Determination of buprenorphine, norbuprenorphine, naloxone, and their glucuronides in urine by liquid chromatography-tandem mass spectrometry

A liquid chromatography-tandem mass spectrometry method for the simultaneous quantification of buprenorphine (BUP), norbuprenorphine (NBUP), naloxone (NAL), and their glucuronide conjugates BUP-G, NBUP-G, and NAL-G in urine samples was developed. The method, omitting a hydrolysis step, involved non-polar solid-phase extraction, liquid chromatography on a C18 column, electrospray positive ionization, and mass analysis by multiple reaction monitoring. Quantification was based on the corresponding deuterium-labelled internal standards for each of the six analytes. The limit of quantification was 0.5 μg/L for BUP and NAL, 1 μg/L for NAL-G, and 3 μg/L for NBUP, BUP-G, and NBUP-G. Using the developed method, 72 urine samples from buprenorphine-dependent patients were analysed to cover the concentration ranges encountered in a clinical setting. The median (maximum) concentration was 4.2 μg/L (102 μg/L) for BUP, 74.7 μg/L (580 μg/L) for NBUP, 0.9 μg/L (85.5 μg/L) for NAL, 159.5 μg/L (1370 μg/L) for BUP-G, 307.5 μg/L (1970 μg/L) for NBUP-G, and 79.6 μg/L (2310 μg/L) for NAL-G.

Compensation of matrix effects in a standard addition method for metformin in postmortem blood using liquid chromatography-electrospray-tandem mass spectrometry

This work describes a procedure to evaluate matrix effects in a combined dilution and standard addition method (SAM) using liquid chromatography-electrospray-tandem mass spectrometry. The method was validated and applied to an analysis of metformin in postmortem blood samples. The analytical method included protein precipitation with methanol, followed by liquid chromatographic separation of metformin on Gemini NX-C18 reversed-phase column using a gradient consisting of methanol and ammonium acetate at pH 3.2. The mass spectrometric analysis was performed with a quadrupole-linear ion trap mass spectrometer equipped with a turbo ion spray interface in a positive ion mode using selected reaction monitoring. Quantitation was performed based on an SAM. Validation for metformin revealed a practical limit of quantification of 0.1 mg/L, a linear range from 0.1 to 3.0 mg/L, average precision 10%, accuracy (bias) 9% and reproducibility 10%. Combined matrix effects were evaluated by k-values (slopes) of calibration plots, postextraction addition approach and a comparison of within- and between-sample precision (relative standard deviation). It was demonstrated that the method contained matrix effects which were fully compensated for using dilution and the SAM.

Wastewater analysis reveals regional variability in exposure to abused drugs and opioids in Finland

Abused drug concentrations were determined in nine Finnish wastewater treatment plants (WWTPs), representing the metropolitan area, university cities and rural towns. In an eight-day study period in August 2012, 24-hour composite influent wastewater samples were collected. Biological markers and census-based information were used to estimate the size of the population served. The analytical method included solid phase extraction, liquid chromatographic separation, tandem mass spectrometric identification, and quantification using isotope-labeled internal standards. The study covered amphetamines, cannabis and cocaine. The levels of some opioids used in treatment and their metabolites were also determined. Amphetamine was the most prevalent drug of abuse, the median loads varying between the cities from 4.16 to 29.6 mg/1000 inhabitants/d. In three western cities methamphetamine was detected in even higher amounts, ranging from 0.87 to 47.5mg/1000 inhabitants/d. Ecstasy (MDMA) and cocaine (as benzoylecgonine, BE) were found in higher concentrations during weekends compared to weekdays, the difference being statistically significant. The concentration of tetrahydrocannabinol-9-carboxylic acid (THCA) was below the limit of quantification in the two rural towns, while in the other cities the load varied between 3.77 and 20.7 mg/1000 inhabitants/d. The average variation in BE load was 0.05-6.82 and that of MDMA 0-20.6 mg/1000 inhabitants/d. While the metropolitan area showed the highest loads of abused drugs, the substances were continuously detected at all WWTPs included in the study. The median concentration of codeine ranged from 164 to 325 mg/1000 inhabitants/d and that of morphine from 18.8 to 31.5mg/1000 inhabitants/d. The methadone load was below the level of detection in two towns, and at the other locations were 1.22-9.46 mg/1000 inhabitants/d. The first metabolite of heroin, 6-monoacetylmorphine (6-MAM), was not detected at all. Although the method has limitations, wastewater analysis gives additional information for assessing the degree of drug abuse and range of drugs abused in a society.

Second-generation antihistamines exhibit a protective effect on drivers in traffic-a preliminary population-based case-control study

INTRODUCTION

Although there have been experimental studies concerning driving and drugs, studies on the risk of antihistamines are not numerous. This is the first population-based epidemiological study concerning the association of sedating/nonsedating antihistamines and fatal traffic accidents.

METHODS

Car drivers (n = 428) who died in accidents before reaching the hospital and controls (n = 688) matched for accident area and driving season were studied for antihistamines in blood. At the time of the fatal road traffic accident, 6 drivers had a detectable amount of sedating antihistamines in blood, and the corresponding number for controls was 4; nonsedating antihistamines in blood were detected in 12 accident cases and 28 controls. The fatal accidents occurred between 1998 and 2002 and the information on the controls was collected between 2000 and 2002 in Finland.

RESULTS

Regarding fatal traffic accident causality, the nonsedating antihistamines proved to have a protective effect after adjusting for age and gender (relative risk = 0.40, 95% confidence interval [CI], 0.20 to 0.82; P =.01). The risk of fatal traffic accident of those driving under the influence of sedating antihistamines was 1.61 (0.38 to 6.77, P =.51) times the risk of those without medication.

DISCUSSION

This preliminary study supports the protective effect of second-generation antihistamines with respect to fatal traffic accidents. Due to the small sample size the results are not conclusive.

Does coronary artery bypass surgery affect metoprolol bioavailability

BACKGROUND

beta-blockers are commonly administered in patients with coronary artery bypass surgery (CABG). Despite this therapy, however, the incidence of postoperative atrial fibrillation (AF) is high (9-19%), and it is unknown why the beta-blockers do not reduce the incidence of AF more efficiently. In this pharmacokinetics study, in which the patients acted as their own controls, we have evaluated the bioavailability of perioperative metoprolol tablets in CABG surgery patients.

METHODS

Twelve male patients, aged 45-64 years, scheduled for CABG surgery were administered an initial 50 mg metoprolol tartrate tablet orally on the morning of the preoperative day and thereafter at 12-h intervals. Regular blood samples were collected up to 12 h after the first administration of the drug on the preoperative day as well on the first and third postoperative days. The plasma concentration for metoprolol was analyzed (limit of quantification = 0.001 mg/L) using liquid chromatography-tandem mass spectrometry.

RESULTS

The bioavailability of the metoprolol was significantly less on the first postoperative day, with AUC(0-12) values ranging from 0.7 to 17.1 (median: 7.2) mg min/L, than on the preoperative day, with AUC(0-12) values of 5.1-26.7 (12.6) mg min/L; however, it returned to the preoperative values on the third postoperative day, with AUC(0-12) values of 3.5-25.2 (15.2) mg min/L. Similar changes were observed in C(max) values: preoperative C(max) ranged between 0.026 and 0.123 (0.060) mg/L, on the first postoperative day, the C(max) ranged between 0.003 and 0.093 (0.025) mg/L, and on the third postoperative day, the C(max) ranged between 0.009 and 0.136 (0.061) mg/L. There was no correlation between the pharmacokinetic parameters and patient characteristics, but both the preoperative C(max) and C(60) correlated significantly with the postoperative C(max) (Pearson correlation coefficient: 0.61-0.72). One patient with one of the lowest rates and extent of metoprolol absorption developed AF.

CONCLUSION

This study indicates that the bioavailability of metoprolol is markedly reduced when administered in tablet form during the early phase after CABG.

Blood levels of 3-methylfentanyl in 3 fatal poisoning cases

Three fatal poisoning cases due to 3-methylfentanyl are described. In each case, the death was accidental and occurred after injection of the opioid combined with amphetamine, heroin, or other drugs. The victims' ages, ranging from 30 to 41 years, were higher than those typically found in heroin poisonings in Finland. The blood concentrations of cis-3-methylfentanyl, measured here for the first time by a specific tandem mass spectrometric method, ranged from 0.3 to 0.9 microg/L (mean 0.5 microg/L). These values are significantly lower than the levels reported for alpha-methylfentanyl and fentanyl in fatal poisonings. Repeated seizures of fentanyl and its analogs have been reported in Europe close to the Russian border.

CYP2D6 and CYP2C19 genotypes and amitriptyline metabolite ratios in a series of medicolegal autopsies

In a series of 202 postmortem toxicology cases, the CYP2D6 and CYP2C19 genes were genotyped, and the concentrations of amitriptyline (AT) and six metabolites were analyzed. The polymorphic CYP2D6 and CYP2C19 genes encode enzymes participating in the metabolism of several potentially toxic drugs, and mutations in these genes may lead to adverse drug reactions, possibly even intoxications. AT was chosen as the substrate of interest because it is mainly metabolized by these enzymes, is considered relatively toxic, and ranks among the major causes of fatal drug poisoning in Finland. Our objective was to evaluate genetically determined interindividual variation in conjunction with metabolite ratios of drugs found in toxicological analysis in a series of medicolegal autopsies. Positive correlations were found between the proportion of trans-hydroxylated metabolites and the number of functional copies of CYP2D6 and between the proportion of demethylated metabolites and the number of functional copies of CYP2C19. None of the accidental or undetermined AT poisonings coincided with the CYP2D6 or CYP2C19 genotype which predicts a poor metabolizer phenotype. However, an unusually high femoral blood concentration of AT, 60mg/l, was found in one suicide case with no functional CYP2D6 genes. Our study shows a concordance of AT metabolite patterns with CYP2D6 and CYP2C19 genotypes in the presence of confounding factors typical for postmortem material. This result demonstrates the feasibility of postmortem pharmacogenetic analysis and supports the dominant role of genes in drug metabolism.

Development of a multi-target screening analysis for 301 drugs using a QTrap liquid chromatography/tandem mass spectrometry system and automated library searching

A new multi-target screening (MTS) procedure for drugs in blood and urine for toxicological analysis has been developed using a hybrid triple-quadrupole linear ion trap mass spectrometer (QTrap) for the fast detection and identification of 301 forensically important drugs, e.g. tranquilizers (benzodiazepines), hypnotics, drugs of abuse (opiates, cocaine, amphetamines, cannabinoids), antidepressants, neuroleptics, and some cardiac drugs, in one single liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis. Samples were extracted either with liquid-liquid extraction or solid-phase extraction. A multiple reaction monitoring (MRM) as survey scan and an enhanced product ion (EPI) scan as dependent scan were performed in an information-dependent acquisition (IDA) experiment. Finally, drug identification was carried out by library search with a newly developed MS/MS library based on EPI spectra at three different collision energies in positive mode. The advantage of this newly developed method is the possibility to detect and identify 301 drugs in one single LC/MS/MS run.

Application of Accurate Mass Measurement to Urine Drug Screening

Poor availability of reference standards for designer drugs, metabolites, and new substances prevents toxicology laboratories from rapidly responding to the changing analytical challenges of drug abuse. A novel screening approach comprising determination of accurate masses of sample components and comparison of these with databases of theoretical monoisotopic masses is described. Using liquid chromatography-time-of-flight mass spectrometry (LC-TOFMS), a routine mass search window of 20-30 ppm was applied to urine samples. The ultimate reference technique, liquid chromatography-Fourier transform mass spectrometry (LC-FTMS), was capable of confirming the findings within a 3 ppm mass accuracy. Using a target database of 7640 compounds, the number of potential elemental formulas ranged from one to three with LC-TOFMS, and it was always one with LC-FTMS. In contrast to ordinary techniques requiring primary reference standards, the formula-based databases can be updated instantly with fresh numeric data from scientific literature and authority sources.

Comparison of product ion spectra obtained by liquid chromatography/triple-quadrupole mass spectrometry for library search

Reproducibility of product ion spectra acquired using a liquid chromatography/triple-quadrupole mass spectrometry (LC/MS/MS) instrument over a 4-year period, and with three other LC/MS/MS instruments, one from the same manufacturer and two from a different manufacturer, was examined. The MS/MS spectra of 30 drug substances were generated in positive electrospray ionization mode at low, medium, and high collision energies (20, 35, and 50 eV). Purity and Fit score percentages against a 400-compound LC/MS/MS spectral library were calculated using an algorithm in which fragment intensity ratios and weighting factors were included. The long-term reproducibility study was conducted using a brand A instrument; after 4 years the reproducibility of the product ion spectra was still 94%, expressed as average Purity score. The inter-laboratory study involved two parts. Firstly, two LC/MS/MS spectral libraries, created independently in separate laboratories using brand A instruments, were compared with each other. The average Fit and Purity scores of spectra from one library against the other were better than 93 and 91%, respectively, when the same collision energies were used. Secondly, for the comparison of product ion spectra between brand A and brand B instruments, fragmentation conditions were first standardized for amitriptyline as the standard analyte. The average Fit scores of brand B spectra against the brand A spectral library varied between 79 and 85% at all three collision energies. These results indicate that, after standardizing the instrumental conditions, LC/MS/MS spectral libraries of drug substances are suitable for inter-laboratory use.

Simultaneous screening for 238 drugs in blood by liquid chromatography-ion spray tandem mass spectrometry with multiple-reaction monitoring

A liquid chromatography-tandem mass spectrometry (LC-MS-MS) method is presented for the qualitative screening for 238 drugs in blood samples, which is considerably more than in previous methods. After a two-step liquid-liquid extraction and C(18) chromatography, the compounds were introduced into a triple quadrupole mass spectrometer equipped with a turbo ion spray ion source operating in the positive ionization mode. Identification was based on the compound's absolute retention time, protonated molecular ion, and one representative fragment ion obtained by multiple reaction monitoring (MRM) at an individually selected collision energy of 20, 35, or 50 eV. The limit of detection (LOD) for the majority of the compounds (80%) was < or = 0.05 mg/l, ranging from 0.002 mg/l (e.g., antihistamines) to 5 mg/l (acidic compounds), and for malathion it was 10 mg/l. The LOD values were sufficiently low to allow the majority of compounds to be detected at therapeutic concentrations in the blood.

Simultaneous screening and quantitation of 18 antihistamine drugs in blood by liquid chromatography ionspray tandem mass spectrometry

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method is presented for the simultaneous screening and quantitation of 18 antihistamine drugs in blood samples. Sample pretreatment involved liquid-liquid extraction of the basic antihistamines followed by a second extraction of the acidic antihistamines. The recoveries were 43-113% for basic drugs and 23-66% for acidic drugs. The combined extracts were run by LC on C(18) reversed phase column using acetonitrile-ammonium acetate mobile phase at pH 3.2. The mass spectrometric analysis was performed with a triple stage quadrupole mass analyzer. Screening was performed using multiple reaction monitoring (MRM) and any compounds tentatively identified as antihistamine drugs were then automatedly verified by their Product Ion Spectra in a subsequent MS/MS run. Quantitation was based on the MRM data from the screening step. In validation tests, the method showed good linearity at the relevant concentrations. The attained limits of quantitation varied between 0.0005 and 0.01mg/l in blood and were lower than the therapeutic concentrations (C(max)). The limits for identification by Product Ion Spectra were also lower than C(max), except for clemastine, which has exceptionally low concentrations in blood. The intra-assay relative standard deviations were better than 10% and the inaccuracy varied between 39% for levocabastine and 5% for cyclizine, the majority of the values being <20%.

Toxicological screening of urine for drugs by liquid chromatography/time-of-flight mass spectrometry with automated target library search based on elemental formulas

The present study describes a novel approach for utilizing liquid chromatography/time-of-flight mass spectrometry (LC/TOFMS) in qualitative screening analysis. An LC/TOFMS method was developed for screening toxicologically relevant substances in urine samples. After solid phase extraction and LC separation, the method included full spectrum acquisition followed by automatic internal calibration, searching against a target library, and reporting positive identifications. The target library, containing 433 toxicologically relevant substances in the mass range of 105-734 Da, was created simply by entering the elemental formulas of substances into the instrument software for the calculation of their respective monoisotopic masses. In addition to parent drugs, the library contained selected urinary drug metabolites, based on their structures available in the literature. Identification was based on the exact masses of the compounds. The LC/TOFMS method provided 5-10 ppm mass accuracy for a majority of identified compounds in authentic urine samples. Compared with established thin-layer and gas chromatographic methods, the LC/TOFMS method produced similar findings in urine with the additional advantage of metabolite identification without actual reference substances.

Automated liquid chromatographic/tandem mass spectrometric method for screening beta-blocking drugs in urine

An automated liquid chromatographic/tandem mass spectrometric (LC/MS/MS) method is presented for the screening and confirmation of 16 beta-blocking drugs in clinical and autopsy urine samples. The described method involved C(18) solid phase extraction, LC separation and MS analysis on a triple-stage quadrupole mass analyser. Samples were initially pre-screened for the presence of any beta-blocking drugs using LC/MS with selected ion monitoring. Any compounds tentatively identified as beta-blocking drugs on the basis of their LC retention time and protonated molecular ion were then automatedly subjected to a second analysis in which the relevant MS/MS product ion mass spectra were acquired. These product ion mass spectra were then automatically searched against a 400-substance mass spectral library containing previously acquired beta-blocking drugs. The results demonstrated that library search of beta-blocking drugs in urine with MS/MS product ion mass spectra was more reliable and produced fewer false negatives than library searching with mass spectra derived from single-stage quadrupole MS. The limits of identification in the MS/MS product ion scan ranged from 0.02 mg l(-1) for carvedilol to 1.2 mg l(-1) for pindolol, the majority of the values being below 0.2 mg l(-1).