM degradation depend on the type of biological samples, and the duration and conditions of storage. In order to optimize conditions for measuring heroin and its metabolites in samples collected for pharmacokinetic studies in rats, we investigated the time course of degradation of heroin, 6-MAM, and morphine in four biological matrices: rat blood, rat brain homogenate, bovine serum, and human plasma under various conditions. Analyte concentrations were measured by LC-MS. The goal was to identify conditions that allow maximum flexibility in scheduling sample collection and analysis, as well as gain more information on the stability of heroin in blood and tissue samples. A solid-phase extraction method with ice-cold solvents, sodium fluoride (NaF) and a low pH (3.0) maintained sample stability. Quality controls were within 94.0-105% of the target value. Variability was 4.0-8.9% for all analytes within the range of 5-200 ng/mL for heroin, 5-1000 ng/mL for 6-MAM, and 10-200 ng/mL for morphine. Heroin degradation to 6-MAM was faster in rat whole blood than in plasma, and faster in rat plasma than in rat brain homogenate. Maintaining NaF at 4 mg/mL throughout processing enhanced stability; higher NaF concentrations added to whole blood caused hemolysis. Samples processed through solid phase extraction and stored as dried pellets at 80°C constituted the most stable environment for heroin, and was superior to the storing of samples in solution prior to or after extraction. Nevertheless, post-extraction heroin and 6-MAM levels declined by 6.7-8.3% over one week in rat plasma under these conditions, and by <1-4.7% in bovine serum or human plasma.

Toxicology Analysis for Pathologists: A Review of the Available Techniques and Technologies, Including Recommendations for Best Practice

The success of the forensic postmortem investigation that is suspected to involve drugs or poisons depends on the toxicologist and pathologist/medical examiner working closely together as a team. The pathologist relies on the experience and analytical skills of the toxicology laboratory to provide answers concerning the possible presence of drugs in autopsy specimens; however, in order that this may be successful, the toxicologist relies on the pathologist to provide appropriate specimens for analysis. The role of the forensic toxicologist is to then identify drugs or toxins in the human body tissues and to offer an interpretation as to whether or not their presence may be a contributory factor to the death.

This review will consider the scope of toxicology analysis in relation to forensic investigations, outline the processes undertaken in the forensic laboratory and offer guidance to assist the medical examiner who may wish to employ near-body drug screening. The review will also demonstrate the importance of specimen collection at autopsy and relate this to the techniques available in the forensic toxicology laboratory; recommendations for appropriate specimen preservation and storage will also be discussed. The pathologist and toxicologist must work closely as a team to ensure that poisoning is not missed.

The influence of putrefaction and sample storage on post-mortem toxicology results

There are numerous biochemical and biological processes that occur after death that may have a significant influence on post-mortem drug concentrations. These processes may render the quantification of particular drugs unreliable, or even result in drugs being undetectable in some instances, despite the use of several methods. Problems may occur with changes in the drug concentration via bacterial degradation, residual tissue enzymatic activity, or via post-mortem redistribution from tissues of a higher to a lower concentration. Many analytical techniques can suffer from interferences due to co-extracted putrefactive compounds that mask or alter the way a drug is detected, depending on the analytical technique utilised. The following paper reviews problems associated with post-mortem drug concentration changes, and the significance of microbial influences during the post-mortem interval and sample storage.

Stabilizing Drug Molecules in Biological Samples

Stability is one of the basic parameters, along with accuracy, precision, selectivity, and sensitivity, for bioanalytic method validation in nonhuman and clinical pharmacology/toxicology, bioavailability (BA), bioequivalence (BE), and other studies related to the drug approval process. In the drug development stage where stability evaluation is obligatory, instability of drug candidates in biologic samples will seriously complicate assay validation. In this article, we review the general strategies and methodologies such as temperature adjustment, pH control, derivatization, and addition of inhibitors and oxidant that are commonly employed to stabilize pharmaceuticals that might be unstable in biologic samples.

Preanalytic aspects in postmortem toxicology

The preanalytic phase has been recognized to have a substantial role for the quality and reliability of analytical results, which very much depend on the type and quality of specimens provided. There are several unique challenges to select and collect specimens for postmortem toxicology investigation. Postmortem specimens may be numerous, and sample quality may be quite variable. An overview is given on specimens routinely collected as well as on alternative specimens that may provide additional information on the route of administration, a long term or a recent use/exposure to a drug or poison. Autolytic and putrefactive changes limit the selection and utility of specimens. Some data from case reports as well as experimental investigations on drug degradation and/or formation during putrefaction are discussed. Diffusion processes as well as postmortem degradation or formation may influence ethanol concentration in autopsy specimens. Formalin fixation of specimens or embalmment of the corpse may cause considerable changes of initial drug levels. These changes are due to alterations of the biological matrix as well as to dilution of a sample, release or degradation of the drug or poison. Most important seems a conversion of desmethyl metabolites to the parent drug. Some general requirements for postmortem sampling are given based on references about specimen collection issues, for a harmonized protocol for sampling in suspected poisonings or drug-related deaths does not exist. The advantages and disadvantages of specimen preservation are shortly discussed. Storage stability is another important issue to be considered. Instability can either derive from physical, chemical or metabolic processes. The knowledge on degradation mechanisms may enable the forensic toxicologist to target the right substance, which may be a major break down product in the investigation of highly labile compounds. Although it is impossible to eliminate all interfering factors or influences occurring during the preanalytic phase, their consideration should facilitate the assessment of sample quality and the analytical result obtained from that sample.